0000950170-22-025667 | 10-K | XBRL Viewer | Enanta Pharmaceuticals INC

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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Sep. 30, 2022	Nov. 01, 2022	Mar. 31, 2022
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Sep. 30, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Trading Symbol	ENTA
Entity Registrant Name	ENANTA PHARMACEUTICALS, INC
Entity Central Index Key	0001177648
Current Fiscal Year End Date	--09-30
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
ICFR Auditor Attestation Flag	true
Entity Common Stock, Shares Outstanding		20,797,491
Entity Public Float			$ 1,262,330,179
Title of 12(b) Security	Common Stock, par value $0.01 per share
Security Exchange Name	NASDAQ
Entity File Number	001-35839
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	04-3205099
Entity Address, Address Line One	500 Arsenal Street
Entity Address, City or Town	Watertown
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02472
City Area Code	617
Local Phone Number	607-0800
Document Annual Report	true
Document Transition Report	false
Documents Incorporated by Reference	Portions of the registrant’s Definitive Proxy Statement for its 2023 Annual Meeting of Stockholders scheduled to be held on March 2, 2023, which Definitive Proxy will be filed with the Securities and Exchange Commission not later than 120 days after the registrant’s fiscal year end of September 30, 2022 are incorporated by reference into Part III of this Form 10-K.
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Boston, Massachusetts
Auditor Firm ID	238

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021
Current assets:
Cash and cash equivalents	$ 43,994	$ 57,206
Short-term marketable securities	205,238	186,796
Accounts receivable	20,318	23,576
Prepaid expenses and other current assets	13,445	14,188
Income tax receivable	28,718	37,255
Total current assets	311,713	319,021
Long-term marketable securities	29,285	108,416
Property and equipment, net	6,173	5,943
Operating lease, right-of-use assets	23,575	4,711
Restricted cash	3,968	608
Other long-term assets	696	92
Total assets	375,410	438,791
Current liabilities:
Accounts payable	6,000	9,540
Accrued expenses and other current liabilities	20,936	22,429
Operating lease liabilities	2,891	4,203
Total current liabilities	29,827	36,172
Operating lease liabilities, net of current portion	22,372	1,126
Series 1 nonconvertible preferred stock	1,423	1,506
Other long-term liabilities	454	558
Total liabilities	54,076	39,362
Commitments and contingencies (Note 12)
Stockholders' equity:
Common stock; $0.01 par value per share, 100,000 shares authorized; 20,791 and 20,238 shares issued and outstanding at September 30, 2022 and September 30, 2021, respectively	208	202
Additional paid-in capital	398,029	351,033
Accumulated other comprehensive loss	(3,724)	(382)
Retained earnings (accumulated deficit)	(73,179)	48,576
Total stockholders' equity	321,334	399,429
Total liabilities and stockholders' equity	$ 375,410	$ 438,791

Consolidated Balance Sheets (Parenthetical) - $ / shares shares in Thousands	Sep. 30, 2022	Sep. 30, 2021
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	100,000	100,000
Common stock, shares issued	20,791	20,238
Common stock, shares outstanding	20,791	20,238

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Revenue
Royalty revenue	$ 86,160	$ 97,074	$ 122,473
Type Of Revenue Extensible List	us-gaap:RoyaltyMember	us-gaap:RoyaltyMember	us-gaap:RoyaltyMember
Operating expenses:
Research and development	$ 164,522	$ 174,111	$ 136,756
General and administrative	45,482	32,536	27,356
Total operating expenses	210,004	206,647	164,112
Loss from operations	(123,844)	(109,573)	(41,639)
Other income (expense):
Interest and investment income, net	1,573	2,021	6,471
Change in fair value of Series 1 nonconvertible preferred stock	83	(27)	149
Total other income , net	1,656	1,994	6,620
Loss before income taxes	(122,188)	(107,579)	(35,019)
Income tax benefit (expense)	433	28,583	(1,149)
Net loss	$ (121,755)	$ (78,996)	$ (36,168)
Net loss per share:
Basic	$ (5.91)	$ (3.92)	$ (1.81)
Diluted	$ (5.91)	$ (3.92)	$ (1.81)
Weighted average shares outstanding:
Basic	20,603	20,171	19,940
Diluted	20,603	20,171	19,940

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net loss	$ (121,755)	$ (78,996)	$ (36,168)
Other comprehensive income (loss):
Net unrealized gains (losses) on marketable securities, net of tax expense of $0, $0, and $388	(3,342)	(1,226)	698
Total other comprehensive income (loss), net of tax	(3,342)	(1,226)	698
Comprehensive loss	$ (125,097)	$ (80,222)	$ (35,470)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Consolidated Statements of Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net unrealized gains (losses) on marketable securities, tax	$ 0	$ 0	$ 388

Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings (Accumulated Deficit) [Member]
Beginning Balance at Sep. 30, 2019	$ 462,492	$ 197	$ 298,409	$ 146	$ 163,740
Beginning Balance, Shares at Sep. 30, 2019		19,703
Exercise of stock options	10,481	$ 4	10,477
Exercise of stock options, Shares		327
Vesting of restricted stock units, net of withholding	(1,498)		(1,498)
Vesting of restricted stock units, net of withholding, Shares		47
Stock-based compensation expense	19,575		19,575
Other comprehensive income, net of tax	698			698
Net loss	(36,168)				(36,168)
Ending Balance at Sep. 30, 2020	455,580	$ 201	326,963	844	127,572
Ending Balance, Shares at Sep. 30, 2020		20,077
Exercise of stock options	3,614	$ 1	3,613
Exercise of stock options, Shares		129
Vesting of restricted stock units, net of withholding	(534)		(534)
Vesting of restricted stock units, net of withholding, Shares		32
Stock-based compensation expense	20,991		20,991
Other comprehensive income, net of tax	(1,226)			(1,226)
Net loss	(78,996)				(78,996)
Ending Balance at Sep. 30, 2021	399,429	$ 202	351,033	(382)	48,576
Ending Balance, Shares at Sep. 30, 2021		20,238
Exercise of stock options	$ 21,262	$ 6	21,256
Exercise of stock options, Shares	517	517
Vesting of restricted stock units, net of withholding	$ (1,229)		(1,229)
Vesting of restricted stock units, net of withholding, Shares		36
Stock-based compensation expense	26,969		26,969
Other comprehensive income, net of tax	(3,342)			(3,342)
Net loss	(121,755)				(121,755)
Ending Balance at Sep. 30, 2022	$ 321,334	$ 208	$ 398,029	$ (3,724)	$ 73,179
Ending Balance, Shares at Sep. 30, 2022		20,791

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

- Definition

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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+ Details

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities
Net loss	$ (121,755)	$ (78,996)	$ (36,168)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Stock-based compensation expense	26,969	20,991	19,575
Depreciation and amortization expense	2,973	3,334	3,644
Deferred income taxes	0	345	10,608
Premium paid on marketable securities	(846)	(4,028)	(3,575)
Amortization of premium on marketable securities	1,171	2,116	304
Change in fair value of Series 1 nonconvertible preferred stock	(83)	27	(149)
Other non-cash items	0	(97)	(51)
Change in operating assets and liabilities:
Accounts receivable	3,258	(84)	27,821
Prepaid expenses and other current assets	743	(533)	(7,270)
Income tax receivable	8,537	(24,214)	(4,127)
Operating lease, right-of-use assets	4,776	5,418	3,184
Other long-term assets	(604)	0	0
Accounts payable	(4,634)	3,774	(883)
Accrued expenses	(1,477)	8,350	(1,368)
Operating lease liabilities	(3,706)	(5,879)	(3,535)
Other long-term liabilities	(104)	(520)	(922)
Net cash provided by (used in) operating activities	(84,782)	(69,996)	7,088
Cash flows from investing activities
Purchase of marketable securities	(171,446)	(307,348)	(338,553)
Proceeds from maturities and sale of marketable securities	228,468	345,089	359,828
Purchase of property and equipment	(2,125)	(750)	(1,445)
Net cash provided by investing activities	54,897	36,991	19,830
Cash flows from financing activities
Proceeds from exercise of stock options	21,262	3,614	10,481
Payments for settlement of share-based awards	(1,229)	(534)	(1,498)
Net cash provided by financing activities	20,033	3,080	8,983
Net increase (decrease) in cash, cash equivalents and restricted cash	(9,852)	(29,925)	35,901
Cash, cash equivalents and restricted cash at beginning of period	57,814	87,739	51,838
Cash, cash equivalents and restricted cash at end of period	47,962	57,814	87,739
Supplemental cash flow information:
Cash paid for taxes	0	32	105
Supplemental disclosure of noncash information:
Purchases of fixed assets included in accounts payable and accrued expenses	1,215	137	188
Operating lease liabilities arising from obtaining right-of-use assets	$ 23,910	$ 3,320	$ 3,053

Nature of the Business

12 Months Ended

Sep. 30, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Nature of the Business

1. Nature of the Business

Enanta Pharmaceuticals, Inc. (the “Company”), incorporated in Delaware in 1995, is a biotechnology company that uses its robust, chemistry-driven approach and drug discovery capabilities to become a leader in the discovery and development of small molecule drugs, with an emphasis on treatments for viral infections. The Company discovered glecaprevir, the second of two protease inhibitors discovered and developed through its collaboration with AbbVie for the treatment of chronic infection with hepatitis C virus (“HCV”). Glecaprevir is co-formulated as part of AbbVie’s leading direct-acting antiviral (“DAA”) combination treatment for HCV, which is marketed under the tradenames MAVYRET® (U.S.) and MAVIRET® (ex-U.S.) (glecaprevir/pibrentasvir). Royalties from the Company’s AbbVie collaboration and its existing financial resources provide funding to support the Company’s wholly-owned research and development programs, which are primarily focused on the following disease targets: respiratory syncytial virus (“RSV”), SARS-CoV-2, hepatitis B virus (“HBV”) and human metapneumovirus (“hMPV”).

The Company is subject to many of the risks common to companies in the biotechnology industry, including but not limited to, the uncertainties of research and development, competition from technological innovations of others, dependence on collaborative arrangements, protection of proprietary technology, dependence on key personnel and compliance with government regulation. Product candidates currently under development will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approvals, prior to commercialization. These efforts require significant amounts of capital, adequate personnel and infrastructure, and extensive compliance reporting capabilities.

COVID-19

In March 2020, the World Health Organization declared COVID-19 a global pandemic and countries worldwide implemented various measures to contain the spread of the SARS-CoV-2 virus. National, state and local governments in affected regions have implemented and may continue to implement varying safety precautions, including quarantines, border closures, increased border controls, travel restrictions, shelter-in-place orders and shutdowns, business closures, cancellations of public gatherings and other measures. The extent and severity of the impact on the Company’s business and clinical trials will be determined largely by the extent to which there are disruptions in the supply chains for its research and product candidates, delays in the conduct of ongoing and future clinical trials, or reductions in the number of patients accessing AbbVie’s HCV regimens, or any combination of those events. In addition, AbbVie experienced a decline in HCV sales compared to periods prior to March 2020 as a result of a reduction in patients accessing AbbVie’s HCV regimens due to the COVID-19 pandemic.

The full extent to which the COVID-19 pandemic will directly or indirectly impact the Company’s business, results of operations and financial condition will depend on future developments that are highly uncertain and cannot be accurately predicted, including new information that may emerge concerning COVID-19 and its variants and public health actions taken to contain it, as well as the cumulative economic impact of both of those factors.

Summary of Significant Accounting Policies

12 Months Ended

Sep. 30, 2022

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Presentation

The accompanying consolidated financial statements include those of the Company and its subsidiary, Enanta Pharmaceuticals Security Corporation, after elimination of all intercompany accounts and transactions. The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”).

Use of Estimates

The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of revenues and expenses during the reporting period. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, management’s judgments with respect to its revenue arrangements; valuation of stock-based awards and the accrual of research and development expenses. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. The future developments of the COVID-19 pandemic also may directly or indirectly impact the Company’s business. The Company has made estimates of the impact of COVID-19 in the Company’s consolidated financial statements as of September 30, 2022. Actual results could differ from the Company’s estimates.

Cash Equivalents and Marketable Securities

The Company considers all short-term, highly liquid investments with original maturities of ninety days or less at acquisition date to be cash equivalents. Marketable securities with original maturities of greater than ninety days and remaining maturities of less than one year from the balance sheet date are classified as short-term marketable securities. Marketable securities with remaining maturities of greater than one year from the balance sheet date are classified as long-term marketable securities.

The Company classifies all of its marketable securities as available-for-sale. The Company continually evaluates the credit ratings of its investment portfolio and underlying securities. The Company invests in accordance with its investment policy and invests at the date of purchase in securities with a rating of A3/A- or higher according to Moody’s or S&P or A- by Fitch. The Company reports available-for-sale investments at fair value as of each balance sheet date and records any unrealized gains or losses as a component of stockholders’ equity. The cost of securities sold is determined on a specific identification basis and realized gains and losses are included in other income (expense) within the consolidated statements of operations. When the fair value is below the amortized cost of a marketable security, an estimate of expected credit losses is made. The credit-related impairment amount is recognized in the consolidated statements of operations. Credit losses are recognized through the use of an allowance for credit losses account in the consolidated balance sheet and subsequent improvements in expected credit losses are recognized as a reversal of an amount in the allowance account. If the Company has the intent to sell the security or it is more likely than not that the Company will be required to sell the security prior to recovery of its amortized cost basis, then the allowance for the credit loss is written-off and the excess of the amortized cost basis of the asset over its fair value is recorded in the consolidated statements of operations. There were no credit losses recorded during the years ended September 30, 2022, 2021, and 2020.

Restricted Cash

As of September 30, 2022 and 2021 the Company had outstanding letters of credit collateralized by a money market account of $3,968 and $608, respectively, to the benefit of the landlord of the Company’s building leases. These amounts were classified as long-term restricted cash as of September 30, 2022 and 2021.

Concentration of Credit Risk and of Significant Customers and Suppliers

Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, cash equivalents, short-term and long-term marketable securities and accounts receivable. The Company has all cash and investment balances at one accredited financial institution, including cash in amounts that exceed federally insured limits. The Company does not believe it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships.

The Company has historically generated the majority of its revenue from its collaborative research and license agreements. As of September 30, 2022 and 2021, accounts receivable consisted of amounts due from the Company’s principal collaborator (see Note 7).

The Company is completely dependent on third-party manufacturers for product supply for preclinical and clinical research activities. The Company relies and expects to continue to rely exclusively on several manufacturers to supply the Company with its drug supply requirements related to these activities. These research programs would be adversely affected by a significant interruption in the supply from these third-party manufacturers.

Fair Value Measurements

Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. A fair value hierarchy is based on three levels of inputs that are used to measure fair value, of which the first two levels are considered observable and the last is considered unobservable:

•

Level 1—Quoted prices in active markets for identical assets or liabilities.

•

Level 2—Observable inputs (other than Level 1 quoted prices) such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data.

•

Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques.

The Company’s instruments that are carried at fair value are cash equivalents, short-term and long-term marketable securities and the Series 1 nonconvertible preferred stock. The carrying values of accounts receivable, prepaid and other assets, accounts payable and accrued expenses approximate their fair value due to the short-term nature of these assets and liabilities.

Property and Equipment

Property and equipment are stated at cost less accumulated depreciation. Depreciation expense is recognized using the straight-line method over the following estimated useful lives:


Laboratory and office equipment	5 years
Leasehold improvements	Shorter of life of lease or estimated useful life
Purchased software	3 years
Computer equipment	3 years
Furniture	7 years

Expenditures for repairs and maintenance of assets are charged to expense as incurred. Costs of major additions and betterments are capitalized and depreciated on a straight-line basis over their useful lives. Upon retirement or sale, the cost and related accumulated depreciation of assets disposed are removed from the accounts and any resulting gain or loss is included in income from operations in the consolidated statements of operations.

Leases

The Company accounts for a contract as a lease when it has the right to control the asset for a period of time while obtaining substantially all of the asset’s economic benefits. The Company determines if an arrangement is a lease or contains an embedded lease at inception. For arrangements that meet the definition of a lease, the Company determines the initial classification and measurement of its right-of-use asset and lease liability at the lease commencement date and thereafter if modified. The lease term includes any renewal options that the Company is reasonably assured to exercise. The present value of lease payments is determined by using the interest rate implicit in the lease, if that rate is readily determinable; otherwise, the Company uses its estimated secured incremental borrowing rate for that lease term. The Company’s policy is to not record leases with an original term of 12 months or less on its consolidated balance sheets and recognizes those lease payments in the consolidated statements of operations on a straight-line basis over the lease term.

In addition to rent, the leases may require the Company to pay additional costs, such as utilities, maintenance and other operating costs, which are generally referred to as non-lease components. The Company has elected to not separate lease and non-lease components. Only the fixed costs for lease components and their associated non-lease components are accounted for as a single lease component and recognized as part of a right-of-use asset and lease liability. Rent expense for operating leases is recognized on a straight-line basis over the reasonably assured lease term based on the total lease payments and is included in operating expense in the consolidated statements of operations.

Impairment of Long-Lived Assets

The Company reviews long-lived assets, primarily property and equipment and right-of-use assets, for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. Factors that the Company considers in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative industry or economic trends, and significant changes or planned changes in the use of the assets. If an impairment review is performed to evaluate a long-lived asset for recoverability, the Company compares forecasts of undiscounted cash flows expected to result from the use and eventual disposition of the long-lived asset to its carrying value. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of an asset are less than its carrying amount. The impairment loss would be based on the excess of the carrying value of the impaired asset over its fair value, determined based on discounted cash flows. To date, the Company has not recorded any impairment losses on long-lived assets.

Revenue Recognition

The Company’s revenue has been generated primarily through collaborative research and license agreements. The terms of these agreements contain multiple deliverables, which may include (i) licenses, (ii) research and development activities, and (iii) participation in joint research and development steering committees. The terms of these agreements may include nonrefundable upfront license fees, payments for research and development activities, payments based upon the achievement of certain milestones, and royalty payments based on product sales derived from the collaboration.

The Company recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those goods or services. The Company receives sales-based

royalties for which the license is deemed to be the predominant item to which the royalties relate and thus the Company recognizes sales-based royalties as the underlying sales are earned.

Research and Development Costs

Included in research and development costs are wages, stock-based compensation and benefits of employees performing research and development, third-party license fees and other operational costs related to the Company’s research and development activities, including facility-related expenses and external costs of outside contractors engaged to conduct both preclinical and clinical studies and manufacture quantities of product for preclinical and clinical studies. The Company expenses the cost of each contract as the work is performed.

Upfront payments and milestone payments made for the licensing of technology are expensed as research and development in the period in which they are incurred. Advance payments for goods or services to be received in the future for use in research and development activities are recorded as prepaid expenses. The prepaid amounts are expensed as the related goods are delivered or the services are performed.

Research and Development and Pharmaceutical Drug Manufacturing Accruals

The Company has entered into various contracts with third parties to perform research and development and pharmaceutical drug manufacturing. This includes contracts with contract research organizations (“CROs”), clinical manufacturing organizations (“CMOs”), testing laboratories, research hospitals and not for profit organizations and other entities to support our research and development activities. When billing terms under these contracts do not coincide with the timing of when the work is performed, the Company is required to make estimates of outstanding obligations to those third parties as of period end. The accrual estimates are based on a number of factors, including the Company’s knowledge of the research and development programs and pharmaceutical drug manufacturing activities and associated timelines, invoicing to date, and the provisions in the contract. Significant judgments and estimates are made in determining the accrued balances at the end of any reporting period. Actual results could differ from our estimates.

Patent Costs

All patent-related costs incurred in connection with filing and prosecuting patent applications are recorded as general and administrative expenses as incurred.

Stock-Based Compensation

The Company measures all stock options and other stock-based awards granted to employees at fair value on the date of grant. The Company uses the Black-Scholes option-pricing model in the valuation of its stock options. The fair value of restricted stock units with service-based and performance-based vesting is based on the fair value of the stock on the date of grant. The Company uses the Monte-Carlo model to calculate the fair value on the date of grant of market-based awards. The fair value of service-based awards is recognized as stock-based compensation expense over the requisite service period, which is generally the vesting period of the respective award. For awards with graded vesting, the straight-line method of expense recognition is applied to all awards with service-only based conditions. The Company uses the graded-vesting method to record the expense of awards with both service-based and performance-based vesting conditions, commencing once achievement of the performance condition becomes probable. The Company classifies stock-based compensation expense in the consolidated statements of operations in the same manner in which the award recipient’s payroll costs are classified. The Company accounts for stock-based compensation expense related to forfeitures as the forfeitures occur.

Income Taxes

The Company accounts for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the financial statements or in the Company’s tax returns. Deferred taxes are determined based on the difference between the financial reporting and tax basis of assets and liabilities using enacted tax rates in effect in the years in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in income tax expense.

The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent it believes based upon the weight of available evidence, that it is more likely than not that all or a portion of deferred tax assets will not be realized, a valuation allowance is established through a charge to income tax expense. The realization of deferred tax assets is dependent upon the Company’s ability to generate future taxable income during the periods in which those temporary differences become deductible. Potential for recovery of deferred tax assets is evaluated by estimating the future taxable profits expected and considering prudent and feasible tax planning strategies.

Uncertain tax positions represent tax positions for which reserves have been established. The Company accounts for uncertainty in income taxes recognized in the consolidated financial statements by applying a two-step process to determine the amount to be

recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities. If the tax position is deemed more likely than not to be sustained, the tax position is then assessed to determine the amount of benefit to be recognized in the financial statements. The amount that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement. Income tax expense includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties.

Net Income (Loss) per Share

Basic net income (loss) per common share is computed by dividing the net income (loss) by the weighted average number of shares of common stock outstanding for the period. Diluted net income (loss) per common share is computed by dividing net income (loss) by the weighted average number of common shares outstanding for the period, including potential dilutive common shares assuming the dilutive effect of outstanding stock options and unvested restricted stock units. For periods in which the Company reported a net loss, diluted net loss per common share is the same as basic net loss per common share, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive.

The Company reported net losses for each of the years ended September 30, 2022, 2021 and 2020. The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect:


	Years Ended September 30,
	2022		2021		2020
	(in thousands)
Options to purchase common stock		3,993		3,852		3,262
Unvested rTSRUs		101		111		46
Unvested PSUs		101		111		46
Unvested restricted stock units		219		117		45

Segment Data

The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions. The Company is a biotechnology company focused on discovering and developing small molecule drugs, with an emphasis on treatments for viral infections. Revenue is generated exclusively from transactions occurring with partners located in the United States, and all assets are held in the United States.

Comprehensive Income (Loss)

Comprehensive income (loss) includes net income (loss) as well as other changes in stockholders’ equity that result from transactions and economic events other than those with stockholders. The Company’s only element of other comprehensive income (loss) is unrealized gains and losses on available-for-sale marketable securities.

Going Concern

In August 2014, the FASB issued ASU 2014-15, Presentation of Financial Statements - Going Concern (Subtopic 205-40) (“ASU 2014-15”). The Company adopted this standard as of September 30, 2017. The standard requires the Company to assess its ability to continue as a going concern one year beyond the date of filing and, in certain circumstances, provide additional footnote disclosures. Based on a detailed cash forecast incorporating current research and development activities and related spending plans, the Company believes that its current cash, cash equivalents and short-term and long-term marketable securities on hand at September 30, 2022 is sufficient to fund operations for at least the next twelve months beyond the date of issuance of these consolidated financial statements. The amount of capital available will depend on the Company’s management of its existing cash, cash equivalents and short-term and long-term marketable securities, as well as the level of future royalties the Company earns under its agreement with AbbVie. If the Company should require financing beyond these resources to fund its research and development efforts, it may not be able to obtain financing on acceptable terms, or at all.

Recently Adopted Accounting Pronouncements

In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes (Topic 740), which removes certain exceptions to the general principles in Topic 740 – Income Taxes and improves consistent application of and simplifies GAAP for other areas of Topic 740 by clarifying and amending existing guidance. This ASU became effective for the Company beginning October 1, 2021 and interim periods within that year. The adoption of the standard did not have a material impact on the Company's financial position or results of operations.

Recently Issued Accounting Pronouncements

Accounting standards that have been issued or proposed by the FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s consolidated financial statements upon adoption.

Fair Value of Financial Assets and Liabilities

12 Months Ended

Sep. 30, 2022

Fair Value Disclosures [Abstract]

Fair Value of Financial Assets and Liabilities

3. Fair Value of Financial Assets and Liabilities

The following tables present information about the Company’s financial assets and liabilities that were subject to fair value measurement on a recurring basis as of September 30, 2022 and 2021 and indicate the fair value hierarchy of the valuation inputs utilized to determine such fair value:


	Fair Value Measurements at September 30, 2022 Using:
	Level 1		Level 2		Level 3		Total
	(in thousands)
Assets:
Cash equivalents:
Money market funds	$	13,905	$	—	$	—	$	13,905
Marketable securities:
U.S. Treasury notes		91,328		—		—		91,328
Corporate bonds		—		76,411		—		76,411
Commercial paper		—		66,784		—		66,784
	$	105,233	$	143,195	$	—	$	248,428
Liabilities:
Series 1 nonconvertible preferred stock	$	—	$	—	$	1,423	$	1,423
	$	—	$	—	$	1,423	$	1,423


	Fair Value Measurements at September 30, 2021 Using:
	Level 1		Level 2		Level 3		Total
	(in thousands)
Assets:
Cash equivalents:
Money market funds	$	54,819	$	—	$	—	$	54,819
Marketable securities:
U.S. Treasury notes		83,038		—		—		83,038
Corporate bonds		—		124,703		—		124,703
Commercial paper		—		87,471		—		87,471
	$	137,857	$	212,174	$	—	$	350,031
Liabilities:
Series 1 nonconvertible preferred stock	$	—	$	—	$	1,506	$	1,506
	$	—	$	—	$	1,506	$	1,506

Cash equivalents at September 30, 2022 and 2021 consist of money market funds that are readily convertible to cash and with less than 90 days until maturity.

During the years ended September 30, 2022, 2021, and 2020, there were no transfers between Level 1, Level 2 and Level 3.

The fair value of Level 2 instruments classified as marketable securities were determined through third-party pricing services. The pricing services use many observable market inputs to determine value, including reportable trades, benchmark yields, credit spreads, broker/dealer quotes, bids, offers, and current spot rates.

The outstanding shares of Series 1 nonconvertible preferred stock as of September 30, 2022 and 2021 are measured at fair value. These outstanding shares are financial instruments that might require a transfer of assets because of the liquidation features in the contract and are therefore recorded as liabilities and measured at fair value. The fair value of the outstanding shares is based on significant inputs not observable in the market, which represent a Level 3 measurement within the fair value hierarchy. The Company utilizes a probability-weighted valuation model, which takes into consideration various outcomes that may require the Company to transfer assets upon liquidation. Changes in the fair values of the Series 1 nonconvertible preferred stock are recognized in other income (expense) in the consolidated statements of operations.

The recurring Level 3 fair value measurements of the Company’s outstanding Series 1 nonconvertible preferred stock using probability-weighted discounted cash flow include the following significant unobservable inputs:


Series 1 nonconvertible preferred stock	Range
	September 30,
Unobservable Input	2022	2021
Probabilities of payout	0%-65%	0%-65%
Discount rate	7.25%	4.25%

The following table provides a rollforward of the aggregate fair value of the Company’s outstanding Series 1 nonconvertible preferred stock for which fair value is determined by Level 3 inputs:


	Series 1 Nonconvertible Preferred Stock
	(in thousands)
Balance, September 30, 2019	$	1,628
Decrease in fair value		(149	)
Balance, September 30, 2020		1,479
Increase in fair value		27
Balance, September 30, 2021		1,506
Decrease in fair value		(83	)
Balance, September 30, 2022	$	1,423

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Marketable Securities

12 Months Ended

Sep. 30, 2022

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

4. Marketable Securities

As of September 30, 2022 and 2021, the fair value of available-for-sale marketable securities, by type of security, was as follows:


	September 30, 2022
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Credit Losses		Fair Value
	(in thousands)
Corporate bonds	$	78,663	$	—	$	(2,252	)	$	—	$	76,411
Commercial paper		66,784		—		—			—		66,784
U.S. Treasury notes		92,416		—		(1,088	)		—		91,328
	$	237,863	$	—	$	(3,340	)	$	—	$	234,523


	September 30, 2021
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Credit Losses		Fair Value
	(in thousands)
Corporate bonds	$	124,678	$	93	$	(68	)	$	—	$	124,703
Commercial paper		87,471		—		—			—		87,471
U.S. Treasury notes		83,061		3		(26	)		—		83,038
	$	295,210	$	96	$	(94	)	$	—	$	295,212

As of September 30, 2022 and 2021, marketable securities consisted of investments that mature within one year, with the exception of certain corporate bonds and U.S. Treasury notes, which have maturities between one and three years and an aggregate fair value of $29,285 and $108,416, respectively.

Property and Equipment, Net

12 Months Ended

Sep. 30, 2022

Property, Plant and Equipment [Abstract]

Property and Equipment, Net

5. Property and Equipment, Net

Property and equipment, net consisted of the following as of September 30, 2022 and 2021:


	September 30,
	2022			2021
	(in thousands)
Laboratory and office equipment	$	14,780		$	14,499
Leasehold improvements		7,276			7,140
Purchased software		1,412			1,387
Furniture		1,354			1,294
Computer equipment		653			529
Construction in progress		2,556			20
		28,031			24,869
Less: Accumulated depreciation and amortization		(21,858	)		(18,926	)
	$	6,173		$	5,943

As of September 30, 2022, construction in progress related primarily to leasehold improvements. Depreciation and amortization expense for property and equipment, was $2,973, $3,334 and $3,644 for the years ended September 30, 2022, 2021, and 2020, respectively.

Accrued Expenses and Other Current Liabilities

12 Months Ended

Sep. 30, 2022

Payables and Accruals [Abstract]

Accrued Expenses and Other Current Liabilities

6. Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following as of September 30, 2022 and 2021:


	September 30,
	2022		2021
	(in thousands)
Accrued pharmaceutical drug manufacturing	$	6,932	$	8,402
Accrued research and development expenses		5,532		6,062
Accrued payroll and related expenses		6,439		6,094
Accrued other		2,033		1,871
	$	20,936	$	22,429

Collaboration Agreements

12 Months Ended

Sep. 30, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Collaboration Agreements

7. Collaboration Agreements

AbbVie Collaboration

The Company has a Collaborative Development and License Agreement (as amended, the “AbbVie Agreement”), with AbbVie to identify, develop and commercialize HCV NS3 and NS3/4A protease inhibitor compounds, including paritaprevir and glecaprevir, under which the Company has received license payments, proceeds from a sale of preferred stock, research funding payments, milestone payments and royalties totaling approximately $1,207,000 through September 30, 2022. Since the Company satisfied all of its performance obligations under the AbbVie Agreement by the end of fiscal 2011, all milestone payments received since then have been recognized as revenue when the milestones were achieved by AbbVie.

The Company is receiving annually tiered royalties per Company protease product ranging from ten percent up to twenty percent, or on a blended basis from ten percent up to the high teens, on the portion of AbbVie’s calendar year net sales of each HCV regimen that is allocated to the protease inhibitor in the regimen. Beginning with each January 1, the cumulative net sales of a given royalty-bearing protease inhibitor product start at zero for purposes of calculating the tiered royalties on a product-by-product basis. The following table details the royalty tiers associated with cumulative calendar year net sales allocated to each royalty-bearing product as provided in the AbbVie Agreement:


Calendar Year Net Sales		Royalty Tier
(in thousands)		(%)
up to $500,000		10%
from $500,000 up to $750,000		12%
from $750,000 up to $1,000,000		14%
from $1,000,000 up to $2,500,000		17%
greater than or equal to $2,500,000		20%

Royalties owed to the Company under the agreement can be reduced by AbbVie in certain circumstances, including (i) if AbbVie exercises its right to license or otherwise acquire rights to intellectual property controlled by a third party where a product could not be legally developed or commercialized in a country without the third-party intellectual property right, (ii) where a product developed under the collaboration agreement is sold in a country and not covered by a valid patent claim in such country, and (iii) where sales of a generic product are equal to at least a specified percentage of AbbVie’s market share of its product in a country.

AbbVie’s obligation to pay royalties on a product developed under the agreement expires on a country-by-country basis upon the later of (i) the date of expiration of the last of the licensed patents with a valid claim covering the product in the applicable country, or (ii) ten years after the first commercial sale of the product in the applicable country.

Subject to certain exceptions, a party’s rights and obligations under the agreement continue until (i) such time as AbbVie is no longer developing a product candidate or (ii) if, as of the time AbbVie is no longer developing any product candidates, AbbVie is commercializing any other protease inhibitor product, such time as all royalty terms for all covered products have ended. Accordingly, the final expiration date of the agreement is currently indeterminable.

Either party may terminate the agreement for cause in the event of a material breach, subject to prior notice and the opportunity to cure, or in the event of the other party’s bankruptcy. Additionally, AbbVie may terminate the agreement for any reason upon specified prior notice.

If the Company terminates the agreement for cause or AbbVie terminates without cause, any licenses and other rights granted to AbbVie will terminate and AbbVie will be deemed to have granted the Company (i) a non-exclusive, perpetual, fully-paid, worldwide, royalty-free license, with the right to sublicense, under AbbVie’s intellectual property used in any product candidate, and (ii) an exclusive (even as to AbbVie), perpetual, fully-paid, worldwide, royalty-free license, with the right to sublicense, under AbbVie’s interest in any joint intellectual property rights to develop product candidates resulting from covered compounds and to commercialize any products derived from such compounds. Upon the Company’s request, AbbVie will also transfer to the Company all right, title and interest in any related product trademarks, regulatory filings and clinical trials.

If AbbVie terminates the agreement for the Company’s uncured breach, the milestone and royalty payments payable by AbbVie may be reduced, the licenses granted to AbbVie will remain in place, the Company will be deemed to have granted AbbVie an exclusive license under the Company’s interest in joint intellectual property, AbbVie will continue to have the right to commercialize any covered products, and all rights and licenses granted to the Company by AbbVie will terminate.

Stockholders' Equity

12 Months Ended

Sep. 30, 2022

Equity [Abstract]

Stockholders' Equity

8. Stockholders’ Equity

The Company is authorized to issue 100,000 shares of common stock at a par value of $0.01 per share. Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are entitled to receive such dividends as may be declared by the board of directors, if any.

The Company also is authorized to issue 5,000 shares of preferred stock at a par value of $0.01 per share, of which 2,000 shares are designated as Series 1 Nonconvertible preferred stock and 3,000 shares are undesignated and unissued.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496158-112644

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
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-Subparagraph (SX 210.3-04)
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496189-112644

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Series 1 Nonconvertible Preferred Stock

12 Months Ended

Sep. 30, 2022

Debt Disclosure [Abstract]

Series 1 Nonconvertible Preferred Stock

9. Series 1 Nonconvertible Preferred Stock

The Company’s Certificate of Incorporation authorizes the issuance of up to 2,000 shares of Series 1 nonconvertible preferred stock at a par value of $0.01 per share. Holders of Series 1 nonconvertible preferred stock are not entitled to receive dividends. In the event of any liquidation, deemed liquidation, dissolution or winding up of the Company, the Series 1 nonconvertible preferred stockholders are entitled to receive in preference to all other stockholders, an amount equal to $1.00 per share, adjusted for any stock dividends, stock splits or reclassifications. Series 1 nonconvertible preferred stockholders will not be entitled to vote unless required by the Company pursuant to the laws of the State of Delaware. The Company may redeem the Series 1 nonconvertible preferred stock with the approval of the holders of a majority of the outstanding shares of Series 1 nonconvertible preferred stock at a redemption price of $1.00 per share. The Company must redeem the stock within 60 days of such election. Shares that are redeemed will be retired or canceled and not reissued by the Company. As these shares qualify as a derivative, they are classified as a liability on the Company’s consolidated balance sheet.

As of September 30, 2022 and 2021, 1,930 shares of Series 1 nonconvertible preferred stock were issued and outstanding. For the years ended September 30, 2022, 2021, and 2020, the remeasurement of the Series 1 nonconvertible preferred stock resulted in income (expense) of $83, $(27), and $149, respectively, which was recorded in other income (expense) in the consolidated statements of operations. The total fair value of the Series 1 nonconvertible preferred stock was $1,423 and $1,506 as of September 30, 2022 and 2021, respectively.

Stock-Based Awards

12 Months Ended

Sep. 30, 2022

Share-Based Payment Arrangement [Abstract]

Stock-Based Awards

10. Stock-Based Awards

The Company grants stock-based awards, including stock options, restricted stock units and other unit awards under its 2019 Equity Incentive Plan (the “2019 Plan”), which was approved by its stockholders on February 28, 2019 and amended in March 2021 and March 2022. The Company also has outstanding stock option awards under its 2012 Equity Incentive Plan (the “2012 Plan”) and its

amended and restated 1995 Equity Incentive Plan (the “1995 Plan”), but is no longer granting awards under these plans. The Company’s 2019 Plan permits the Company to sell or issue awards of common stock or restricted common stock or to grant awards of incentive stock options or nonqualified stock options for the purchase of common stock, restricted stock units, performance units, stock appreciation rights or other cash incentive awards, to employees, members of the board of directors and consultants of the Company. The number of shares of common stock that may be issued under the 2019 Plan is subject to increase by the number of shares forfeited under any options forfeited and not exercised under the 2019 Plan or any predecessor plans such as the 2012 Plan or the 1995 Plan. As of September 30, 2022, 1,363 shares remained available for future awards under the 2019 Plan.

Under the Company’s Employee Stock Purchase Plan (“ESPP”) a total of 186 shares of common stock are reserved for issuance. As of September 30, 2022, the Company had not commenced any offering under the ESPP and no ESPP shares have been issued.

Options granted under the 2019 Plan to employees generally vest over four years and to non-employee directors over one year, and expire after ten years. As required under the equity plans, the exercise price for awards granted is not to be less than the fair value of common shares on the date of grant. Restricted stock units with service-based vesting conditions generally vest over four years.

Stock Option Valuation

The fair value of each stock option award is determined on the date of grant using the Black-Scholes option-pricing model. The volatility has been determined using the Company’s traded stock price to estimate expected volatility. The expected term of the Company’s options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. The expected dividend yield is zero due to the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future. The relevant data used to determine the value of the stock option awards are as follows, presented on a weighted average basis:


	Years Ended September 30,
	2022			2021			2020
Risk-free interest rate		1.72	%		0.61	%		1.41	%
Expected term (in years)		6.04			6.05			6.02
Expected volatility		47	%		52	%		53	%
Expected dividends		0	%		0	%		0	%
Weighted average grant date fair value	$	33.22		$	21.76		$	30.47

The following table summarizes stock option activity, including aggregate intrinsic value for the year ended September 30, 2022:


	Shares Issuable Under Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term in years		Aggregate Intrinsic Value
	(in thousands)							(in thousands)
Outstanding as of September 30, 2021		3,852		$	48.61		6.4	$	49,173
Granted		894			71.26
Exercised		(517	)		41.17
Forfeited		(236	)		66.76
Outstanding as of September 30, 2022		3,993		$	53.57		6.2	$	28,778
Options vested and expected to vest as of September 30, 2022		3,993		$	53.57		6.2	$	28,778
Options exercisable as of September 30, 2022		2,621		$	49.76		5.0	$	25,191

The aggregate intrinsic value of options is calculated as the difference between the exercise price of the options and the fair value of the Company’s common stock. The following tables summarize additional exercise and grant date information:


	Years Ended September 30,
	2022		2021		2020
	(in thousands)
Aggregate intrinsic value of stock options exercised	$	17,650	$	2,704	$	7,850
Proceeds to Company from stock options exercised	$	21,262	$	3,614	$	10,481

Market and Performance-Based Stock Unit Awards

The Company awards both performance share units (“PSUs”) and relative total stockholder return units (“rTSRUs”) to its executive officers.

The PSUs vest and result in issuance, or settlement, of common shares for each recipient, based upon the recipient’s continued employment with the Company through the settlement date of the award and the Company’s achievement of specified research and development milestones. The requisite service period of the PSUs is generally two years. The fair value of PSUs is based on the fair value of the stock on the date of grant, which is determined to be the closing price of the Company's common stock. Stock-based compensation expense for PSUs is recorded in the statements of operations over the service period, commencing when it is probable that the specified research and development milestone is achieved.

The rTSRUs vest and result in the issuance of common stock based upon the recipient’s continuing employment with the Company through the settlement date of the award and the relative ranking of the total stockholder return, or TSR, of the Company’s common stock in relation to the TSR of the component companies in the NASDAQ Biotech Index over two specified periods that are two years apart, based on a comparison of average closing stock prices in specified periods noted in the award agreement. The number of market-based rTSRUs awarded represents the target number of shares of common stock that may be earned; however, the actual number of shares that may be earned ranges from 0% to 150% of the target number, depending on the award agreement and the year of the award. The Company used a Monte Carlo model to estimate the grant-date fair value of the rTSRUs. Stock-based compensation expense for rTSRUs is recorded in the statements of operations over the service period regardless of whether the market condition is achieved.

Assumptions and estimates utilized in the calculation of the fair value of the rTSRUs include the risk-free interest rate, dividend yield, expected volatility based on the historical volatility of publicly traded peer companies and the remaining performance period of the award. The table below sets forth the weighted average grant date fair value assumptions used to value the rTSRUs:


	Years Ended September 30,
	2022			2021			2020
Risk-free interest rate		0.94	%		0.13	%		1.62	%
Dividend yield		0	%		0	%		0	%
Expected volatility		80	%		74	%		68	%
Performance period (years)		1.97			1.97			2.03

The following table summarizes PSU and rTSRU activity (at target) for the year ended September 30, 2022:


	PSUs					rTSRUs
	Shares			Weighted Average Grant Date Fair Value per Share		Shares			Weighted Average Grant Date Fair Value per Share
	(in thousands, except per share data)
Unvested at September 30, 2021		111		$	49.31		111		$	31.26
Granted		36			76.84		36			54.67
Vested		(5	)		61.59		(18	)		40.13
Cancelled		(41	)		59.01		(28	)		37.78
Unvested at September 30, 2022		101		$	54.50		101		$	36.14

The total fair value of PSUs and rTSRUs vested during the years ended September 30, 2022, 2021, and 2020 were $1,414, $0 and $1,227, respectively.

Restricted Stock Units

The following table summarizes the restricted stock unit activity for the year ending September 30, 2022:


	Restricted Stock Units			Weighted Average Grant Date Fair Value per Share
	(in thousands, except per share data)
Unvested at September 30, 2021		117		$	43.57
Granted		158			74.82
Vested		(29	)		43.57
Cancelled		(27	)		59.99
Unvested at September 30, 2022		219		$	64.03

The total fair value of restricted stock units vested during the years ended September 30, 2022, 2021, and 2020 were $2,427, $1,897 and $3,149, respectively.

Stock-Based Compensation Expense

The Company recorded the following stock-based compensation expense for the years ended September 30, 2022, 2021, and 2020:


	Years Ended September 30,
	2022		2021		2020
	(in thousands)
Research and development	$	9,728	$	10,075	$	10,096
General and administrative		17,241		10,916		9,479
	$	26,969	$	20,991	$	19,575


	Years Ended September 30,
	2022		2021		2020
	(in thousands)
Stock options	$	19,615	$	18,004	$	17,459
rTSRUs		1,597		1,537		1,216
PSUs		2,628		235		259
Restricted stock units		3,129		1,215		641
	$	26,969	$	20,991	$	19,575

As of September 30, 2022, the Company had an aggregate of $55,346 of unrecognized stock-based compensation cost, which is expected to be recognized over a weighted average period of 2.4 years.

Leases

12 Months Ended

Sep. 30, 2022

Leases [Abstract]

Leases

11. Leases

The Company has two real estate leases for properties located in Watertown, Massachusetts. The first lease, for office and laboratory space at 500 Arsenal Street, was effective in fiscal 2011 and was set to expire in September 2022 with an option to extend the lease term for an additional five years. On November 19, 2021, the Company exercised its option to extend the lease term for an additional five years through September 1, 2027. The option to extend the lease term was not included in the right-of-use asset and lease liabilities as it was not reasonably certain of being exercised. Therefore, the Company accounted for the extension as a modification and re-assessed the classification of the lease as an operating lease. The total remeasurement of the lease resulted in an increase in the right-of-use asset and lease liability of $15,076 during the year ended September 30, 2022.

The second lease, for office space located at 400 Talcott Avenue, was effective September 2018 for a term of six years with two options to extend the lease term for an additional three years each. The options to extend the lease terms were not included in the right-of-use assets and lease liabilities as they were not reasonably certain of being exercised. In May 2022, the Company amended the lease to add additional office space and extend the lease term through June 1, 2034. The amended lease also includes a tenant improvement allowance from the landlord of up to $2,574. The Company accounted for the lease amendment as a modification and re-assessed the classification of the lease as an operating lease. The total remeasurement of the lease resulted in an increase in the right-of-use asset and liability of $8,174 during the year ended September 30, 2022.

Lease payments for the Company's real estate leases include fixed lease payments that escalate over the terms of the leases and require the Company to pay certain operating expenses based on actual costs incurred. Operating expenses that are not fixed in nature are expensed in the period incurred and included in variable lease costs. The leases do not include any restrictions or covenants that had to be accounted for under the lease guidance.

In May 2022, the Company entered into a new ten-year lease agreement with its existing landlord for laboratory and office space in Watertown, Massachusetts, adjacent to its 400 Talcott Avenue premises to accommodate its growing headcount. The new lab and office space will be located at Arsenal on the Charles in Watertown, Massachusetts, at a to-be-constructed facility. The Company expects to gain access to the space to perform tenant improvements beginning in October 2023. The estimated minimum lease payments as a result of the new lease total $76,470 over the ten-year term. The lease also contains a tenant improvement allowance of $15,194. The Company will account for the lease as a right-of-use asset and lease liability upon the lease commencement date.

In conjunction with the new lease agreement at Arsenal on the Charles, the Company amended its 500 Arsenal Street lease to shorten the term of the lease from September 2027 to the date when the Arsenal on the Charles facility is completed and ready for the Company's occupancy. The construction of the Arsenal on the Charles facility is being conducted by the landlord and it is expected that the facility will be ready for the Company's tenant improvement buildout in October 2023. As the construction of the facility and the timing of completion is not in the control of the Company, the Company will remeasure the term for the 500 Arsenal Street lease for financial accounting purposes at the time the contingency regarding occupancy lapses.

The Company leases units of equipment over eighteen-month lease periods commencing upon shipment of each unit. The lease agreements contain options to terminate the leases early or to extend the leases for successive six-month periods, however these options were not included in the right-of-use assets and lease liability as they were not reasonably certain of being exercised. The equipment leases require the Company to pay for certain consumable and peripheral equipment supplies based on actual costs incurred. As these costs are not fixed in nature, they are expensed in the period incurred and included in variable lease costs.

The components of lease expense for the Company’s real estate and equipment leases were as follows:


	Years Ended September 30,
	2022		2021
	(in thousands)
Operating lease cost	$	6,294	$	5,861
Short-term lease cost		—		—
Variable lease cost		2,375		4,057
	$	8,669	$	9,918


	Years Ended September 30,
	2022			2021
	(in thousands)
Cash paid for amounts included in the measurement of operating lease liabilities	$	4,966		$	6,364
Operating lease liabilities arising from obtaining right-of-use assets	$	23,910		$	3,320

	September 30,
	2022			2021
Weighted-average remaining lease term - operating leases (in years)		7.42			1.43
Weighted-average discount rate - operating leases		6.96	%		6.08	%

As the Company’s leases do not provide an implicit rate, the Company utilized its incremental borrowing rate based on information available at the lease commencement date, which represents an internally developed rate that would be incurred to borrow, on a collateralized basis, over a similar term, an amount equal to the lease payments in a similar economic environment.

Future annual minimum lease payments relating to the Company's lease liabilities as of September 30, 2022 were as follows:


Years ended September 30,	(in thousands)
2023		2,290
2024		5,062
2025		5,216
2026		5,373
2027		5,196
Thereafter		11,912
Total future minimum lease payments		35,049
Less: imputed interest		(9,786	)
Total operating lease liabilities	$	25,263


	September 30,
Included in the balance sheet:	2022		2021
	(in thousands)
Current operating lease liabilities	$	2,891	$	4,203
Operating lease liabilities, net of current portion		22,372		1,126
Total operating lease liabilities	$	25,263	$	5,329

The tables above do not include lease payments related to the Company’s Arsenal on the Charles facility because as of September 30, 2022, the lease commencement date had not occurred. Additionally, the tables above do not include the impact of shortening the term for the 500 Arsenal Street Lease as the term date is contingent upon events not in the Company's control.

The Company is required to maintain security deposits of $652 in connection with various of its real estate leases, which amounts are included in other long-term assets on the Company's consolidated balance sheets. In addition, the Company is required to maintain letters of credit for certain of its leases, collateralized by money market accounts of $3,968, which amounts are classified as long-term restricted cash on the consolidated balance sheets.

Commitments and Contingencies

12 Months Ended

Sep. 30, 2022

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

12. Commitments and Contingencies

Litigation and Contingencies Related to Use of Intellectual Property

From time to time, the Company may become subject to legal proceedings, claims and litigation arising in the ordinary course of business. The Company currently is not a party to any threatened or pending litigation. However, third parties might allege that the Company or its collaborators are infringing their patent rights or that the Company is otherwise violating their intellectual property rights. Such third parties may resort to litigation against the Company or its collaborators, which the Company has agreed to indemnify. With respect to some of these patents, the Company expects that it will be required to obtain licenses and could be required to pay license fees or royalties, or both. These licenses may not be available on acceptable terms, or at all. A costly license, or inability to obtain a necessary license, would have a material adverse effect on the Company’s financial condition, results of operations or cash flows. The Company accrues contingent liabilities when it is probable that future expenditures will be made and such expenditures can be reasonably estimated.

In June 2022, the Company announced that it filed suit in the United States District Court for the District of Massachusetts on June 21, 2022, against Pfizer, Inc. seeking damages for infringement of U.S. Patent No. 11,358,953 (the ’953 Patent) in the manufacture, use and sale of Pfizer’s COVID-19 antiviral, Paxlovid™ (nirmatrelvir tablets; ritonavir tablets). The United States Patent and Trademark Office awarded the '953 Patent to the Company in June 2022 based on the Company's July 2020 patent application describing coronavirus protease inhibitors invented by the Company. The Company is seeking fair compensation for Pfizer’s use of a coronavirus protease inhibitor claimed in the ‘953 patent. The Company records all legal expenses associated with the patent infringement suit as incurred in the consolidated statements of operations.

The Company currently is not a party to any other litigation.

Indemnification Agreements

In the ordinary course of business, the Company may provide indemnifications of varying scope and terms to customers, vendors, lessors, business partners, and other parties with respect to certain matters including, but not limited to, losses arising out of breach of

such agreements or from services to be provided to the Company, or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors and its executive officers that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnifications. In addition, the Company maintains directors’ and officers’ insurance coverage. The Company does not believe that the outcome of any claims under indemnification arrangements will have a material effect on its financial position, results of operations or cash flows, and has not accrued any liabilities related to such obligations in its consolidated financial statements as of September 30, 2022 and 2021.

Income Taxes

12 Months Ended

Sep. 30, 2022

Income Tax Disclosure [Abstract]

Income Taxes

13. Income Taxes

Income before income taxes for all periods presented is from domestic operations, which are the Company’s only operations. During the years ended September 30, 2022, 2021, and 2020, the Company recorded income tax benefit (expense) as follows:


	Years Ended September 30,
	2022			2021			2020
	(in thousands)
Current income tax benefit (expense):
Federal	$	—		$	28,721		$	8,491
State		449			205			941
Deferred income tax benefit (expense):
Federal		(16	)		(343	)		(8,916	)
State		—			—			(1,665	)
Income tax benefit (expense)	$	433		$	28,583		$	(1,149	)

A reconciliation of the U.S. federal statutory income tax rate to the Company’s effective tax rate is as follows:


	Years Ended September 30,
	2022				2021				2020
Federal statutory income tax rate		(21.0	)	%		(21.0	)	%		(21.0	)	%
State taxes, net of federal benefit		(2.9	)			(2.3	)			(2.8	)
Change in valuation allowance		30.8				9.9				52.1
Federal research and development tax credit		(4.6	)			(5.3	)			(13.3	)
Share-based compensation		(0.8	)			2.4				2.8
State research and development tax credit		(1.5	)			(0.8	)			(2.6	)
Change in deferred tax rate		(0.1	)			(9.5	)			(10.2	)
Other		(0.3	)			—				(1.7	)
Effective income tax rate		(0.4	)	%		(26.6	)	%		3.3		%

The effective tax rate during the year ended September 30, 2022 differs from the U.S. federal statutory rate primarily due to the full valuation allowance maintained on the Company’s net deferred tax assets. The negative effective income tax rate during the year ended September 30, 2021 reflects an income tax benefit due to the Company’s ability to carryback the pre-tax loss for the year under the Coronavirus Aid, Relief and Economic Security Act (“CARES Act”).

Changes in the valuation allowance for deferred tax assets during the years ended September 30, 2022, 2021, and 2020 are as follows:


	Years Ended September 30,
	2022			2021			2020
	(in thousands)
Valuation allowance, beginning of year	$	(29,298	)	$	(18,259	)	$	—
Increase recorded to valuation allowance		(38,428	)		(11,039	)		—
Initial recording of valuation allowance		—			—			(18,259	)
Valuation allowance, end of year	$	(67,726	)	$	(29,298	)	$	(18,259	)

Net deferred tax assets as of September 30, 2022 and 2021 consisted of the following:


	September 30,
	2022			2021
	(in thousands)
Deferred tax assets:
Share-based compensation	$	14,983		$	11,843
Tax credit carryforwards		20,663			13,170
Operating lease liability		6,007			1,232
Accrued compensation		1,362			1,284
Net operating loss carryforward		29,105			3,095
Accrued expenses		541			378
Other temporary differences		245			366
Total deferred tax assets		72,906			31,368
Valuation allowance		(67,726	)		(29,298	)
Net deferred tax assets		5,180			2,070

Deferred tax liabilities:
Operating lease, right-of-use assets		(5,606	)		(1,110	)
Depreciation		(88	)		(684	)
Prepaid expenses		(280	)		(275	)
Unrealized loss		794			(1	)
Total deferred tax liabilities		(5,180	)		(2,070	)
Net deferred income tax assets (liabilities)	$	—		$	—

As of September 30, 2022, the Company had federal net operating loss carryforwards of $109,363, which may be available to offset future taxable income and do not expire but are limited in their usage to an annual deduction equal to 80% of annual taxable income. As of September 30, 2022, the Company had state net operating loss carryforwards of $97,128, which may be available to offset future taxable income and expire at various dates beginning in 2040. As of September 30, 2022, the Company also had federal and state research and development tax credit carryforwards of $16,870 and $4,986, respectively, which may be available to reduce future tax liabilities and expire at various dates beginning in 2039 and 2034, respectively.

Utilization of the federal and state net operating loss carryforwards and research and development tax credit carryforwards may be subject to a substantial annual limitation under Sections 382 and 383 of the Internal Revenue Code of 1986, and corresponding provisions of state law, due to ownership changes that may have occurred previously or that could occur in the future. These ownership changes may limit the amount of net operating loss and research and development tax credit carryforwards that can be utilized annually to offset future tax liabilities.

The Company has evaluated the positive and negative evidence bearing upon its ability to realize the deferred tax assets, which are comprised primarily of net operating loss carryforwards, research and development tax credit carryforwards and stock compensation expense. The Company considers it more likely that it will not have sufficient taxable income in the future that will allow it to realize all of its existing deferred tax assets. This is due to the fact the Company continues to progress its wholly-owned research and development programs and its declining royalty revenues from its Collaboration Agreement with AbbVie. As a result, the Company continued to record a valuation allowance as of September 30, 2022 against its deferred tax assets to reduce a portion of the Company’s deferred tax assets for which the Company does not believe it is more likely than not these will be realized.

The Company files tax returns as prescribed by the tax laws of the jurisdictions in which it operates. In the normal course of business, the Company is subject to examination by federal and state jurisdictions, where applicable. The Company’s tax years in the U.S. are still open under statute from 2018 to the present. Earlier years may be examined to the extent that tax credit or net operating loss carryforwards are used in future periods. The Company has not received notice of examination by any jurisdiction for any tax year open under statute.

In response to the COVID-19 pandemic, the CARES Act was signed into law in March 2020. The CARES Act lifted certain deduction limitations originally imposed by the Tax Cuts and Jobs Act of 2017 (the “Tax Act”). Under the CARES Act, the Company was permitted to carryback net operating losses for up to five years for losses generated in fiscal 2018 through fiscal 2021. Net operating loss carrybacks were previously prohibited under the Tax Act. The CARES Act also eliminated the 80% of taxable income limitations by allowing corporate entities to fully utilize net operating loss carryforwards to offset taxable income in fiscal years 2018, 2019 or 2020. In addition, the CARES Act made qualified improvement property eligible for 15-year cost-recovery and 100% bonus depreciation. The enactment of the CARES Act resulted in a $28,721 and $8,581 income tax benefit related to a federal net operating loss carryback at the previously enacted 35% rate in the Company’s consolidated financial statements during the years ended

September 30, 2021 and 2020, respectively. As of September 30, 2022 and 2021, the Company had an income tax receivable of $28,718 and $37,255, respectively.

Uncertain tax positions represent tax positions for which reserves have been established. The Company’s policy is to record interest and penalties related to uncertain tax positions as part of income tax expense. Total interest related to uncertain tax positions recorded as a liability on the Company’s consolidated balance sheets were $44 and $105 as of September 30, 2022 and 2021, respectively. A reconciliation of the beginning and ending amount of uncertain tax positions is summarized as follows:


	September 30,
	2022			2021
	(in thousands)
Beginning Balance	$	622		$	844
Additions based on tax positions for the current period		10			10
Reductions for tax positions due to lapse of statute of limitations		(367	)		(134	)
Reductions for tax positions of prior periods		(39	)		(98	)
Ending Balance	$	226		$	622

The Company does not expect that its uncertain tax position will materially change within the next twelve months.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 21
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32857-109319

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-URI https://asc.fasb.org/extlink&oid=122134291&loc=d3e330215-122817

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 17
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32809-109319

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-URI https://asc.fasb.org/extlink&oid=122134291&loc=d3e330036-122817

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 14
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32705-109319

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 270
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=6424409&loc=d3e44925-109338

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-URI https://asc.fasb.org/topic&trid=2144680

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=6424122&loc=d3e41874-109331

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

401(k) Plan

12 Months Ended

Sep. 30, 2022

Postemployment Benefits [Abstract]

401(k) Plan

14. 401(k) Plan

The Company has a 401(k) plan. This plan covers substantially all employees who meet minimum age and service requirements. During the years ended September 30, 2022, 2021, and 2020, the Company recognized $1,596, $1,353, and $1,190, respectively, of expense related to its contributions to this plan.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Sep. 30, 2022

Accounting Policies [Abstract]

Basis of Presentation

Use of Estimates

Cash Equivalents

Cash Equivalents and Marketable Securities

The Company considers all short-term, highly liquid investments with original maturities of ninety days or less at acquisition date to be cash equivalents.

Marketable Securities

Marketable securities with original maturities of greater than ninety days and remaining maturities of less than one year from the balance sheet date are classified as short-term marketable securities. Marketable securities with remaining maturities of greater than one year from the balance sheet date are classified as long-term marketable securities.

Restricted Cash

Concentration of Credit Risk and of Significant Customers and Suppliers

Fair Value Measurements

•

Level 1—Quoted prices in active markets for identical assets or liabilities.

•

Property and Equipment

Property and equipment are stated at cost less accumulated depreciation. Depreciation expense is recognized using the straight-line method over the following estimated useful lives:


Laboratory and office equipment	5 years
Leasehold improvements	Shorter of life of lease or estimated useful life
Purchased software	3 years
Computer equipment	3 years
Furniture	7 years

Leases

Impairment of Long-Lived Assets

Revenue Recognition

royalties for which the license is deemed to be the predominant item to which the royalties relate and thus the Company recognizes sales-based royalties as the underlying sales are earned.

Research and Development Costs

Research and Development and Clinical Manufacturing Accruals

Research and Development and Pharmaceutical Drug Manufacturing Accruals

Patent Costs

All patent-related costs incurred in connection with filing and prosecuting patent applications are recorded as general and administrative expenses as incurred.

Stock-Based Compensation

Income Taxes

Net Income (Loss) per Share


	Years Ended September 30,
	2022		2021		2020
	(in thousands)
Options to purchase common stock		3,993		3,852		3,262
Unvested rTSRUs		101		111		46
Unvested PSUs		101		111		46
Unvested restricted stock units		219		117		45

Segment Data

Comprehensive Income (Loss)

Going Concern

Recently Adopted and Issued Accounting Pronouncements

Recently Adopted Accounting Pronouncements

Recently Issued Accounting Pronouncements

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Sep. 30, 2022

Accounting Policies [Abstract]

Property and Equipment Estimated Useful Lives

Property and equipment are stated at cost less accumulated depreciation. Depreciation expense is recognized using the straight-line method over the following estimated useful lives:


Laboratory and office equipment	5 years
Leasehold improvements	Shorter of life of lease or estimated useful life
Purchased software	3 years
Computer equipment	3 years
Furniture	7 years

Diluted Net Loss Per Share With Anti-dilutive effect

The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect:


	Years Ended September 30,
	2022		2021		2020
	(in thousands)
Options to purchase common stock		3,993		3,852		3,262
Unvested rTSRUs		101		111		46
Unvested PSUs		101		111		46
Unvested restricted stock units		219		117		45

Fair Value of Financial Assets and Liabilities (Tables)

12 Months Ended

Sep. 30, 2022

Fair Value Disclosures [Abstract]

Financial Assets and Liabilities that were Subject to Fair Value Measurement on Recurring Basis


	Fair Value Measurements at September 30, 2022 Using:
	Level 1		Level 2		Level 3		Total
	(in thousands)
Assets:
Cash equivalents:
Money market funds	$	13,905	$	—	$	—	$	13,905
Marketable securities:
U.S. Treasury notes		91,328		—		—		91,328
Corporate bonds		—		76,411		—		76,411
Commercial paper		—		66,784		—		66,784
	$	105,233	$	143,195	$	—	$	248,428
Liabilities:
Series 1 nonconvertible preferred stock	$	—	$	—	$	1,423	$	1,423
	$	—	$	—	$	1,423	$	1,423


	Fair Value Measurements at September 30, 2021 Using:
	Level 1		Level 2		Level 3		Total
	(in thousands)
Assets:
Cash equivalents:
Money market funds	$	54,819	$	—	$	—	$	54,819
Marketable securities:
U.S. Treasury notes		83,038		—		—		83,038
Corporate bonds		—		124,703		—		124,703
Commercial paper		—		87,471		—		87,471
	$	137,857	$	212,174	$	—	$	350,031
Liabilities:
Series 1 nonconvertible preferred stock	$	—	$	—	$	1,506	$	1,506
	$	—	$	—	$	1,506	$	1,506

Fair Value Measurements of the Company's Series 1 Nonconvertible Preferred Stock


Series 1 nonconvertible preferred stock	Range
	September 30,
Unobservable Input	2022	2021
Probabilities of payout	0%-65%	0%-65%
Discount rate	7.25%	4.25%

Rollforward of Aggregate Fair Value of Company's Outstanding Series 1 Nonconvertible Preferred Stock

The following table provides a rollforward of the aggregate fair value of the Company’s outstanding Series 1 nonconvertible preferred stock for which fair value is determined by Level 3 inputs:


	Series 1 Nonconvertible Preferred Stock
	(in thousands)
Balance, September 30, 2019	$	1,628
Decrease in fair value		(149	)
Balance, September 30, 2020		1,479
Increase in fair value		27
Balance, September 30, 2021		1,506
Decrease in fair value		(83	)
Balance, September 30, 2022	$	1,423

Marketable Securities (Tables)

12 Months Ended

Sep. 30, 2022

Investments, Debt and Equity Securities [Abstract]

Fair Value of Available-for-Sale Marketable Securities by Type of Security

As of September 30, 2022 and 2021, the fair value of available-for-sale marketable securities, by type of security, was as follows:


	September 30, 2022
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Credit Losses		Fair Value
	(in thousands)
Corporate bonds	$	78,663	$	—	$	(2,252	)	$	—	$	76,411
Commercial paper		66,784		—		—			—		66,784
U.S. Treasury notes		92,416		—		(1,088	)		—		91,328
	$	237,863	$	—	$	(3,340	)	$	—	$	234,523


	September 30, 2021
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Credit Losses		Fair Value
	(in thousands)
Corporate bonds	$	124,678	$	93	$	(68	)	$	—	$	124,703
Commercial paper		87,471		—		—			—		87,471
U.S. Treasury notes		83,061		3		(26	)		—		83,038
	$	295,210	$	96	$	(94	)	$	—	$	295,212

Property and Equipment, Net (Tables)

12 Months Ended

Sep. 30, 2022

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment, Net

Property and equipment, net consisted of the following as of September 30, 2022 and 2021:


	September 30,
	2022			2021
	(in thousands)
Laboratory and office equipment	$	14,780		$	14,499
Leasehold improvements		7,276			7,140
Purchased software		1,412			1,387
Furniture		1,354			1,294
Computer equipment		653			529
Construction in progress		2,556			20
		28,031			24,869
Less: Accumulated depreciation and amortization		(21,858	)		(18,926	)
	$	6,173		$	5,943

Accrued Expenses and Other Current Liabilities (Tables)

12 Months Ended

Sep. 30, 2022

Payables and Accruals [Abstract]

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following as of September 30, 2022 and 2021:


	September 30,
	2022		2021
	(in thousands)
Accrued pharmaceutical drug manufacturing	$	6,932	$	8,402
Accrued research and development expenses		5,532		6,062
Accrued payroll and related expenses		6,439		6,094
Accrued other		2,033		1,871
	$	20,936	$	22,429

Collaboration Agreements (Tables)

12 Months Ended

Sep. 30, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Summary of Royalty Tiers Associated with Cumulative Calendar Year Net Sales Allocated to Each Royalty-bearing Product

The following table details the royalty tiers associated with cumulative calendar year net sales allocated to each royalty-bearing product as provided in the AbbVie Agreement:


Calendar Year Net Sales		Royalty Tier
(in thousands)		(%)
up to $500,000		10%
from $500,000 up to $750,000		12%
from $750,000 up to $1,000,000		14%
from $1,000,000 up to $2,500,000		17%
greater than or equal to $2,500,000		20%

Stock-Based Awards (Tables)

12 Months Ended

Sep. 30, 2022

Data Used to Determine Value of Stock Option Grants, Presented on Weighted Average Basis

The relevant data used to determine the value of the stock option awards are as follows, presented on a weighted average basis:


	Years Ended September 30,
	2022			2021			2020
Risk-free interest rate		1.72	%		0.61	%		1.41	%
Expected term (in years)		6.04			6.05			6.02
Expected volatility		47	%		52	%		53	%
Expected dividends		0	%		0	%		0	%
Weighted average grant date fair value	$	33.22		$	21.76		$	30.47

Summary of Stock Option Activity Including Performance Based Options

The following table summarizes stock option activity, including aggregate intrinsic value for the year ended September 30, 2022:


	Shares Issuable Under Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term in years		Aggregate Intrinsic Value
	(in thousands)							(in thousands)
Outstanding as of September 30, 2021		3,852		$	48.61		6.4	$	49,173
Granted		894			71.26
Exercised		(517	)		41.17
Forfeited		(236	)		66.76
Outstanding as of September 30, 2022		3,993		$	53.57		6.2	$	28,778
Options vested and expected to vest as of September 30, 2022		3,993		$	53.57		6.2	$	28,778
Options exercisable as of September 30, 2022		2,621		$	49.76		5.0	$	25,191

Summary of Additional Exercise and Grant Date Information


	Years Ended September 30,
	2022		2021		2020
	(in thousands)
Aggregate intrinsic value of stock options exercised	$	17,650	$	2,704	$	7,850
Proceeds to Company from stock options exercised	$	21,262	$	3,614	$	10,481

Summary of Restricted Stock Unit Activity

The following table summarizes the restricted stock unit activity for the year ending September 30, 2022:


	Restricted Stock Units			Weighted Average Grant Date Fair Value per Share
	(in thousands, except per share data)
Unvested at September 30, 2021		117		$	43.57
Granted		158			74.82
Vested		(29	)		43.57
Cancelled		(27	)		59.99
Unvested at September 30, 2022		219		$	64.03

Stock-Based Compensation Expense

The Company recorded the following stock-based compensation expense for the years ended September 30, 2022, 2021, and 2020:


	Years Ended September 30,
	2022		2021		2020
	(in thousands)
Research and development	$	9,728	$	10,075	$	10,096
General and administrative		17,241		10,916		9,479
	$	26,969	$	20,991	$	19,575

Stock-Based Compensation Expense


	Years Ended September 30,
	2022		2021		2020
	(in thousands)
Stock options	$	19,615	$	18,004	$	17,459
rTSRUs		1,597		1,537		1,216
PSUs		2,628		235		259
Restricted stock units		3,129		1,215		641
	$	26,969	$	20,991	$	19,575

Relative Total Stockholder Return Units [Member]

Data Used to Determine Value of Stock Option Grants, Presented on Weighted Average Basis

The table below sets forth the weighted average grant date fair value assumptions used to value the rTSRUs:


	Years Ended September 30,
	2022			2021			2020
Risk-free interest rate		0.94	%		0.13	%		1.62	%
Dividend yield		0	%		0	%		0	%
Expected volatility		80	%		74	%		68	%
Performance period (years)		1.97			1.97			2.03

Performance Share Units and Relative Total Stockholder Return Units [Member]

Summary of PSUs and rTSRUs Activity

The following table summarizes PSU and rTSRU activity (at target) for the year ended September 30, 2022:


	PSUs					rTSRUs
	Shares			Weighted Average Grant Date Fair Value per Share		Shares			Weighted Average Grant Date Fair Value per Share
	(in thousands, except per share data)
Unvested at September 30, 2021		111		$	49.31		111		$	31.26
Granted		36			76.84		36			54.67
Vested		(5	)		61.59		(18	)		40.13
Cancelled		(41	)		59.01		(28	)		37.78
Unvested at September 30, 2022		101		$	54.50		101		$	36.14

Leases (Tables)

12 Months Ended

Sep. 30, 2022

Leases [Abstract]

Components of Lease Expense for Real Estate and Equipment Leases and Other Information Related to Leases

The components of lease expense for the Company’s real estate and equipment leases were as follows:


	Years Ended September 30,
	2022		2021
	(in thousands)
Operating lease cost	$	6,294	$	5,861
Short-term lease cost		—		—
Variable lease cost		2,375		4,057
	$	8,669	$	9,918


	Years Ended September 30,
	2022			2021
	(in thousands)
Cash paid for amounts included in the measurement of operating lease liabilities	$	4,966		$	6,364
Operating lease liabilities arising from obtaining right-of-use assets	$	23,910		$	3,320

	September 30,
	2022			2021
Weighted-average remaining lease term - operating leases (in years)		7.42			1.43
Weighted-average discount rate - operating leases		6.96	%		6.08	%

Schedule of Future Annual Minimum Lease Payments

Future annual minimum lease payments relating to the Company's lease liabilities as of September 30, 2022 were as follows:


Years ended September 30,	(in thousands)
2023		2,290
2024		5,062
2025		5,216
2026		5,373
2027		5,196
Thereafter		11,912
Total future minimum lease payments		35,049
Less: imputed interest		(9,786	)
Total operating lease liabilities	$	25,263

Schedule of Lease Included in Balance Sheet


	September 30,
Included in the balance sheet:	2022		2021
	(in thousands)
Current operating lease liabilities	$	2,891	$	4,203
Operating lease liabilities, net of current portion		22,372		1,126
Total operating lease liabilities	$	25,263	$	5,329

Income Taxes (Tables)

12 Months Ended

Sep. 30, 2022

Income Tax Disclosure [Abstract]

Summary of Income Tax Benefit (Expense)

During the years ended September 30, 2022, 2021, and 2020, the Company recorded income tax benefit (expense) as follows:


	Years Ended September 30,
	2022			2021			2020
	(in thousands)
Current income tax benefit (expense):
Federal	$	—		$	28,721		$	8,491
State		449			205			941
Deferred income tax benefit (expense):
Federal		(16	)		(343	)		(8,916	)
State		—			—			(1,665	)
Income tax benefit (expense)	$	433		$	28,583		$	(1,149	)

Reconciliation of Income Tax Provision at Federal Statutory Income Tax Rate and Effective Tax Rate

A reconciliation of the U.S. federal statutory income tax rate to the Company’s effective tax rate is as follows:


	Years Ended September 30,
	2022				2021				2020
Federal statutory income tax rate		(21.0	)	%		(21.0	)	%		(21.0	)	%
State taxes, net of federal benefit		(2.9	)			(2.3	)			(2.8	)
Change in valuation allowance		30.8				9.9				52.1
Federal research and development tax credit		(4.6	)			(5.3	)			(13.3	)
Share-based compensation		(0.8	)			2.4				2.8
State research and development tax credit		(1.5	)			(0.8	)			(2.6	)
Change in deferred tax rate		(0.1	)			(9.5	)			(10.2	)
Other		(0.3	)			—				(1.7	)
Effective income tax rate		(0.4	)	%		(26.6	)	%		3.3		%

Changes in the Valuation Allowance for Deferred Tax Assets

Changes in the valuation allowance for deferred tax assets during the years ended September 30, 2022, 2021, and 2020 are as follows:


	Years Ended September 30,
	2022			2021			2020
	(in thousands)
Valuation allowance, beginning of year	$	(29,298	)	$	(18,259	)	$	—
Increase recorded to valuation allowance		(38,428	)		(11,039	)		—
Initial recording of valuation allowance		—			—			(18,259	)
Valuation allowance, end of year	$	(67,726	)	$	(29,298	)	$	(18,259	)

Net Deferred Tax Assets and Liabilities

Net deferred tax assets as of September 30, 2022 and 2021 consisted of the following:


	September 30,
	2022			2021
	(in thousands)
Deferred tax assets:
Share-based compensation	$	14,983		$	11,843
Tax credit carryforwards		20,663			13,170
Operating lease liability		6,007			1,232
Accrued compensation		1,362			1,284
Net operating loss carryforward		29,105			3,095
Accrued expenses		541			378
Other temporary differences		245			366
Total deferred tax assets		72,906			31,368
Valuation allowance		(67,726	)		(29,298	)
Net deferred tax assets		5,180			2,070

Deferred tax liabilities:
Operating lease, right-of-use assets		(5,606	)		(1,110	)
Depreciation		(88	)		(684	)
Prepaid expenses		(280	)		(275	)
Unrealized loss		794			(1	)
Total deferred tax liabilities		(5,180	)		(2,070	)
Net deferred income tax assets (liabilities)	$	—		$	—

Schedule of Reconciliation of Uncertain Tax Positions

A reconciliation of the beginning and ending amount of uncertain tax positions is summarized as follows:


	September 30,
	2022			2021
	(in thousands)
Beginning Balance	$	622		$	844
Additions based on tax positions for the current period		10			10
Reductions for tax positions due to lapse of statute of limitations		(367	)		(134	)
Reductions for tax positions of prior periods		(39	)		(98	)
Ending Balance	$	226		$	622

Nature of the Business - Additional Information (Detail)	12 Months Ended
	Sep. 30, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Entity incorporated, in year	1995

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Summary of Accounting and Financial Policies [Line Items]
Adjustment to fair value	$ 0	$ 0	$ 0
Cash and investment restricted as a collateral for outstanding letter of credit	3,968,000	608,000
Impairment losses on long-lived assets	0
Letter of Credit [Member]
Summary of Accounting and Financial Policies [Line Items]
Cash and investment restricted as a collateral for outstanding letter of credit	$ 3,968,000	$ 608,000
Maximum [Member]
Summary of Accounting and Financial Policies [Line Items]
Short-term investments maturity period	90 days
Short-term marketable securities maturity period	1 year
Minimum [Member]
Summary of Accounting and Financial Policies [Line Items]
Short-term marketable securities maturity period	90 days
Long-term marketable securities maturity period	1 year
Income tax benefit recognition, percentage of likelihood of being realized upon settlement	50.00%

Summary of Significant Accounting Policies - Property and Equipment Estimated Useful Lives (Detail)	12 Months Ended
	Sep. 30, 2022
Laboratory and Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment useful life	5 years
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Leasehold improvements useful life	Shorter of life of lease or estimated useful life
Purchased Software [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment useful life	3 years
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment useful life	3 years
Furniture [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment useful life	7 years

Summary of Significant Accounting Policies - Diluted Net Loss Per Share Attributable to Common Stockholders With Anti-dilutive effect (Detail) - shares shares in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Unvested PSUs [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	101	111	46
Unvested rTSRUs [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	101	111	46
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	3,993	3,852	3,262
Unvested Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	219	117	45

Fair Value of Financial Assets and Liabilities - Financial Assets and Liabilities that were Subject to Fair Value Measurement on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Assets:
Marketable securities	$ 234,523	$ 295,212
Assets, Fair Value Disclosure, Total	248,428	350,031
Liabilities:
Liabilities, Fair Value Disclosure, Total	1,423	1,506
Series 1 Nonconvertible Preferred Stock [Member]
Liabilities:
Liabilities	1,423	1,506	$ 1,479	$ 1,628
Level 1 [Member]
Assets:
Assets, Fair Value Disclosure, Total	105,233	137,857
Liabilities:
Liabilities, Fair Value Disclosure, Total	0	0
Level 1 [Member] \| Series 1 Nonconvertible Preferred Stock [Member]
Liabilities:
Liabilities	0	0
Level 2 [Member]
Assets:
Assets, Fair Value Disclosure, Total	143,195	212,174
Liabilities:
Liabilities, Fair Value Disclosure, Total	0	0
Level 2 [Member] \| Series 1 Nonconvertible Preferred Stock [Member]
Liabilities:
Liabilities	0	0
Level 3 [Member]
Assets:
Assets, Fair Value Disclosure, Total	0	0
Liabilities:
Liabilities, Fair Value Disclosure, Total	1,423	1,506
Level 3 [Member] \| Series 1 Nonconvertible Preferred Stock [Member]
Liabilities:
Liabilities	1,423	1,506
U.S. Treasury Notes [Member]
Assets:
Marketable securities	91,328	83,038
U.S. Treasury Notes [Member] \| Level 1 [Member]
Assets:
Marketable securities	91,328	83,038
U.S. Treasury Notes [Member] \| Level 2 [Member]
Assets:
Marketable securities	0	0
U.S. Treasury Notes [Member] \| Level 3 [Member]
Assets:
Marketable securities	0	0
Money Market Funds [Member]
Assets:
Cash equivalents	13,905	54,819
Money Market Funds [Member] \| Level 1 [Member]
Assets:
Cash equivalents	13,905	54,819
Money Market Funds [Member] \| Level 2 [Member]
Assets:
Cash equivalents	0	0
Money Market Funds [Member] \| Level 3 [Member]
Assets:
Cash equivalents	0	0
Commercial Paper [Member]
Assets:
Marketable securities	66,784	87,471
Commercial Paper [Member] \| Level 1 [Member]
Assets:
Marketable securities	0	0
Commercial Paper [Member] \| Level 2 [Member]
Assets:
Marketable securities	66,784	87,471
Commercial Paper [Member] \| Level 3 [Member]
Assets:
Marketable securities	0	0
Corporate Bonds [Member]
Assets:
Marketable securities	76,411	124,703
Corporate Bonds [Member] \| Level 1 [Member]
Assets:
Marketable securities	0	0
Corporate Bonds [Member] \| Level 2 [Member]
Assets:
Marketable securities	76,411	124,703
Corporate Bonds [Member] \| Level 3 [Member]
Assets:
Marketable securities	$ 0	$ 0

Fair Value of Financial Assets and Liabilities - Additional Information (Detail) - USD ($)	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Transfers between Level 1, Level 2 and Level 3	$ 0	$ 0	$ 0

Fair Value of Financial Assets and Liabilities - Fair Value Measurements of the Company's Series 1 Nonconvertible Preferred Stock (Detail) - Level 3 [Member] - Series 1 Nonconvertible Preferred Stock [Member]	Sep. 30, 2022	Sep. 30, 2021
Probabilities of Payout [Member] \| Minimum [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Range	0	0
Probabilities of Payout [Member] \| Maximum [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Range	65	65
Discount Rate [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Range	7.25	4.25

Fair Value of Financial Assets and Liabilities - Rollforward of Aggregate Fair Value of Company's Outstanding Series 1 Nonconvertible Preferred Stock (Detail) - Series 1 Nonconvertible Preferred Stock [Member] - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 1,506	$ 1,479	$ 1,628
Increase (Decrease) in fair value	(83)	27	(149)
Ending Balance	$ 1,423	$ 1,506	$ 1,479

Marketable Securities - Fair Value of Available-for-Sale Marketable Securities by Type of Security (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 237,863	$ 295,210
Gross Unrealized Gains	0	96
Gross Unrealized Losses	(3,340)	(94)
Fair value	234,523	295,212
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	78,663	124,678
Gross Unrealized Gains	0	93
Gross Unrealized Losses	(2,252)	(68)
Fair value	76,411	124,703
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	66,784	87,471
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Fair value	66,784	87,471
U.S. Treasury Notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	92,416	83,061
Gross Unrealized Gains	0	3
Gross Unrealized Losses	(1,088)	(26)
Fair value	$ 91,328	$ 83,038

Marketable Securities - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Schedule of Available-for-sale Securities [Line Items]
Long-term marketable securities	$ 29,285	$ 108,416
Short Term Marketable Securities [Member] \| Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
Maturity period of the marketable securities	1 year
Corporate Bonds and U.S. Treasury Notes [Member] \| Long Term Marketable Securities [Member] \| Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
Maturity period of the marketable securities	3 years
Corporate Bonds and U.S. Treasury Notes [Member] \| Long Term Marketable Securities [Member] \| Minimum [Member]
Schedule of Available-for-sale Securities [Line Items]
Maturity period of the marketable securities	1 year

Property and Equipment, Net - Schedule of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021
Property, Plant and Equipment [Line Items]
Property and equipment	$ 28,031	$ 24,869
Less: Accumulated depreciation and amortization	(21,858)	(18,926)
Property and equipment, net	6,173	5,943
Laboratory and Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	14,780	14,499
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	7,276	7,140
Purchased Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	1,412	1,387
Furniture [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	1,354	1,294
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	653	529
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 2,556	$ 20

Property and Equipment, Net - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	$ 2,973	$ 3,334	$ 3,644

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021
Accrued expenses and other current liabilities:
Accrued pharmaceutical drug manufacturing	$ 6,932	$ 8,402
Accrued research and development expenses	5,532	6,062
Accrued payroll and related expenses	6,439	6,094
Accrued other	2,033	1,871
Accrued expenses	$ 20,936	$ 22,429

Collaboration Agreements - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended			190 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2022
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone revenue payments received	$ 86,160	$ 97,074	$ 122,473
AbbVie [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration agreement tiered royalty description	from ten percent up to twenty percent, or on a blended basis from ten percent up to the high teens, on the portion of AbbVie’s calendar year net sales
Agreement continuation period	10 years
Collaboration arrangement aggregate amount received				$ 1,207,000

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8906-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e9031-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e9038-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8933-108599

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8933-108599

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126920106&loc=SL49130543-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8736-108599

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8736-108599

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e9054-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI https://asc.fasb.org/extlink&oid=126920106&loc=SL49130545-203045

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 924
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-URI https://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856

+ Details

Collaboration Agreements - Summary of Royalty Tiers Associated with Cumulative Calendar Year Net Sales Allocated to Each Royalty-bearing Product (Detail) - AbbVie [Member] $ in Thousands	12 Months Ended
	Sep. 30, 2022 USD ($)
Scenario One [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Royalty Tier	10.00%
Scenario One [Member] \| Maximum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Calendar Year Net Sales	$ 500,000
Scenario Two [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Royalty Tier	12.00%
Scenario Two [Member] \| Minimum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Calendar Year Net Sales	$ 500,000
Scenario Two [Member] \| Maximum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Calendar Year Net Sales	$ 750,000
Scenario Three [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Royalty Tier	14.00%
Scenario Three [Member] \| Minimum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Calendar Year Net Sales	$ 750,000
Scenario Three [Member] \| Maximum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Calendar Year Net Sales	$ 1,000,000
Scenario Four [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Royalty Tier	17.00%
Scenario Four [Member] \| Minimum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Calendar Year Net Sales	$ 1,000,000
Scenario Four [Member] \| Maximum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Calendar Year Net Sales	$ 2,500,000
Scenario Five [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Royalty Tier	20.00%
Scenario Five [Member] \| Minimum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Calendar Year Net Sales	$ 2,500,000

Stockholders' Equity - Additional Information (Detail) - $ / shares shares in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Class Of Stock [Line Items]
Common stock, shares authorized	100,000	100,000
Common stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000
Preferred stock, par value per share	$ 0.01
Shares are undesignated and unissued	3,000
Common stock voting rights, description	Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders
Series 1 Nonconvertible Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, shares authorized	2,000
Preferred stock, par value per share	$ 0.01

Series 1 Nonconvertible Preferred Stock - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Class Of Stock [Line Items]
Preferred stock, shares authorized	5,000
Preferred stock, par value per share	$ 0.01
Change in fair value of Series 1 nonconvertible preferred stock	$ 83	$ (27)	$ 149
Fair value of the Series 1 nonconvertible preferred stock	$ 1,423	$ 1,506
Series 1 Nonconvertible Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, shares authorized	2,000
Preferred stock, par value per share	$ 0.01
Per share value adjusted for stock dividend	1.00
Preferred stock redemption price per share	$ 1.00
Redemption period	60 days
Preferred stock, shares issued	1,930	1,930
Preferred stock, shares outstanding	1,930	1,930
Change in fair value of Series 1 nonconvertible preferred stock	$ 83	$ (27)	$ 149
Fair value of the Series 1 nonconvertible preferred stock	$ 1,423	$ 1,506

Stock-Based Awards - Additional Information (Detail) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%	0.00%
Aggregate of unrecognized stock-based compensation cost	$ 55,346
Weighted average recognition period	2 years 4 months 24 days
PSUs and rTSRUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total fair value, vested during period	$ 1,414	$ 0	$ 1,227
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total fair value, vested during period	$ 2,427	$ 1,897	$ 3,149
Restricted Stock Units [Member] \| Service Based [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Executive Officers [Member] \| Relative Total Stockholder Return Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares range percentage	0.00%
Number of shares range percentage	150.00%
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock reserved for issuance	186
Shares issued	0
2019 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant	1,363
Options granted, expiration period	10 years
2019 Equity Incentive Plan [Member] \| Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
2019 Equity Incentive Plan [Member] \| Non-Employee Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year

Stock-Based Awards - Data Used to Determine Value of Stock Option Grants, Presented on Weighted Average Basis (Detail) - $ / shares	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Share Based Payment Award Stock Options Valuation Assumptions [Line Items]
Risk-free interest rate	1.72%	0.61%	1.41%
Expected term (in years)	6 years 14 days	6 years 18 days	6 years 7 days
Expected volatility	47.00%	52.00%	53.00%
Expected dividends	0.00%	0.00%	0.00%
Weighted average grant date fair value	$ 33.22	$ 21.76	$ 30.47
Executive Officer [Member] \| Relative Total Stockholder Return Units [Member]
Share Based Payment Award Stock Options Valuation Assumptions [Line Items]
Expected term (in years)	1 year 11 months 19 days	1 year 11 months 19 days	2 years 10 days
Expected volatility	80.00%	74.00%	68.00%
Risk-free interest rate	0.94%	0.13%	1.62%
Dividend yield	0.00%	0.00%	0.00%

Stock-Based Awards - Summary of Stock Option Activity Including Performance Based Options (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Options
Outstanding as of beginning of period	3,852
Granted	894
Exercised	(517)
Forfeited	(236)
Outstanding as of end of period	3,993	3,852
Options vested and expected to vest as of end of period	3,993
Options exercisable as of end of period	2,621
Weighted Average Exercise Price
Outstanding	$ 48.61
Granted	71.26
Exercised	41.17
Forfeited	66.76
Outstanding	53.57	$ 48.61
Options vested and expected to vest as of end of period	53.57
Options exercisable as of end of period	$ 49.76
Weighted Average Remaining Contractual Term
Outstanding as of end of period	6 years 2 months 12 days	6 years 4 months 24 days
Options vested and expected to vest as of end period	6 years 2 months 12 days
Options exercisable as of end of period	5 years
Aggregate Intrinsic Value
Aggregate Intrinsic Value	$ 28,778	$ 49,173
Options vested and expected to vest as of end of period	28,778
Options exercisable as of end of period	25,191
Aggregate intrinsic value of stock options exercised	17,650	2,704	$ 7,850
Proceeds to Company from stock options exercised	$ 21,262	$ 3,614	$ 10,481

Stock-Based Awards - Summary of PSUs and rTSRUs Activity (Detail) shares in Thousands	12 Months Ended
	Sep. 30, 2022 $ / shares shares
PSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested, beginning balance \| shares	111
Granted \| shares	36
Vested \| shares	(5)
Cancelled \| shares	(41)
Unvested, ending balance \| shares	101
Weighted Average Grant Date Fair Value Per Share, Unvested beginning balance \| $ / shares	$ 49.31
Weighted Average Grant Date Fair Value Per Share, Granted \| $ / shares	76.84
Weighted Average Grant Date Fair Value Per Share, Vested \| $ / shares	61.59
Weighted Average Grant Date Fair Value Per Share, Cancelled \| $ / shares	59.01
Weighted Average Grant Date Fair Value Per Share, Unvested ending balance \| $ / shares	$ 54.50
rTSRUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested, beginning balance \| shares	111
Granted \| shares	36
Vested \| shares	(18)
Cancelled \| shares	(28)
Unvested, ending balance \| shares	101
Weighted Average Grant Date Fair Value Per Share, Unvested beginning balance \| $ / shares	$ 31.26
Weighted Average Grant Date Fair Value Per Share, Granted \| $ / shares	54.67
Weighted Average Grant Date Fair Value Per Share, Vested \| $ / shares	40.13
Weighted Average Grant Date Fair Value Per Share, Cancelled \| $ / shares	37.78
Weighted Average Grant Date Fair Value Per Share, Unvested ending balance \| $ / shares	$ 36.14

Stock-Based Awards - Summary of Restricted Stock Unit Activity (Detail) - Restricted Stock Units [Member] shares in Thousands	12 Months Ended
	Sep. 30, 2022 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested, beginning balance \| shares	117
Granted \| shares	158
Vested \| shares	(29)
Cancelled \| shares	(27)
Unvested, ending balance \| shares	219
Weighted Average Grant Date Fair Value Per Share, Unvested beginning balance \| $ / shares	$ 43.57
Weighted Average Grant Date Fair Value Per Share, Granted \| $ / shares	74.82
Weighted Average Grant Date Fair Value Per Share, Vested \| $ / shares	43.57
Weighted Average Grant Date Fair Value Per Share, Cancelled \| $ / shares	59.99
Weighted Average Grant Date Fair Value Per Share, Unvested ending balance \| $ / shares	$ 64.03

Stock-Based Awards - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 26,969	$ 20,991	$ 19,575
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	19,615	18,004	17,459
PSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	2,628	235	259
rTSRUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	1,597	1,537	1,216
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	3,129	1,215	641
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	9,728	10,075	10,096
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 17,241	$ 10,916	$ 9,479

Leases - Additional Information (Detail) $ in Thousands			1 Months Ended	12 Months Ended
Leases - Additional Information (Detail) $ in Thousands	Nov. 19, 2021	Sep. 30, 2018	May 31, 2022 USD ($)	Sep. 30, 2022 USD ($) Lease	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2011
Lessee Lease Description [Line Items]
Number of Leases \| Lease				2
Increase in operating lease, right-of-use assets				$ (4,776)	$ (5,418)	$ (3,184)
Increase in operating lease liabilities				(3,706)	(5,879)	$ (3,535)
Lease Payment				4,966	6,364
Lease Payment				35,049
Security deposit of real estate lease				652
Cash and investment restricted as a collateral for outstanding letter of credit				3,968	608
Letter of Credit [Member]
Lessee Lease Description [Line Items]
Cash and investment restricted as a collateral for outstanding letter of credit				$ 3,968	$ 608
Equipment [Member]
Lessee Lease Description [Line Items]
Operating lease, description				The Company leases units of equipment over eighteen-month lease periods commencing upon shipment of each unit. The lease agreements contain options to terminate the leases early or to extend the leases for successive six-month periods
500 Arsenal Street, Watertown, Massachusetts [Member]
Lessee Lease Description [Line Items]
Office lease expiration period	Sep. 01, 2027
Office lease expiration period							2022-09
Lease option to extend							an option to extend the lease term for an additional five years.
Lease extension term	extend the lease term for an additional five years
Increase in operating lease, right-of-use assets				$ 15,076
Increase in operating lease liabilities				15,076
400 Talcott Avenue, Watertown, Massachusetts [Member]
Lessee Lease Description [Line Items]
Office lease expiration period			Jun. 01, 2034
Period of lease agreement		2018-09
Lease option to extend		two options to extend the lease term for an additional three years each.
Increase in operating lease, right-of-use assets				8,174
Increase in operating lease liabilities				$ 8,174
Lease periods commencing upon shipment		6 years
Tenant improvement allowance			$ 2,574
Adjacent to 400 Talcott Avenue, Watertown, Massachusetts [Member]
Lessee Lease Description [Line Items]
Lease periods commencing upon shipment			10 years
Tenant improvement allowance			$ 15,194
Lease Payment			$ 76,470

Leases - Components of Lease Expense for Real Estate and Equipment Leases and Other Information Related to Leases (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Leases [Abstract]
Operating lease cost	$ 6,294	$ 5,861
Short-term lease cost	0	0
Variable lease cost	2,375	4,057
Lease, cost	8,669	9,918
Cash paid for amounts included in the measurement of operating lease liabilities	4,966	6,364
Operating lease liabilities arising from obtaining right-of-use assets	$ 23,910	$ 3,320	$ 3,053
Weighted-average remaining lease term - operating leases (in years)	7 years 5 months 1 day	1 year 5 months 4 days
Weighted-average discount rate - operating leases	6.96%	6.08%

Leases - Schedule of Future Annual Minimum Lease Payments (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021
Leases [Abstract]
2022	$ 2,290
2023	5,062
2024	5,216
2025	5,373
2026	5,196
Thereafter	11,912
Total future minimum lease payments	35,049
Less: Imputed interest	(9,786)
Total operating lease liabilities	$ 25,263	$ 5,329

Leases - Schedule of Lease Included in Balance Sheet (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021
Leases [Abstract]
Operating lease liabilities	$ 2,891	$ 4,203
Operating lease liabilities, net of current portion	22,372	1,126
Total operating lease liabilities	$ 25,263	$ 5,329

Income Taxes - Summary of Income Tax Benefit (Expense) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Current income tax benefit (expense):
Federal		$ 28,721	$ 8,491
State	$ 449	205	941
Deferred income tax benefit (expense):
Federal	(16)	(343)	(8,916)
State		0	(1,665)
Income tax benefit (expense)	$ 433	$ 28,583	$ (1,149)

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

Income Taxes - Reconciliation of Income Tax Provision at Federal Statutory Income Tax Rate and Effective Tax Rate (Detail)	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Federal statutory income tax rate	(21.00%)	(21.00%)	(21.00%)
State taxes, net of federal benefit	(2.90%)	(2.30%)	(2.80%)
Change in valuation allowance	30.80%	9.90%	52.10%
Federal research and development tax credit	(4.60%)	(5.30%)	(13.30%)
Share-based compensation	(0.80%)	2.40%	2.80%
State research and development tax credit	(1.50%)	(0.80%)	(2.60%)
Change in deferred tax rate	(0.10%)	(9.50%)	(10.20%)
Other	(0.30%)	(0.00%)	(1.70%)
Effective income tax rate	(0.40%)	(26.60%)	3.30%

Income Taxes - Changes in the Valuation Allowance for Deferred Tax Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Valuation allowance, beginning of year	$ (29,298)	$ (18,259)	$ 0
Increase recorded to valuation allowance	(38,428)	(11,039)	0
Initial recording of valuation allowance	0	0	(18,259)
Valuation allowance, end of year	$ (67,726)	$ (29,298)	$ (18,259)

Income Taxes - Net Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Deferred tax assets:
Share-based compensation	$ 14,983	$ 11,843
Tax credit carryforwards	20,663	13,170
Operating lease liability	6,007	1,232
Accrued compensation	1,362	1,284
Net operating loss carryforward	29,105	3,095
Accrued expenses	541	378
Other temporary differences	245	366
Total deferred tax assets	72,906	31,368
Valuation allowance, beginning of year	(67,726)	(29,298)	$ (18,259)	$ 0
Net deferred tax assets	5,180	2,070
Deferred tax liabilities:
Operating lease, right-of-use assets	(5,606)	(1,110)
Depreciation	(88)	(684)
Prepaid expenses	(280)	(275)
Unrealized loss	794	(1)
Total deferred tax liabilities	(5,180)	(2,070)
Net deferred income tax assets (liabilities)	$ 0	$ 0

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Income Tax [Line Items]
Valuation allowance	$ 67,726	$ 29,298	$ 18,259	$ 0
Description of effects of COVID-19	In response to the COVID-19 pandemic, the CARES Act was signed into law in March 2020. The CARES Act lifted certain deduction limitations originally imposed by the Tax Cuts and Jobs Act of 2017 (the “Tax Act”). Under the CARES Act, the Company was permitted to carryback net operating losses for up to five years for losses generated in fiscal 2018 through fiscal 2021. Net operating loss carrybacks were previously prohibited under the Tax Act. The CARES Act also eliminated the 80% of taxable income limitations by allowing corporate entities to fully utilize net operating loss carryforwards to offset taxable income in fiscal years 2018, 2019 or 2020. In addition, the CARES Act made qualified improvement property eligible for 15-year cost-recovery and 100% bonus depreciation. The enactment of the CARES Act resulted in a $28,721 and $8,581 income tax benefit related to a federal net operating loss carryback at the previously enacted 35% rate in the Company’s consolidated financial statements during the years ended September 30, 2021 and 2020, respectively.
Federal income tax expense (benefit), continuing operations	$ (433)	$ (28,583)	$ 1,149
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	21.00%
Liability for uncertainty in income taxes, current	$ 44	$ 105
Income tax receivable	$ 28,718	37,255
Percentage of annual tax deduction	80.00%
Net operating loss carryforward	$ 29,105	3,095
Earliest Tax Year [Member]
Income Tax [Line Items]
Open tax year	2018
Federal [Member]
Income Tax [Line Items]
Research and development tax credit carryforward	$ 16,870
Operating Loss Carryforwards	$ 109,363
Tax credit carry forward expiration year	2039
State [Member]
Income Tax [Line Items]
Research and development tax credit carryforward	$ 4,986
Operating Loss Carryforwards	$ 97,128
Net operating loss carryforward, state, expiration year	2040
Tax credit carry forward expiration year	2034
CARES Act [Member]
Income Tax [Line Items]
Federal income tax expense (benefit), continuing operations		$ 28,721	$ 8,581
Prior to CARES Act [Member]
Income Tax [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		35.00%	35.00%

Income Taxes - Schedule of Reconciliation of Uncertain Tax Positions (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Beginning Balance	$ 622	$ 844
Additions based on tax positions for the current period	10	10
Reductions for tax positions due to lapse of statute of limitations	(367)	(134)
Reductions for tax positions of prior periods	(39)	(98)
Ending Balance	$ 226	$ 622

401(k) Plan - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Compensation Related Costs [Abstract]
Benefits charged to operating expenses	$ 1,596	$ 1,353	$ 1,190