0000950170-24-055581 | 10-Q | XBRL Viewer | Enanta Pharmaceuticals INC

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Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares shares in Thousands	Mar. 31, 2024	Sep. 30, 2023
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	21,179	21,059
Common stock, shares outstanding	21,179	21,059

Accrued Expenses

6 Months Ended

Mar. 31, 2024

Payables and Accruals [Abstract]

Accrued Expenses

5. Accrued Expenses

Accrued expenses and other current liabilities consisted of the following as of March 31, 2024 and September 30, 2023:


	March 31,		September 30,
	2024		2023
	(in thousands)
Accrued professional fees	$	3,547	$	1,632
Accrued payroll and related expenses		2,967		7,037
Accrued research and development expenses		1,529		6,120
Accrued pharmaceutical drug manufacturing		1,515		3,083
Accrued other		1,072		467
	$	10,630	$	18,339

Income Taxes	6 Months Ended
Mar. 31, 2024
Income Tax Disclosure [Abstract]
Income Taxes	10. Income Taxes For the six months ended March 31, 2024, the Company recorded an income tax benefit of $985 due to interest recorded on a pending federal income tax refund as compared to income tax expense of $10 during the six months ended March 31, 2023.

Income Taxes

6 Months Ended

Mar. 31, 2024

Income Tax Disclosure [Abstract]

Income Taxes

10. Income Taxes

For the six months ended March 31, 2024, the Company recorded an income tax benefit of $985 due to interest recorded on a pending federal income tax refund as compared to income tax expense of $10 during the six months ended March 31, 2023.

- 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.

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+ Details

Commitment and Contingencies (Tables)

6 Months Ended

Mar. 31, 2024

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Annual Minimum Lease Payments

Future annual minimum facility and equipment lease payments, net of the tenant improvement allowance under the Company’s 4 Kingsbury Avenue lease as of March 31, 2024, are as follows:


Years ended September 30,	(in thousands)
2024	$	3,289
2025		8,158
2026		8,467
2027		8,721
2028		8,983
Thereafter		59,191
Total future minimum lease payments		96,809
Less: imputed interest		(34,763	)
Less: tenant improvement allowance		(15,053	)
Total operating lease liabilities	$	46,993

Marketable Securities - Fair Value of Available-for-Sale Marketable Securities by Type of Security (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Sep. 30, 2023
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 237,051	$ 285,312
Gross Unrealized Gains	2	12
Gross Unrealized Losses	(285)	(802)
Fair Value	236,768	284,522
U.S. Treasury Notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	218,561	236,880
Gross Unrealized Gains	2	12
Gross Unrealized Losses	(192)	(110)
Fair Value	218,371	236,782
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	18,490	27,127
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(93)	(692)
Fair Value	$ 18,397	26,435
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		21,305
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Fair Value		$ 21,305

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

Fair Value of Financial Assets and Liabilities - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended		6 Months Ended
	Apr. 30, 2023	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers between Level 1, Level 2 and Level 3		$ 0	$ 0	$ 0	$ 0
Omers Royalty Sale Agreement [Member ]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Proceeds from sale of future royalties	$ 200,000,000
Percentage of future quarterly royalty payments on net sales received in cash	54.50%
Future quarterly royalty payments, description	after June 30, 2023, through June 30, 2032, subject to a cap on aggregate payments equal to 1.42 times the purchase price.
Series 1 Nonconvertible Preferred Stock [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in fair value of nonconvertible preferred stock		$ 0	$ 0

Series 1 Nonconvertible Preferred Stock - Additional Information (Detail) - Series 1 Nonconvertible Preferred Stock [Member] shares in Thousands	Mar. 31, 2024 shares
Class Of Stock [Line Items]
Preferred stock, shares issued	1,930
Preferred stock, shares outstanding	1,930

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

Stock-Based Awards

6 Months Ended

Mar. 31, 2024

Share-Based Payment Arrangement [Abstract]

Stock-Based Awards

9. 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, March 2022, March 2023 and March 2024, and its 2024 Inducement Stock Incentive Plan, which was adopted by the Board of Directors in April 2024 for awards to new employees. The Company also has outstanding stock option awards under its 2012 Equity Incentive Plan (the “2012 Plan”) but is no longer granting awards under this plan.

The following table summarizes stock option activity, including performance-based options, for the year-to-date period ending March 31, 2024:


	Shares Issuable Under Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
	(in thousands)					(in years)		(in thousands)
Outstanding as of September 30, 2023		4,365		$	52.68		5.9	$	—
Granted		1,196			9.54
Exercised		(6	)		8.99
Forfeited		(318	)		39.18
Outstanding as of March 31, 2024		5,237		$	43.70		6.6	$	9,273
Options vested and expected to vest as of March 31, 2024		5,237		$	43.70		6.6	$	9,273
Options exercisable as of March 31, 2024		3,229		$	52.51		5.1	$	523

Market and Performance-Based Stock Unit Awards

The Company awards both performance share units, or PSUs, and relative total stockholder return units, or rTSRUs, to its executive officers. The number of units granted 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. The number of shares cancelled represents the target number of shares, less any shares that vested. The following table summarizes PSU and rTSRU activity for the year-to-date period ending March 31, 2024:


	PSUs					rTSRUs
	Shares			Weighted Average Grant Date Fair Value		Shares			Weighted Average Grant Date Fair Value
	(in thousands)					(in thousands)
Unvested as of September 30, 2023		81		$	58.58		81		$	45.82
Granted		51			9.38		48			9.89
Vested		(25	)		68.67		—			—
Cancelled		(19	)		51.14		(41	)		47.25
Unvested as of March 31, 2024		88		$	28.71		88		$	25.50

Restricted Stock Units

The following table summarizes the restricted stock unit activity for the year-to-date period ending March 31, 2024:


	Restricted Stock Units			Weighted Average Grant Date Fair Value
	(in thousands)
Unvested as of September 30, 2023		411		$	51.78
Granted		167			9.09
Vested		(116	)		52.00
Cancelled		(19	)		26.93
Unvested as of March 31, 2024		443		$	36.68

Stock-Based Compensation Expense

During the three and six months ended March 31, 2024 and 2023, the Company recognized the following stock-based compensation expense:



	Three Months Ended March 31,				Six Months Ended March 31,
	2024		2023		2024		2023
	(in thousands)
Research and development	$	1,794	$	2,520	$	3,849	$	5,052
General and administrative		3,767		4,843		9,811		9,450
	$	5,561	$	7,363	$	13,660	$	14,502



	Three Months Ended March 31,				Six Months Ended March 31,
	2024		2023		2024		2023
	(in thousands)
Stock options	$	3,711	$	5,011	$	8,173	$	10,057
Restricted stock units		1,459		1,631		3,072		2,896
rTSRUs		258		546		703		1,007
Performance stock units		133		175		1,712		542
	$	5,561	$	7,363	$	13,660	$	14,502

During the three and six months ended March 31, 2024 and 2023, the Company recognized stock-based compensation expense for performance-based stock units for which vesting became probable upon achievement of performance-based targets that occurred during the performance period.

As of March 31, 2024, the Company had an aggregate of $52,286 of unrecognized stock-based compensation cost, which is expected to be recognized over a weighted average period of 2.1 years.

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Total revenue	$ 17,054	$ 17,795	$ 35,057	$ 41,380
Operating expenses:
Research and development	35,585	43,468	71,956	84,370
General and administrative	14,235	13,778	30,753	26,474
Total operating expenses	49,820	57,246	102,709	110,844
Loss from operations	(32,766)	(39,451)	(67,652)	(69,464)
Other income (expense):
Interest expense	(2,563)	0	(6,004)	0
Interest and investment income, net	3,809	1,837	8,107	2,830
Total other income, net	1,246	1,837	2,103	2,830
Loss before income taxes	(31,520)	(37,614)	(65,549)	(66,634)
Income tax benefit (expense)	363	(44)	985	(10)
Net loss	$ (31,157)	$ (37,658)	$ (64,564)	$ (66,644)
Net loss per share:
Basic	$ (1.47)	$ (1.79)	$ (3.06)	$ (3.19)
Diluted	$ (1.47)	$ (1.79)	$ (3.06)	$ (3.19)
Weighted average shares outstanding:
Basic	21,167	21,035	21,128	20,882
Diluted	21,167	21,035	21,128	20,882
Royalty [Member]
Total revenue	$ 17,054	$ 17,795	$ 35,057	$ 40,380
License [Member]
Total revenue	$ 0	$ 0	$ 0	$ 1,000

Stock-Based Awards - Additional Information (Detail) - USD ($) shares in Thousands	6 Months Ended
	Mar. 31, 2024	Sep. 30, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Shares, Issued	21,179	21,059
Aggregate of unrecognized stock-based compensation cost	$ 52,286
Weighted average recognition period	2 years 1 month 6 days
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%

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

AbbVie Collaboration

6 Months Ended

Mar. 31, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

AbbVie Collaboration

6. 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 $1,304,000 through March 31, 2024. 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.

AbbVie Collaboration - Additional Information (Detail) - AbbVie [Member]	6 Months Ended
	Mar. 31, 2024 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Cash consideration received under collaboration from milestone payments and royalties	$ 1,304,000
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

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities
Net loss	$ (64,564)	$ (66,644)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	13,660	14,502
Depreciation and amortization expense	1,263	1,051
Non cash interest expense associated with the sale of future royalties	(531)	0
Non-cash royalty revenue	1,013	0
Premium paid on marketable securities	0	(42)
Amortization (accretion) of premiums (discounts) on marketable securities	299	(1,345)
Loss on disposal of property and equipment	0	7
Change in operating assets and liabilities:
Accounts receivable	858	2,523
Prepaid expenses and other current assets	2,331	(1,039)
Income tax receivable	(1,027)	(56)
Operating lease, right-of-use assets	2,517	1,891
Other long-term assets	616	0
Accounts payable	261	5,963
Accrued expenses	(7,709)	(6,052)
Operating lease liabilities	(2,137)	(137)
Other long-term liabilities	(439)	(46)
Net cash used in operating activities	(53,589)	(49,424)
Cash flows from investing activities
Purchase of marketable securities	(212,134)	(90,627)
Proceeds from maturities and sale of marketable securities	260,096	176,500
Purchase of property and equipment	(2,455)	(5,539)
Net cash provided by investing activities	45,507	80,334
Cash flows from financing activities
Payments on royalty sale liability, net of imputed interest	(13,540)	0
Payments for settlement of share-based awards	(275)	(3,734)
Proceeds from exercise of stock options	51	2,008
Net cash used in financing activities	(13,764)	(1,726)
Net increase (decrease) in cash, cash equivalents and restricted cash	(21,846)	29,184
Cash, cash equivalents and restricted cash at beginning of period	89,356	47,962
Cash, cash equivalents and restricted cash at end of period	67,510	77,146
Supplemental disclosure of noncash information:
Purchases of fixed assets included in accounts payable and accrued expenses	2,792	1,611
Operating lease liabilities arising from obtaining right-of-use assets	22,617	2,870
Supplemental disclosure of cash flow information
Cash paid for interest	$ 6,575	$ 0

Commitment and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Sep. 30, 2023	May 31, 2022
Loss Contingencies [Line Items]
Minimum lease pyments	$ 96,809
Lease liability	46,993
Operating lease, right-of-use assets	42,894	$ 22,794
Tenant improvement allowance	(15,053)
500 Arsenal Street, Watertown, Massachusetts [Member]
Loss Contingencies [Line Items]
Increase in right of use asset and lease liability	9,322
Lease liability	22,617
400 Talcott Avenue, Watertown, Massachusetts [Member]
Loss Contingencies [Line Items]
Minimum lease pyments			$ 76,470
Lease periods commencing upon shipment			10 years
Operating lease, right-of-use assets	32,499
Lease Payment	$ 31,939
Tenant improvement allowance			$ 15,205

Summary of Significant Accounting Policies (Tables)

6 Months Ended

Mar. 31, 2024

Accounting Policies [Abstract]

Anti-dilutive Securities Excluded from the Computation of Diluted Net Loss

Therefore, the Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss as its effect would have been anti-dilutive:


	As of March 31,
	2024		2023
	(in thousands)
Options to purchase common stock		5,237		4,522
Unvested rTSRUs		88		81
Unvested PSUs		88		81
Unvested restricted stock units		443		430

Summary of Significant Accounting Policies - Anti-dilutive Securities Excluded from the Computation of Diluted Net Loss (Detail) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	5,237	4,522
Unvested rTSRUs [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	88	81
Unvested PSUs [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	88	81
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	443	430

Commitments and Contingencies

6 Months Ended

Mar. 31, 2024

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

11. 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. Except as described below, the Company currently is not a party to any material 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 condensed consolidated statements of operations.

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 condensed consolidated financial statements as of March 31, 2024.

Leases

The Company leases laboratory and office space under various non-cancelable operating leases.

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. The new lab and office space is located at Arsenal on the Charles in Watertown, Massachusetts at 4 Kingsbury Avenue. Construction of the facility shell was completed by the landlord and the Company gained access to the building to construct tenant improvements during the three months ended March 31, 2024. The estimated minimum lease payments for the 4 Kingsbury Avenue facility total $76,470 over the ten-year term. The lease also contains a tenant improvement allowance of $15,205. The Company recorded a right-of-use asset of $32,499 and lease liability of $31,939 upon commencement of the lease during the three months ended March 31, 2024.

In conjunction with the new lease agreement at 4 Kingsbury Avenue, the Company amended its 500 Arsenal Street lease to shorten the term of the lease from September 2027 to the date the 4 Kingsbury Avenue facility is ready for the Company’s occupancy which is expected to be by the end of November 2024. The Company remeasured the lease term and remaining lease payments for the 500 Arsenal Street facility during the three months ended March 31, 2024 when the Company gained access to the 4 Kingsbury Avenue building. The Company recorded an adjustment to the right-of-use asset and lease liability for 500 Arsenal Street of $9,322.

The noncash change arising from the new 4 Kingsbury Avenue lease, net of the remeasurement of the 500 Arsenal lease liability totaled $22,617 during the six months ended March 31, 2024.

Future annual minimum facility and equipment lease payments, net of the tenant improvement allowance under the Company’s 4 Kingsbury Avenue lease as of March 31, 2024, are as follows:


Years ended September 30,	(in thousands)
2024	$	3,289
2025		8,158
2026		8,467
2027		8,721
2028		8,983
Thereafter		59,191
Total future minimum lease payments		96,809
Less: imputed interest		(34,763	)
Less: tenant improvement allowance		(15,053	)
Total operating lease liabilities	$	46,993

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Mar. 31, 2024 $ / shares shares
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	Rule 10b5-1 Trading Arrangements. During the three months ended March 31, 2024, the following officers (as defined in Rule 16a-1(f) under the Exchange Act) of the Company adopted a “Rule 10b5-1 trading arrangement” as that term is defined in Item 408(a) of Regulation S-K, all of which were entered into during an open trading window in accordance with the Company’s Securities Trading Policy and all of which were intended to satisfy Rule 10b5-1(c): • On March 14, 2024, Tara L. Kieffer, Ph.D., our Chief Product Strategy Officer, adopted a Rule 10b5-1 trading plan providing for the sale of up to 37, 288 shares of our common stock, including shares vested under performance stock units and restricted stock units, as well as shares vesting under outstanding stock options, so long as the market price of our common stock is higher than certain minimum threshold prices specified in the plan in various periods between June 17, 2024 and May 30, 2025, or such earlier date as all authorized sales under the plan are completed; • On March 15, 2024, Yat Sun Or, our Chief Scientific Officer, adopted a Rule 10b5-1 trading plan providing for the sale of up to (i) 25,171 shares of our common stock and (ii) 36,500 shares of our common stock subject to vested stock options with an exercise price of $44.00 that are due to expire on November 20, 2024, so long as in each case the market price of our common stock is higher than certain minimum threshold prices specified in the plan, in various periods between June 17, 2024 and December 31, 2024, or such earlier date as all authorized sales under the plan are completed; and • On March 15, 2024, Scott T. Rottinghaus, M.D., our Chief Medical Officer, adopted a Rule 10b5-1 trading plan providing for the sale of up to 25,695 shares of our common stock, including shares vested under performance stock units and restricted stock units, as well as shares vesting under outstanding stock options and restricted stock units, so long as the market price of our common stock is higher than certain minimum threshold prices specified in the plan, in various periods between June 17, 2024 and March 31, 2025, or such earlier date as all authorized sales under the plan are completed. Except as set forth above, no director or officer (as defined in Rule 16a-1(f) under the Exchange Act) of the Company adopted or terminated a “Rule 10b5-1 trading arrangement” or “non-rule 10b5-1 trading arrangement,” as each term is defined in item 408(a) of Regulation S-K.
Non-Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Terminated	false
Tara L Kieffer
Trading Arrangements, by Individual
Name	Tara L. Kieffer
Title	Chief Product Strategy Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	March 14, 2024
Arrangement Duration	347 days
Aggregate Available	37,288
Yat Sun Or
Trading Arrangements, by Individual
Name	Yat Sun Or
Title	Chief Scientific Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	March 15, 2024
Termination Date	November 20, 2024
Arrangement Duration	197 days
Aggregate Available	25,171
Exercise Price \| $ / shares	$ 44
Scott T. Rottinghaus
Trading Arrangements, by Individual
Name	Scott T. Rottinghaus
Title	Chief Medical Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	March 15, 2024
Arrangement Duration	287 days
Aggregate Available	25,695

Liability Related to the Sale of Future Royalties

6 Months Ended

Mar. 31, 2024

Nonmonetary Transactions [Abstract]

7. Liability Related to the Sale of Future Royalties

Because the royalty sale agreement will be paid back to OMERS up to a capped amount as well as the Company’s significant continuing involvement in the generation of future cash flows under its AbbVie Agreement, the Company recorded the proceeds from the transaction as a liability on its condensed consolidated balance sheets which will be amortized as interest expense in the condensed consolidated statements of operations under the effective interest rate method over the life of the royalty sale agreement. The Company will continue to record the full amount of royalties earned on MAVYRET/MAVIRET sales as royalty revenue in the condensed consolidated statements of operations.

The Company’s liability related to the sale of future royalties is estimated based on forecasted worldwide MAVYRET/MAVYRET royalties to be paid to OMERS over the course of the royalty sale agreement. This estimate requires significant judgment, including the amount and timing of royalty payments up until the end of the royalty sale agreement, which is estimated to be the stated term of June 30, 2032. As royalties are earned by OMERS, the liability is reduced on the Company’s condensed consolidated balance sheets.

At March 31, 2024, the estimated future cash flows resulted in an effective annual imputed interest rate of approximately 5.6%.

The following table summarizes the activity of the liability related to the sale of future royalties:


	Liability related to the sale of future royalties
	(in thousands)
Balance - September 30, 2023	$	194,505
Royalty payable to purchaser		(9,297	)
Payments on royalty sale liability		(9,822	)
Interest expense, net of capitalized interest		6,061
Balance - March 31, 2024	$	181,447

Fair Value of Financial Assets and Liabilities (Tables)

6 Months Ended

Mar. 31, 2024

Fair Value Disclosures [Abstract]

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

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 March 31, 2024 and September 30, 2023, and indicate the fair value hierarchy of the valuation inputs utilized to determine such fair value:


	Fair Value Measurements as of March 31, 2024 Using:
	Level 1		Level 2		Level 3		Total
	(in thousands)
Assets:
Cash equivalents:
Money market funds	$	63,272	$	—	$	—	$	63,272
Marketable securities:
U.S. Treasury notes		218,371		—		—		218,371
Corporate bonds		—		18,397		—		18,397
	$	281,643	$	18,397	$	—	$	300,040
Liabilities:
Series 1 nonconvertible preferred stock	$	—	$	—	$	1,423	$	1,423
	$	—	$	—	$	1,423	$	1,423


	Fair Value Measurements as of September 30, 2023 Using:
	Level 1		Level 2		Level 3		Total
	(in thousands)
Assets:
Cash equivalents:
Money market funds	$	55,357	$	—	$	—	$	55,357
U.S. Treasury notes		29,755		—		—		29,755
Marketable securities:
U.S. Treasury notes		236,782		—		—		236,782
Corporate bonds		—		26,435		—		26,435
Commercial paper		—		21,305		—		21,305
	$	321,894	$	47,740	$	—	$	369,634
Liabilities:
Series 1 nonconvertible preferred stock	$	—	$	—	$	1,423	$	1,423
	$	—	$	—	$	1,423	$	1,423

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

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:


	Range
	March 31,	September 30,
Unobservable Input	2024	2023
Probabilities of payout	0%-65%	0%-65%
Discount rate	7.25%	7.25%

Fair Value of Financial Assets and Liabilities

6 Months Ended

Mar. 31, 2024

Fair Value Disclosures [Abstract]

Fair Value of Financial Assets and Liabilities

3. Fair Value of Financial Assets and Liabilities


	Fair Value Measurements as of March 31, 2024 Using:
	Level 1		Level 2		Level 3		Total
	(in thousands)
Assets:
Cash equivalents:
Money market funds	$	63,272	$	—	$	—	$	63,272
Marketable securities:
U.S. Treasury notes		218,371		—		—		218,371
Corporate bonds		—		18,397		—		18,397
	$	281,643	$	18,397	$	—	$	300,040
Liabilities:
Series 1 nonconvertible preferred stock	$	—	$	—	$	1,423	$	1,423
	$	—	$	—	$	1,423	$	1,423


	Fair Value Measurements as of September 30, 2023 Using:
	Level 1		Level 2		Level 3		Total
	(in thousands)
Assets:
Cash equivalents:
Money market funds	$	55,357	$	—	$	—	$	55,357
U.S. Treasury notes		29,755		—		—		29,755
Marketable securities:
U.S. Treasury notes		236,782		—		—		236,782
Corporate bonds		—		26,435		—		26,435
Commercial paper		—		21,305		—		21,305
	$	321,894	$	47,740	$	—	$	369,634
Liabilities:
Series 1 nonconvertible preferred stock	$	—	$	—	$	1,423	$	1,423
	$	—	$	—	$	1,423	$	1,423

During the three and six months ended March 31, 2024 and 2023 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 March 31, 2024 and September 30, 2023 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 condensed consolidated statements of operations.


	Range
	March 31,	September 30,
Unobservable Input	2024	2023
Probabilities of payout	0%-65%	0%-65%
Discount rate	7.25%	7.25%

There were no changes in the fair value of nonconvertible preferred stock during the three months ended March 31, 2024 and 2023.

In 2023, the Company entered into a royalty sale agreement with an affiliate of OMERS, pursuant to which the Company was paid a $200,000 cash purchase price in exchange for 54.5% of future quarterly royalty payments on net sales of MAVYRET/MAVIRET, after June 30, 2023, through June 30, 2032, subject to a cap on aggregate payments equal to 1.42 times the purchase price. The Company accounted for the upfront payment as a liability related to the sale of future royalties. The carrying value of the liability related to the sale of future royalties approximates fair value as of March 31, 2024 and is based on current estimates of future royalties expected to be paid to OMERS over the next 10 years, which are considered Level 3 inputs. See Note 7 for a rollforward of the liability.

- 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

Stock-Based Awards - Summary of Restricted Stock Unit Activity (Detail) - Restricted Stock Units [Member] shares in Thousands	6 Months Ended
	Mar. 31, 2024 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested, beginning balance \| shares	411
Granted \| shares	167
Vested \| shares	(116)
Cancelled \| shares	(19)
Unvested, ending balance \| shares	443
Weighted Average Grant Date Fair Value, Unvested beginning balance \| $ / shares	$ 51.78
Weighted Average Grant Date Fair Value, Granted \| $ / shares	9.09
Weighted Average Grant Date Fair Value, Vested \| $ / shares	52
Weighted Average Grant Date Fair Value, Cancelled \| $ / shares	26.93
Weighted Average Grant Date Fair Value, Unvested ending balance \| $ / shares	$ 36.68

Liability Related to the Sale of Future Royalties - Additional Information (Detail) - OMERS Royalty Purchase Agreement [Member] $ in Thousands	12 Months Ended
	Sep. 30, 2023 USD ($)	Mar. 31, 2024
Nonmonetary Transaction [Line Items]
Payment received royalty purchase agreement	$ 200,000
Percentage of future quarterly royalty payments on net sales received in cash	54.50%
Future royalty payment description	after June 30, 2023, through June 30, 2032, subject to a cap on aggregate payments equal to 1.42 times the purchase price.
Royalty purchase agreement annual imputed interest rate		5.6

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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+ Details

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Income Tax [Line Items]
Income tax benefit	$ (363)	$ 44	$ (985)	$ 10

- Definition

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

+ References + Details

Nature of the Business and Basis of Presentation - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended		12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2024	Mar. 31, 2023	Sep. 30, 2023
Entity incorporated, in year					1995
Net loss	$ 31,157	$ 33,407	$ 37,658	$ 28,986	$ 64,564	$ 66,644	$ 133,816
Accumulated deficit	271,559				271,559		$ 206,995
Cash, cash equivalents and short-term and long-term marketable securities	$ 300,310				$ 300,310

- 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

Amount of accumulated undistributed earnings (deficit).

+ References + Details

Marketable Securities (Tables)

6 Months Ended

Mar. 31, 2024

Investments, Debt and Equity Securities [Abstract]

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

As of March 31, 2024 and September 30, 2023, the fair value of available-for-sale marketable securities, by type of security, was as follows:


	March 31, 2024
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Credit Losses		Fair Value
	(in thousands)
U.S. Treasury notes	$	218,561	$	2	$	(192	)	$	—	$	218,371
Corporate bonds		18,490		—		(93	)		—		18,397
	$	237,051	$	2	$	(285	)	$	—	$	236,768


	September 30, 2023
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Credit Losses		Fair Value
	(in thousands)
U.S. Treasury notes	$	236,880	$	12	$	(110	)	$	—	$	236,782
Corporate bonds		27,127		—		(692	)		—		26,435
Commercial paper		21,305		—		—			—		21,305
	$	285,312	$	12	$	(802	)	$	—	$	284,522

Summary of Significant Accounting Policies (Policies)

6 Months Ended

Mar. 31, 2024

Accounting Policies [Abstract]

Use of Estimates

The preparation of condensed 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 condensed consolidated financial statements, and the reported amounts of revenues and expenses during the reporting period. Significant estimates and assumptions reflected in these condensed consolidated financial statements include, but are not limited to, management’s judgments with respect to its revenue arrangements; liability related to the sale of future royalties; 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.

Net Loss per Share

Basic net loss per common share is computed by dividing the net loss by the weighted average number of shares of common stock outstanding for the period. In periods in which the Company has 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. Therefore, the Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss as its effect would have been anti-dilutive:


	As of March 31,
	2024		2023
	(in thousands)
Options to purchase common stock		5,237		4,522
Unvested rTSRUs		88		81
Unvested PSUs		88		81
Unvested restricted stock units		443		430

Recently Issued Accounting Pronouncements

In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, which requires public entities to disclose information about their reportable segments’ significant expenses and other segment items on an interim and annual basis. Public entities with a single reportable segment are required to apply the disclosure requirements in ASU 2023-07, as well as all existing segment disclosures and reconciliation requirements in ASC 280 on an interim and annual basis. This amendment is effective for the Company in the fiscal year beginning October 1, 2024, with early adoption permitted. The Company is currently evaluating the potential impact that ASU 2023-07 may have on its financial statement disclosures.

In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which requires public entities, on an annual basis, to provide disclosure of specific categories in the rate reconciliation, as well as disclosure of income taxes paid disaggregated by jurisdiction. ASU 2023-09 is effective for the Company in the fiscal year beginning October 1, 2025, with early adoption permitted. The Company is currently evaluating the potential impact that ASU 2023-09 may have on its financial statement disclosures.

Marketable Securities

6 Months Ended

Mar. 31, 2024

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

4. Marketable Securities

As of March 31, 2024 and September 30, 2023, the fair value of available-for-sale marketable securities, by type of security, was as follows:


	March 31, 2024
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Credit Losses		Fair Value
	(in thousands)
U.S. Treasury notes	$	218,561	$	2	$	(192	)	$	—	$	218,371
Corporate bonds		18,490		—		(93	)		—		18,397
	$	237,051	$	2	$	(285	)	$	—	$	236,768


	September 30, 2023
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Credit Losses		Fair Value
	(in thousands)
U.S. Treasury notes	$	236,880	$	12	$	(110	)	$	—	$	236,782
Corporate bonds		27,127		—		(692	)		—		26,435
Commercial paper		21,305		—		—			—		21,305
	$	285,312	$	12	$	(802	)	$	—	$	284,522

As of March 31, 2024 and September 30, 2023, marketable securities consisted of investments that mature within one year.

Stock-Based Awards - Summary of Stock Option Activity Including Performance Based Options (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended	12 Months Ended
	Mar. 31, 2024 USD ($) $ / shares shares	Sep. 30, 2023 USD ($) $ / shares shares
Options
Outstanding as of beginning of period \| shares	4,365
Granted \| shares	1,196
Exercised \| shares	(6)
Forfeited \| shares	(318)
Outstanding as of end of period \| shares	5,237	4,365
Options vested and expected to vest as of end of period \| shares	5,237
Options exercisable as of end of period \| shares	3,229
Weighted Average Exercise Price
Outstanding \| $ / shares	$ 52.68
Granted \| $ / shares	9.54
Exercised \| $ / shares	8.99
Forfeited \| $ / shares	39.18
Outstanding \| $ / shares	43.7	$ 52.68
Options vested and expected to vest as of end of period \| $ / shares	43.7
Options exercisable as of end of period \| $ / shares	$ 52.51
Weighted Average Remaining Contractual Term
Outstanding as of end of period	6 years 7 months 6 days	5 years 10 months 24 days
Options vested and expected to vest as of end period	6 years 7 months 6 days
Options exercisable as of end of period	5 years 1 month 6 days
Aggregate Intrinsic Value
Aggregate Intrinsic Value \| $	$ 9,273	$ 0
Options vested and expected to vest as of December 31, 2021 \| $	9,273
Options exercisable as of end of period \| $	$ 523

Fair Value of Financial Assets and Liabilities - Fair Value Measurements of the Company's Outstanding Series 1 Nonconvertible Preferred Stock (Detail) - Level 3 [Member] - Series 1 Nonconvertible Preferred Stock [Member]	Mar. 31, 2024	Sep. 30, 2023
Probabilities of Payout [Member] \| Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range	0	0
Probabilities of Payout [Member] \| Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range	65	65
Discount Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range	7.25	7.25

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended				6 Months Ended		12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2024	Mar. 31, 2023	Sep. 30, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (31,157)	$ (33,407)	$ (37,658)	$ (28,986)	$ (64,564)	$ (66,644)	$ (133,816)

- Definition

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

+ References

+ Details

Summary of Significant Accounting Policies

6 Months Ended

Mar. 31, 2024

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

For the Company’s Significant Accounting Policies, please refer to its Annual Report on Form 10-K for the fiscal year ended September 30, 2023. 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

Net Loss per Share


	As of March 31,
	2024		2023
	(in thousands)
Options to purchase common stock		5,237		4,522
Unvested rTSRUs		88		81
Unvested PSUs		88		81
Unvested restricted stock units		443		430

Recently Issued Accounting Pronouncements

Condensed 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]	(Accumulated Deficit) Retained Earnings [Member]
Beginning Balance at Sep. 30, 2022	$ 321,334	$ 208	$ 398,029	$ (3,724)	$ (73,179)
Beginning Balance, Shares at Sep. 30, 2022		20,791
Exercise of stock options	1,126	$ 1	1,125
Exercise of stock options, Shares		56
Vesting of restricted stock units, net of withholding	(825)		(825)
Vesting of restricted stock units, net of withholding, Shares		37
Stock-based compensation expense	7,139		7,139
Other comprehensive (loss) income	1,049			1,049
Net loss	(28,986)				(28,986)
Ending Balance at Dec. 31, 2022	300,837	$ 209	405,468	(2,675)	(102,165)
Ending Balance, Shares at Dec. 31, 2022		20,884
Beginning Balance at Sep. 30, 2022	321,334	$ 208	398,029	(3,724)	(73,179)
Beginning Balance, Shares at Sep. 30, 2022		20,791
Other comprehensive (loss) income	1,909
Net loss	(66,644)
Ending Balance at Mar. 31, 2023	269,375	$ 210	410,803	(1,815)	(139,823)
Ending Balance, Shares at Mar. 31, 2023		21,049
Beginning Balance at Sep. 30, 2022	321,334	$ 208	398,029	(3,724)	(73,179)
Beginning Balance, Shares at Sep. 30, 2022		20,791
Net loss	(133,816)
Ending Balance at Sep. 30, 2023	216,735	$ 211	424,693	(1,174)	(206,995)
Ending Balance, Shares at Sep. 30, 2023		21,059
Beginning Balance at Dec. 31, 2022	300,837	$ 209	405,468	(2,675)	(102,165)
Beginning Balance, Shares at Dec. 31, 2022		20,884
Exercise of stock options	882	$ 1	881
Exercise of stock options, Shares		61
Vesting of restricted stock units, net of withholding	(2,909)		(2,909)
Vesting of restricted stock units, net of withholding, Shares		104
Stock-based compensation expense	7,363		7,363
Other comprehensive (loss) income	860			860
Net loss	(37,658)				(37,658)
Ending Balance at Mar. 31, 2023	269,375	$ 210	410,803	(1,815)	(139,823)
Ending Balance, Shares at Mar. 31, 2023		21,049
Beginning Balance at Sep. 30, 2023	216,735	$ 211	424,693	(1,174)	(206,995)
Beginning Balance, Shares at Sep. 30, 2023		21,059
Vesting of restricted stock units, net of withholding	(183)	$ 1	(184)
Vesting of restricted stock units, net of withholding, Shares		97
Stock-based compensation expense	8,099		8,099
Other comprehensive (loss) income	640			640
Net loss	(33,407)				(33,407)
Ending Balance at Dec. 31, 2023	191,884	$ 212	432,608	(534)	(240,402)
Ending Balance, Shares at Dec. 31, 2023		21,156
Beginning Balance at Sep. 30, 2023	$ 216,735	$ 211	424,693	(1,174)	(206,995)
Beginning Balance, Shares at Sep. 30, 2023		21,059
Exercise of stock options, Shares	6
Other comprehensive (loss) income	$ 507
Net loss	(64,564)
Ending Balance at Mar. 31, 2024	166,114	$ 212	438,128	(667)	(271,559)
Ending Balance, Shares at Mar. 31, 2024		21,179
Beginning Balance at Dec. 31, 2023	191,884	$ 212	432,608	(534)	(240,402)
Beginning Balance, Shares at Dec. 31, 2023		21,156
Exercise of stock options	51		51
Exercise of stock options, Shares		6
Vesting of restricted stock units, net of withholding	(92)		(92)
Vesting of restricted stock units, net of withholding, Shares		17
Stock-based compensation expense	5,561		5,561
Other comprehensive (loss) income	(133)			(133)
Net loss	(31,157)				(31,157)
Ending Balance at Mar. 31, 2024	$ 166,114	$ 212	$ 438,128	$ (667)	$ (271,559)
Ending Balance, Shares at Mar. 31, 2024		21,179

- Definition

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

+ References

+ Details

- Definition

Amount of equity (deficit) attributable to parent. Excludes temporary equity and equity attributable to noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
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+ Details

Liability Related to the Sale of Future Royalties (Tables)

6 Months Ended

Mar. 31, 2024

Nonmonetary Transactions [Abstract]

Summary of the Liability Related to the Sale of Future Royalties

The following table summarizes the activity of the liability related to the sale of future royalties:


	Liability related to the sale of future royalties
	(in thousands)
Balance - September 30, 2023	$	194,505
Royalty payable to purchaser		(9,297	)
Payments on royalty sale liability		(9,822	)
Interest expense, net of capitalized interest		6,061
Balance - March 31, 2024	$	181,447

Stock-Based Awards (Tables)

6 Months Ended

Mar. 31, 2024

Summary of Stock Option Activity Including Performance Based Options

The following table summarizes stock option activity, including performance-based options, for the year-to-date period ending March 31, 2024:


	Shares Issuable Under Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
	(in thousands)					(in years)		(in thousands)
Outstanding as of September 30, 2023		4,365		$	52.68		5.9	$	—
Granted		1,196			9.54
Exercised		(6	)		8.99
Forfeited		(318	)		39.18
Outstanding as of March 31, 2024		5,237		$	43.70		6.6	$	9,273
Options vested and expected to vest as of March 31, 2024		5,237		$	43.70		6.6	$	9,273
Options exercisable as of March 31, 2024		3,229		$	52.51		5.1	$	523

Summary of Restricted Stock Unit Activity

The following table summarizes the restricted stock unit activity for the year-to-date period ending March 31, 2024:


	Restricted Stock Units			Weighted Average Grant Date Fair Value
	(in thousands)
Unvested as of September 30, 2023		411		$	51.78
Granted		167			9.09
Vested		(116	)		52.00
Cancelled		(19	)		26.93
Unvested as of March 31, 2024		443		$	36.68

Stock-Based Compensation Expense

During the three and six months ended March 31, 2024 and 2023, the Company recognized the following stock-based compensation expense:



	Three Months Ended March 31,				Six Months Ended March 31,
	2024		2023		2024		2023
	(in thousands)
Research and development	$	1,794	$	2,520	$	3,849	$	5,052
General and administrative		3,767		4,843		9,811		9,450
	$	5,561	$	7,363	$	13,660	$	14,502



	Three Months Ended March 31,				Six Months Ended March 31,
	2024		2023		2024		2023
	(in thousands)
Stock options	$	3,711	$	5,011	$	8,173	$	10,057
Restricted stock units		1,459		1,631		3,072		2,896
rTSRUs		258		546		703		1,007
Performance stock units		133		175		1,712		542
	$	5,561	$	7,363	$	13,660	$	14,502

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

Summary of PSUs and rTSRUs Activity

The following table summarizes PSU and rTSRU activity for the year-to-date period ending March 31, 2024:


	PSUs					rTSRUs
	Shares			Weighted Average Grant Date Fair Value		Shares			Weighted Average Grant Date Fair Value
	(in thousands)					(in thousands)
Unvested as of September 30, 2023		81		$	58.58		81		$	45.82
Granted		51			9.38		48			9.89
Vested		(25	)		68.67		—			—
Cancelled		(19	)		51.14		(41	)		47.25
Unvested as of March 31, 2024		88		$	28.71		88		$	25.50

Accrued Expenses - Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Sep. 30, 2023
Accrued expenses:
Accrued professional fees	$ 3,547	$ 1,632
Accrued payroll and related expenses	2,967	7,037
Accrued research and development expenses	1,529	6,120
Accrued pharmaceutical drug manufacturing	1,515	3,083
Accrued other	1,072	467
Accrued expenses	$ 10,630	$ 18,339

Liability Related to the Sale of Future Royalties - Summary Of The Liability Related To The Sale Of Future Royalties (Details) - Sale Of Future Royalties [Member] - OMERS Royalty Purchase Agreement [Member] $ in Thousands	6 Months Ended
	Mar. 31, 2024 USD ($)
Nonmonetary Transaction [Line Items]
Royalty liability - beginning balance	$ 194,505
Royalty payable to purchaser	(9,297)
Payments on royalty sale liability	(9,822)
Interest expense, net of capitalized interest	6,061
Royalty liability - ending balance	$ 181,447

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Statement of Comprehensive Income [Abstract]
Net loss	$ (31,157)	$ (37,658)	$ (64,564)	$ (66,644)
Other comprehensive income (loss):
Net unrealized gains (loss) on marketable securities	(133)	860	507	1,909
Total other comprehensive income (loss)	(133)	860	507	1,909
Comprehensive loss	$ (31,290)	$ (36,798)	$ (64,057)	$ (64,735)

- Definition

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

+ References

+ Details

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	Mar. 31, 2024	Sep. 30, 2023
Assets:
Marketable securities	$ 236,768	$ 284,522
Assets, Fair Value Disclosure, Total	300,040	369,634
Liabilities:
Liabilities, Fair Value Disclosure, Total	1,423	1,423
Series 1 Nonconvertible Preferred Stock [Member]
Liabilities:
Liabilities	1,423	1,423
Level 1 [Member]
Assets:
Assets, Fair Value Disclosure, Total	281,643	321,894
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	18,397	47,740
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	1,423
Level 3 [Member] \| Series 1 Nonconvertible Preferred Stock [Member]
Liabilities:
Liabilities	1,423	1,423
Money Market Funds [Member]
Assets:
Cash equivalents	63,272	55,357
Money Market Funds [Member] \| Level 1 [Member]
Assets:
Cash equivalents	63,272	55,357
Money Market Funds [Member] \| Level 2 [Member]
Assets:
Cash equivalents	0	0
Money Market Funds [Member] \| Level 3 [Member]
Assets:
Cash equivalents	0	0
U.S. Treasury Notes [Member]
Assets:
Cash equivalents		29,755
Marketable securities	218,371	236,782
U.S. Treasury Notes [Member] \| Level 1 [Member]
Assets:
Cash equivalents		29,755
Marketable securities	218,371	236,782
U.S. Treasury Notes [Member] \| Level 2 [Member]
Assets:
Cash equivalents		0
Marketable securities	0	0
U.S. Treasury Notes [Member] \| Level 3 [Member]
Assets:
Cash equivalents		0
Marketable securities	0	0
Corporate Bonds [Member]
Assets:
Marketable securities	18,397	26,435
Corporate Bonds [Member] \| Level 1 [Member]
Assets:
Marketable securities	0	0
Corporate Bonds [Member] \| Level 2 [Member]
Assets:
Marketable securities	18,397	26,435
Corporate Bonds [Member] \| Level 3 [Member]
Assets:
Marketable securities	$ 0	0
Commercial Paper [Member]
Assets:
Marketable securities		21,305
Commercial Paper [Member] \| Level 1 [Member]
Assets:
Marketable securities		0
Commercial Paper [Member] \| Level 2 [Member]
Assets:
Marketable securities		21,305
Commercial Paper [Member] \| Level 3 [Member]
Assets:
Marketable securities		$ 0

Series 1 Nonconvertible Preferred Stock	6 Months Ended
Series 1 Nonconvertible Preferred Stock	Mar. 31, 2024
Debt Disclosure [Abstract]
Series 1 Nonconvertible Preferred Stock	8. Series 1 Nonconvertible Preferred Stock As of March 31, 2024, 1,930 shares of Series 1 nonconvertible preferred stock were issued and outstanding. The outstanding shares are financial instruments that might require a transfer of assets because of the liquidation features in the contract and are carried at fair value as a liability on the Company’s condensed consolidated balance sheets

Stock-Based Awards - Summary of PSUs and rTSRUs Activity (Detail) shares in Thousands	6 Months Ended
	Mar. 31, 2024 $ / shares shares
PSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested, beginning balance \| shares	81
Granted \| shares	51
Vested \| shares	(25)
Cancelled \| shares	(19)
Unvested, ending balance \| shares	88
Weighted Average Grant Date Fair Value, Unvested beginning balance \| $ / shares	$ 58.58
Weighted Average Grant Date Fair Value, Granted \| $ / shares	9.38
Weighted Average Grant Date Fair Value, Vested \| $ / shares	68.67
Weighted Average Grant Date Fair Value, Cancelled \| $ / shares	51.14
Weighted Average Grant Date Fair Value, Unvested ending balance \| $ / shares	$ 28.71
rTSRUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested, beginning balance \| shares	81
Granted \| shares	48
Vested \| shares	0
Cancelled \| shares	(41)
Unvested, ending balance \| shares	88
Weighted Average Grant Date Fair Value, Unvested beginning balance \| $ / shares	$ 45.82
Weighted Average Grant Date Fair Value, Granted \| $ / shares	9.89
Weighted Average Grant Date Fair Value, Vested \| $ / shares	0
Weighted Average Grant Date Fair Value, Cancelled \| $ / shares	47.25
Weighted Average Grant Date Fair Value, Unvested ending balance \| $ / shares	$ 25.5

Nature of the Business and Basis of Presentation

6 Months Ended

Mar. 31, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Nature of the Business and Basis of Presentation

1. Nature of the Business and Basis of Presentation

Enanta Pharmaceuticals, Inc. (collectively with its subsidiary, the “Company”), incorporated in Delaware in 1995, is a biotechnology company that uses its robust, chemistry-driven approach and drug discovery capabilities to discover and develop small molecule drugs with an emphasis on virology and immunology indications. 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). The Company’s existing financial resources, as well as the retained portion of its royalties from the AbbVie collaboration, provide funding to support the Company’s wholly-owned research and development programs, which have been primarily focused on the following disease targets: respiratory syncytial virus (“RSV”), SARS-CoV-2, hepatitis B virus (“HBV”) and chronic spontaneous urticaria (“CSU”).

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.

Unaudited Interim Financial Information

The condensed consolidated balance sheet as of September 30, 2023 was derived from audited financial statements but does not include all disclosures required by accounting principles generally accepted in the United States of America (“GAAP”). The accompanying unaudited condensed consolidated financial statements as of March 31, 2024 and for the three and six months ended March 31, 2024 and 2023 have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) for interim financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. These condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the fiscal year ended September 30, 2023.

In the opinion of management, all adjustments, consisting of normal recurring adjustments necessary for a fair statement of the Company’s financial position as of March 31, 2024 and results of operations for the three and six months ended March 31, 2024 and 2023 and cash flows for the six months ended March 31, 2024 and 2023 have been made. The results of operations for the three and six months ended March 31, 2024 are not necessarily indicative of the results of operations that may be expected for subsequent quarters or the year ending September 30, 2024.

The accompanying condensed consolidated financial statements have been prepared in conformity with GAAP. All amounts in the condensed consolidated financial statements and in the notes to the condensed consolidated financial statements, except per share amounts, are in thousands unless otherwise indicated.

The accompanying condensed consolidated financial statements have been prepared based on continuity of operations, realization of assets and the satisfaction of liabilities and commitments in the ordinary course of business. The Company began reporting a net loss in fiscal 2020 and reported a net loss of $64,564 for the six months ended March 31, 2024 and $133,816 for the year ended September 30, 2023. As of March 31, 2024, the Company had an accumulated deficit of $271,559. The Company expects to continue to generate operating losses for the foreseeable future as the Company continues to advance its wholly-owned programs. As of March 31, 2024, the Company had $300,310 in cash, cash equivalents and short-term marketable securities. The Company expects that its cash, cash equivalents and short-term marketable securities will be sufficient to fund its operating expenses and capital expenditure requirements for at least 12 months from the issuance date of the interim condensed consolidated financial statements. The Company may seek additional funding through equity offerings, non-dilutive financings, collaborations, strategic alliances or licensing agreements. The Company may not be able to obtain sufficient financing on acceptable terms, or at all, and the Company may not be able to enter into collaborations or other arrangements. The terms of any financing may adversely affect the holdings or the rights of the Company’s stockholders. If the Company is unable to obtain funding, the Company could be forced to delay, reduce or eliminate some or all of its research and development programs, product expansion or commercialization efforts, or the Company may be unable to continue operations.

Accrued Expenses (Tables)

6 Months Ended

Mar. 31, 2024

Payables and Accruals [Abstract]

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following as of March 31, 2024 and September 30, 2023:


	March 31,		September 30,
	2024		2023
	(in thousands)
Accrued professional fees	$	3,547	$	1,632
Accrued payroll and related expenses		2,967		7,037
Accrued research and development expenses		1,529		6,120
Accrued pharmaceutical drug manufacturing		1,515		3,083
Accrued other		1,072		467
	$	10,630	$	18,339

Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Mar. 31, 2024	Apr. 30, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q2
Trading Symbol	ENTA
Entity Registrant Name	ENANTA PHARMACEUTICALS, INC
Entity Central Index Key	0001177648
Current Fiscal Year End Date	--09-30
Entity Filer Category	Large Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity File Number	001-35839
Security Exchange Name	NASDAQ
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
Title of 12(b) Security	Common Stock, par value $0.01 per share
Local Phone Number	607-0800
Entity Incorporation, State or Country Code	DE
Document Transition Report	false
Document Quarterly Report	true
Entity Interactive Data Current	Yes
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding		21,179,400

Commitment and Contingencies - Schedule of Future Annual Minimum Lease Payments (Detail) $ in Thousands	Mar. 31, 2024 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2024	$ 3,289
2025	8,158
2026	8,467
2027	8,721
2028	8,983
Thereafter	59,191
Total future minimum lease payments	96,809
Less: Imputed interest	(34,763)
Less: tenant improvement allowance	(15,053)
Total operating lease liabilities	$ 46,993

Stock-Based Awards - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 5,561	$ 7,363	$ 13,660	$ 14,502
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	3,711	5,011	8,173	10,057
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	1,459	1,631	3,072	2,896
rTSRUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	258	546	703	1,007
Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	133	175	1,712	542
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	1,794	2,520	3,849	5,052
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 3,767	$ 4,843	$ 9,811	$ 9,450

Marketable Securities - Additional Information (Detail)	6 Months Ended	12 Months Ended
Marketable Securities - Additional Information (Detail)	Mar. 31, 2024	Sep. 30, 2023
Maximum [Member] \| Short Term Marketable Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Maturity period of the marketable securities	1 year	1 year

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2024	Sep. 30, 2023
Current assets:
Cash and cash equivalents	$ 63,542	$ 85,388
Short-term marketable securities	236,768	284,522
Accounts receivable	7,756	8,614
Prepaid expenses and other current assets	10,932	13,263
Income tax receivable	32,031	31,004
Total current assets	351,029	422,791
Property and equipment, net	15,479	11,919
Operating lease, right-of-use assets	42,894	22,794
Restricted cash	3,968	3,968
Other long-term assets	187	803
Total assets	413,557	462,275
Current liabilities:
Accounts payable	6,726	4,097
Accrued expenses and other current liabilities	10,630	18,339
Liability related to the sale of future royalties	33,671	35,076
Operating lease liabilities	3,581	5,275
Total current liabilities	54,608	62,787
Liability related to the sale of future royalties, net of current portion	147,776	159,429
Operating lease liabilities, net of current portion	43,412	21,238
Series 1 nonconvertible preferred stock	1,423	1,423
Other long-term liabilities	224	663
Total liabilities	247,443	245,540
Commitments and contingencies (Note 11)
Stockholders' equity:
Common stock; $0.01 par value per share, 100,000 shares authorized; 21,179 and 21,059 shares issued and outstanding at March 31, 2024 and September 30, 2023, respectively	212	211
Additional paid-in capital	438,128	424,693
Accumulated other comprehensive loss	(667)	(1,174)
Accumulated deficit	(271,559)	(206,995)
Total stockholders' equity	166,114	216,735
Total liabilities and stockholders' equity	$ 413,557	$ 462,275