Press Release Details

• Decision from FDA on New Drug Application anticipated in second half of 2016
• Regimen contains Enanta’s lead protease inhibitor, paritaprevir

WATERTOWN, Mass.--(BUSINESS WIRE)--Dec. 2, 2015-- Enanta Pharmaceuticals, Inc., (NASDAQ: ENTA), a research and development-focused biotechnology company dedicated to creating small molecule drugs for viral infections and liver diseases, today announced AbbVie’s New Drug Application (NDA) has been accepted by the U.S. Food and Drug Administration (FDA) for a once-daily, fixed-dose formulation of the components of VIEKIRA PAK® (ombitasvir, paritaprevir, and ritonavir tablets; dasabuvir tablets). VIEKIRA PAK is an all-oral, interferon-free treatment approved with or without ribavirin (RBV) in the United States for patients with genotype 1 (GT1) chronic hepatitis C virus (HCV) infection, including those with compensated cirrhosis. VIEKIRA PAK is not for people with advanced decompensated cirrhosis.

The proposed dosing for the fixed-dose formulation (dasabuvir, ombitasvir, paritaprevir, ritonavir tablets) is three oral tablets once daily with a meal, with or without twice-daily RBV, which may offer another important treatment option for people living with GT1 HCV. The NDA filing is supported by data from two bioavailability studies. Currently, VIEKIRA PAK is given twice daily as three tablets in the morning and one tablet in the evening, taken with a meal.

The Centers for Disease Control and Prevention (CDC) estimates that in the United States, approximately 2.7 million people are chronically infected with HCV.¹ Genotype 1 is the most prevalent form of HCV in the U.S., accounting for approximately 74 percent of all cases.² Hepatitis C is inflammation of the liver caused by an infection with HCV. It is transmitted when an infected person's blood enters the bloodstream of an uninfected person. There are six major HCV genotypes (GT1-6). Presently, there is no vaccine for HCV infection.

About VIEKIRA PAK

USE

VIEKIRA PAK® (ombitasvir, paritaprevir, and ritonavir tablets; dasabuvir tablets) is a prescription medicine used with or without ribavirin to treat adults with genotype 1 chronic (lasting a long time) hepatitis C (hep C) virus infection, including people who have a certain type of cirrhosis (compensated).

VIEKIRA PAK is not for people with advanced cirrhosis (decompensated). If people have cirrhosis, they should talk to a doctor before taking VIEKIRA PAK.

IMPORTANT SAFETY INFORMATION

When taking VIEKIRA PAK in combination with ribavirin, people should read the Medication Guide that comes with ribavirin, especially the important pregnancy information.

What is the most important information to know about VIEKIRA PAK?

• VIEKIRA PAK may cause severe liver problems, especially in people with certain types of cirrhosis. These severe liver problems can lead to the need for a liver transplant, or can lead to death.
• VIEKIRA PAK can cause increases in liver function blood test results, especially if people use ethinyl estradiol-containing medicines (such as some birth control products).
  • Ethinyl estradiol-containing medicines (combination birth control pills or patches, such as Lo Loestrin® FE, Norinyl®, Ortho Tri-Cyclen Lo®, Ortho Evra®; hormonal vaginal rings such as NuvaRing®; and the hormone replacement therapy medicine, Fem HRT®) must be stopped before starting treatment with VIEKIRA PAK. If these medicines are used as a method of birth control, another method must be used during treatment with VIEKIRA, and for about 2 weeks after treatment with VIEKIRA PAK ends. A doctor can provide instruction on when to begin taking ethinyl estradiol-containing medicines.
• A doctor should do blood tests to check liver function during the first 4 weeks of treatment and then as needed.
• A doctor may tell people to stop taking VIEKIRA PAK if signs or symptoms of liver problems develop. A doctor must be notified right away if any of the following symptoms develop or if they worsen during treatment with VIEKIRA PAK: tiredness, weakness, loss of appetite, nausea, vomiting, yellowing of the skin or eyes, color changes in stools, confusion, or swelling of the stomach area.

VIEKIRA PAK must not be taken if people:

• have certain liver problems
• take any of the following medicines: alfuzosin hydrochloride (Uroxatral®) • carbamazepine (Carbatrol®, Epitol®, Equetro®, Tegretol®) • colchicine (Colcrys®) • efavirenz (Sustiva®, Atripla®) • ergot containing medicines, including ergotamine tartrate (Cafergot®, Migergot®, Ergomar®, Ergostat®, Medihaler®, Wigraine®, Wigrettes®), dihydroergotamine mesylate (D.H.E. 45®, Migranal®), methylergonovine (Ergotrate®, Methergine®) • ethinyl estradiol-containing medicines • gemfibrozil (Lopid®) • lovastatin (Advicor®, Altoprev®, Mevacor®) • midazolam (when taken by mouth) • phenytoin (Dilantin®, Phenytek®) • phenobarbital (Luminal®) • pimozide (Orap®) • rifampin (Rifadin®, Rifamate®, Rifater®, Rimactane®) • sildenafil citrate (Revatio®), when taken for pulmonary artery hypertension (PAH) • simvastatin (Zocor®, Vytorin®, Simcor®) • St. John’s wort (Hypericum perforatum) or a product that contains St. John’s wort • triazolam (Halcion®)
• have had a severe skin rash after taking ritonavir (Norvir®)

What should people tell a doctor before taking VIEKIRA PAK?

• If they have: liver problems other than hep C infection, HIV infection, or any other medical conditions.
• If they have had a liver transplant. If they take the medicines tacrolimus (Prograf®) or cyclosporine (Gengraf®, Neoral®, Sandimmune®), a doctor should check blood levels and, if needed, may change the dose of these medicines or how often they are taken, both during and after treatment with VIEKIRA PAK.
• If they are pregnant or plan to become pregnant or if they are breastfeeding or plan to breastfeed. It is not known if VIEKIRA PAK will harm a person’s unborn baby or pass into breast milk. A doctor should be consulted about the best way to feed a baby if taking VIEKIRA PAK. Pregnant females who have both hep C and HIV infection should talk with a doctor about enrolling in the antiretroviral pregnancy registry.
• About all the medicines they take, including prescription and over-the-counter medicines, vitamins, and herbal supplements. Some medicines interact with VIEKIRA PAK.
  • A new medicine must not be started without telling a doctor. A doctor will provide instruction on whether it is safe to take VIEKIRA PAK with other medicines.
  • When VIEKIRA PAK is finished, a doctor should be consulted on what to do if one of the usual medicines taken was stopped or if the dose changed during VIEKIRA PAK treatment.

What are the common side effects of VIEKIRA PAK?

• For VIEKIRA PAK used with ribavirin, side effects include tiredness, nausea, itching, skin reactions such as redness or rash, sleep problems, and feeling weak.
• For VIEKIRA PAK used without ribavirin, side effects include nausea, itching, and sleep problems.

These are not all of the possible side effects of VIEKIRA PAK. A doctor should be notified if there is any side effect that is bothersome or that does not go away.

This is the most important information to know about VIEKIRA PAK. For more information, talk with a doctor.

People are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch or call 1-800-FDA-1088.

Click here for full Prescribing Information, including the Medication Guide.

If people cannot afford their medication, they should contact www.pparx.org for assistance.

Additional Information about VIEKIRA PAK®

VIEKIRA PAK® has been studied in a broad range of genotype 1 (GT1) patients with chronic hepatitis C virus (HCV) infection, ranging from treatment-naive to difficult to treat patients, such as those with compensated (mild, Child-Pugh A) cirrhosis of the liver, HCV/HIV-1 co-infection, liver transplant recipients with normal hepatic function and mild fibrosis, and those who have failed previous treatment with pegylated interferon (pegIFN) and ribavirin (RBV). VIEKIRA PAK is contraindicated in patients with moderate to severe hepatic impairment (Child-Pugh B and C) due to risk of potential toxicity. VIEKIRA PAK consists of the fixed-dose combination of ombitasvir 25mg (an NS5A inhibitor), paritaprevir 150mg (an NS3/4A protease inhibitor), and ritonavir 100mg (an HIV-1 protease inhibitor), dosed once daily with a meal, and dasabuvir 250mg (a non-nucleoside NS5B palm polymerase inhibitor), dosed twice daily with a meal. VIEKIRA PAK is taken for 12 weeks, except in GT1a patients with cirrhosis, who should take it for 24 weeks. Ribavirin should be co-administered in GT1a patients, and in all patients who have cirrhosis or who have received a liver transplant.

Protease Inhibitor Collaboration with AbbVie (formerly the research-based pharmaceutical business of Abbott Laboratories)
In December 2006, Enanta and Abbott announced a worldwide agreement to collaborate on the discovery, development and commercialization of HCV NS3 and NS3/4A protease inhibitors and HCV- protease-inhibitor-containing drug combinations. Paritaprevir and ABT-493 are protease inhibitors identified through the collaboration. Under the agreement, AbbVie is responsible for all development and commercialization activities for the collaboration’s lead compound, paritaprevir, as well as ABT-493, the collaboration’s next-generation protease inhibitor. Enanta is eligible to receive annually tiered, double-digit royalties per product on AbbVie’s worldwide net sales allocable to any of the collaboration’s protease inhibitor products.

About Enanta
Enanta Pharmaceuticals is a research and development-focused biotechnology company that uses its robust chemistry-driven approach and drug discovery capabilities to create small molecule drugs for viral infections and liver diseases. Enanta has discovered novel protease and NS5A inhibitors that are direct-acting-antivirals (DAAs) designed for use against the hepatitis C virus (HCV). Enanta’s protease inhibitors developed through its collaboration with AbbVie include paritaprevir, which is contained in AbbVie’s marketed DAA regimens for HCV, and ABT-493, Enanta’s next-generation protease inhibitor which recently entered phase 3 development in combination with ABT-530, AbbVie’s next-generation NS5A inhibitor. Enanta has also discovered EDP-494, a host-targeted antiviral (HTA) inhibitor for HCV targeted against cyclophilin, which Enanta plans to study in a phase 1 clinical trial beginning in the quarter ending March 31, 2016. In addition, Enanta has a preclinical program in non-alcoholic steatohepatitis, or NASH, which is a condition that results in liver inflammation and liver damage caused by a buildup of fat in the liver.

Forward Looking Statements Disclaimer
This press release contains forward-looking statements, including statements with respect to the prospects for FDA approval of a once daily formulation of AbbVie’s 3-DAA HCV treatment regimen containing paritaprevir. Statements that are not historical facts are based on management’s current expectations, estimates, forecasts and projections about Enanta’s business and the industry in which it operates and management’s beliefs and assumptions. The statements contained in this release are not guarantees of future performance and involve certain risks, uncertainties and assumptions, which are difficult to predict. Therefore, actual outcomes and results may differ materially from what is expressed in such forward-looking statements. Important factors and risks that may affect actual results include: Enanta’s revenues are dependent upon the success of AbbVie’s planned regulatory approval and commercialization efforts for its treatment regimens containing paritaprevir; the pricing, market acceptance and reimbursement rates of treatment regimens containing paritaprevir or ABT-493 compared to competitive HCV products on the market and product candidates of other companies under development; and other risk factors described or referred to in “Risk Factors” in Enanta’s most recent Form 10-K for the fiscal year ended September 30, 2014 and other periodic reports filed more recently with the Securities and Exchange Commission. Enanta cautions investors not to place undue reliance on the forward-looking statements contained in this release. These statements speak only as of the date of this release, and Enanta undertakes no obligation to update or revise these statements, except as may be required by law.

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¹Centers for Disease Control and Prevention. Hepatitis C FAQs for Health Professionals. Centers for Disease Control and Prevention website. http://www.cdc.gov/hepatitis/hcv/hcvfaq.htm. Accessed November 30, 2015

² Wedemeyer H. Hepatitis C. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran’s Gastrointestinal and Liver Disease: Pathophysiology/Diagnosis/Management. 10th ed, Vol 2. Philadelphia, PA: Saunders Elsevier. 2016:1332-1351

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Source: Enanta Pharmaceuticals, Inc.

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