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Enanta Announces SVR12 results of 95% from AbbVie’s GIFT-1 Study in Non-cirrhotic, Japanese Patients with Genotype 1b Hepatitis C Virus1

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Enanta Pharmaceuticals, Inc. (NASDAQ:ENTA) , a research and development-focused biotechnology company dedicated to creating small molecule drugs for viral infections and liver diseases, announced today that new data from AbbVie’s phase 3 GIFT-I study, its investigational, all-oral, interferon (IFN)- and ribavirin (RBV)-free, two direct-acting antiviral treatment with ombitasvir/paritaprevir/ritonavir, was presented at the Annual Meeting of the Japan Society of Hepatology in Kumamoto, Japan.1

GIFT-I evaluated genotype 1b (GT1b) chronic hepatitis C virus (HCV) infected Japanese patients, with and without cirrhosis, who were either treatment-na”ive or Interferon (with or without RBV) treatment-experienced.1 The primary endpoint was achieved, demonstrating 95 percent (n=106/112) SVR12 in a sub-group of treatment-na”ive, non-cirrhotic, adult GT1b HCV infected Japanese patients who were eligible for therapy with IFN and had a high viral load.1 In study results related to the secondary endpoint, GT1b HCV patients with compensated cirrhosis achieved 91 percent (n=38/42) SVR12.

In an additional intent-to-treat (ITT) analysis, SVR12 was achieved in 98 percent (n=104/106) of the GT1b HCV infected patients without cirrhosis (Arm B) who were randomized to initially receive double-blind placebo for 12 weeks, followed by open-label treatment with ombitasvir/paritaprevir/ritonavir.1 The ITT population included every patient that was randomized to placebo and received at least one dose of active, open-label study drug.

Across all study arms, three patients (n=3/363) discontinued treatment due to adverse events.1 The most commonly reported adverse events (>5 percent in any arm) were nasopharyngitis, headache, peripheral edema, nausea, pyrexia and decreased platelet count.1

In Japan, approximately 1.5 to 2 million people are living with HCV.2 60 to 70 percent of Japanese HCV patients are infected with Genotype 1, and of those, about 95 percent are infected with the GT1b sub-type.3 AbbVie studied its two direct-acting antiviral treatment regimen without RBV in Japan due to patient and viral characteristics specific to the Japanese population, including high prevalence of GT1b.

Paritaprevir is Enanta’s lead protease inhibitor identified within the ongoing Enanta-AbbVie collaboration and is one of the two direct-acting antivirals (2-DAA) in AbbVie’s treatment regimen currently under priority review by the Japanese Ministry of Health, Labour and Welfare. AbbVie has previously announced that it expects regulatory approval of the 2-DAA treatment regimen in Japan in the second half of 2015. Upon commercialization regulatory approval in Japan, Enanta will be entitled to a $30 million milestone payment from AbbVie. In addition, Enanta will be eligible to receive annually tiered royalties, ranging from the low double digits up to twenty percent, on AbbVie’s aggregate net sales of all paritaprevir-containing regimens, including 45% of AbbVie’s worldwide net sales of any 2-DAA regimen.

Paritaprevir is included in AbbVie’s HCV treatment regimens approved in the U.S. in late 2014 and in the E.U. in early 2015.

About GIFT-I Study
GIFT-I comprises 363 patients in two sub-studies. In sub-study 1, 321 genotype 1b (GT1b) patients without cirrhosis, both treatment-na”ive and interferon (IFN) [with or without ribavirin (RBV)] treatment-experienced, were randomized to receive either ombitasvir/paritaprevir/ritonavir (Arm A) [OBV/PTV/r] or placebo (Arm B) [2:1 randomization ratio, stratified by treatment history, past response, viral load and IFN eligibility]. Patients initially randomized to placebo (Arm B) then received OBV/PTV/r for an additional 12 weeks of open-label treatment. Sustained virologic response was assessed 12 weeks post-treatment (SVR12) as a primary efficacy endpoint in a sub-group of previously untreated, non-cirrhotic GT1b patients who were eligible for therapy with IFN and had a high viral load, defined as an HCV RNA level >= 100,000 IU/mL and received at least one dose of the double-blind, active study drug.1

In sub-study 2, 42 GT1b treatment-na”ive and IFN (with our without RBV) treatment-experienced patients with compensated cirrhosis received open-label treatment for 12 weeks (Arm C) with SVR12 and assessed as a secondary efficacy endpoint.1

One patient from each arm (n=3/363) experienced on-treatment virologic failure [Arm A, 0.5% (n=1/215); Arm B, 0.9% (n=1/106); Arm C, 2.4% (n=1/42)].1 Across all arms, eight patients (n=8/354) experienced post-treatment relapse [Arm A, 2.4% (n=5/209); Arm B, 1.0% (n=1/105); Arm C, 5.0% (n=2/40)].1

Protease Inhibitor Collaboration with AbbVie
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. AbbVie is Abbott’s successor under the agreement and is responsible for all development and commercialization activities for paritaprevir, as well as ABT-493, the collaboration’s next-generation protease inhibitor.

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 is discovering, and in some cases developing, novel inhibitors designed for use against the hepatitis C virus (HCV). These inhibitors include members of the direct-acting-antiviral (DAA) inhibitor classes – protease (partnered with AbbVie), NS5A, and nucleotide polymerase – as well as a host-targeted antiviral (HTA) inhibitor class targeted against cyclophilin. In addition, Enanta has a preclinical program in non-alcoholic steatohepatitis, or NASH, which is a condition that results in liver inflammation and damage caused by a buildup of fat in the liver.

Forward Looking Statements Disclaimer
This press release contains forward-looking statements, including with respect to the prospects for AbbVie’s paritaprevir-containing, 2-DAA regimen under development for HCV in Japan. . Statements that are not historical facts are based on our management’s current expectations, estimates, forecasts and projections about our business and the industry in which we operate and our 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 that may affect actual results include the efforts of AbbVie (our collaborator on paritaprevir) regarding regulatory approval and commercialization in Japan for AbbVie’s treatment regimens containing paritaprevir and for competitive treatment regimens; the level of market acceptance and the pricing and rate of reimbursement for the AbbVie’s regimen in Japan; the impact of competitive products on the use and sales of the AbbVie regimen in Japan; 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.

1 Chayama K, et al. Ombitasvir/paritaprevir/ritonavir for Treatment of HCV Genotype 1b in Japanese Patients With or Without Cirrhosis: Results from GIFT-I. Presented at the Annual Meeting of the Japan Society of Hepatology. May 21-23; Kumamoto, Japan

2 Kohnodai Hospital. National Center for Global Health and Medicine [cited 20 February 2013]. Available from:

3 Hajarizadeh B et al. Nat Rev Gastroenterol Hepatol 2013; 10: 553-562.

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