Enanta Pharmaceuticals, Inc., a research and development-focused biotechnology company, announced that its partner AbbVie has received Breakthrough Therapy designation from the US Food and Drug Administration (FDA) for its investigational direct-acting antiviral (DAA) combination regimen with and without ribavirin for the treatment of genotype 1 (GT1) hepatitis C virus (HCV) infection. ABT-450, Enanta’s lead HCV protease inhibitor identified in its ongoing collaboration with AbbVie, is one of three DAAs in the regimen.

The all-oral, triple-DAA combination regimen is currently being studied in phase III clinical trials that are being conducted by AbbVie. The phase III programme includes more than 2,000 patients with genotype 1 HCV infection, with trial sites in 29 countries. The DAAs in the trials include ABT-450/r (protease inhibitor and ritonavir) combined with two of AbbVie’s proprietary investigational DAAs, ABT-267 (NS5A inhibitor) and ABT-333 (non-nucleoside polymerase inhibitor), and are being dosed with and without ribavirin.

According to the FDA, Breakthrough Therapy designation is intended to expedite the development and review of drugs for serious or life-threatening conditions. The criteria for Breakthrough Therapy designation include preliminary clinical evidence demonstrating a drug may have substantial improvement on at least one clinically significant endpoint compared to available therapy. A Breakthrough Therapy designation conveys all of the fast track programme features, as well as more intensive FDA guidance on an efficient drug development programme.

Hepatitis C is a liver disease and the virus is typically spread through direct contact with the blood of an infected person. Hepatitis C increases a person’s risk of developing chronic liver disease, cirrhosis, liver cancer and death. There is an acute need for new HCV therapies that are safer and more effective for many variants of the virus.

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. Under the agreement, AbbVie (as the successor to Abbott) is responsible for all development and commercialization activities for ABT-450. Enanta received a $57 million upfront payment upon signing the collaboration agreement, has received all clinical milestone payments, and is eligible to receive an additional $195 million in payments for regulatory milestones, as well as double-digit royalties worldwide on any revenue allocable to the collaboration’s protease inhibitors. Also, for any additional collaborative HCV protease inhibitor product candidate developed under the agreement, Enanta holds an option to modify the US portion of it rights to receive milestone payments and worldwide royalties. With this option, Enanta can fund 40 percent of US development costs and US commercialization efforts (sales and promotion costs) in exchange for 40 per cent of any US profits ultimately achieved after regulatory approval instead of receiving payments for US commercial regulatory approval milestones and royalties on US sales.

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 in the infectious disease field.