The US Food and Drug Administration has granted breakthrough therapy designation to Bristol-Myers Squibb’s investigational combination treatment for hepatitis C.

Specifically, the agency will give support to daclatasvir (DCV) and asunaprevir (ASV) for use as a combination therapy in the treatment of genotype 1b chronic HCV infection. The designation is based on data from the company’s ongoing Phase III programme evaluating the all-oral combo of DCV, an NS5A replication complex inhibitor, and ASV, a NS3 protease inhibitor, without the mainstay HCV drug ribavirin.

Breakthrough designation differs from the FDA's other fast-track programmes, such as accelerated approval and priority review, as it involves more intensive guidance from the agency on putting together an efficient drug development programme. The criteria for the designation require preliminary clinical evidence that demonstrates the drug may have substantial improvement on at least one clinically significant endpoint over available therapy.

This is the second DCV-based regimen to get breakthrough designation. Last April, the status was conferred on a combo of DCV, ASV and and BMS-791325, an NS5B non-nucleoside polymerase inhibitor. Brian Daniels, head of global development and medical affairs at the US major, said the news represents "an important milestone [as]potential expedited review can make a critical difference for patients".

Roughly 170 million people worldwide are infected with HCV, including 2.7-3.9 million chronically infected in the USA.