US regulators have turned down Bristol-Myers Squibb’s New Drug Application for daclatasvir in combination with other hepatitis C drugs.

The Food and Drug Administration has issued a complete response letter on daclatasvir, requesting additional data for the NS5A complex inhibitor, in combination with other antivirals. The situation is a little complicated given that the initial daclatasvir NDA, which focused on its use in combination with asunaprevir, an NS3/4A protease inhibitor, was withdrawn by B-MS in October.

The company pulled the file on the daclatasvir/asunaprevir combo citing the “rapidly-evolving HCV treatment landscape in the USA” where Gilead Sciences’ Sovaldi (sofosbuvir) and combos thereof dominate. The B-MS plan is is to focus on the “unique unmet medical need of each local market” and the company argued back in October that daclatasvir/asunaprevir was developed to meet the need of the genotype 1b-rich Japanese patient population, where it received a green light in July as the first all-oral, interferon- and ribavirin-free treatment regimen.

Therefore the FDA wants additional data on other daclatasvir combos and B-MS says it is in discussions with the agency “about the scope of these data”. Chief scientific officer Francis Cuss said that “despite the recent advances in the treatment of HCV there remain significant areas of unmet high need in this disease area”.

He added that “our commitment remains to make daclatasvir-based regimens available to help these difficult-to-treat patients achieve cure”. The drug is already approved in Europe where it is sold as Daklinza and used in combination with Sovaldi.