With challenges looming over Gilead Science’s dominance in hepatitis C treatments, FDA has put a brake on Bristol-Myers Squibb’s bid for a hep. C combo drug entry.

BMS announced FDA has issued a Complete Response Letter regarding its NDA for daclatasvir in combination with other agents for treating the virus.

BMS last month announced it would abandon an effort to win FDA approval for a two-drug combo of NS5A inhibitor daclatasvir and asunaprevir, an NS3/4A protease inhibitor. The pair had earned breakthrough status back in February.

Following the withdrawal of asunaprevir, FDA is requesting additional data for daclatasvir used in combination with other agents, BMS said in a statement, adding that it is in discussion with FDA about the scope of the data.

The drugmakersaid it is committed to the ongoing clinical development of daclatasvir, which is currently being investigated  in multiple treatment regiments for HCV patients globally.

“Our commitment remains to make daclatasvir-based regimens available to help these difficult-to-treat patients achieve cure, and we will continue to collaborate with the FDA to bring daclatasvir to patients in the US as quickly as possible,’ Bristol’s Francis Cuss, EVP and chief scientific officer, R&D, noted in a statement.

“Despite the recent advances in the treatment of hepatitis C there remain significant areas of unmet need in this disease area,” he stated.

AbbVie is expecting an FDA decision on its hep. C combination entry in December, an injection-free multiple-drug combination that will challenge Gilead’s Harvoni.

The all-oral combination of top-seller Sovaldi and ​the NS5A inhibitor ledipasvir, Harvoni has achieved strong uptake since its approval last month. AbbVie also won a European Medicines Agency recommendation for the drug last month.

Merck remains a contender in the space, although it has reported a mixed bag of results in trials of its HCV combo therapy. Boehringer Ingelheim, on the other hand, dropped out of the hep. C race in June.