Gilead Sciences has filed for US approval of its investigational oral hepatitis C drug sofosbuvir, a little ahead of expectations.

The move, which had been scheduled for sometime in the second quarter, has shifted the group a big step closer to becoming the first to bag approval of an all-oral regimen for certain types of the disease on the all-important US market.

The company is asking permission from the US Food and Drug Administration to market its drug in combination with oral ribavirin to treat patients with HCV genotypes 2 and 3, as well as alongside ribavirin and pegylated interferon (peg-IFN) injections to treat genotypes 1, 4, 5 and 6.

Treatment for HCV currently includes 24-48 weeks of therapy with peg-IFN, which is linked with significant side effects leaving some patients unable to complete therapy.

If approved, sofosbuvir - which was acquired through Gilead's purchase of Pharmasset - would shorten HCV therapy to 12 to 16 weeks, and depending on the genotype, would either eliminate or reduce the duration of peg-IFN injections, it said.

Improving cure rates

“Sofosbuvir’s antiviral potency, safety profile and once-daily administration have the potential to improve cure rates by simplifying and shortening therapy for patients with this disease," noted chief executive John Martin, highlighting the drug's potential impact.

The New Drug Application contains data from four Phase III studies showing that 12 or 16 weeks of sofosbuvir-based therapy was superior or non-inferior to currently available treatment options or historical controls.

RBC Capital Markets analysts have reportedly upped their expectations for the drug, forecasting speedy US and EU approvals and sales next year of $2 billion, according to FierceBiotech.