Unauthorized knock-offs of Gilead’s pricey blockbuster hepatitis C therapy, Sovaldi, may soon hit the market in India after the government refused to grant it patent protection.

The Director General of Patent Designs and Trademarks sided this week with a challenge by Indian drugmaker Natco Pharma and the Initiative for Medicines, Access & Knowledge, a U.S.-based nonprofit devoted to challenging nonmeritorious patents in developing countries. According to I-MAK cofounder Tahir Amin, the patent office agreed that Gilead’s bid failed to meet the stringent IP requirements of Indian patent law to qualify as brand new and not simply an improvement on existing science.

Gilead had argued that Solvadi (sofosbuvir) was a wholly new therapy not anticipated by the existing science, according to the patent ruling.

With the patent bid denied, there is now nothing blocking generic entry of Sovaldi copies, Amin said. He expects unauthorized generic versions from Natco and others could hit the market in six months.

Those competitors would join seven others that have signed nonexclusive licenses with Gilead to sell generic Sovaldi in the developing world—an effort to limit the sticker shock of a drug that costs $84,000 for a full treatment in the U.S. Six of those seven firms are based in India.

Gilead will likely appeal the ruling, Amin says, adding that the patent office is still considering a challenge to another Sovaldi patent application. Until India actually recognizes any of the protections sought by Gilead, there is nothing stopping generic entry, Amin says. The fight over Sovaldi’s patent protections could stretch on for years, he says.

Natco and Gilead did not respond to requests for comment by press time. — Bryan Koenig