Singapore: China's State Intellectual Property Office (SIPO) has yanked the patent for Gilead Sciences popular HIV and hepatitis B drug Viread (tenofovir), claiming that it lacks novelty.

The country has a growing HIV/AIDS population and as many as 30 million people with chronic hepatitis B. The revocation came on a challenge from Chinese API maker Aurisco. As China invalidated the patent instead of using its compulsory licensing law, any drugmaker will now be able to produce tenofovir.

The move is expected to at least halve the cost of the drug from its current $240 a month price.