The patent on Viread has been revoked by China, BioWorld reports. The Gilead Sciences drug, which is its third best seller worldwide, has been at the heart of China’s push to get pharmaceutical companies to become more flexible with the pricing of lifesaving drugs around the world. Experts say taking away the patent for the HIV/AIDS and hepatitis B virus (HBV) drug will open the door for tenofovir, its active ingredient, to be produced generically and allow China to export the cheaper version of the drug to other countries. The high price of Viread ($240 for a 30-pack of 300 milligram pills) has put treatment for both diseases beyond the reach of many patients worldwide, who often have to pay much of their medical expenses out-of-pocket. China’s intellectual property office revoked the patent after a challenge by Aurisco, the largest pharmaceutical manufacturer in China, claimed the drug lacked novelty and was not entitled to protection.