(Adds Gilead comment, further details)
LONDON, March 27 (Reuters) - International groups representing doctors and patients have launched a fresh challenge to the patent on Gilead Sciences' hepatitis C drug sofosbuvir at the European Patent Office in order to increase access to the treatment.
Sofosbuvir is sold by the U.S. drugmaker as Sovaldi and is included in other hepatitis C medicines such as Harvoni and Epclusa.
The treatment is transforming the fight against the liver-destroying viral disease by offering an effective cure, but Medecins Sans Frontieres (MSF) and Medecins du Monde (MdM) said its high cost was a serious barrier.
The campaigners argue that the patent on the drug, which costs tens of thousands of dollars for a typical course, is open to challenge because the science behind sofosbuvir is not new.
Previously, in 2015, MdM had accused Gilead of abusing its patent on sofosbuvir.
If the latest patent challenge is successful, it could make cheaper generic versions of sofosbuvir available in Europe.
MSF and MdM, who have been joined by 28 groups from across Europe, said key patents on sofosbuvir had already been revoked in China and Ukraine, and decisions were pending in other countries, including Argentina, India, Brazil, Russia and Thailand.
Gilead said it was working to ensure patients had access to its hepatitis drugs and it had cured more people in the past 2-1/2 years than were cured in the previous 20 years combined.
"This action has no immediate impact on Gilead’s patents or on our exclusive right to make and sell Sovaldi, Harvoni and Epclusa in the EU," a spokeswoman said of the patent challenge. (Editing by Keith Weir)