By Declan Butler

India has rejected applications from two US companies for patents on two key AIDS drugs in a move that could mean more people in poor countries will have access to life-saving medicines.

The decisions are the latest in a string of legal victories for Cipla, India's largest generic drug maker. The move could also signal that patent offices in emerging economies are set to take a tougher line than industrialized countries on which drugs deserve patents.

India's patent office rejected claims by Gilead on Tenofovir -- a nucleoside reverse transcriptase inhibitor, which is a frontline drug against HIV/AIDS in poor countries -- and by Tibotec on Darunavir, a newer and more expensive protease inhibitor used as a second-line drug. Both drugs block enzymes that HIV needs to replicate.

The rejection of patents on the two drugs opens the way for India to not only produce cheaper generics for its own population, but also export them to countries where the drug is not patented -- reaffirming India's role as the 'pharmacy' of poor countries. "I only fight cases where I'm sure I've a very strong wicket," says Yusuf Hamied, chairman and managing director of Cipla. "We are delighted that we have been vindicated."

Karen Manson, a spokeswoman for Tibotec, says the company is still "studying the decision" and it is too soon to comment. A Gilead spokeswoman said the company has yet to receive an official notification of the decision from the Indian patent office.

Double-edged deal

The major battle was over Tenofovir, given its extensive use. In 2006, Cipla and a group of Indian and Brazilian non-government organizations (NGOs) independently filed oppositions to Gilead's patent applications on the drug -- marking the first time foreign NGOs had joined Indian ones in contesting a drug patent, a move motivated by the fact that the decision could impact pricing of the drug in Brazil. Gilead responded by striking a deal the same year with 13 other Indian generic manufacturers, giving them a license to make the drug for a 5% royalty.

"Gilead was worried that they might lose, so they offered licenses, but these came with a sting in the tail," says Michelle Childs, director of Médecins sans Frontières's Access to Essential Medicines Campaign. Manufacturers could only buy the active ingredient -- the most expensive part of a drug -- from Gilead-approved suppliers, and they could only sell the drug to 95 of the poorest countries, not to middle-income countries such as China and Brazil which nonetheless have substantial poor populations.

Together these restrictions limited the price reductions the generic makers could offer, says Childs. The Indian patent office decision now guarantees such countries access to a cheap generic supplier, she says.

"Cipla decided to fight rather than sign up to the license; it took a risk and it has paid off," says Childs, noting that Cipla risked patent infringement if it lost. The patent office decision -- taken on 30 July but communicated to Cipla on 29 August -- appears to vindicate the company's case. The decision threw out Gilead's patent claims and upheld the opponent's assertion that the drug was not sufficently novel to deserve a patent.

On a roll

In both claims on Tenofovir and Darunavir, the office also turned down patent applications on variants of the drugs. The decision is seen as a strong rejection of a process known as "evergreening", where companies seek new patents on minor modifications to drugs that may offer only small increases in clinical efficacy. The tactic can effectively extend the patent life of a drug and block competitors from producing cheaper, generic counterparts to these drugs.

The rulings mark a significant application of a little-known provision in the Trade-Related Aspects of Intellectual Property Rights (TRIPS) agreement, which allows countries flexibility in setting the criteria for what is patentable. India is using the provision in ways that put it ahead of industrialized countries in dealing with evergreening, says Childs.

The decisions come on the heels of two other major legal victories notched up by Cipla. On 19 August, the Delhi High Court threw out a suit brought by Bayer against both Cipla and the country's drug regulator, the Drug Controller General of India, for approving Cipla's generic version of Bayer's patented kidney cancer drug Nexavar. And on 29 August, the Supreme Court of India rejected a challenge by Roche to a High Court decision in April that allowed Cipla to market a generic of its lung cancer drug Tarceva.

The former ruling sets a significant precedent for future drug approvals in India because it suggests that those decisions should not be influenced by the status of the drug's patent. And all three cases underscore the current struggle in emerging economies to balance the need for patents to reward innovation while ensuring they do not prevent access to affordable medicines.