The US Food and Drug Administration's Anti-viral Advisory board has voted against Gilead's application for a US marketing license for adefovir.
At a hearing on November 1, the committee voted against approval after hearing from FDA analysts that:
- A Kaplan-Meier projection of the risk of kidney toxicity at a dose of 60mg suggested that everyone who took the lower dose would ultimately develop kidney toxicity - the only difference from the 120mg dose is that it would take longer to occur.
- Approximately 5% of people previously treated with adefovir appear to have sustained permanent kidney damage
- Gilead had presented only one study which convincingly demonstrated virological efficacy; other studies were poorly designed
- The case for an enhanced anti-viral effect of adefovir against virus with the M184V mutation was not convincing
The committee was also urged to reject adefovir by testimony from the
Treatment Action Group(click to read the statement) and the European AIDS Treatment Group, but other treatment advocates have urged that adefovir should be licensed for use as salvage therapy to provide another option for people with multi-drug experience. HIVandhepatitis.com editor Ron Baker is calling for the FDA to reject the advice of its advisory committee and license the drug in this way, arguing that Gilead's offer of a physician and patient education programme on monthly monitoring for toxicity will be an adequate safeguard.
Gilead must now decide whether to carry out further studies or whether to shelve adefovir and concentrate on the development of the more potent nucleotide analogue tenofovir.