The European AIDS Treatment Group has appealed to Europe's medicines licensing body to speed up access to tenofovir, the nucleotide analogue under development by Gilead Sciences. The appeal follows a meeting between the EATG and Gilead Sciences at which European activists learnt that Gilead does not expect the drug to be licensed before 2003 if the US Food and Drug Administration sticks to its demands for 48 week safety data from a controlled study. The FDA could deny Gilead the opportunity to register for accelerated approval, which might allow more rapid licensing of the drug and the commencement of an expanded access programme during the first quarter of 2001.
However, Gilead will be in the position to produce commercial quantities of the drug by the end of 2000, but has hinted to European activists that a large scale expanded access programme lasting more than two years will not be acceptable to company shareholders unless the company is confident of final licensing approval.
The FDA is believed to have tightened its requirements for tenofovir because of fears that the drug may cause serious bone mineral loss. Whether the association with bone mineral loss is greater than reported in protease inhibitor recipients is unclear, since the side effect has only been detected in animal studies. A 48 week bone safety study is due to begin enrolling in June 2000 and will recruit 600 patients.
In Europe, regulators are being asked to approve the drug for salvage therapy based on more limited data, and as quickly as possible.
Tenofovir is an important drug because it is potentially active against HIV that is resistant to all currently nucleoside analogues, making it an attractive component of salvage therapy regimens. Prompt tenofovir availability will be particularly important, say activists and clinicians, because it could complement new protease inhibitors from Bristol-Myers-Squibb and Boehringer Ingelheim (tipranavir) and the fusion inhibitor T-20, all of which appear to be active against HIV with high levels of resistance to all currently available drugs. This would allow people with extensive drug experience to assemble potent combinations of three or four drugs at once, rather than adding single agents to a failing regimen one at a time.
Recent data on tenofovir can be reviewed in Drugs used by people with HIV on this website.