FDA AdCom backs Gilead's move to expand Descovy label — but stops short of endorsing broad PrEP use
Gilead is one step closer to unlocking a potentially blockbuster new use of its two-drug HIV regimen Descovy — though probably not all of it.
In a meeting late Wednesday, the FDA’s Antimicrobial Drugs Advisory Committee voted 16 to 2 endorsing Descovy as a pre-exposure prophylaxis, or PrEP, in men and transgender women who have sex with men. On the question of expanding the indication to include cisgender women, though, a slight majority of experts (10 versus 8) voted against it, citing a lack of data.
The recommendations were largely in line with the agency’s in-house review, which pointed out that an approval covering cisgender women would require a questionable extrapolation of PK data. While Gilead did provide proof of systemic drug concentrations, the measurements were largely unhelpful in quantifiable and interpreting whether there are adequate drug concentrations in cervicovaginal tissues.
In a statement, Diana Brainard — SVP of HIV and emerging viruses — praised the AdCom for a “thoughtful review and discussion of the data.” Though the company did not comment directly on expanding Descovy’s use to cisgender women, it had this to add:
Gilead recognizes the value that Descovy could bring to HIV prevention efforts for the broadest possible at-risk population in the United States and will continue to work with FDA as the agency completes its review of the application.
In terms of seizing a big piece of the market, though, missing out on the cisgender women label might not be that big of a deal after all. Cisgender women form less than 7% of PrEP use, according to Jefferies analyst Michael Yee.
SVB Leerink’s Geoffrey Porges noted just a few days ago that MSMs form the most important population for Descovy’s add-on OK, though “for Gilead’s purposes it is useful to have a broad label with all relevant at-risk populations included, and getting such an endorsement from the AdCom would give their Descovy launch additional momentum.”
His peak sales estimate for Descovy stands at $3.8 billion.
Additional momentum matters here because Descovy will likely be going up against generics of Gilead’s own Truvada, with launches scheduled for next September. Descovy’s advantages over Truvada — substituting TAF, or tenofovir alafenamide, for TDF (tenofovir disoproxil fumarate) in combination with emtricitabine — could appear slight under the best of circumstances. It remains to be seen whether payers will be willing to cover a new branded drug over a generic for safety issues such as bone mineral density.