The FDA has approved Gilead’s Descovy for HIV pre-exposure prophylaxis (PrEP), giving the company a chance to push the drug in the new indication before generics dent its current PrEP therapy Truvada.
Descovy (emtricitabine and tenofovir alafenamide) has been cleared for adolescents and adults who are at risk of HIV infection because they have sex with an HIV-positive partner. However, the FDA followed the advice of its advisor committee and didn’t approve use of the drug in people at-risk for HIV from receptive vaginal sex, saying the data in this case wasn’t strong enough.
That excludes cisgender women from the label, in other words women whose perceived gender corresponds to their birth sex, a group thought to account for around 7% of current PrEP prescriptions.
The FDA’s advisors had suggested that the data wasn’t compelling in adolescents either, so Descovy’s label is stronger than it might have been.
In a statement, the FDA said that Descovy’s efficacy in preventing HIV transmission was similar to Truvada (emtricitabine/tenofovir disoproxil fumarate), which became the first drug approved in the US for PrEP in 2012, and has since grown into a $3bn product, with PrEP estimated to account for around $2bn of that total.
Gilead says it has data showing that Descovy has a more favourable side-effect profile, with less bone and kidney toxicity than Truvada, which is due to lose patent protection soon.
The FDA didn’t comment on that position, other than to note that the most common side effect with Descovy is diarrhoea and that like Truvada the drug has a boxed warning that patients with HIV and hepatitis B virus (HBV) co-infections can experience exacerbation when stopping treatment with the drug.
Gilead’s chief executive Daniel O’Day said that Descovy’s offers “statistically significant improvements in renal and bone safety, which can be an important consideration as people at risk increasingly use PrEP for longer periods of time”.
The company will have to convince payers that advantage is worth switching PrEP patients from Truvada, as cheaper alternatives reach the market. An authorised generic made by Teva is due to launch next year, with a more general launch expected after the patent expiry in 2021.
At the moment, both Truvada and Descovy are priced at around $1,800 for a month’s supply, and that has drawn criticism from HIV advocacy groups including the PrEP4All coalition, which says it should be much cheaper as public money paid “for almost the full cost of its development”.
Gilead has also been attacked by US lawmakers for its pricing policy for Truvada, and responded by pledging enough of the drug to supply 200,000 patients annually for more than a decade.
Some analysts think that Descovy’s PrEP approval will unlock sales of $3bn-plus for the drug, which would be a big increase given its $700m tally in the first half of 2019.
However, Tim Horn, director of medication access and pricing at the National Alliance of State and Territorial AIDS Directors (NASTAD) recently told Reuters that “based on the science that we have seen thus far, there is no indication that everyone needs to be taking Descovy”.
He added: “We see no reason to push back against commercial payers or Medicaid programmes that would move to prefer generic Truvada…provided there are guard-rails that do not deny access to Descovy for those who need Descovy.”