Gilead, Harvard infectious disease expert disagree
The marketing policies of Gilead, the manufacturer of the only two PrEP formulations currently on the market, may “undermine the end-the-epidemic effort,” says Rochelle Walensky, the lead author of a cost-effectiveness model of the Gilead’s PrEP formulations published in the Annals of Internal Medicine this week.
Gilead is encouraging people to switch to Descovy, its branded PrEP product, and Walensky says she is concerned that nobody is going to switch back to the generic version of Truvada that is expected to become available later this year or in early 2021. Generic Truvada is likely to cheaper than Descovy and therefore might mean broader acceptance of PrEP.
“We have an amazing opportunity with Truvada going generic to give a lot of people a lot more access,” says Walensky.
In a prepared statement emailed to Managed Healthcare Executive on Tuesday, Gilead says Walensky's cost-effectiveness model is flawed and understimates the value of Descovy. The company says ncomplete clinical data and assumptions about potential pricing are "inadequate to enable a sufficiently robust analysis and are a disservice to efforts to improve access to PrEP medications."
PrEP stands for pre-exposure prophylaxis. In the context of HIV, it means having people who are at risk of contracting HIV but who are not infected with the virus take antiviral medications. The medications prevent the virus from taking hold and causing infection if people are exposed to HIV. Expanding the use of PrEP is a central element of the Trump administration’s “Ending the HIV Epidemic” plan that the president mentioned in his 2019 State of the Union address. Currently about 1.2 million Americaans are deemed at risk for HIV infection but only about 1 in 10 are on a PrEP regimen.
In an important head-to-head trial, called DISCOVER, Descovy did have advantages over Truvada with respect to a possible risk of kidney failure and fracture risk. “Our big question is, is it [Descovy] worth it?” says Walensky, a professor at Harvard Medical School and an infectious disease physician at Massachusetts General Hospital.
Building what she said were some worst-case assumptions about Truvada into their cost-effectiveness model, Walensky and her co-authors calculated that Descovy could theoretically avert 2,101 fractures and 25 cases of end-stage renal disease over five years if everyone on PrEP were to switch to Descovy instead of taking Truvada (assuming a PrEP population of roughly 123,000 men who have sex with men). But Walensky says she knows those numbers aren’t realistic and that the model was intentionally built to set a ceiling value for Descovy. In addition to painting a worst-case for Truvada’s adverse effects, she says the model doesn’t include possible drawbacks for Descovy, namely, adverse effects on lipid levels and weight.
Using the $100,000-per-QALY ratio commonly used in cost-effectiveness evaluations (by ICER and others), Walensky and her co-authors calculated that Descovy and its superior safety profile is worth only $370 more per year than generic Truvada (for an older population, it would be a bit more because of the higher risk of kidney problems and fractures). Assuming that generic Truvada will be priced at 50% of Descovy, that would mean a price of $8,670 per year for Descovy. According to Walensky and her colleagues, the current Federal Supply Schedule price-the price that the VA pays-is $16,600 per year, so by their figuring, Descovy is overpriced by $7,930 per year.
Gilead's prepared statement says data from the DISCOVER trial after 96 weeks reinforces the bone and renal differences betwen Descovy and Truvada seen at 48 weeks and that the data suggest that "the longer we follow people, the more pronounced the differences in bone and renal safety parameters." Gilead also says assumption that generic Truvada would be priced at 50% less than Descovy is off the mark and that the typical discount of first generics tends to be between 14% and 20%.
The statement also mention that Gilead has said it will donate 2.4 million free bottles of PrEP to uninsured Americans per year for the next 10 years; the statement describes the donation as one of the largest medication donations in U.S. history.
The FDA approved Truvada (emtricitabine and tenofovir disoproxil fumarate) for PrEP in 2012, and it was the only PrEP product on the market for the next seven years. Descovy (emtricitabine and tenofovir alafenamide) was approved in October 2019 for PrEP, although that approval was limited to men who have sex with men and transgender women.
Once Descovy was approved “out came the ads galore from Gilead to update your PrEP,” says Walensky.
The accompanying editorial to Walensky's model by Carlos de Rio and Wendy S. Armstrong, both from Emory University in Atlanta, says that for “PrEP-eligible persons at low risk for fracture and renal disease, it is very hard to justify use of F/TAF [Descovy] knowing that F/TDF [Truvada] will be soon be generic.”