Gilead's Descovy nabs PrEP nod. Next step: Convert Truvada patients before generics hit

Clock’s ticking. After an expected FDA nod for Descovy as the second HIV PrEP drug, Gilead Sciences now has one year to convince its current Truvada takers to switch over before generics hit.

The FDA approval is for Descovy use in men and transgender women for HIV prevention. The exclusion of cisgender women from the label was expected, as they were not included in Descovy’s clinical program. Plus, the move follows both the FDA’s own review and the recommendation from an independent expert panel in August.

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That shouldn’t be much of a problem—Gilead has said that women account for less than 10% of current patients on Truvada. Instead, the company's focus will now be on getting as many people to switch from the first-generation PrEP to Descovy before it falls to generic competition in September 2020, analysts at SVB Leerink and Jefferies argued.

In a head-to-head study, Descovy showed it could match its predecessor when it comes to preventing HIV infection. But even though Gilead has long touted Descovy’s better safety profile in bone and kidney toxicities, the FDA still threw a renal impairment warning on the new drug’s label.

The lack of warnings for bone mineral density loss could be a key selling point for Descovy, though, and “should provide sufficient ammunition for Gilead to drive substantial switching from Truvada in men,” SVB Leerink’s Geoffrey Porges wrote in a Thursday note to clients. Plus, Descovy has also demonstrated more rapid onset and maintained drug concentration longer than Truvada.

“Descovy for PrEP provides a new HIV prevention option that matches Truvada’s high efficacy with 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,” Gilead CEO Daniel O'Day said in a statement.

However, winning payers for what he called a “modest” difference between the two products might be challenging, and it remains to be seen whether patients will transition back after Truvada generics hit, Porges previously noted.

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In the clinical study, Descovy did demonstrate both bone and kidney benefits, which can be attributed to its newer tenofovir alafenamide (TAF) component, versus tenofovir disoproxil fumarate (TDF, sold under the brand Viread) that’s used in Truvada. Those two ingredients are at the center of a lawsuit from patients and 31 states that claims Gilead deliberately withheld TAF so that TDF could enjoy better sales within its patent protection period.

Even the remaining 10% female population might not hurt after all. Some of these patients might switch over anyway, Porges argued, since there’s likely a safety benefit. Jefferies’ Michael Yee, in a Thursday note to investors, said his team anticipates Descovy will eventually get a broad label “given the similarities between Descovy and Truvada … and Gilead’s likely willingness to run additional studies in women.”

Total global Truvada sales in the first half of 2019 fell to $1.32 billion, from $1.42 billion a year ago, mainly due to the decline in Europe, where it has already gone generic. In the meantime, Descovy as part of HIV treatment (rather than prevention) also dropped over 8% to $700 million.

SVB Leerink’s Porges noted current consensus pegs Descovy could grow from about $1.5 billion in 2019 to $3 billion in 2022, suggesting it could capture about half of Truvada’s current PrEP revenue.

Gilead in May pledged to donate up to 2.4 million bottles of Truvada to the U.S. Centers for Disease Control and Prevention each year for uninsured Americans at risk for HIV until 2030. The donation will transition to Descovy now that it’s also approved for PrEP.