Gilead's Descovy snared its PrEP data, but can it stand up to Truvada generics?

Gilead Sciences has the data it’ll need to start transitioning patients taking Truvada for PrEP over to Descovy, a drug with a longer patient life. But once Truvada generics hit, it might be a different story.

The Big Biotech recently touted noninferiority data showing that Descovy had matched Truvada when it came to preventing HIV infection. Numerically speaking, Descovy beat out its predecessor, though its seven HIV cases to Truvada’s 15 came out to a difference that wasn’t statistically significant.

The “numerical Descovy benefit” was “likely driven by noncompliance and enrollment errors,” Leerink Partners’ Geoffrey Porges wrote in a note to clients.

Still, the result “sets the stage for Gilead to actively transition the >$2 billion in current PrEP revenue for Truvada to Descovy,” he said, adding that investors would likely expect most of that revenue haul to head Descovy’s way before Truvada’s September 2021 patent expiration.

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But while “the trial results will provide Gilead with marketing ammunition” to switch scripts over to Descovy, the differences between the two products “remain modest, and it is difficult to tell how much of the transition will stick” after Truvada generics hit, Porges noted.

In the study, Descovy did come out significantly ahead of Truvada on the safety side, though Porges described its bone and kidney benefits as “small.” Still, the difference may convince physicians and patients to use the medicine; people are taking PrEP therapy longer than originally expected, increasing the importance of metabolic safety.

Payers, on the other hand? For them, Descovy may be a tougher pill to swallow. “At this stage paying about $18,000 per year for a 1% difference in Bone Mineral Density and a 2-4 mL/min difference in renal function might challenge the generosity of post-2020 government and private payers,” Porges wrote.

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As Gilead gears up for the Truvada-to-Descovy transition, it's also pouring money into PrEP awareness. The company “actually put a significant amount of additional funding” behind Truvada for PrEP this year, commercial chief Laura Hamill said on Gilead's fourth-quarter earnings call, and it brought two DTC campaigns to the airwaves in 2018 to build buzz.

Gilead is counting on HIV to bring in big sales as the company finds its footing elsewhere. Hep C revenues have flagged in recent years, prompting the company to dive into oncology with its Kite buy. But CAR-T drug Yescarta has hardly been an instant success; on the contrary, it’s been slow to get off the ground, as has fellow CAR-T therapy and archrival Kymriah from Novartis.