Two HIV projects become one for Gilead and Merck

Long-acting HIV therapies are shaping up to be competitive. But Gilead and Merck & Co are calling a truce – at least in part – to develop combinations of their respective projects lenacapavir, a capsid inhibitor, and islatravir, a nucleoside reverse transcriptase translocation inhibitor. The deal covers oral and injectable formulations; the “sweet spot”, in terms of improving compliance, would be once-weekly administration for oral, and once every three months or longer for injectable. The only financial terms given involved potential revenue splits. Trials of the oral combo should start in the second half of 2021, while the injectable project will not hit the clinic until next year owing to the technical difficulties around coformulation, Merck executives said during a conference call today. They added that the projects could reach the market in 2025 and 2027 respectively. The deal also covers an option for either company to license the other’s oral integrase inhibitors, which are currently preclinical, for combination. But outside the agreement the groups remain fierce rivals in HIV, the Merck execs stressed. That group is developing islatravir monotherapy for pre-exposure propyhlaxis; Gilead is also taking lenacapavir into phase III in PrEP soon.

Notable trials with Gilead's lenacapavir and Merck's islatravir
Setting Dosing Study details Timing
Lenacapavir (Gilead)
Heavily treatment-experienced pts with multidrug-resistant HIV-1 Oral lead in then SC every 6 mo Ph2/3 Capella, NCT04150068 Positive data reported, filing due H2 2021
Treatment-naive HIV pts, combo with other antiretroviral agents Oral lead in then SC every 6 mo Ph2 Calibrate, NCT04143594 Data H2 2021
PrEP in men who have sex with men and trans people SC every 6 mo Ph3 Due to start H1 2021
PrEP in young women SC every 6 mo Ph3 Due to start H2 2021
Islatravir (Merck & Co)
Plus doravirine* in treatment-naive pts Daily oral Ph3, NCT04233879 PC Mar 2024
Plus doravirine* in heavily treatment-experienced pts Daily oral Ph3, NCT04233216 PC Jul 2024
Plus MK-8507*, switch study Weekly oral Ph2, NCT04564547 PC Jun 2022
Monotherapy PrEP in men and transgender women who have sex with men Monthly oral Ph3 3 Impower-024, NCT04652700 PC Jan 2024
Monotherapy PrEP in women Monthly oral Ph3 Impower-022, NCT04644029 PC Jul 2024
Monotherapy PrEP Yearly implant "Entering ph2" Ph1 data presented at CROI in Mar 2021

*Doravirine (Pifeltro) and MK-8507 are non-nucleoside reverse transcriptase inhibitors. PC: primary completion. Source: Evaluate Pharma, & company releases.

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