Monthly pill shows promise for HIV PrEP, will enter phase 3 development
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A once-monthly pill showed promise for HIV PrEP in a phase 2a trial, according to an interim analysis of the data.
Islatravir, formerly known as MK-8591, is a novel investigational nucleoside reverse transcriptase translocation inhibitor being developed by Merck.
Speaking with reporters during the HIV Research for Prevention virtual meeting, Sharon L. Hillier, PhD, professor of reproductive infectious disease at the University of Pittsburgh School of Medicine and director of reproductive infectious disease research at UPMC Magee-Womens Hospital in Pittsburgh, called Islatravir “extremely potent [with] an extremely long half-life.”
“Which means that it’s a long-acting agent that can be used for prevention or treatment,” she said.
An ongoing randomized, double-blind, placebo-controlled, parallel-group, multicenter study is evaluating the safety, tolerability and pharmacokinetics (PK) of oral Islatravir among adults aged 18 to 65 years at low risk for HIV.
The results presented during the meeting came from an analysis of participants who had been randomly assigned in a 2:2:1 ratio to receive six monthly oral doses of Islatravir 60 mg, Islatravir 120 mg, or placebo.
According to Merck, as of the analysis, 192 of the 250 participants had received six doses of Islatravir, which was found to be well tolerated and able to “achieve thresholds thought to be enough to prevent HIV,” Hillier said. Specifically, according to the abstract, an interim analysis of pharmacokinetics (PK) data demonstrated that trough concentrations after either dose “were well above the prespecified PK threshold for HIV-1” and a preliminary analysis of biopsied tissues suggested a “rapid, sustained and adequate distribution” of Islatravir to sampled tissues.
Clinical phase 3 trials will be launched later this year to test whether once-monthly Islatravir can prevent HIV — the first in cisgender women in the United States and Africa and the second in transgender women and men who have sex with men in a global trial, Hillier said.
Because it is a once-monthly medication, it is “probably a little bit more forgiving,” Hillier said.
“That is, if the dose is taken late or people miss a dose, it may still in fact achieve that level that will allow for protection,” she said.
Researchers also have reported promising data on long-acting injectable PrEP, specifically cabotegravir, which received a breakthrough therapy designation from the FDA for HIV prevention.
Hillier said both long-acting injectable PrEP and once-monthly oral PrEP could provide options for patients wishing to prevent HIV while being discreet — something that a daily oral medication does not do.
“I don’t think there’s going to be a single magic bullet that’s the right thing for any one person,” Hillier said.
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Hillier S, et al. Abstract 1363. Presented at: HIV Research for Prevention; Jan. 27-28 and Feb. 3-4, 2021 (virtual meeting).
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