Study Finds Once-Yearly Intramuscular Injections Efficacious for HIV PrEP

A new study has demonstrated the "pharmacokinetics and safety of two once-yearly intramuscular lenacapavir formulations.”

The phase 1 study examined participants aged 18-55 without HIV who “evaluated the pharmacokinetics, safety, and tolerability of two lenacapavir free acid formulations administered by ventrogluteal intramuscular injection as a single 5000 mg dose.” Certain pharmacokinetic parameters were evaluated, including “the area under the concentration-time curve for the once-yearly dosing interval calculated from days 1 to 365” to test plasma concentration. This data was compared with plasma concentration data from phase 3 studies of twice-yearly subcutaneous lenacapavir.

The study included 20 participants who received lenacapavir formulation 1 and 20 who received lenacapavir formulation 2. Following the administration of intramuscular lenacapavir, “concentrations increased rapidly, and median time to maximum concentration was 84·1 days (IQR 56·1–112·0) for formulation 1 and 69·9 days (55·3–105·5) for formulation 2.” The “highest median concentration of once-yearly intramuscular lenacapavir…remained above the highest median twice-yearly subcutaneous lenacapavir concentration.”

The study authors wrote that “following administration of once-yearly intramuscular lenacapavir, median plasma concentrations exceeded those associated with efficacy in phase 3 studies of twice-yearly subcutaneous lenacapavir for PrEP for at least 56 weeks. Both formulations were safe and well tolerated. These data show the potential for biomedical HIV prevention with a once-yearly dosing interval.”