according to results from the ATLAS-2M study, presented at the HIV Glasgow 2020 Virtual Conference, held October 5-8. The women also reported high satisfaction with the regimen, compared with daily oral antiretroviral therapy.
Previously reported results had shown that the two-drug combination administered every 8 weeks (600 mg cabotegravir and 900 mg rilpivirine) was noninferior to injections every 4 weeks (400 mg cabotegravir and 600 mg rilpivirine) in adults with HIV during the open-label phase 3b ATLAS-2M trial. Further, the ATLAS and FLAIR phase 3 trials had shown the 4-week administration of the therapy to be noninferior to a daily oral three-drug antiretroviral therapy.
, of ViiV Healthcare (which is seeking regulatory approval for CAB/RPV treatment), and his colleagues completed a planned subgroup analysis of women in the ATLAS-2M trial. The primary endpoint was the proportion of intention-to-treat participants with plasma HIV-1 RNA of at least 50 copies/mL with a noninferiority margin of 4% at 48 weeks. The secondary endpoint was the proportion of participants with HIV-1 RNA under 50 copies/mL with a noninferiority margin of 10%.
Among the 280 women enrolled, 137 were randomly assigned to receive injections every 8 weeks, and 143 to receive injections every 4 weeks. A majority of the women (56%) were White, the median age was 44 years, and just over half (53%) were treatment naive with cabotegravir and rilpivirine.
At 48 weeks, 3.6% of women in the 8-week group and 0% of women in the 4-week group had at least 50 copies/mL of HIV-1 RNA. In both arms, 91% of participants had HIV-1 RNA under 50 copies/mL. Plasma concentrations of cabotegravir and rilpivirine were similar between the women and the overall study population.
Confirmed virologic failure occurred in five women, all before week 24. Three of the women were subtype A/A1, and four of them had archived nonnucleoside reverse transcriptase inhibitor (NNRTI) resistance–associated mutations.
There were no significant differences in the safety profile between the groups; 99% of injection site reactions that occurred were mild to moderate and lasted a median 3-4 days. Fewer than 4% of participants discontinued because of adverse events – five women in the 8-week group and five women in the 4-week group. Four women cited injection site reactions as the reason for discontinuation.
Women not previously treated with CAB/RPV reported increased treatment satisfaction on the HIV Treatment Satisfaction Questionnaire, a score of 5.4 in the 8-week group and 3.9 in the 4-week group. Among those with prior CAB/RPV treatment, 88% preferred the 8-weekly injections, 8% preferred the 4-weekly injections, and 2% preferred oral dosing.
Long-acting CAB/RPV is an investigational formulation. In December 2019, the Food and Drug Administration denied approval to the formulation on the basis of manufacturing and chemistry concerns, according to a company
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