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Long-Acting CAB Maintains Superiority to
TDF/FTC in Preventing HIV in Women
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AIDS 2022, July 29-August 2, Montreal
Mark Mascolini
In the 12 months after unblinding of the HPTN 084 trial, long-acting injected cabotegravir (CAB) remained superior to tenofovir disoproxil/emtricitabine (TDF/FTC) in preventing HIV infection in African participants assigned female at birth [1]. No new safety concerns arose in the year after unblinding.
Earlier, HPTN 084 researchers reported about a 90% lower risk of HIV infection in the CAB group (hazard ratio [HR] vs TDF/FTC 0.12, 95% confidence interval [CI] 0.05 to 0.31, P < 0.0001) in this large 7-country trial [2]. HPTN 084 is a phase 3, randomized, double-blind, double-dummy superiority trial that assigned 1614 women to injected CAB and 1610 to oral TDF/FTC. Through 3898 person-years of follow-up, 4 new HIV infections appeared in the CAB group (incidence 0.2 cases per 100 person-years) and 36 in the TDF/FTC group (incidence 1.85 cases per 100 person-years) [2].
The blinded phase of the trial stopped after an interim review in November 2020 because results until then clearly favored CAB. Participants continued their initial treatment assignment as trial planners created a protocol amendment offering open-label (unblinded) CAB to all women. Data presented at AIDS 2022 cover the 12 months after unblinding. Researchers estimated cumulative HIV incidence for the combined blinded part of HPTN 084 plus the 12-month unblinded period.
HIV incidence in the combined blinded and unblinded periods stood at 6 infections in the CAB group (0.18 cases per 100 person-years) and 56 infections in the TDF/FTC group (1.70 cases per 100 person-years). Those numbers meant CAB maintained the same 90% lower risk of HIV infection for the combined blinded-unblinded period (HR 0.11, 95% CI 0.05 to 0.24).
The new HIV infections that occurred in the CAB group all involved women not getting the full dose of CAB, or not getting CAB at all. No HIV infections occurred in women receiving their CAB injections as prescribed (injections every 8 weeks after an initial 4-week interval load).
During the 12-month unblinded period only, serious adverse events arose in 2% of the CAB group and 2% of the TDF/FTC group. Thirty-two women getting CAB (2%) had grade 2 or worse injection site reactions during the unblinded phase.
Among women getting CAB, pregnancy incidence rose from 1.5 pregnancies per 100 person-years in the blinded period to 2.6 pregnancies per 100 person-years in the unblinded period. Among women receiving TDF/FTC, pregnancy incidence climbed from 1 per 100 person-years in the blinded phase to 3.8 per 100 person-years in the unblinded phase. The CAB and TDF/FTC groups did not differ in proportion of live births, and researchers observed no congenital anomalies in either study arm.
The researchers concluded that “CAB access should be a priority for populations with greatest need.”
References
1. Delany-Moretlwe S, Hughes JP, Bock P, et al. Long acting cabotegravir: updated efficacy and safety results from HPTN 084. AIDS 2022, July 29-August 2, Montreal. Abstract OALBX0108.
2. Delany-Moretlwe S, Hughes JP, Bock P, et al; HPTN 084 study group. Cabotegravir for the prevention of HIV-1 in women: results from HPTN 084, a phase 3, randomised clinical trial. Lancet. 2022;399:1779-1789. doi: 10.1016/S0140-6736(22)00538-4.
https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(22)00538-4/fulltext
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