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Transgender women (TGW) in HPTN 083: an evaluation of safety, efficacy, and gender affirming hormonal therapy (GAHT) interactions with long-acting cabotegravir (CAB-LA)

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BACKGROUND: HPTN 083 demonstrated a 66% reduced risk of HIV acquisition for long-acting injectable cabotegravir (CAB-LA) vs. daily oral TDF/FTC. As transgender women (TGW) remain a priority group for HIV prevention, we report the safety, prevention efficacy, and pharmacokinetics (PK) of CAB-LA in TGW during the blinded phase of HPTN 083.
METHODS: Participant characteristics, including history of interpersonal violence, HIV risk perception, and grade 2+ adverse events, were compared between TGW and the larger study cohort. CAB drug concentrations were measured in a subset of TGW with and without gender-affirming hormonal therapy (GAHT) to evaluate the potential impact of GAHT on CAB PK.
RESULTS: Of 4566 participants enrolled in HPTN 083, 570 (12.5%) were TGW (United States 21.9%, Latin America 36.0%, Asia 39.5%, and Africa 2.6%).During the study, 330 (57.9%) TGW reported GAHT use, with estradiol valerate (44.5%) and spironolactone (32.4%) most frequently reported. HIV incidence among TGW was 1.80% (TDF/FTC) and 0.54% (CAB-LA) during the blinded phase of HPTN 083 (hazard ratio: 0.34, 95%, CI 0.08-1.56).When compared to the larger HPTN 083 cohort, TGW experienced an increased frequency of sexual (56.7% vs. 45.4%), physical (30.2% vs. 19.2%), and emotional (47.4% vs. 36.4%) interpersonal violence, and lower self-perceived HIV acquisition risk (53.3% vs. 66.5%). CAB-LA was well tolerated in TGW; the frequency of grade 2+ adverse events did not differ between TGW receiving CAB-LA or TDF/FTC (92.5% vs. 88.8%). CAB drug concentrations were measured in a subset of TGW who received on-time CAB injections (23 not taking GAHT, 30 taking GAHT).CAB drug concentrations were comparable between the two groups, suggesting the lack of a GAHT effect on CAB PK (Figure 1).


CONCLUSIONS: CAB-LA is a safe and effective HIV prevention strategy for TGW. Initial findings suggest there is no impact of GAHT on CAB concentrations.