Katrina Ortblad

This session, moderated by Dr. Walter Jaoko (University of Nairobi), included late-breaker abstract presentations on adherence to, resistance to, and safety/pharmacokinetics of existing and emerging PrEP products, including the dapivirine vaginal ring, daily oral tenofovir disoproxil fumarate (TDF)-based pills, and oral islatravir (ISL) once monthly pills.

Dr. Gonasagrie (Lulu) Nair (Stellenbosh University) presented data on PrEP adherence among 247 AGYWs in SSA enrolled in MTN-034 (REACH), a crossover randomized trial where AGYWs either received the monthly dapivirine ring or daily oral TDF/FTC. Most participants had moderate adherence (77.8% ring; 58.6% oral PrEP) 26 months into the study; high adherence was observed in 50.2% of ring and 22.4% of oral PrEP users. Acceptability varied (88.5% ring; 63.9% oral PrEP) and HIV incidence was low (1 seroconversion). Dr. Urvi Parivh (University of Pittsburg) presented data from the Global Evaluation of Microbicide Sensitivity (GEMS) project, which was established to monitor HIV drug resistance in TDF-based PrEP rollout programs (36 partners) in SSA. Using cross-sectional data, the study observed 229 HIV seroconversions among 104,000 PrEP users. Among the 118 samples for seroconversions sequenced, the study found 23% (27/118) had drug resistance with high adherence. Dr. Sharon Hillier (Magee-Women’s Research Institute) presented data on the safety and pharmacokinetics of oral ISL once monthly PrEP through Week 24 of an ongoing phase 2a trial. Of the 242 participants randomized, 60% reported an adverse event (15% drug-related). Additionally, grade 3-4 laboratory values were uncommon and ISL trough concentrations remained above the pre-specified threshold.

This session highlighted the potential new PrEP products have for increasing choice among individuals at HIV risk, as well as the need for continued drug resistance monitoring and improved tools for acute HIV infection measurement with the delivery of existing products. The choice of different prevention products with different profiles is important so individuals can select a product that best fits their lifestyle, resulting in the greatest HIV protection. Drug resistance and breakthrough HIV infections among PrEP users is concerning, thus more research is needed on partner transmission, non-protective PrEP blood levels, and other areas to better understand this resistance.