Tenofovir alafenamide and elvitegravir loaded nanoparticles for long-acting prevention of HIV-1 vaginal transmission

Abstract

Objective: This report presents tenofovir (TFV) alafenamide (TAF) and elvitegravir (EVG) fabricated into nanoparticles for subcutaneous delivery as prevention strategy. Design: Prospective prevention study in humanized bone marrow-liver-thymus (hu- BLT) mice. Methods: Using an oil-in-water emulsion solvent evaporation technique, TAF+EVG drugs were entrapped together into nanoparticles containing poly(lactic-co-glycolic acid). In-vitro prophylaxis studies (90% inhibition concentration) compared nanoparticles with drugs in solution. Hu-BLT (n=5/group) mice were given 200 mg/kg subcutaneous, and vaginally challenged with HIV-1 [5×105 tissue culture infectious dose for 50% of cells cultures (TCID50)] 4 and 14 days post-nanoparticle administration (postnanoparticle injection). Control mice (n=5) were challenged at 4 days. Weekly plasma viral load was performed using RT-PCR. Hu-BLT mice were sacrificed and lymph nodes were harvested for HIV-1 viral RNA detection by in-situ hybridization. In parallel, CD34+ humanized mice (3/time point) compared TFV and EVG drug levels in vaginal tissues from nanoparticles and solution. TFV and EVG were analyzed from tissue using liquid chromatograph-tandem mass spectrometry (LC-MS/MS). Results: TAF+EVG nanoparticles were less than 200nm in size. In-vitro prophylaxis indicates TAF+EVG nanoparticles 90% inhibition concentration was 0.002mg/ml and TAF+EVG solution was 0.78mg/ml. TAF+EVG nanoparticles demonstrated detectable drugs for 14 days and 72 h for solution, respectively. All hu-BLT control mice became infected within 14 days after HIV-1 challenge. In contrast, hu-BLT mice that received nanoparticles and challenged at 4 days post-nanoparticle injection, 100% were uninfected, and 60% challenged at 14 days post-nanoparticle injection were uninfected (P=0.007; Mantel-Cox test). In-situ hybridization confirmed these results. Conclusion: This proof-of-concept study demonstrated sustained protection for TAF+EVG nanoparticles in a hu-BLT mouse model of HIV vaginal transmission.