Preventive efficacy of a tenofovir alafenamide fumarate nanofluidic implant in SHIV-challenged nonhuman primates

Abstract

36Pre-exposure prophylaxis (PrEP) using antiretroviral oral drugs is effective at preventing HIV 37 transmission when individuals adhere to the dosing regimen. Tenofovir alafenamide (TAF) is a 38 potent antiretroviral drug, with numerous long-acting (LA) delivery systems under development 39 to improve PrEP adherence. However, none has undergone preventive efficacy assessment. Here 40 we show that LA TAF using a novel subcutaneous nanofluidic implant (nTAF) confers 41 protection from HIV transmission. We demonstrate that sustained subcutaneous delivery through 42 nTAF in rhesus macaques maintained tenofovir diphosphate concentration at a median of 390.00 43 fmol/10 6 peripheral blood mononuclear cells, 9 times above clinically protective levels. In a non-44 blinded, placebo-controlled rhesus macaque study with repeated low-dose rectal SHIVSF162P3 45 3 challenge, the nTAF cohort had a 62.50% reduction in risk of infection per exposure compared 46 to the control. Our finding mirrors that of tenofovir disoproxil fumarate (TDF) monotherapy, 47 where 60.00% protective efficacy was observed in macaques, and clinically, 67% reduction in 48 risk with 86.00% preventive efficacy in individuals with detectable drug in the plasma. Overall, 49 our nanofluidic technology shows potential as a subcutaneous delivery platform for long-term 50PrEP and provides insights for clinical implementation of LA TAF for HIV prevention. 51 52 65 Long-acting (LA) antiretroviral (ARV) formulations and delivery systems offer systemic 66 delivery for prolonged periods, obviating the need for frequent dosing. Currently, LA ARV 67 strategies for HIV PrEP are largely geared towards developing single-agent drugs for prevention 68 mg of TAF over 10 days (Fig. 1i). However, an increase of TAF degradation products was 131 observed throughout the study, attributable to decrease in TAF stability ( Supplementary Fig. 1). 132 133 nTAF pharmacokinetic profile in NHP 134For in vivo evaluation of pharmacokinetic (PK) and PrEP efficacy, rhesus macaques were 135 subcutaneously implanted with either nTAF (n=8) or control nPBS (n=6) in the dorsum for 4 136 months. We used TFV-DP concentration in PBMC of 100.00 fmol/10 6 cells as the benchmark 137 phase 2a trial. Lancet HIV 4, e331-e340 (2017). 595

Viral load Reduction in SHIV-Positive Nonhuman Primates via Long-Acting Subcutaneous Tenofovir Alafenamide Fumarate Release from a Nanofluidic Implant

“…The silicon membrane was glued to the implant using UV epoxy (OG116, Epoxy Technologies, Inc., Billerica, MA, USA) and cured for 2 h with a UV lamp (UVP UVL-18 EL Series, Analytik Jena US LLC, Upland, CA, USA). Implants were assembled and primed with 1X phosphate-buffered saline (PBS) as previously described [ 18 ] and were loaded with approximately 250 mg TAF fumarate. Implants were maintained in sterile 1X PBS in a hermetically sealed container until implantation shortly after preparation.…”

“…The macaques used in this study were enrolled in a SHIV prevention study as controls ( n = 6). Once a week, these macaques were rectally challenged with SHIV SF162P3 for up to 10 weeks until initial detection of plasma SHIV RNA [ 18 ]. Macaques were weekly monitored for SHIV infection and infection was confirmed after a consecutive detection of plasma SHIV RNA.…”

“…Macaques were weekly monitored for SHIV infection and infection was confirmed after a consecutive detection of plasma SHIV RNA. After 2 and 4 exposure challenges, 50 and 100% of macaques, respectively, tested SHIV-positive [ 18 ]. Upon confirmation of viral infection, animals were transferred to this treatment study.…”

“…Upon confirmation of viral infection, animals were transferred to this treatment study. Macaques were implanted with nTAF t a week after confirmed infection via a minimally invasive 1 cm dorsal skin incision on the left lateral side of the thoracic spine as previously described [ 18 ].…”

“…Another notable drug candidate for LA platform is tenofovir alafenamide (TAF), a potent drug widely used as a first-line ART regimen in combination with other antiretrovirals. For HIV-1 pre-exposure prophylaxis (PrEP), TAF is under development as a single-agent LA in several drug delivery systems [ 17 , 18 , 19 , 20 , 21 , 22 ], however, none of these systems have yet been tested for HIV-1 treatment.…”