Affiliation:
1. UNC Eshelman School of Pharmacy, Chapel Hill, North Carolina, USA
2. RTI International, Research Triangle Park, North Carolina, USA
3. Center for AIDS Prevention Studies, Dept of Medicine, University of California San Francisco, San Francisco, CA, USA
4. ASTRA Consulting, Kensington, CA, USA
Abstract
Abstract
Background
Islatravir (4′-ethynyl-2-fluoro-2′-deoxyadenosine; EFdA) is a first-in-class nucleoside reverse transcriptase translocation inhibitor (NRTTI) being investigated for HIV treatment and prevention. EFdA is intracellularly phosphorylated to EFdA-triphosphate (EFdA-tp), a competitive substrate of deoxyadenosine-triphosphate (dATP). Thus, translating safety and efficacy findings from preclinical studies relies on the assumption that EFdA’s intracellular pharmacology can be extrapolated across species.
Objectives
We investigated how EFdA is phosphorylated across animal species commonly used for preclinical models in drug development to identify those that most closely matched humans.
Methods
PBMCs were isolated from whole blood of six species (human, rhesus macaque non-human primate (rmNHP), rat, minipig, dog, and rabbit) using Ficoll separation and counted on a haemocytometer by Trypan blue staining. One million live cells were cultured in media supplemented with 10 U/mL human IL-2, 10% FBS and 1% antibiotics and treated with 0, 17, 170, and 1700 nM EFdA (n = 3 replicates per concentration). After 24 h, representative cell counts were derived from untreated control wells (as above), cells were washed in PBS, and lysed with 70:30 methanol:water. EFdA-tp and dATP concentrations were quantified by HPLC-MS/MS and normalized to the representative live cell counts for each species.
Results
When compared to human values, EFdA-tp concentrations for each EFdA treatment concentration were lower in all species (rmNHP 1.5–2.1-fold, rat 4.5–15-fold, minipig 37–71-fold, dog and rabbit >100-fold). Additionally, rmNHP and dog PBMCs exhibited significantly higher (7–10-fold; P < 0.001) dATP when compared with human PBMCs.
Conclusions
Given intracellular pharmacology differences, these preclinical models may be a conservative estimate of EFdA’s intracellular pharmacokinetics and efficacy in humans.
Funder
U.S. President’s Emergency Plan for AIDS Relief
USAID
CFAR
NIH
Publisher
Oxford University Press (OUP)
Subject
Infectious Diseases,Pharmacology (medical),Pharmacology,Microbiology (medical)
Cited by
7 articles.
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