Cellular pharmacology of NRTI anabolites in PBMCS and platelets among persons with HIV receiving ABC/3TC- or TAF/FTC-based art

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Cellular pharmacology of NRTI anabolites in PBMCS and platelets among persons with HIV receiving ABC/3TC- or TAF/FTC-based art

Stefanie Schwab¹, Travis Nemkov¹, David Nerguizian¹, Brian Branchford², Seth Hosford¹, Vincent Mainella¹, Ryan Coyle¹, Nicholas Barker¹, Bethany Johnson¹, Laura Roon¹, Erin Garst¹, Martin Williams¹, Jia-Hua Zheng¹, Lucas Ellison¹, Lane Bushman¹, Peter Anderson¹ and Kristina Brooks¹

¹University Of Colorado Anschutz Medical Campus; ²Medical Sciences Institute Versiti

Background: Nucleos(t)ide reverse transcriptase inhibitors (NRTIs) undergo phosphorylation within a variety of cell types due to structural similarities with endogenous nucleotides. Characterizing the intracellular pharmacology of NRTI anabolites in less commonly studied cell types, such as platelets, may provide insight into associations with cardiometabolic side effects. The objectives of these analyses were to compare (1) relative cellular concentrations of NRTIs in peripheral blood mononuclear cells (PBMCs) and platelets and (2) profiles of platelet metabolomics among persons with HIV (PWH) taking either tenofovir (TFV) alafenamide (TAF)/emtricitabine (FTC) or abacavir (ABC; converted to carbovir [CBV])/lamivudine (3TC).

Materials and methods: PWH receiving ABC/3TC 600/300 mg or TAF/FTC 25/200 mg as part of their antiretroviral therapy (ART) with HIV VL < 200 copies/mL for ≥6 months were enrolled (NCT04301661). Adherence was confirmed using video directly observed therapy (vDOT) for 28 ± 3 days prior to pharmacokinetic sample collection (2 ± 1 h post-dose). Whole blood was processed into PBMCs and platelets. LC-MS/MS methods were used to quantify anabolites (TFV-DP, CBV-TP, FTC-TP, 3TC-TP) in both cell types, in addition to the monophosphate (MP) and diphosphate (DP) fractions in platelets. Drug concentrations (per 106 cells) were normalized to cell volume to determine relative intracellular concentrations in PBMCs and platelets, reported as geometric mean (GM) and GM ratio (GMR). Extracts of resting platelets were analysed using a previously established targeted metabolomics MS assay. Differences between arms were screened using fold changes and Wilcoxon rank-sum tests between median metabolite peak intensities.

Results: Data were available in 25 PWH receiving ART containing either ABC/3TC (n = 12) or TAF/FTC (n = 13); 88% were male, 52% White, 20% Black, and 24% Hispanic/Latino. Median (IQR) age was 46 (38, 54) years and BMI 26.0 (22.1, 31.3). Baseline demographics were comparable between treatment arms. Participants on ABC/3TC were on dolutegravir (n = 12); darunavir/cobicistat (n = 1) or darunavir/ritonavir (n = 1). Participants on TAF/FTC were on bictegravir (n = 12) or both raltegravir and rilpivirine (n = 1). Overall median (IQR) adherence was 96% (90%, 100%). The GM concentrations of active drug (per 106 cells) in PBMC were 619 fmol for TFV-DP, 78.2 fmol for CBV-TP, 6.72 pmol for FTC-TP and 8.66 pmol for 3TC-TP and platelets: 10.0 fmol for TFV-DP, 3.25 fmol for CBV-TP, 0.15 pmol for FTC-TP and 0.14 pmol for 3TC-TP. GMRs of NRTI anabolite concentrations in platelets vs. PBMC, normalized to cell volume, were 0.42 (TFV-DP), 1.08 (CBV-TP), 0.56 (FTC-TP) and 0.41 (3TC-TP). Cellular anabolite fractions within platelets were: TFV-DP > TFV > TFV-MP, CBV/3TC-TP > CBV/3TC-MP > CBV/3TC-DP and FTC-TP > FTC-DP > FTC-MP. Metabolomics analysis showed no significant differences in platelet metabolites between arms.

Conclusions: NRTIs exhibited preferential cell loading into PBMCs compared to platelets except for CBV, which has similar concentrations in both PBMC and platelets. The TP fraction was highest across all NRTIs in platelets, and the MP fraction was higher than DP for CBV, 3TC and TFV. These results suggest that the NRTI type and cell-specific process dictate differential patterns in drug accumulation. Metabolomic profiles in resting platelets did not reveal differences between PWH on either TAF/FTC or ABC/3TC. Further investigation is needed to determine the clinical significance of these findings.