The determination of human peripheral blood mononuclear cell counts using a genomic DNA standard and application in tenofovir diphosphate quantitation

Rapid Enzymatic Assay for Antiretroviral Drug Monitoring Using CRISPR-Cas12a-Enabled Readout

Maintaining the efficacy of human immunodeficiency virus (HIV) medications is challenging among children because of dosing difficulties, the limited number of approved drugs, and low rates of medication adherence. Drug level feedback (DLF) can support dose optimization and timely interventions to prevent treatment failure, but current tests are heavily instrumented and centralized. We developed the REverse transcriptase ACTivity crispR (REACTR) for rapid measurement of HIV drugs based on the extent of DNA synthesis by HIV reverse transcriptase. CRISPR-Cas enzymes bind to the synthesized DNA, triggering collateral cleavage of quenched reporters and generating fluorescence. We measured azidothymidine triphosphate (AZT-TP), a key drug in pediatric HIV treatment, and investigated the impact of assay time and DNA template length on REACTR's sensitivity. REACTR selectively measured clinically relevant AZT-TP concentrations in the presence of genomic DNA and peripheral blood mononuclear cell lysate. REACTR has the potential to enable rapid point-of-care HIV DLF to improve pediatric HIV care.

Rapid enzymatic assay for antiretroviral drug monitoring using CRISPR-Cas12a enabled readout

Maintaining efficacy of human immunodeficiency virus (HIV) medications is challenging among children because of dosing difficulties, the limited number of approved drugs, and low rates of medication adherence. Drug level feedback (DLF) can support dose optimization and timely interventions to prevent treatment failure, but current tests are heavily instrumented and centralized. We developed the REverse-transcriptase ACTivity-crispR (REACTR) assay for rapid measurement of HIV drugs based on the extent of DNA synthesis by HIV reverse transcriptase. CRISPR-Cas enzymes bind to synthesized DNA, triggering collateral cleavage of quenched reporters and generating fluorescence. We measured azidothymidine triphosphate (AZT-TP), a key drug in pediatric HIV treatment, and investigated the impact of assay time and DNA template length on REACTR's sensitivity. REACTR selectively measured clinically relevant AZT-TP concentrations in the presence of genomic DNA and peripheral blood mononuclear cell lysate. REACTR has the potential to enable rapid point-of-care HIV DLF to improve pediatric HIV care.

Pharmacokinetics and Safety of Remdesivir in Pregnant and Nonpregnant Women With COVID-19: Results From IMPAACT 2032

BACKGROUND

Pregnant people with coronavirus disease 2019 (COVID-19) experience higher risk for severe disease and adverse pregnancy outcomes, but no pharmacokinetic (PK) data exist to support dosing of COVID-19 therapeutics during pregnancy. We report PK and safety data for intravenous remdesivir in pregnancy.

METHODS

IMPAACT 2032 was a phase 4 prospective, open-label, nonrandomized opportunistic study of hospitalized pregnant and nonpregnant women receiving intravenous remdesivir as part of clinical care. Intensive PK sampling was performed on infusion days 3, 4, or 5 with collection of plasma and peripheral blood mononuclear cells (PBMCs). Safety data were recorded from first infusion through 4 weeks after last infusion and at delivery. Geometric mean ratios (GMR) (90% confidence intervals [CI]) of PK parameters between pregnant and nonpregnant women were calculated.

RESULTS

Fifty-three participants initiated remdesivir (25 pregnant; median gestational age, 27.6 weeks; interquartile range, 24.9-31.0 weeks). Plasma exposures of remdesivir, its 2 major metabolites (GS-704277 and GS-441524), and the free remdesivir fraction were similar between pregnant and nonpregnant participants. Concentrations of the active triphosphate (GS-443902) in PBMCs increased 2.04-fold (90% CI, 1.35-3.03) with each additional infusion in nonpregnant versus pregnant participants. Three adverse events in nonpregnant participants were related to treatment (1 grade 3; 2 grade 2 resulting in treatment discontinuation). There were no treatment-related adverse pregnancy outcomes or congenital anomalies detected.

CONCLUSIONS

Plasma remdesivir PK parameters were comparable between pregnant and nonpregnant women, and no safety concerns were identified based on our limited data. These findings suggest no dose adjustments are indicated for intravenous remdesivir during pregnancy.

CLINICAL TRIALS REGISTRATION

NCT04582266.

Gender Affirming Hormones Do Not Affect the Exposure and Efficacy of F/TDF or F/TAF for HIV Preexposure Prophylaxis: A Subgroup Analysis from the DISCOVER Trial

Purpose

Transgender women are disproportionately affected by HIV and are underutilizing preexposure prophylaxis (PrEP). The lower uptake of PrEP by transgender women may be, in part, owing to the perception that taking PrEP may lower the efficacy of gender-affirming hormone therapy (GAHT) or to provider concerns that GAHT may lower the efficacy of PrEP.

Methods

DISCOVER was a randomized, double-blind, noninferiority trial comparing emtricitabine (FTC, F) and tenofovir alafenamide (F/TAF) versus emtricitabine and tenofovir disoproxil fumarate (F/TDF) as PrEP among transgender women and cisgender men who have sex with men (MSM). This nested substudy of the DISCOVER trial compared the exposure of the active intracellular metabolites of FTC and tenofovir (TFV), FTC triphosphate (FTC-TP) and TFV diphosphate (TFV-DP), in peripheral blood mononuclear cells (PBMC) among transgender women receiving GAHT versus MSM within the F/TAF and F/TDF groups.

Results

Our results demonstrate that TFV-DP and FTC-TP levels in PBMC were comparable between transgender women on GAHT and MSM receiving F/TAF, and between transgender women on GAHT and MSM receiving F/TDF. TFV-DP concentrations remained above the EC90 of 40 fmol/106 cells across all groups. No clinically significant drug-drug interactions of GAHT were observed with either F/TAF or F/TDF in this subanalysis.

Conclusions

These findings are consistent with the clinical pharmacology of GAHT, FTC, TDF, and TAF reported in previous studies, and support the continued use of F/TAF and F/TDF for PrEP in transgender women.

Clinicaltrials.gov registration number: NCT02842086.