Low-level viremia is associated with cumulative adherence to antiretroviral therapy in persons with HIV

The drivers of low-level viremia (LLV) between 20-200 copies/mL remain unclear. In 1,042 person-visits from 497 persons with HIV on TDF-containing ART, the association between LLV and cumulative antiretroviral adherence (quantified using tenofovir diphosphate (TFV-DP) in dried blood spots) was assessed. Lower TFV-DP levels were associated with higher odds of LLV. As TFV-DP (fmol/punch) categories decreased from >1,650 to 800-1,650; 800-1,650 to <800; and >1,650 to <800, the adjusted odds ratios for LLV versus HIV VL <20 copies/mL were: 2.0 [1.2, 3.1]; 2.4 [1.1, 5.0]; and 4.6 [2.2, 9.9], respectively. This suggests that adherence could impact LLV.

Infection with antiretroviral-susceptible HIV in an individual adherent to pre-exposure prophylaxis: strategies for treatment initiation

HIV pre-exposure prophylaxis (PrEP) is effective at preventing sexual acquisition of HIV, and failures in clinical trials are largely attributable to medication nonadherence. We report here a case of infection with a fully susceptible strain of HIV in an individual adherent to PrEP as demonstrated by pharmacy records and intracellular tenofovir diphosphate levels. At diagnosis, the viral load was 90 copies/mL precluding initial genotype testing due to low copy number. While PrEP failure is rare, this case underscores the importance of regular HIV testing for patient on PrEP and prompts discussion regarding the approach to treatment following failure where an initial genotype is not yet available or not possible due to low viral load. Few other case reports of PrEP failure exist in the literature and approaches to treatment varied widely. We suggest the initial viral copy number may guide next steps and discuss the risks and benefits of stopping PrEP, escalating therapy with integrase inhibitors or boosted protease inhibitors, or switching to non-nucleoside antiretroviral treatment regimens.

Tenofovir diphosphate concentrations in dried blood spots from pregnant and postpartum adolescent and young women receiving daily observed pre-exposure prophylaxis in sub-Saharan Africa

Background Intracellular tenofovir diphosphate (TFV-DP) concentration measured in dried blood spots (DBS) is used to monitor cumulative adherence to pre-exposure prophylaxis (PrEP). We evaluated TFV-DP in DBS following daily oral PrEP (emtricitabine 200mg/tenofovir diphosphate 300mg) among pregnant and postpartum adolescent girls and young women (AGYW). Methods Directly observed PrEP was administered for 12 weeks in a pregnancy group (14-24 weeks gestation, n=20) and a postpartum group (6-12 weeks postpartum, n=20) of AGYW aged 16-24 years in sub-Saharan Africa. Weekly DBS TFV-DP was measured by validated liquid chromatography-tandem mass spectrometry assay. Week 12 TFV-DP distributions were compared between groups with the Wilcoxon test. Population pharmacokinetic models were fit to estimate steady-state concentrations and create benchmarks for adherence categories. Baseline correlates of TFV-DP were evaluated. Results Participant median age was 20 years (IQR:19,22). Of 3360 doses, 3352 (>99%) were directly observed. TFV-DP median half-life was ten days (IQR:7, 12) in pregnancy and 17 days (IQR:14, 21) postpartum, with steady-state achieved by five and eight weeks, respectively. Observed median steady-state TFV-DP was 965 fmol/punch (IQR:691, 1166) in pregnancy vs 1406 fmol/punch (IQR:1053, 1859) postpartum (p=0.006). Modelled median steady-state TFV-DP was 881 fmol/punch (IQR: 667,1105) in pregnancy vs 1438 fmol/punch (IQR: 1178,1919) postpartum. In pooled analysis, baseline creatinine clearance was associated with observed TFV-DP concentrations. Conclusion TFV-DP in African AGYW was approximately one-third lower in pregnancy than postpartum. Population-specific benchmarks provided by this study can be used to guide PrEP adherence support in pregnant/postpartum African women.

Associations Between Tenofovir Diphosphate in Dried Blood Spots, Impaired Physical Function, and Fracture Risk

Background In this study, we evaluate associations between cumulative antiretroviral adherence/exposure, quantified using tenofovir diphosphate (TFV-DP) in dried blood spots (DBS), and human immunodeficiency virus (HIV)-related aging factors. Methods This is a cross-sectional analysis of younger (ages 18–35) and older (ages ≥60) persons with HIV (PWH) taking TFV disoproxil fumarate. Tenofovir diphosphate concentrations were quantified in DBS. Linear and logistic regression models were used to evaluate associations between TFV-DP and bone mineral density (BMD), physical function, frailty, and falls. Results Forty-five PWH were enrolled (23 younger, 22 older). Every 500 fmol/punch (equivalent to an increase in ~2 doses/week) increase in TFV-DP was associated with decreased hip BMD (−0.021 g/cm2; 95% confidence interval [CI], −0.040 to −0.002; P = .03). Adjusting for total fat mass, every 500 fmol/punch increase in TFV-DP was associated with higher odds of Short Physical Performance Battery impairment (score ≤10; adjusted odds ratio [OR], 1.6; 95% CI, 1.0–2.5; P = .04). Every 500 fmol/punch increase in TFV-DP was associated with slower 400-meter walk time (14.8 seconds; 95% CI, 3.8–25.8; P = .01) and remained significant after adjusting for age, lean body mass, body mass index (BMI), and fat mass (all P ≤ .01). Every 500 fmol/punch increase in TFV-DP was associated with higher odds of reporting a fall in the prior 6 months (OR, 1.8; 95% CI, 1.1–2.8; P = .02); this remained significant after adjusting for age, lean body mass, BMI, and total fat mass (all P < .05). Conclusions Higher TFV-DP levels were associated with lower hip BMD, poorer physical function, and greater risk for falls, a concerning combination for increased fracture risk.