Background
LA CAB/RPV has transformed the HIV treatment paradigm as an alternative to daily oral antiretroviral therapy (ART). Potential challenges with CAB/RPV include therapeutic failures characterized by virologic failure and/or the development of resistance-associated mutations (RAMs).
Methods
This was a single-center, retrospective cohort study of adults with HIV on LA CAB/RPV at the Ohio State University Wexner Medical Center (OSUWMC) from 3/1/22 to 12/31/23. We describe clinical outcomes among LA CAB/RPV recipients and investigated associations with HIV-specific factors.
Results
115 participants were referred for initiation of LA CAB/RPV and 91 received at least one dose (79.1%). Reasons for not starting treatment varied and included insurance issues, participant decision, unable to follow up, labs not completed, and prior RPV resistance. 69/115 (60%) had a genotype (next-generation sequencing assay or proviral assay) available for review prior to CAB/RPV initiation. 1/91 had a detectable viral load between 40 and 200 copies/mL at treatment start with all other participants undetectable prior to CAB/RPV start. 8/91 (8.8%) had detectable HIV-1 viral load (VL) (range 42-445 copies/mL) after initiating CAB/RPV. 4/8 (50%) experienced low-level viremia (LLV) (≥2 VL >40 copies/mL but <200 copies/mL) and 4/8 (50%) had at least one blip (isolated VL >40 copies/mL but <200 copies/mL). The duration of LLV ranged from 1 to 5 months. 6/8 (75%) of those that experienced LLV or blips subsequently experienced them again at another point within the study period. 1/4 (25%) with LLV was temporarily transitioned from 8 to 4-week dosing with subsequent viral suppression. Notably, all participants with LLV or blips received on time LA CAB/RPV, had a genotype available prior to treatment initiation without CAB or RPV RAMs, and none subsequently developed therapeutic failure. Apart from body mass index ≥30kg/m2, our study population lacked other risk factors for virologic failure with LA CAB/RPV (Table 1).
Conclusions
Clinicians should have awareness of and develop monitoring processes for the early detection of LA CAB/RPV therapeutic failures. This study is the first to report that low-level viremia was not associated with virologic failure in clinical practice. Further research is needed to identify those at risk of virologic failure and to develop optimal prevention strategies.