Data are lacking evaluating predictors of varying levels of on-treatment elevations in viral load in patients receiving long-acting cabotegravir plus rilpivirine (CAB/RPV) for people with HIV (PWH). Study objectives were to I) quantify the occurrence of detectable viremia on CAB/RPV and II) determine if HIVRNA values in the preceding year predicted virologic outcomes.
A retrospective cohort study was performed among those receiving care at the University of California San Diego Owen Clinic. Inclusion criteria included treatment with CAB/RPV for at least three months, availability of both pre- and on-treatment HIVRNA values, and at least one on-treatment HIVRNA collected >21 days after start of CAB/RPV. Demographic and laboratory data were extracted from the electronic medical record. Outcomes of interest were incidence of on-treatment HIVRNA values ≥20, ≥50 and ≥200 copies/mL (cpm).
Among 144 PWH the median duration of follow up was 131 days. The most frequent (58.3%) regimen prior to CAB/RPV was a second-generation integrase inhibitor plus two NRTIs. In PWH with a baseline HIVRNA < 20 cpm (Nf116, 80.6%) at time of switch to injectable CAB/RPV, the occurrences of HIVRNA ≥20, ≥50 and ≥200 cpm after switch were 27.6%, 10.3%, and 1.7% respectively. Patients with at least one HIVRNA value ≥20 cpm in the 12 months preceding initiation of CAB/RPV were significantly more likely to have an HIVRNA ≥20 cpm while on CAB/RPV compared to those with no HIVRNA values ≥20 cpm (19/47, 40.4% versus 13/69, 18.8%, p=0.01). Time to event analyses comparing these groups corroborated this relationship (Figure 1, log-rank p=0.02). Multiple consecutive HIVRNA values ≥20 cpm in the preceding year was also associated with increased probability of on-treatment HIVRNA ≥20 cpm (10/21, 47.6% versus 22/95, 23.2%, p=0.02). An HIVRNA value ≥20 in preceding year did not significantly predict the other two virologic outcomes (HIVRNA ≥50 or ≥200).
Despite virologic suppression at time of switch to CAB/RPV, over 25% of patients experienced at least one HIVRNA >20 cpm with incidence highest among patients with at least one HIVRNA >20 cpm in the preceding year. While the impact of low-level increases in viral load is not entirely clear, initiating CAB/RPV in patients with multiple HIVRNA values >20 cpm in the preceding year should be done cautiously.
Time to Event Analyses Comparing Probability of HIVRNA Remaining < 20 copies/mL