Study analyzes factors related to non-sustained viral suppression when transitioning to long-acting HIV treatment

Clinicians should consider a patient’s entire virological history, including viral load at diagnosis and recent viremic episodes, before switching them to long-acting injectable HIV treatment, the authors of a small single-site study recommend.

About This Study

“Virological History Predicts Non-sustained Viral Suppression with Long-Acting Cabotegravir and Rilpivirine Therapy, independent of Pharmacokinetic Parameters” was published online on Sept. 19, 2024, in Clinical Infectious Diseases. The lead author is Félix Gutiérrez, M.D., M.Sc. of Hospital General Universitario de Elche, Universidad Miguel Hernández, in Alicante, and CIBERINFEC in Madrid, all in Spain.

Key Research Findings

In a prospective cohort study at a single site in Spain, researchers analyzed viral load trajectories and pharmacokinetic data in 173 people living with HIV who switched from oral antiretroviral treatment to long-acting injectable cabotegravir/rilpivirine in 2023. Most participants were white (76%) and identified as male at birth (86%). Median age was 48 years.

Study inclusion criteria included viral loads <50 copies/mL. Non-sustained viral suppression was defined as having any episode of a plasma viral load >20 copies/mL after the switch to the long-acting treatment.

By the time participants switched to the study drug, after meeting the baseline criteria of a viral load of <50 copies/mL, 4% of participants had viral loads of 50-99 copies/mL. During a median 11 months of follow-up, 31% of all participants had intermittent low-range viremia (single viral load 20-199 copies/mL), 4% of participants had intermittent high-range viremia (single viral load 200-999 copies/mL), and 4% of participants had persistent low-level viremia (two consecutive low-range viral loads), while two participants experienced virological failure.

Viremia on the study regimen was associated with a higher viral load at HIV diagnosis (a median 11 years before study start), detectable viremia during the year preceding the switch, or not being fully suppressed when starting the study drug. Viremia was not associated with pharmacokinetic parameters before viremic episodes.

Discussion Highlights and Implications for Practice

Study limitations reported included the small sample size, participants’ demographic characteristics (mostly non-Black men), relatively short follow-up, limited information on prior rilpivirine resistance, and few obese participants.

The researchers believe these findings indicate that viremic episodes after transition to long-acting injectable HIV treatment may be related to the viral reservoir size, as indicated by higher viral loads at diagnosis and recent detectable viremia. Providers should consider their patients’ entire virological history, as well as current viral suppression status, before starting long-acting treatment, study authors said. They also pointed out that these findings do not indicate a need for therapeutic drug monitoring to optimize treatment during this transition.

By Barbara Jungwirth