Maintenance with ABC/3TC + RPV sustains virological suppression in HIV-1

Switching to abacavir/lamivudine plus rilpivirine (ABC/3TC + RPV) for maintenance therapy is a safe and effective option for patients with virologically suppressed HIV-1, according to a recent Singapore study.

“Our results showed that a high proportion of individuals who switched to ABC/3TC + RPV had maintained virologic suppression. The result is similar regardless of the type of pre-switch ART regimen,” the researchers said. “The findings of our study corroborated existing primary literature that individuals on treatment with ABC/3TC + RPV can achieve effective, sustained virologic suppression.”

The retrospective, single-centre analysis included 222 patients with HIV-1 (median age 47 years, 92.3 percent men) who had viral load <50 copies/mL immediately before being switched to ABC/3TC + RPV. Patients were followed for 48±12 weeks, during which they were assessed for the primary outcome of the maintenance of virologic suppression. None of the patients had documented history of resistance mutations or virological failure.

Overall, 197 patients were able to maintain a viral load of <50 copies/mL after switching, yielding a maintenance suppression rate of 88.8 percent. Four patients (1.8 percent) saw virological failure, three of whom reached viral loads of >500 copies/mL at the end of the study and developed emergent antiretroviral resistance. [AIDS Res Ther 2021;18:80]

Twenty-one individuals (9.5 percent) opted to discontinue ABC/3TC + RPV treatment for nonvirologic reasons, most frequent of which (n=13, 61.9 percent) were adverse events (AEs) attributed to the drug combination. Concerns about drug-drug interactions with ongoing medications and financial difficulties were also reasons for discontinuation.

Forty-nine AEs were recorded in 31 individuals during follow-up, yielding an incidence rate of 14.0 percent. All side effects resolved either spontaneously or after discontinuing therapy. Neuropsychiatric AEs, such as insomnia and forgetfulness, were dominant, comprising 53.1 percent of all AEs reported. No cardiovascular AEs were observed.

In terms of laboratory parameter, the researchers reported a significant increase in CD4 (median absolute change, 31 cells/uL; p<0.01) and a decrease in estimate glomerular filtration rate (median absolute change, –4.24 mL/min/1.73m²; p<0.01). Switching regimens had no such effects were reported for fasting blood glucose, glycated haemoglobin, estimated creatine clearance, and blood lipid profile.

“While no statistically significant changes were detected for lipids, fasting blood glucose and HbA1c, the results warrant careful interpretation due to the small number of individuals with both baseline and follow-up values,” the researchers said.

Aside from the small sample size, the study also had other limitations worth noting. “The absence of a control group prevented us from comparing the effectiveness and safety in individuals who would have continued with the prior regimen,” the researchers said.

Moreover, “in practice, it will be crucial to take into account the relatively low genetic barrier to resistance and the ability of the individual to adhere to the caloric requirements of RPV when selecting this regimen,” they added.