Short-cycle therapy in {HIV}-infected adults: rilpivirine combination 4 days on/3 days off therapy

Background Short-cycle therapy (SCT) is the administration of ART for 4 or 5 consecutive days a week, followed by 3 or 2 days off therapy. Its benefits include improving patient satisfaction and reducing ART toxicity and costs. Methods In this observational study we included HIV-infected adults with a three-drug ART containing rilpivirine, a history of long-term virological suppression and no evidence of resistance to previous drug regimens. Patients switched to a SCT of 4 days on/3 days off and were followed for 48 weeks with regular check-ups. The primary outcome was virological suppression; secondary outcomes were changes in CD4+ cells and rilpivirine plasma concentration, the occurrence of adverse events and resistance in the case of failure, and patient satisfaction. Results At week 48 no virological failure was observed, with a virological suppression rate of 30/30 (100%). Three patients switched back to continuous therapy for other reasons, with an overall success rate of SCT of 30/33 (90.9%, 95% CI = 81.24% to 100%). The CD4+ mean value increased by +64 cells/mm(3) (95% CI = -59 to +187 cells/mm(3); P = 0.052). No adverse events were observed and the mean total score in the satisfaction questionnaire was 57.7/60 (96.22%). Rilpivirine plasma concentration was below the efficacy threshold in 71.3% of the samples, suggesting that the patients' characteristics, more than the drug's pharmacokinetics, played a role in maintaining virological suppression. Conclusions SCT with rilpivirine-containing regimens could be an effective alternative to continuous therapy in selected HIV-infected patients with previous long-term virological suppression.