Background: In the week 48 primary analysis of ECHO and THRIVE, rilpivirine demonstrated noninferior efficacy and more favourable tolerability versus efavirenz in treatment-naive, HIV-1-infected adults. Pooled 96-week results are presented.
Methods: Patients (N = 1368) received rilpivirine 25 mg once-daily (q.d.) or efavirenz 600 mg q.d., with two background nucleoside/nucleotide reverse transcriptase inhibitors, in two randomized, double-blind, double-dummy Phase III trials.
Results: At week 96, response rate (% confirmed viral load <50 copies/ml; intent-to-treat, time-to-loss-of-virologic response) was 78% in both groups. Responses were similar for both treatments by background regimen, sex, race, and in patients with more than 95% adherence (M-MASRI) or baseline viral load 100,000 copies/ml or less. Responses were lower and virologic failure higher for rilpivirine versus efavirenz in patients with 95% or less adherence or baseline viral load more than 100,000 copies/ml. Beyond week 48, the incidence of virologic failure was comparable (3 versus 2%) between treatment groups, rilpivirine resistance-associated mutations were consistent with those observed in year 1, there were few adverse events in both groups and no new safety concerns. Over 96 weeks, discontinuations due to adverse events (4 versus 9%), treatment-related grade 2-4 adverse events (17 versus 33%), rash (4 versus 15%), dizziness (8 versus 27%) and abnormal dreams/nightmares (8 versus 13%), and grade 2-4 lipid abnormalities were lower with rilpivirine than efavirenz. Only 2 and 4% of patients in the rilpivirine and efavirenz treatment groups, respectively, reported at least possibly treatment-related grade 2-4 adverse events during the second year of treatment.
Conclusions: Rilpivirine 25 mg q.d. and efavirenz 600 mg q.d. had comparable responses at week 96. Rilpivirine had more virologic failures but improved tolerability versus efavirenz. The majority of virologic failures occurred in the first 48 weeks.