We explored the relationship between virologic response in the first year of treatment and long-term outcomes in the BENCHMRK studies.

Patients failing ART with 3-class resistant HIV-1 received double-blinded raltegravir (or placebo) with optimized background therapy (OBT) until week 156, then open-label raltegravir with OBT up to week 240. In this exploratory analysis of patients randomized to raltegravir, virologic response over weeks 16–48 was categorized as�continuous suppression (CS: vRNA always <50 copies/mL), low-level viremia�(LLV: vRNA always < 400 copies/mL; <50 copies/mL at least once), or not suppressed (NS: vRNA <400 copies/mL at least once). The association between these first-year vRNA response categories and baseline factors was analyzed with univariate and multivariate models. Virologic and immunologic outcomes for years 2–5 were assessed by first-year vRNA response category (observed failure approach).

Baseline vRNA, baseline CD4 count, and rapid viral decay (vRNA <50 copies/mL between weeks 2–12) correlated with first-year vRNA response (p<0.001); only rapid viral decay remained significant by multiple regression. Virologic response rates were similar in the LLV and CS groups and lowest in the NS group. CD4 increased through week 240 in the CS and LLV groups. Time to loss of virologic response (confirmed vRNA ≥400 copies/mL) through Week 240 did not support as strong a difference between the LLV and CS groups (log-rank p=0.11) as previously reported through Week 156 and 192 (p<0.05).

Treatment-experienced patients on a raltegravir-based regimen with early LLV may have long-term virologic and immunologic benefit when their therapy is maintained.