Replacing Enfuvirtide with Raltegravir

Since raltegravir was approved, clinicians (and indeed many patients) have wondered whether it might be a safe replacement for enfuvirtide in fully suppressive regimens. A new case series, conducted with support from the maker of raltegravir, provides early reassuring data about this strategy.

Thirty-five patients in British Columbia with undetectable viral loads (<50 copies/mL) accepted the option of switching the enfuvirtide in their regimens to raltegravir. The median time on enfuvirtide before the switch was 25 months, and the median time with undetectable viral loads was 24 months. The switch was done in a single day without overlapping doses.

As of January 2008, all 35 patients remained on raltegravir (median duration, 7 months; range, 1–13 months). All but one maintained consistently undetectable viral loads. That patient had a single measurement of 60 copies/mL after 5 months of raltegravir; since then, according to personal communication with the authors, his viral load has remained below 50 copies/mL without a change in regimen. Notably, he had similar episodes of intermittent low-level viremia while taking enfuvirtide. No patient experienced adverse effects that could be linked unequivocally to raltegravir.