October 26, 2008
Results of a phase 2 study of elvucitabine, an experimental NRTI being developed by Achillion Pharmaceuticals, were presented at the joint 2008 ICAAC / IDSA in Washington, DC. The results, while not bad, failed to make much of an argument in favor of further development of this drug.
In lab studies, elvucitabine is much more potent than Epivir (lamivudine), a drug with a similar chemical structure. Dr. DeJesus presented data of a study comparing elvucitabine to Epivir, both combined with Viread (tenofovir) and Sustiva (efavirenz). Overall, both groups experienced similar reductions in HIV levels -- 2.8log for people taking elvucitabine and 3.0log for those on Epivir.
However, in an intent-to-treat analysis (which counts people who drop out of the study as treatment failures), significantly fewer people -- 65% vs. 78% -- of people on elvucitabine had HIV levels below 50 copies. Dr. DeJesus claimed this was due mostly to people in the elvucitabine group being lost to follow-up, which was supported by something called an as-treated analysis (which looks only at people who are still taking a drug at the end of the study). However, as-treated analyses are considered less reliable than intent-to-treat.
People taking elvucitabine also experienced smaller increases in CD4 counts -- an average of 132 cells vs. 177 for Epivir. Overall rates of adverse events, or side effects, were low and similar, with slightly more elevations in blood fats and peripheral neuropathy in people on elvucitabine.
The overall rationale for further development of this drug is unclear. While it is stronger in test tube experiments than Epivir, those results are not backed up by these clinical study results. Without any obvious benefit in terms of side effects or resistance, the only clear advantage this drug has over Epivir is the size of the pill. While Project Inform generally wants to see new drugs developed for HIV, the benefit of this one looks unclear at this point.