This is one of two open-label, phase 3b clinical trials reported in the Lancet Infectious Diseases, assessing efficacy and safety of switching to coformulated elvitegravir, cobicistat, emtricitabine, and tenofovir disoproxil fumarate (tenofovir) from a non-nucleoside reverse transcriptase inhibitor-based regimen (STRATEGY-NNRTI) or a protease inhibitor-based regimen (STRATEGY-PI) with emtricitabine and tenofovir in adult patients with stably suppressed HIV (HIV-1 RNA viral load < 50 copies per mL).
The authors of a Comment article note that no guidance exists for a preferred non-inferiority margin in switch studies, and in these two trials a 12% margin was used, as in studies in treatment-naïve patients, though HIV was already successfully suppressed with the patients’ existing regimens inn these studies. In the worst case scenario, this margin allows a new regimen to be 12% worse than the successful existing regimen. They question if this margin is acceptable, acknowledging that a more stringent margin would require larger numbers of patients and increase costs, but nevertheless would enable better comparisons and safer guidelines. They suggest that overall, “these trials have shown that coformulated elvitegravir, cobicistat, emtricitabine, and tenofovir is a safe and effective switch option for stably controlled patients on non-nucleoside reverse transcriptase inhibitor-based or protease-inhibitor-based regimens who want or need to switch. Although the development of this single-tablet regimen might have initially been driven by the expiry of the patent for efavirenz in 2013, we are encouraged by the overall outcome.”