Dolutegravir and the 88% Rule
Paul Sax • October 28th, 2012
In the latest treatment-naive trials of elvitegravir and dolutegravir, there’s a striking consistency in the results of the “test” regimen. Here are the studies, with the percentage of responders by treatment arm:
- Study 102: TDF/FTC/EFV (84%) vs. TDF/FTC/EVG/c (88%) — non-inferior
- Study 103: TDF/FTC + ATV/r (87%) vs. TDF/FTC/EVG/c (90%) — non-inferior
- SPRING-2: TDF/FTC or ABC/3TC + RAL (85%) vs. DTG (88%) — non-inferior
- SINGLE: TDF/FTC/EFV (81%) vs. ABC/3TC + DTG (88%) — ABC/3TC + DTG — superior
The last of these, the SINGLE study, is the only one where there’s superiority in the primary outcome for the experimental arm, here ABC/3TC + dolutegravir. As the investigators noted, this favorable result was largely due to a significantly higher proportion of subjects in the TDF/FTC/EFV group discontinuing therapy for adverse events (10% vs 2%), as rates of virologic failure were similar between arms. ABC/3TC + dolutegravir also was better than TDF/FTC/EFV from both the immunologic and resistance perspective.
And though cross study comparisons are frowned upon by purists, we can’t resist. Just a quick glance at all four of the EVG and DTG arms, and you can easily see that an 88% response rate is the new price of admission for any treatment-naive regimen.
Anything shy of the high 80s, and there has to be something else very special about the treatment — for example, better tolerability, much lower cost, better long-term safety, it helps you become a virtuoso violinist — to make it compete with options for therapy we already have, or will have soon.