The two-drug combination of dolutegravir (Tivicay, DTG) and lamivudine (3TC, Epivir) is effective for treatment-naive patients regardless of age, gender, or race, according to a new subgroup analysis of the GEMINI clinical studies presented at the IDWeek conference in Washington, D.C.
Previously, researchers reported 96-week data from the GEMINI studies, which showed that DTG/3TC is non-inferior to the three-drug regimen of DTG + tenofovir/emtricitabine (TDF/FTC), with no drug-resistant mutations associated with two-drug therapy treatment.
At IDWeek, researchers presented findings of a subgroup analysis of the 96-week data that compared efficacy outcomes among study subjects according to their age, gender, race, and CD4 count at baseline. Although there was no difference in efficacy between study participants grouped by age, gender, or race, the new analysis did find lower response rates among patients with a CD4 count of less than 200.
Of the 63 patients with low CD4 count who took the treatment regimen, 20 (32%) were categorized as "non-responders." That's a high level of non-response compared to the three-drug treatment arm, in which seven out of 55 patients (13%) with low baseline CD4 count did not respond to treatment.
However, only a few of the patients categorized as non-responders were actually unresponsive to the study drugs, explained Jean A. van Wyk, M.B., Ch.B., global medical lead for dolutegravir at ViiV Healthcare, who presented the subgroup findings at IDWeek. The rest of the "non-response" patients can be explained by extenuating circumstances, van Wyk said.
For example, some of the patients were incarcerated, changed locations, or were withdrawn from treatment for non-drug-related reasons. In the two-drug arm, one patient became pregnant, two were incorrectly randomized, three changed locations, three experienced non-treatment-related adverse events, one was incarcerated, and one started hepatitis C treatment.
Of the 20 patients categorized as non-responders, one was attributed to treatment-related adverse effects, and two did not attain undetectable HIV viral load (HIV-1 RNA <50 copies/mL) within a preset window.
Finally, there were three confirmed virologic withdrawals in the two-drug arm, compared to two in the three-drug arm.
At IDWeek, van Wyk concluded that the subgroup analysis results were "generally consistent" with prior 96-week study results, and that overall safety and tolerability were comparable across subgroups.
DTG/3TC was approved by the Food and Drug Administration for treatment-naive adults in April 2019 under the brand name Dovato. According to van Wyk, the IDWeek subgroup analysis continues to support Dovato's existing product label.