A study conducted in 30 Spanish hospitals has confirmed the effectiveness of a two-drug HIV therapy

SEIMC-GeSIDA Foundation and ViiV Healthcare announced positive 48-week results from the Paso Doble study (GeSIDA study 11720), the largest randomized phase IV clinical trial comparing the two-drug regimen Dovato (dolutegravir/lamivudine (DTG/3TC)) with the three-drug regimen Biktarvy (bictegravir/emtricitabine/tenofovir alafenamide fumarate (BIC/FTC/TAF)) for the treatment of HIV-1 in people with suppressed viral load.

The study showed that switching to dual-drug DTG/3TC therapy in HIV-infected adults with suppressed viral load is as effective as switching to triple-drug BIC/FTC/TAF therapy in maintaining virologic suppression. The findings were presented at the 25th International AIDS Conference (AIDS 2024), which is taking place in Munich, Germany, from 22 to 26 July.

The Paso Doble randomized clinical trial (NCT04884139) is an open-label, randomized, multicenter, phase IV clinical trial involving 30 hospitals from ten Spanish provinces.

553 HIV-infected individuals with suppressed viral load were randomized to receive DTG/3TC (n=277) or BIC/FTC/TAF (n=276). Enrollees had not previously received either drug and had received a multiple-pill or single-pill regimen containing at least one of the following drugs within the previous 24 weeks: cobicistat as a booster, efavirenz, or tenofovir disoproxil fumarate).

The study met its primary objective when DTG/3TC demonstrated non-inferiority to BIC/FTC/TAF (based on the percentage of participants with HIV-1 RNA greater than or equal to 50 copies/mL at 48 weeks, according to a snapshot analysis (FDA non-inferiority margin of 4% in the intent-to-treat population).

At 48 weeks, the DTG/3TC combination was non-inferior to BIC/FTC/TAF (risk difference between DTG/3TC (2.2%) minus BIC/FTC/TAF (0.7%) was 1.4%, 95% CI -0.5 to 3.4.

Less weight gain

The study also found that weight gain was significantly greater in participants who switched to the three-drug regimen (adjusted mean 1.81 kg, 95% CI: 1.28-2.34) than in those who switched to the two-drug regimen (adjusted mean 0.89 kg, 95% CI: 0.37-1.41) (adjusted mean difference 0.92 kg, 95% CI: 0.17-1.66). Similarly, the proportion of participants who gained more than 5% of their weight at week 48 was significantly higher with BIC/FTC/TAF than with DTG/3TC (29.9% vs 20.0%, respectively, adjusted OR 95% CI: 1.81 (1.19-2.76) )

Weight change with DTG/3TC did not differ between men and women or by participants’ prior treatment regimen, while the proportion of study participants who experienced a weight gain of more than 5% with BIC/FTC/TAF was approximately 50% higher than in those on DTG/3TC when switching from abacavir and approximately twice as high when switching from tenofovir. There were a few discontinuations due to adverse events in both study arms (DTG/3TC = 1, 0.4%; BIC/FTC/TAF = 2, 0.7%), with no differences between groups.

Esteban Martinez, the study’s principal investigator and a senior consultant in infectious diseases at the Barcelona Hospital Clinic, said: “All the antiretroviral treatments for HIV that are prescribed today are very effective, so it is vital that we study the impact of these treatments beyond viral suppression. The results show that Dovato not only maintained the same efficacy as the three-drug regimen, but also showed significantly less weight gain over 48 weeks.”