Dual therapy with dolutegravir plus lamivudine as first-line ART
Simon Collins, HIV i-Base
Results from a US pilot study using dolutegravir plus lamivudine dual therapy in treatment-naive participants reported good early efficacy including with high baseline viral load.
ACTG A5353 was a single-arm, open-label, phase 2 pilot study in 120 participants with viral load <500,000 copies/mL. Exclusion criteria included active hepatitis B infection or major drug-associated mutations in RT, PI or integrase.
Baseline characteristics included median age 30 (IQR: 24 to 41) years; 87% male; 40% black, 28% white, 27% Hispanic. Median CD4 count and viral load were 387 (288 to 596) cells/mm3 and 4.61 (3.94, 5.05) log copies/mL.
At week 24, the primary endpoint of viral load <50 copies/mL was reported for 108/120 participants (90%CI: 83% to 95%). Response rates were similar when stratified by baseline viral load being above/below 100,000 copies/mL, even though baseline characteristics of the >100,000 group (n=37) by definition had higher viral load and lower CD4 counts associated with more advanced HIV infection.
However, there were more virological failures in the high viral load group: n=3 (8%) vs n=2 (2%). In contrast, failure due to missing data was less common for the high viral load group: n=1 (3%) vs n=6 (7%), though numbers are small.
Three participants met protocol-defined viral failure linked to low adherence (confirmed by low drug levels), one of whom developed R263R/K (integrase) and M184V (RT).
Taiwo BO et al. ACTG A5353: A pilot study of dolutegravir (DTG) + lamivudine (3TC) for initial treatment of HIV-1-infected participants with HIV-1 RNA <500,000 copies/mL. IAS 2017, Paris. Oral abstract TULBPEB21.