Background

Boosted protease inhibitor (bPI) monotherapy (bPImono) potentially has substantial cost, safety and operational benefits. It has never been evaluated as second-line antiretroviral therapy (ART) in Africa.

Methods

After 24 weeks of lopinavir/ritonavir- containing second-line therapy, DART participants were randomized to remain on combination therapy (CT), or change to bPI-mono maintenance (SARA trial; ISRCTN53817258). Joint primary end points were CD4⁺ T-cell changes 24 weeks later and serious adverse events (SAEs); retrospectively assayed viral load (VL) was a secondary end point. Analyses were intention-to-treat.

Results

A total of 192 participants were randomized to CT (n=95) or bPImono (n=97) and followed for median 60 weeks (IQR 45–84). Participants received median 4.0 years (IQR 3.5–4.4) first-line ART. Median CD4⁺ T-cell count at first-line failure was 86 cells/mm³ (47–136), increasing to 245 cells/mm³ (173–325) after 24-week induction when 77% had VL<50 copies/ml. Overall, 44 (23%) were receiving second-line therapy with bPI and nucleoside reverse transcriptase inhibitors (NRTI) only, and 148 (77%) with bPI plus non-NRTI (NNRTI) with or without NRTI. At 24 weeks after randomization to CT versus bPImono, mean CD4⁺ T-cell increase was 42 (CT, n=85) versus 49 cells/mm³ (bPImono, n=88; adjusted difference 13 [95% CI -15, 43], P=0.37; non-inferior compared with predetermined non-inferiority margin [-33]). Virological suppression was greater for CT versus bPImono (trend P=0.009): 77% (70/91) versus 60% (56/94) were <50 copies/ml, and 5% (5) versus 14% (13) were ≥1,000 copies/ml, respectively. A total of 0 (0%) versus 5 (5%) participants had major protease inhibitor mutations and 3 (3%) versus 0 (0%) new NNRTI/NRTI mutations were detected during follow-up. Two participants (1 CT and 1 bPImono) died >24 weeks after randomization, and 5 (2 CT and 3 bPImono) experienced SAEs (P=0.51).

Conclusions

bPImono following a 24-week second-line induction was associated with similar CD4⁺ T-cell response, but increased low-level viraemia, generally without protease inhibitor resistance. Longer-term trials are needed to provide definitive evidence about effectiveness in Africa.