Simplification from tenofovir disoproxil fumarate plus lamivudine or emtricitabine plus ritonavir-boosted protease inhibitor to ritonavir-boosted atazanavir plus lamivudine in virologically suppressed HIV-infected adults with osteopenia: a pilot study

Background Tenofovir disoproxil fumarate, particularly when given with a ritonavir-boosted PI, reduces bone mineral density (BMD) and increases bone turnover markers (BTMs). Ritonavir-boosted atazanavir plus lamivudine is a feasible simplified option. We evaluated whether switching from a triple ritonavir-boosted PI plus tenofovir disoproxil fumarate to a two-drug regimen of lamivudine plus ritonavir-boosted atazanavir would improve BMD. Methods Single-arm pilot study. Virologically suppressed patients on tenofovir disoproxil fumarate plus lamivudine or emtricitabine plus ritonavir-boosted PI with low BMD, without previous resistance mutations and/or virological failure to study drugs were switched to 100/300 mg of ritonavir-boosted atazanavir plus 300 mg of lamivudine once daily. The primary endpoint was BMD change by DXA at Week 48. Results There were 31 patients, 4 (13%) female, and median age was 40 years. Seven participants (22.5%) had osteoporosis. At 48 weeks, mean (SD) changes in spine and hip BMD were +0.01 (0.03) (P = 0.0239) and +0.013 (0.03) g/cm(2) (P = 0.0046), respectively. Mean (SD) T-score changes were +0.1 (0.23) (P = 0.0089) and +0.25 (0.76) (P = 0.0197), respectively. N-telopeptide and urine tenofovir disoproxil fumarate toxicity markers showed significant improvements. One participant withdrew from the study and two were lost to follow-up. There were no virological failures, or serious or grade 3-4 adverse events. Conclusions Switching from a tenofovir disoproxil fumarate plus ritonavir-boosted PI triple therapy to a lamivudine plus ritonavir-boosted atazanavir two-drug regimen in virologically suppressed HIV-infected adults with low BMD was safe, increased low BMD and reduced plasma markers of bone turnover and urine markers of tenofovir disoproxil fumarate toxicity over 48 weeks.

Automated summary

The study evaluated the switch from a triple therapy of tenofovir disoproxil fumarate plus ritonavir-boosted PI to a two-drug regimen of lamivudine plus ritonavir-boosted atazanavir in virologically suppressed HIV-infected adults with low BMD. The results showed significant improvements in bone density for some patients after the switch over a 48-week period, with no virological failures.