319. SWORD 1 and 2: Switch from TDF Containing Regimen to DTG+RPV Maintains Bone Mineral Density and Decreases Bone Turnover Markers Over 148 Weeks

Abstract Background HIV infection and antiretroviral therapy (ART), particularly tenofovir (TDF), is associated with loss of bone mineral density (BMD). The SWORD studies demonstrated noninferiority of the 2-drug regimen (2DR) dolutegravir (DTG) + rilpivirine (RPV) to continuing current triple-therapy ART (CAR) at 48 weeks and continued viral suppression on DTG+RPV through Week 148. A substudy of SWORD 1 and 2 evaluated a change in BMD by DEXA for those participants who switched from triple ART containing TDF to DTG+RPV. The primary analysis reported at 48 weeks showed a significant increase in total hip and lumbar spine BMD and a significant decrease in bone turnover markers in patients receiving DTG+RPV compared with CAR. Here we present data through Week 148. Methods HIV-infected adult patients with HIV-1 RNA < 50 c/mL received ART containing TDF for ≥6 months prior to randomization to DTG+RPV (Early Switch group, ES) or CAR on Day 1 (Baseline, BL) through Week 48 in SWORD-1/2. CAR patients suppressed at Week 48 switched to DTG+RPV at Week 52 (Late Switch group, LS). Hip and lumbar spine BMD were measured by DEXA scans read centrally. Secondary endpoints include a change in BMD and bone turnover markers through Week 148. Results Following switch to DTG+RPV significant increases were observed for total hip in the ES and LS groups through 100 weeks with a non-significant increase at Week 148 in ES (Figure 1a). Lumbar spine BMD significantly increased from BL at 48 weeks post switch, remained increased, though not significantly from BL through Week 148 (Figure 1b). The BMD of the LS group was similar to that of the ES group through 100 weeks exposure. The majority of patients remained in their pre-switch T-score category or improved a category for both hip and spine through Wk148 (Table 1). Through Wk148, BMI increased minimally and bone turnover markers significantly decreased (P < 0.001 to 0.042 across markers) from BL/LS BL except Type I Collagen C-Telopeptide at Wk148 in the LS group (P = 0.279). Conclusion Switch to the DTG+RPV 2DR was associated with sustained improvements in BMD through Week 148, along with a reduction in bone markers. The favorable effects on skeletal health were observed despite the ageing of study patients and other factors decreasing BMD. A switch to DTG+RPV in suppressed patients provides a robust option for preserving bone health while continuing suppressive HIV treatment. Disclosures All authors: No reported disclosures.