CROI 2023: Bone density profiles for CAB-LA vs TDF/FTC oral PrEP in young adults
TDF/FTC oral PrEP is associated with BMD loss but the impact of CAB-LA on BMD is unknown. CROI 2023 included a BMD study that demonstrated median increased BMD percentage from baseline (from +0.5 to +1.5%) for participants who received CAB-LA PrEP. 
A bone sub-study of HPTN-083 was conducted at 19 sites and included people taking oral (TDF/FTC, n=122) or CAB-LA (n=132) PrEP. Low BMD (Z-score ≤2.0) at baseline was observed for 15% (oral) and 16% (LA) of participants. The study measured BMD at lumbar spine, femoral neck and hip.
At week 105, participants in the oral group saw a median percentage decline in BMD across the three sites of –0.5 to –1%. Conversely, median BMD increased by +0.5 to +1.5% for participants receiving CAB-LA. These findings suggest that those at risk of osteoporosis or fracture may be better suited to CAB-LA PrEP.
This sub-study recruited gay men (90%) and trans women (10%) and other baseline demographics included: white (47%), Black (31%) and Asian (12%). Median age was 29 years (IQR: 23 to 41) for oral and 26 years (IQR: 22 to 31 years) for CAB-LA PrEP formulations. 8% of the study population were ≥50 years old.
These results are not unexpected although it is unclear whether the overall differences at week 105 are statistically significant given the lower age at baseline in the CAB-LA arm, when bones are still growing.
Brown TT et al. Bone density changes with CAB-LA or TDF/FTC PrEP in MSM and TGW in HPTN 083. 30th CROI, 19–22 February 2023, 30th Conference on Retroviruses and Opportunistic Infections, 19 – 22 February 2023, Seattle and hybrid . Poster Presentation 987.
This report was first published on 9 March 2023.