LB-7. Weight Change in Suppressed People with HIV (PWH) Switched from Either Tenofovir Disoproxil Fumarate (TDF) or Abacavir (ABC) to Tenofovir Alafenamide (TAF)

BACKGROUND: Weight gain in PWH occurred in both naïve and switch studies and is linked to use of integrase inhibitors (INSTIs) with varying associations with nucleoside reverse transcriptase inhibitors (NRTIs). One hypothesis is that gain associated with TAF when switching from TDF is a result of cessation of TDF-induced weight suppression. METHODS: The study evaluated weight change in suppressed PWH on INSTI+NRTIs switched from ABC or TDF to TAF. Eligible pts had HIV, were ≥ 18 yrs at index (date of switch), treatment-experienced with known prior regimen, suppressed at index (-12 to +1 mo) and 1 yr, ≥ 6 mo pre-index history, with weight measures at index and 1 yr, no current or pre-index use of protease inhibitor or non-nucleoside reverse transcriptase inhibitor. Univariate comparisons were performed using Χ(2) for categorical and t-test for continuous variables; negative binomial model with log link function evaluated risk of gain ≥ 3% of body weight between groups accounting for age, gender, race, body mass index (BMI), CD4. Linear mixed effects model was used to estimate mean weight at index and 1 yr post switch. RESULTS: Of 970 pts, 828 (85%) switched from TDF to TAF and 142 (15%) from ABC to TAF. Groups were balanced by race, gender, index BMI [Table 1]. Figures 1a-b describe pre- and post-switch INSTI use. At 1 yr, mean unadjusted weight change was 1.4 kg in TDF and 0.2 in ABC group p=0.039. TDF to TAF had higher proportion of PWH with gain ≥ 3% vs ABC to TAF (40% vs 27% p=0.003); differences in gain ≥ 5% and ≥ 10% were not statistically significant (26% vs 22% p=0.323 and 10% vs 6% p=0.220). Pts who gained ≥ 3% were younger, with greater proportion of females, non-obese, with 1 prior regimen, and prior elvitegravir (EVG) use. In adjusted analysis TDF to TAF had higher risk of gain ≥ 3% vs ABC to TAF [Figure 2]. In sensitivity analysis accounting for EVG or dolutegravir (DTG) use, TDF to TAF also had higher risk of ≥ 3% gain vs ABC to TAF: adjusted risk ratio (aRR)= 1.38 [1.01–1.89] and aRR= 1.42 [1.02–1.97]. Table 1. Baseline (index) characteristics. [Image: see text] Figures 1a-b. Distribution of pre switch and post switch INSTI use. [Image: see text] Figure 2. Risk of weight gain ≥ 3% of body weight at 1 year post switch accounting for age, gender, race, index BMI, and CD4. [Image: see text] CONCLUSION: Switching from TDF to TAF in INSTI-based regimens had a greater risk of weight gain vs ABC to TAF. This difference persisted when accounting for impact of the INSTI agent in the current regimen. These data suggest that differences in weight gain between TAF and TDF are driven by removal of TDF-associated weight suppression. DISCLOSURES: Paul Sax, MD, Gilead (Consultant, Research Grant or Support)Janssen (Consultant)Merck (Consultant, Research Grant or Support)ViiV Healthcare (Consultant, Research Grant or Support) Keri N. Althoff, PhD, MPH, Gilead (Advisor or Review Panel member) Keri N. Althoff, PhD, MPH, All of Us Study (NIH) (Individual(s) Involved: Self): Consultant; MedIQ (Individual(s) Involved: Self): Consultant; TrioHealth (Individual(s) Involved: Self): Advisor or Review Panel member Todd T. Brown, MD, PhD, Gilead (Consultant)Merck (Consultant)Theratechnologies (Consultant)ViiV Healthcare (Consultant) Janna Radtchenko, MBA, Trio Health (Employee) Helena Diaz Cuervo, PhD, Gilead Sciences (Employee) Steven Santiago, MD, Gilead (Advisor or Review Panel member, Speaker's Bureau)Janssen (Speaker's Bureau) Graeme Moyle, MD, Theratechnologies (Consultant) Karam Mounzer, MD, Epividian (Advisor or Review Panel member)Gilead (Advisor or Review Panel member, Research Grant or Support, Speaker's Bureau)Janssen (Advisor or Review Panel member, Research Grant or Support, Speaker's Bureau)Merck (Advisor or Review Panel member, Research Grant or Support, Speaker's Bureau)ViiV Healthcare (Advisor or Review Panel member, Research Grant or Support, Speaker's Bureau) Richard Elion, MD, Gilead (Advisor or Review Panel member, Research Grant or Support, Speaker's Bureau)Janssen (Speaker's Bureau)Proteus (Research Grant or Support)ViiV Healthcare (Advisor or Review Panel member, Research Grant or Support)