Background
Fostemsavir [FTR] is approved for use with other active antiretrovirals [ARVs] for treatment of heavily treatment-experienced people with HIV [PWH] and multi-drug resistance [MDR]. We described characteristics and treatment outcomes among PWH prescribed FTR in a real-world setting in the US.
Methods
PWH initiating FTR from July 2020 (FDA approval) to June 2023 identified from electronic health records in the Trio Health HIV Cohort were followed for 12 months [mo] from first FTR prescription (baseline [BL]). Analyses were stratified by viral load [VL] at BL (suppressed: VL <50 copies/mL [cpm]; viremic: VL ≥50 cpm). Outcomes included suppression (VL <50 cpm), virologic failure ([VF]: 2 consecutive VL ≥200 cpm or 1 VL ≥200 cpm + FTR discontinuation within 4 mo), and CD4 recovery (CD4 > 350 cells/µL or +50 cells/µL per 6 months on FTR). We defined BL ARV class resistance as intermediate/high resistance to ≥ 1 ARV in a class by Stanford HIVdb algorithm, and MDR HIV as resistance to ≥ 3 ARV classes.
Results
Of 82 PWH initiating FTR, 46 (56%) were viremic at BL, 31 (38%) suppressed, 5 (6%) with unknown BL VL; 79% received FTR with an integrase inhibitor. Among viremic PWH, 54% initiated FTR as part of a new ARV regimen, while 70% suppressed PWH added FTR to an existing regimen. Compared to suppressed PWH, viremic PWH receiving FTR were younger (48% < 50 yrs vs. 10%), more likely to be female (26% vs. 10%), Black race (54% vs. 23%), and BL CD4 <350 cells/µL (62% vs. 52%). BL resistance data was available for 63% viremic and 39% suppressed PWH: 76% viremic had resistance to ≥ 1 ARV class (vs. 67% suppressed) and 31% had MDR HIV (vs. 17%). Of 82 PWH, 69% were on FTR at the end of follow-up (65% viremic; 71% suppressed), 16% discontinued FTR (11% viremic; 23% suppressed), and 16% were lost to follow-up (24% viremic; 6% suppressed). Of PWH with VLs on FTR, 36% (14/39) of BL viremic became suppressed during the study period; 77% (20/26) of BL suppressed maintained suppression and 12% (3/26) had VF. Median (IQR) CD4 increase was 24 (0-55) cells/µL in BL viremic vs. 58 (24-106) in BL suppressed. Among PWH with BL CD4 < 350 cells/µL, CD4 recovery was similar (36% BL viremic vs. 38% BL suppressed).
Conclusions
In routine clinical care, FTR was prescribed to a heterogeneous population. Most BL suppressed PWH maintained suppression over follow up. While only 36% of BL viremic PWH fully suppressed, most remained on FTR at end of follow up. CD4 recovery was similar between suppressed and viremic PWH.