A French National Real-World Survey of People With Multiresistant HIV-1 Viruses Receiving an Antiretroviral Regimen Including Fostemsavir or Ibalizumab.

BACKGROUND

Attachment inhibitor fostemsavir (FTR) and postattachment inhibitor ibalizumab (IBA) are used in people with HIV-1 (PWH) who are highly treatment experienced and harboring multidrug-resistant viruses, and real-world data remain limited. We describe population characteristics and pharmacovirologic outcomes of PWH initiating FTR- or IBA-based regimens.

METHODS

We conducted a French retrospective observational study within the AIDS Research National Agency | Emerging Infectious Diseases virology and pharmacology network. Virologic failure (VF) was defined as 2 consecutive plasma viral loads (VLs) ≥50 copies/mL; nonvirologic response was considered a VL decrease <1 log10 copies/mL or failure to achieve virologic suppression.

RESULTS

Among 70 PWH receiving FTR-based treatment, 50% were virologically suppressed at initiation; median VL among viremic cases was 3.6 log10 copies/mL. Resistance to at least 2 antiretrovirals was observed among participants by inhibitor class: 96%, nucleoside reverse transcriptase inhibitor; 94%, nonnucleoside reverse transcriptase inhibitor; 74%, protease inhibitor; and 64%, integrase strand transfer inhibitor. The genotypic susceptibility score was ≤1 in 47%, and median follow-up was 20 months. Eight VFs and 8 nonvirologic responses occurred. At failure, emergence of FTR resistance-associated mutations occurred in 1 case. Suboptimal temsavir concentrations were observed in 2 of 8 participants in failure. Eleven PWH who were viremic initiated IBA-based treatment: the genotypic susceptibility score was ≤1 in 4, and median follow-up was 7 months with 5 VFs and 2 nonvirologic responses. One new resistance mutation (N74D, capsid) was detected at VF; suboptimal plasma concentrations of oral antiretrovirals were observed in 3 of 5 participants.

CONCLUSIONS

PWH receiving FTR or IBA had extensive multidrug resistance and limited therapeutic options. Among PWH who were viremic and initiating FTR- and IBA-based regimens, virologic success was achieved in 63% and 36%, respectively, and maintained in 91% who were virologically suppressed and starting an FTR-based regimen.