Evaluation and real-world experience of a neutralization susceptibility screening assay for broadly neutralizing anti-HIV-1 antibodies.

BACKGROUND Development of a screening assay for the clinical use of broadly neutralizing antibodies (bnAbs) is a priority for HIV therapy and cure initiatives. METHODS We assessed the PhenoSense Monoclonal Antibody (mAb) Assay (Labcorp-Monogram Biosciences) which is CLIA-validated and has been used prospectively and retrospectively in multiple recent bnAb clinical trials. RESULTS When performed on pre-ART plasma and on-ART longitudinal PBMC samples sourced from a recent clinical trial, the PhenoSense mAb Assay produced robust reproducibility, concordance across sample types, and expected ranges in the susceptibility measures of bnAbs in clinical development. PhenoSense mAb applied retrospectively to baseline samples from three recent studies correlated with published laboratory-based study evaluations, but baseline bnAb susceptibility was not consistently predictive of durable virus suppression. Assessment of the feasibility of the assay in four recent clinical studies provides estimates of assay success rate and processing time. CONCLUSIONS The PhenoSense mAb Assay provides reproducible bnAb susceptibility measurements across relevant sample types yet was not consistently predictive of virus suppression. Logistical and operational assay requirements can impact timely clinical trial conduct. These results inform bnAb studies in development.