No cytokine production by human PBMCs with soluble or immobilized antibody at 10-100 µg/mL
“Upon exposure of PBMCs to retifanlimab concentrations of 10 µg/mL and 100 µg/mL (ie, 10-200 times higher than the positive control antibody OKT3), no cytokine production was observed with all three conditions of retifanlimab presentation.”
Human TCR staining limited to lymphocytes in expected tissues
“Staining was observed in expected tissues and was limited to lymphocytes.”
✓ VerifiedFDA multi-discipline review, p. 41Source ↗
Modality-specific risk
Potential for severely enhanced immune responses to infection with PD-1 blockade
“Based on data from the literature and its mechanism of action, there may be a potential for severely enhanced immune responses to infection following treatment with retifanlimab.”
✓ VerifiedFDA multi-discipline review, p. 30Source ↗
In vitro whole-blood cytokine release far below alemtuzumab/TGN1412 controls; no effects on monkey TDAR, lymphocyte subsets or serum cytokines; ADA in some monkeys