In vitro interleukin release by human white blood cells prompted a clinical hold for potential cytokine release syndrome
“The Agency placed the application on full clinical hold on January 6, 2017, due to the potential risk of cytokine release syndrome (based on demonstration of release of interleukins induced in human white blood cells in an in vitro cytokine release assay).”
Possible FcRn competition with maternal IgG from YTE modification, potentially reducing passive immunity in infants
“It is unknown if competition could exist between maternal antibodies and clesrovimab for FcRn binding sites/IgG-recycling and if clesrovimab is preferentially recycled over endogenous maternal IgG due to the increased affinity for FcRn through the YTE modification”
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