Cotton rat intranasal RSV A2 challenge model dosed with clesrovimab (0.03-2.5 mg/kg)
“Clesrovimab and RB-1 LALA were administered at doses of 0.03, 0.09, 0.28, 0.83, or 2.5 mg/kg to cotton rats. Challenge with 1 x 105 pfu RSV strain A2 followed on the day after immunization.”
Parental antibody RB-1 used in main cotton rat studies because YTE increases rodent FcRn binding and reduces exposure
“The use of the parental antibody was justified by the fact that the YTE modification leads to increased binding to the rodent FcRn which, in turn, reduces the overall exposure to the Ab.”
EMA: parental RB-1 efficacy similar to D25 and higher than palivizumab against RSV A and B in cotton rats
“In an in vivo efficacy study in a cotton rat model RB-1, the parental antibody of clesrovimab lacking the Fc modifications, was demonstrated to be of similar efficacy as D25 and of higher efficacy than palivizumab in reducing the pfu of RSV A and RSV B strains in nose and after passive immunization.”