“Spesolimab does not bind to IL36R in common nonclinical species. Therefore, BI 674304, a surrogate monoclonal antibody that specifically binds to mouse IL36R was developed to assess the pharmacology and toxicology of IL36R inactivation in mice.”
✓ VerifiedFDA multi-discipline review, p. 35Source ↗
Why that species
No binding to mouse, rat, minipig, rhesus, marmoset or hamster IL-36R; very low affinity and poor potency in cynomolgus monkey
“spesolimab did not bind to IL36R from the mouse, mini pig, rhesus money, marmoset, rat, or hamster, and had very low affinity to IL36R from cynomolgus monkey.”
✓ VerifiedFDA multi-discipline review, p. 36Source ↗
Surrogate molecule
Yes: rat-mouse chimeric anti-mouse receptor antibody BI 674304, used for repeat-dose toxicity and DART studies in mice
“BI 674304 was evaluated in a battery of nonclinical studies that included evaluation of PK, immunotoxicity, repeat-dose toxicity, and reproductive and developmental toxicology.”
✓ VerifiedFDA multi-discipline review, p. 35Source ↗