Libtayo: which tox species, and why?

“In in vitro studies, cemiplimab (REGN2810) bound to human and cynomolgus monkey PD-1 with similar affinity, but did not bind rodent PD-1, supporting the use of cynomolgus monkeys as the single pharmacologically relevant species for toxicity assessment.”

“REGN2810 exhibited similar binding affinity for human and cynomolgus monkey PD-1 (see Table 2), but did not bind mouse or rat PD-1, supporting the use of cynomolgus monkeys as a pharmacologically relevant species for toxicity assessment.”

“Since REGN2810 does not bind mouse PD-1, mice were genetically engineered to express a human/mouse PD-1 chimeric receptor (huPD-1 mice); these mice have a functional human PD-1 with expression regulated by the mouse PD-1 promoter.”