Keytruda: which tox species, and why?

“consisted of pivotal 1-month and 6-month repeat-dose chronic toxicity studies both with 4-month recovery periods in Cynomolgus monkey”

“Its binding affinities to PD-1 derived from human and cynomolgus monkeys were comparable (~2X difference), however, the antibody did not bind to rodent or dog PD-1.”

“Given the lack of cross-reactivity of MK-3475 with murine PD-1, a commercially available hamster anti-murine PD-1 mAb, J43, was used as surrogate for in vivo pharmacology studies.”