“Pivotal nonclinical studies of sarilumab were conducted in Cynomolgus monkeys by intravenous and SC dosing since only monkeys were identified as a relevant species for sarilumab in a series of pharmacology studies.”
✓ VerifiedFDA pharmacology/toxicology review, p. 2Source ↗
Why that species
Binds human and cynomolgus IL-6Ra (KD 54 and 123 pM); no binding to murine IL-6Ra
“Sarilumab binds human and Cynomolgus monkey IL-6Rα with an equilibrium dissociation constant (Kd) of 54 pM and 123 pM, respectively, but no binding of sarilumab to the murine IL-6Rα was observed.”
✓ VerifiedFDA pharmacology/toxicology review, p. 46Source ↗
Surrogate molecule
Yes: murine anti-mouse IL-6Ra surrogate REGN844, used for mouse fertility and juvenile toxicity studies
“Fertility and juvenile toxicity studies were also conducted in mice with an analogous monoclonal antibody (REGN844).”
✓ VerifiedFDA pharmacology/toxicology review, p. 2Source ↗