Cynomolgus monkey (relevant) plus rat (non-binding species)
“DS-8201a and MAAL-9001 bound to cynomolgus monkey HER2 protein but not to mouse or rat HER2 proteins, showing that the cynomolgus monkey is an appropriate species in which to conduct toxicity evaluation with DS-8201a, based on its binding to HER2.”
✓ VerifiedFDA multi-discipline review, p. 41Source ↗
Why that species
ADC and naked antibody bind cyno HER2 with affinity similar to human; no binding to mouse or rat HER2
“In the same assay, DS-8201a and MAAL-9001 bound to cynomolgus monkey HER2-His protein (Kd [ED50] = 7.46 ng/mL and 6.77 ng/mL, respectively) but not to mouse or rat HER2-His proteins.”
✓ VerifiedFDA multi-discipline review, p. 44Source ↗
Surrogate molecule
No surrogate; clinical ADC (process 1 and process 2 material) tested; DXd payload and naked antibody tested separately
“In the studies with trastuzumab deruxtecan, the rodent study and one monkey study were performed with process 1 material, whereas the 2 additional cynomolgus monkey studies were performed with process 2 material.”