Dose-dependent lymphoid depletion (GALT, lymph nodes, spleen, thymus) in dogs, incompletely reversible at 4 mg/kg/day
“Dogs had dose-dependent decreased cellularity of lymphoid tissues, including gut-associated lymphoid tissue (GALT), lymph nodes, spleen, and thymus, which did not completely resolve in the 4 mg/kg/day group.”
✓ VerifiedFDA multi-discipline review, p. 38Source ↗
Biodistribution & persistence
Rapid wide tissue distribution in rats (within 15 minutes), including male reproductive and melanin-pigmented tissues (uvea, skin)
“Following a single oral dose to rats, 14C-zidesamtinib distributed to nearly all tissues within 15 minutes. Radioactivity was detected in male reproductive tissues (seminal vesicle, prostate gland, epididymis, and testes) and melanin-pigmented tissues (uveal tract and skin).”
✓ VerifiedFDA multi-discipline review, p. 37Source ↗
Modality-specific risk
Off-target TRK inhibition: CNS toxicity and embryo-fetal toxicity
“the totality of the nonclinical and clinical data demonstrates a functional off-target TRK inhibition by zidesamtinib, which can have safety implications for both CNS toxicity and embryo-fetal development (discussed below).”
✓ VerifiedFDA multi-discipline review, p. 36Source ↗