13 NONCLINICAL TOXICOLOGY
13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility
The carcinogenic potential of sunitinib has been evaluated in 2 species: rasH2 transgenic mice and Sprague-Dawley rats. There were similar positive findings in both species. In rasH2 transgenic mice, gastroduodenal carcinomas and/or gastric mucosal hyperplasia, as well as an increased incidence of background hemangiosarcomas were observed at sunitinib daily doses of ≥25 mg/kg/day in studies of 1 or 6 months duration. No proliferative changes were observed in rasH2 transgenic mice at 8 mg/kg/day. Similarly, in a 2-year rat carcinogenicity study, administration of sunitinib in 28-day cycles followed by 7-day dose-free periods resulted in findings of duodenal carcinoma at doses as low as 1 mg/kg/day [approximately 0.9 times the combined AUC (combined systemic exposure of sunitinib plus its active metabolite) in patients administered the RDD of 50 mg]. At the high dose of 3 mg/kg/day (approximately 8 times the combined AUC in patients administered the RDD of 50 mg), the incidence of duodenal tumors was increased and was accompanied by findings of gastric mucous cell hyperplasia and by an increased incidence of pheochromocytoma and hyperplasia of the adrenal gland.
Sunitinib did not cause genetic damage when tested in in vitro assays [bacterial mutation (Ames test), human lymphocyte chromosome aberration] and an in vivo rat bone marrow micronucleus test.
In a female fertility and early embryonic development study, female rats were administered oral sunitinib (0.5, 1.5, 5 mg/kg/day) for 21 days prior to mating and for 7 days after mating. Preimplantation loss was observed in females administered 5 mg/kg/day (approximately 5 times the combined AUC in patients administered the RDD of 50 mg). No adverse effects on fertility were observed at doses ≤1.5 mg/kg/day (approximately equal to the combined AUC in patients administered the RDD of 50 mg). In addition, effects on the female reproductive system were identified in a 3-month oral repeat-dose monkey study (2, 6, 12 mg/kg/day). Ovarian changes (decreased follicular development) were noted at 12 mg/kg/day (approximately 5 times the combined AUC in patients administered the RDD of 50 mg), while uterine changes (endometrial atrophy) were noted at ≥2 mg/kg/day (approximately 0.4 times the combined AUC in patients administered the RDD of 50 mg). With the addition of vaginal atrophy, the uterine and ovarian effects were reproduced at 6 mg/kg/day (approximately 0.8 times the combined AUC in patients administered the RDD of 50 mg) in a 9-month monkey study (0.3, 1.5, and 6 mg/kg/day administered daily for 28 days followed by a 14-day respite).
In a male fertility study, no reproductive effects were observed in male rats dosed with 1, 3, or 10 mg/kg/day oral sunitinib for 58 days prior to mating with untreated females. Fertility, copulation, conception indices, and sperm evaluation (morphology, concentration, and motility) were unaffected by sunitinib at doses ≤10 mg/kg/day (approximately ≥26 times the combined AUC in patients administered the RDD of 50 mg).