13 NONCLINICAL TOXICOLOGY
13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility
Carcinogenicity testing of topotecan has not been performed. Topotecan is known to be genotoxic to mammalian cells and is a probable carcinogen. Topotecan was mutagenic to L5178Y mouse lymphoma cells and clastogenic to cultured human lymphocytes with and without metabolic activation. It was also clastogenic to mouse bone marrow. Topotecan did not cause mutations in bacterial cells.
Topotecan given to female rats prior to mating at an intravenous dose of 1.4 mg/m2 (about equal to the 1.5 mg/m2 clinical dose based on BSA) caused superovulation possibly related to inhibition of follicular atresia. This dose given to pregnant female rats also caused increased pre-implantation loss. A one month study in dogs given a daily intravenous topotecan dose of 0.4 mg/m2 (about 0.25 times the 1.5 mg/m2 clinical dose based on BSA) suggests that treatment may cause an increase in the incidence of multinucleated spermatogonial giant cells in the testes.