13 NONCLINICAL TOXICOLOGY
13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility
The carcinogenic potential of filgrastim products has not been studied. Filgrastim failed to induce bacterial gene mutations in either the presence or absence of a drug metabolizing enzyme system. Filgrastim had no observed effect on the fertility of male or female rats at doses up to 500 mcg/kg.
13.2 Animal Toxicology and Pharmacology
Filgrastim was administered to monkeys‚ dogs‚ hamsters‚ rats‚ and mice as part of a nonclinical toxicology program, which included studies up to 1 year duration. In the repeated-dose studies‚ changes observed were attributable to the expected pharmacological actions of filgrastim (i.e.‚ dose-dependent increases in white blood cell counts‚ increased circulating segmented neutrophils‚ and increased myeloid:erythroid ratio in bone marrow). Histopathologic examination of the liver and spleen revealed evidence of ongoing extramedullary granulopoiesis, and dose-related increases in spleen weight were seen in all species. These changes all reversed after discontinuation of treatment.