Based on findings from animal studies, etrasimod may cause fetal harm when administered to a pregnant woman. Available data from reports of pregnancies from the clinical development program with etrasimod are insufficient to identify a drug-associated risk of major birth defects, miscarriage, or other adverse maternal or fetal outcomes. There are risks to the mother and the fetus associated with increased disease activity in women with inflammatory bowel disease during pregnancy, including preterm delivery (before 37 weeks of gestation), low birth weight (less than 2500 g) infants, and small for gestational age at birth.^L48496

In an embryo-fetal development study in pregnant rats, etrasimod was orally administered at 1, 2, or 4 mg/kg/day (5, 11, and 21 times the exposure at the maximum recommended human dose (MRHD) of 2 mg, based on AUC comparison) during the period of organogenesis, from gestation day 6 to 17. No maternal toxicity was observed up to 21 times the exposure at the MRHD. Increased post-implantation loss with a corresponding decrease in the number of viable fetuses was observed at 4 mg/kg/day (21 times the exposure at the MRHD). Etrasimod-related fetal external and/or visceral malformations were noted at all dose levels (?5 times the exposure at the MRHD).^L48496

In an embryo-fetal development study in pregnant rabbits, etrasimod was orally administered at 2, 10, or 20 mg/kg/day (0.8, 6, and 11 times the exposure at the MRHD of 2 mg, based on AUC comparison) during the period of organogenesis, from gestation day 7 to 20. Increased post-implantation loss with a corresponding decrease in the number of viable fetuses was observed at 10 and 20 mg/kg/day (7 and 11 times the exposure at the MRHD). Etrasimod-related fetal malformations including aortic arch defects and fused sternebrae were noted at 10 and/or 20 mg/kg/day (7 and 11 times the exposure at the MRHD). There were no adverse effects on embryofetal development at 2 mg/kg/day (less than the exposure at the MRHD).^L48496

In a pre-and post-natal development study in rats, etrasimod was orally administered at 0.4, 2, or 4 mg/kg/day (2, 10, and 24 times the exposure at the MRHD of 2 mg, based on AUC comparison) throughout pregnancy and lactation, from gestation day 6 through lactation day 20. Mortality during delivery and impaired maternal performance including increased post-implantation loss, increased number of females with stillborn pups, increased number of stillborn pups per litter, decreased viability index, and/or decreased lactation index was observed at 2 and 4 mg/kg/day (10 and 24 times the exposure at the MRHD). Etrasimod was detected in the plasma of F1 offspring, indicating exposure from the milk of the lactating dam. Decreased pup body weights were observed during the preweaning period at all dose levels (maternal exposures ?2 times the exposure at the MRHD), and decreased pup viability was observed at 2 and 4 mg/kg/day (maternal exposures 10 and 24 times the exposure at the MRHD). Reduced fertility and reproductive performance including reduction in implantations and increased preimplantation loss in F1 offspring occurred at the highest dose tested (maternal exposures 24 times the exposure at the MRHD).^L48496

Oral carcinogenicity studies with etrasimod were conducted in mice and rats. In mice administered etrasimod (2, 6, or 20 mg/kg/day) for up to 104 weeks, there was an increase in hemangiosarcoma and hemangioma in males and females at 6 and 20 mg/kg/day (exposures approximately 42 and 121 times, respectively, the exposure at the MRHD of 2 mg, based on AUC comparison). In rats, oral administration of etrasimod (2, 6, or 20 mg/kg/day) for up to 91 weeks did not result in an increase in tumors (male and female exposures 80 and 179 times, respectively, the exposure at MRHD).^L48496

Etrasimod was negative in a battery of in vitro (Ames, chromosomal aberration in human peripheral blood lymphocytes) and in vivo (rat micronucleus) assays.^L48496

Etrasimod administered orally to male rats at 25, 100, or 200 mg/kg/day from pre-mating through mating had no adverse effects on male fertility at exposures up to 467 times the exposure at the MRHD of 2 mg, based on AUC comparison. Etrasimod administered orally to female rats at 1, 2, or 4 mg/kg/day from pre-mating to implantation had no adverse effects on female fertility at exposures up to 21 times the exposure at the MRHD.^L48496