Table 1.

Relevant repeat-dose toxicity and carcinogenicity studies in animals as reviewed by the FDA (at approval)

Study	Conclusions	Systemic immune suppression observed? (AUC; safety margina)	Malignancy findings
Tacrolimus
80-week carcinogenicity of oral (in feed) tacrolimus in CD-1 miceb [16, 44]	No relationship of tumor incidence was found	No (NA; threefold)	NA
104-week carcinogenicity of oral (in feed) tacrolimus in CD ratsb [16, 44]	No relationship of tumor incidence was found	No (NA; ninefold)	NA
104-week oncogenicity of topical tacrolimus ointment (marketed formulation) in B6C3FI mice [44]	The increased incidence of pleomorphic and undifferentiated lymphomas are probably due to the established pharmacologic effect of tacrolimus, but the safety factor is sufficient that “human patients would not have a high risk”	Yes (~180 ng·h/mL; tenfold)	• Topical tacrolimus ointment 0.1 % was associated with a statistically significant increase in the incidence of pleomorphic lymphoma (males and females) and undifferentiated lymphoma (females) mostly of B cell type • No skin carcinomas were noted
Pimecrolimus [45, 46]
13-week toxicity of topical pimecrolimus in ethanol in CD-1 mice	The increased incidence of pleomorphic lymphomas observed in this study may be related to the pharmacological action of and systemic exposure to pimecrolimus	Yes; assumed related to ethanol vehicle (males: 643 ng·h/mL; 17-fold; females: 675 ng·h/mL; 18-fold)	• Topical pimecrolimus 25 and 50 mg/kg/day were associated with lymphoproliferative changes, including malignancies
Oncogenicity of oral (gavage) pimecrolimus in CD-l mice for their life-span	The increased incidence of malignant lymphoma was most likely a consequence of systemic immunosuppression, but the safety factor is “adequate” for use in humans	Yes (males: 2,260 ng·h/mL; 60-fold/females: 5,059 ng·h/mL; 133-fold)	• Oral pimecrolimus 45 mg/kg/day was associated with a statistically significant increase in the incidence of follicular center cell lymphoma, pleomorphic lymphoma, and combined lymphoma in both males and females
104-week oncogenicity of oral (gavage) pimecrolimus in Wistar rats (2 replicates)	The increased incidence of benign thymoma is a significant finding but may not be relevant to humans; the safety factor for females is “adequate” for use in humans, but not for males	Yes (males: 42 ng·h/mL; 1.1-fold/females: 805 ng·h/mL; 21-fold)	• Oral pimecrolimus 5 mg/kg/day (males) and 10 mg/kg/day (males and females) were associated with a “biologically significant” increase in the incidence of benign thymoma
104-week carcinogenicity of topical pimecrolimus cream (marketed formulation) in Wistar ratsc	The increased incidence of follicular cell adenoma of the thyroid is a significant finding but may not be relevant to humans; the safety margin is not as great as noted in other carcinogenicity studies, but since the highest feasible dose was used, the study was considered adequate	Not clear; but no significant toxicity was noted (57 ng·h/mL based on highest feasible dose; 1.5-fold)	• A statistically significant increase in the incidence of follicular cell adenoma in the thyroid in all topical pimecrolimus cream dose groups (0.2, 0.6, and 1.0 %) was noted in males onlyd • A slight (non-significant) increase in benign thymoma was seen in males at all doses and in females at the 0.2 % dose levele • Non-neoplastic minimal-to-moderate application site epithelial hyperplasia was noted for both pimecrolimus cream and vehicle; this was attributed to vehicle effects • No lymphomas were noted

AUC area under concentration–time curve, NA not available, NOAEL no observed adverse effect level

^aAUC is based on NOAEL unless otherwise noted; safety margin is in comparison to highest AUC seen with topical administration in humans

^bBoth the mouse and rat oral (in feed) studies were deemed as inadequate because of inadequate duration and low systemic exposure; however, since these studies are heavily referenced in the FDA toxicology review, they are included in this table

^cNo malignancies were found in an additional 104-week carcinogenicity study of topical pimecrolimus in ethanol in CD-1 mice; however, the study was deemed unacceptable by the FDA because of inadequate high dose and is not included in this table

^dMale rats are more sensitive to thyroid effects than female rats or humans because of lower T4 hormone levels; this finding may not be relevant to humans

^eValues fell within the historical range for Wistar rats and/or showed no dose dependence; this finding was determined to be not significant