Negative in Ames, mouse lymphoma and rat micronucleus assays
“Difamilast was negative in a standard battery of genotoxicity tests, including the Ames test, the mouse lymphoma assay, and an in vivo micronucleus study in rats.”
✓ VerifiedFDA multi-discipline review, p. 40Source ↗
Carcinogenicity
2-year dermal rat and mouse: no drug-related tumors (3.7-10x MRHD AUC)
“In 2-year dermal carcinogenicity studies in rats and mice, no test article-related neoplastic findings were observed in rats or mice that received difamilast at dermal doses up to 3% (3.7 to 10 times the MRHD based on AUC comparison).”
✓ VerifiedFDA multi-discipline review, p. 40Source ↗
Instead of carcinogenicity
Not stated in public reviews
Not reported in the public reviews. Reviewers summarise selectively, so this usually means it wasn't discussed publicly, not that it wasn't studied.
Instead of genotoxicity
Not stated in public reviews
Not reported in the public reviews. Reviewers summarise selectively, so this usually means it wasn't discussed publicly, not that it wasn't studied.
DRG histopathology
Not stated in public reviews
Not reported in the public reviews. Reviewers summarise selectively, so this usually means it wasn't discussed publicly, not that it wasn't studied.
Reproductive & developmental
Rat EFD at 100 mg/kg/day: fewer live fetuses, lower fetal weight, retarded ossification, ventricular septum defects
“In embryofetal development studies, fewer live fetuses, decreased fetal weight, retarded ossification, and increased membranous ventricular septum defect were noted in rats at the high dose of 100 mg/kg/day.”
✓ VerifiedFDA multi-discipline review, p. 40Source ↗
Safety pharmacology
No CNS (rat) or cardiovascular/respiratory (dog) effects at single SC doses; hERG IC50 2.54 µM
“There were no significant effects on the central nervous system (CNS) in rats at single SC doses up to 200 mg/kg or cardiovascular or respiratory parameters in conscious dogs at single SC doses up to 30 mg/kg. In an in vitro human Ether-à-go-go Related Gene (hERG) assay, the half-maximal inhibitor concentration (IC50) value for the inhibition on hERG K+ current was 2.54 μM.”
✓ VerifiedFDA multi-discipline review, p. 39Source ↗
Genotox: Ames
Negative
“Difamilast was negative in a standard battery of genotoxicity tests, including the Ames test, the mouse lymphoma assay, and an in vivo micronucleus study in rats.”
✓ VerifiedFDA multi-discipline review, p. 40Source ↗
Genotox: in vitro mammalian
Mouse lymphoma assay: negative
“Difamilast was negative in a standard battery of genotoxicity tests, including the Ames test, the mouse lymphoma assay, and an in vivo micronucleus study in rats.”
✓ VerifiedFDA multi-discipline review, p. 40Source ↗
Genotox: in vivo
Rat micronucleus: negative
“Difamilast was negative in a standard battery of genotoxicity tests, including the Ames test, the mouse lymphoma assay, and an in vivo micronucleus study in rats.”
✓ VerifiedFDA multi-discipline review, p. 40Source ↗
Carcinogenicity model
2-year dermal rat and 2-year dermal mouse; no drug-related neoplasms
“In 2-year dermal carcinogenicity studies in rats and mice, no test article-related neoplastic findings were observed in rats or mice that received difamilast at dermal doses up to 3% (3.7 to 10 times the MRHD based on AUC comparison).”
✓ VerifiedFDA multi-discipline review, p. 40Source ↗
Carcinogenicity timing
2-year dermal rat and 2-year dermal mouse completed; reviewed by ECAC before approval
“These two 2-year dermal carcinogenicity studies have been reviewed by the ECAC. The Committee concluded that the studies were adequate and there was no evidence of drug-related neoplasms in either study.”
✓ VerifiedFDA multi-discipline review, p. 54Source ↗
hERG / QT
hERG margin 7,931-fold; no QTc prolongation in dog at 98x clinical Cmax
“The difamilast nonclinical package demonstrated a large hERG safety margin (7,931-fold) and no QTc prolongation in the in vivo dog study at exposures 98x the clinical Cmax.”
✓ VerifiedFDA multi-discipline review, p. 154Source ↗
Not genotoxic overall: Ames negative; in vitro chromosome aberration positive without (not with) metabolic activation; rat micronucleus and comet negative