Negative in Ames (4 assays), CHL chromosome aberration, mouse micronucleus and rat UDS assays
“Istradefylline was negative in 4 Ames assays for bacterial mutagenicity, the chromosomal aberration assay in Chinese hamster lung cells, the micronucleus assay in mice or the UDS assay in rats.”
✓ VerifiedFDA pharmacology/toxicology review, p. 143Source ↗
Carcinogenicity
Lifetime oral studies in mouse and rat: no evidence of carcinogenicity
“In lifetime oral carcinogenicity studies, there was no evidence of carcinogenicity in mouse (0, 25, 125, or 250 mg/kg) or rat (0, 30, 100, or 320 mg/kg).”
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
Teratogenic, with embryofetal and offspring mortality and growth deficits at clinically relevant exposures, without maternal toxicity
“oral administration of istradefylline during pregnancy resulted in teratogenicity (increased incidences of fetal structural abnormalities, embryofetal and offspring mortality and growth deficits) at clinically relevant exposures and in the absence of maternal toxicity.”
No QT or respiratory effects in telemetered dogs at 1000 mg/kg; no hERG inhibition up to 2 µM
“In a later study, telemeterized dogs were treated for 6 weeks at 1000 mg/kg p.o. daily and no significant effects were reported on the QT interval or respiratory parameters. The in vitro hERG assay showed no inhibition of the Ikr current at concentrations up to 2 µmol/L.”
✓ VerifiedFDA pharmacology/toxicology review, p. 34Source ↗
Genotox: Ames
Negative in 4 Ames assays
“Istradefylline was negative in 4 Ames assays for bacterial mutagenicity, the chromosomal aberration assay in Chinese hamster lung cells, the micronucleus assay in mice or the UDS assay in rats.”
✓ VerifiedFDA pharmacology/toxicology review, p. 143Source ↗
Genotox: in vitro mammalian
Chromosomal aberration in Chinese hamster lung cells: negative; mouse lymphoma not done (precipitation)
“Istradefylline was negative in 4 Ames assays for bacterial mutagenicity, the chromosomal aberration assay in Chinese hamster lung cells, the micronucleus assay in mice or the UDS assay in rats.”
✓ VerifiedFDA pharmacology/toxicology review, p. 143Source ↗
Genotox: in vivo
Mouse micronucleus and rat UDS: negative
“Istradefylline was negative in 4 Ames assays for bacterial mutagenicity, the chromosomal aberration assay in Chinese hamster lung cells, the micronucleus assay in mice or the UDS assay in rats.”
✓ VerifiedFDA pharmacology/toxicology review, p. 143Source ↗
Carcinogenicity model
2-year mouse (up to 250 mg/kg/day) and 2-year rat; no tumor increase
“The 2 year mouse carcinogenicity study appears to have been adequately conducted and assessed but the doses do not appear to have been significantly high enough to elicit even a minor level of toxicity at the highest dose of 250 mg/kg/d.”
✓ VerifiedFDA pharmacology/toxicology review, p. 143Source ↗
Carcinogenicity timing
2-year mouse and 2-year rat completed before the marketing application
“The Exec CAC concluded that the 2-year carcinogenicity studies in mouse and rat were adequate and negative, pending confirmation of the sponsor’s statistical analysis by the Agency.”
✓ VerifiedFDA pharmacology/toxicology review, p. 151Source ↗
hERG / QT
No hERG (IKr) inhibition up to 2 µmol/L; no QT effect in telemetered dogs
“The in vitro hERG assay showed no inhibition of the Ikr current at doses up to 2 µmol/L. No significant treatment-related effects were reported in cardiovascular safety studies in telemeterized conscious dogs.”
✓ VerifiedFDA pharmacology/toxicology review, p. 142Source ↗
Not genotoxic overall: Ames negative; in vitro chromosome aberration positive without (not with) metabolic activation; rat micronucleus and comet negative