Ames negative; positive in vitro chromosome aberration; negative rat bone marrow micronucleus; overall non-genotoxic
“Avapritinib was not mutagenic in vitro in the bacterial reverse mutation assay (Ames test). Avapritinib was positive in the in vitro chromosome aberration test in human peripheral blood lymphocytes but negative in the in vivo rat bone marrow micronucleus test, and overall non-genotoxic.”
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: reduced fetal weight, post-implantation loss, visceral and skeletal malformations at >=10 mg/kg/day (~2.7x human AUC)
“Daily oral administration of avapritinib to pregnant rats resulted in decreased fetal body weights, post-implantation loss, and increases in visceral (hydrocephaly, septal defect, and stenosis of the pulmonary trunk) and skeletal (sternum) malformations at doses ≥ 10 mg/kg/day (a dose resulting in exposures approximately 2.7 times the exposure based on AUC at the 300 mg human dose).”
✓ VerifiedFDA multi-discipline review, p. 29Source ↗
Safety pharmacology
No pulmonary or cardiovascular effects up to 45 mg/kg; hERG IC50 2.4 μM (1.5x human free Cmax)
“There were no avapritinib-related adverse effects on pulmonary function or the cardiovascular system at single doses up to 45 mg/kg. Avapritinib blocked hERG channel potential with an IC50 of 2.4 μM; however, this IC50 is 1.5 times the free Cmax in humans at the 300 mg dose.”
✓ VerifiedFDA multi-discipline review, p. 27Source ↗
Genotox: Ames
Negative (bacterial reverse mutation)
“Avapritinib was not mutagenic in a bacterial reverse mutation (Ames) assay.”
✓ VerifiedFDA multi-discipline review, p. 28Source ↗
Genotox: in vitro mammalian
Chromosome aberration in human lymphocytes: positive (clastogenic at >=5 μg/mL, 22-hour)
“Avapritinib was clastogenic in the in vitro chromosome aberration test in human peripheral blood lymphocytes at concentrations ≥ 5 μg/mL (22-hour incubation); these aberrations appeared structural rather than numerical.”
✓ VerifiedFDA multi-discipline review, p. 28Source ↗
Genotox: in vivo
Rat bone marrow micronucleus: negative up to 150 mg/kg
“Avapritinib was, however, not clastogenic in the in vivo rat bone marrow micronucleus test at doses up to 150 mg/kg.”
✓ VerifiedFDA multi-discipline review, p. 28Source ↗
Carcinogenicity model
6-month transgenic mouse study, negative up to 20 mg/kg/day
“Avapritinib was not mutagenic in a 6-month transgenic mouse study up to the highest dose evaluated at 20 mg/kg/day.”
Not needed for an advanced cancer marketing application; none conducted before approval
“The Applicant did not conduct studies investigating the carcinogenic potential of avapritinib as such studies are not needed to support a marketing application for patients with advanced cancer.”
✓ VerifiedFDA multi-discipline review, p. 28Source ↗
hERG / QT
hERG IC50 2.4 μM, 1.5x human free Cmax at 300 mg; no QT prolongation clinically or in vivo
“Avapritinib blocked hERG channel potential with an IC50 of 2.4 μM; however, this IC50 is 1.5 times the free Cmax in humans at the 300 mg dose. Consistent with these findings, avapritinib did not have effects on QT prolongation clinically or in in vivo nonclinical studies.”
✓ VerifiedFDA multi-discipline review, p. 27Source ↗
Not genotoxic overall: Ames negative; in vitro chromosome aberration positive without (not with) metabolic activation; rat micronucleus and comet negative