Negative in Ames, in vitro human lymphocyte micronucleus and in vivo rat bone marrow micronucleus assays
“Belzutifan was not mutagenic in the in vitro bacterial reverse mutation (Ames) test or clastogenic in the in vitro micronucleus assay in human peripheral blood lymphocytes or the in vivo bone marrow erythrocyte micronucleus test in rats.”
✓ VerifiedFDA multi-discipline review, p. 35Source ↗
Carcinogenicity
6-month rasH2 mouse up to 600 mg/kg/day: no neoplastic findings
“presented the results of the 6-month Tg. rasH2 mouse carcinogenicity study with belzutifan at doses up to 600 mg/kg/day. The results indicate no belzutifan-related neoplastic findings at any dose level and no carcinogenic risk were identified in the study.”
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
Pilot rat EFD only: post-implantation loss at ≥60 mg/kg/day
“The Applicant conducted a pilot embryo-fetal development study in rats. Oral administration of belzutifan at doses up to 200 mg/kg/day to pregnant rats during the period of organogenesis caused embryo-fetal lethality (post-implantation loss) at ≥ 60 mg/kg/day”
✓ VerifiedFDA multi-discipline review, p. 35Source ↗
Safety pharmacology
Low-potency hERG blocker (IC50 >50 µM); no QTc effect in dogs up to 30 mg/kg/day for 3 months
“Belzutifan was a low-potency hERG blocker in vitro (IC50 > 50 µM) and did not influence QTc in dogs dosed up to 30 mg/kg/day for 3 months.”
✓ VerifiedFDA multi-discipline review, p. 33Source ↗
Genotox: Ames
Negative
“Belzutifan was not mutagenic in the in vitro bacterial reverse mutation (Ames) test or clastogenic in the in vitro micronucleus assay in human peripheral blood lymphocytes or the in vivo bone marrow erythrocyte micronucleus test in rats.”
✓ VerifiedFDA multi-discipline review, p. 35Source ↗
Genotox: in vitro mammalian
In vitro micronucleus assay in human peripheral blood lymphocytes: negative
“Belzutifan was not mutagenic in the in vitro bacterial reverse mutation (Ames) test or clastogenic in the in vitro micronucleus assay in human peripheral blood lymphocytes or the in vivo bone marrow erythrocyte micronucleus test in rats.”
✓ VerifiedFDA multi-discipline review, p. 35Source ↗
Genotox: in vivo
Rat bone marrow erythrocyte micronucleus test: negative
“Belzutifan was not mutagenic in the in vitro bacterial reverse mutation (Ames) test or clastogenic in the in vitro micronucleus assay in human peripheral blood lymphocytes or the in vivo bone marrow erythrocyte micronucleus test in rats.”
✓ VerifiedFDA multi-discipline review, p. 35Source ↗
Carcinogenicity model
26-week Tg rasH2 mouse and 104-week rat, initiated April 2023 (not conducted for FDA NDA)
“A 26-week carcinogenicity study in rasH2 transgenic mice and a 104-week carcinogenicity study in WH rats have been initiated in April 2023.”
Not genotoxic overall: Ames negative; in vitro chromosome aberration positive without (not with) metabolic activation; rat micronucleus and comet negative