CarcinogenicityAccepted with a conditionBeyond the letter
Mouse and rat carcinogenicity studies not conducted before approval; deferred to postmarketing requirements as agreed with the Division
Why: Severity of the indication · Serious disease
“Carcinogenicity studies in two species (26-week study in TgRasH2 mouse and 2-year study in rat) are to be conducted as post-marketing requirements (PMR), as agreed to by the Division (IND 44020 Type C Meeting Minutes, January 11, 2018)”
✓ VerifiedFDA pharmacology/toxicology review, p. 2Source ↗ “I agree with Dr. Fisher that the nonclinical studies of ganaxolone are adequate to support approval of the NDA from a nonclinical standpoint, considering the severity of the indication, with appropriate labeling and the following post-marketing requirements:”
✓ VerifiedFDA pharmacology/toxicology review, p. 5Source ↗ Impurity or metaboliteAccepted with a conditionBeyond the letter
Major human metabolite M47 not characterized in animal plasma; metabolite safety evaluation deferred to postmarketing studies
Why: Metabolite M2 carcinogenicity and juvenile studies and M47 brain distribution study required postmarketing
“There is currently no information on plasma levels of M47 in animal species. Although M47 is a sulfate conjugate, there are concerns that it may have pharmacological activity, depending on the extent of its distribution into the CNS (Hartneck C. Molecules 18:12012-12028, 2013). The nonclinical safety of these metabolites is to be addressed in studies conducted as PMRs.”
✓ VerifiedFDA pharmacology/toxicology review, p. 3Source ↗ “a 6-month carcinogenicity study of ganaxolone in TgRasH2 mouse, a 2-year carcinogenicity study of ganaxolone in rat, a carcinogenicity study of metabolite M2 in rat, a juvenile animal toxicology study of metabolite M2 in rat, and a study to evaluate the distribution of metabolite M47 into brain in rat.”
✓ VerifiedFDA pharmacology/toxicology review, p. 5Source ↗ DARTVerdict not stated
No rabbit embryo-fetal study because sufficiently high plasma exposures could not be achieved
Why: Sufficiently high plasma exposures could not be achieved in rabbit · Pharmacology or kinetics
“(An EFD study was not conducted in rabbit because sufficiently high plasma exposures could not be achieved.)”
✓ VerifiedFDA pharmacology/toxicology review, p. 3Source ↗ Safety marginVerdict not stated
No toxicokinetics in the rat embryo-fetal/pre- and postnatal study; dam exposures likely below human exposure at all doses
“Although TK data are not available for these studies, data from separate studies in SD rat suggest that plasma exposures in dams were lower at all doses tested than those in humans at the maximum recommended human dose of 1800 mg/day.”
✓ VerifiedFDA pharmacology/toxicology review, p. 4Source ↗