CarcinogenicityAccepted with a conditionBeyond the letter
No carcinogenicity studies before approval; 26-week rasH2 mouse and 2-year rat required postmarketing
Why: Lifelong use from infancy and leucine tumour-promotion concern make studies necessary; deferred to PMR
“Carcinogenicity studies with levacetylleucine have not been conducted.”
✓ VerifiedFDA integrated review, p. 131Source ↗ “A 26-week carcinogenicity study in the transgenic rasH2 mouse will be required as a PMR, along with a 2-year rat carcinogenicity study.”
✓ VerifiedFDA integrated review, p. 131Source ↗ Juvenile toxAccepted with a conditionBeyond the letter
No juvenile animal toxicity study despite paediatric use from infancy
Why: Clinical safety and efficacy data adequate to support paediatric approval, but data limited; juvenile study required as PMR · Human data
“A juvenile toxicity study with levacetylleucine has not been conducted.”
✓ VerifiedFDA integrated review, p. 130Source ↗ “While the current clinical safety and efficacy data appear to be adequate to support approval in pediatric patients, the available data are limited; therefore, a juvenile toxicity study will be required as a PMR.”
✓ VerifiedFDA integrated review, p. 130Source ↗ DARTAccepted with a conditionBeyond the letter
No fertility/early embryonic development or pre- and postnatal development studies
Why: Absence stated in labeling; fertility studies required as PMRs to support risk communication
“Information was described in the impairment of fertility subsection of labeling (Table 89; Section 13.1) to indicate that studies of fertility and early embryonic development and pre-and postnatal toxicology were not conducted with the drug.”
✓ VerifiedFDA integrated review, p. 130Source ↗ “Rodent male and female fertility and early embryonic development toxicity studies will be required as PMRs to support risk communication to patients and caregivers.”
✓ VerifiedFDA integrated review, p. 130Source ↗ DARTAccepted with a conditionBeyond the letter
Only dose-range-finding rat and rabbit EFD studies submitted; definitive EFD reports outstanding
Why: Final reports required as PMR; EFD Warning and Precaution with contraception advice in labeling
“However, final study reports for EFD toxicity studies in rats and rabbits have not been submitted.”
✓ VerifiedFDA integrated review, p. 129Source ↗ “Submission of final study reports for EFD toxicity studies in rats and rabbits will be required as a postmarketing requirement (PMR).”
✓ VerifiedFDA integrated review, p. 129Source ↗ GenotoxicityAcceptedBeyond the letter
In vivo micronucleus assay lacked toxicokinetic data, a deviation from OECD 474 and ICH S2
Why: Rats exposed to the maximum ethically acceptable dose (2000 mg/kg/day) in toxicology studies · Pharmacology or kinetics
“Although there is a deviation from OECD guideline 474 and ICH guideline S2 on genotoxicity study due to the absence of specific toxicokinetic in vivo data in the micronucleus assay, it is known that the rats were exposed to the maximum ethically acceptable dose toxicology studies (2000 mg/kg/day).”
✓ VerifiedEMA assessment report, p. 35Source ↗