DARTAcceptedBeyond the letter
No dedicated reproductive and developmental toxicity studies
Why: Reproductive toxicity assumed from cytotoxic and genotoxic properties; decades of clinical use and alkylating-agent experience · Weight of evidence · Human data · Class precedent
“A potential for an influence on reproductive performance and intrauterine development in humans can be assumed based on the cytotoxic and genotoxic properties of treosulfan. Therefore, no dedicated reproductive and developmental toxicity studies for treosulfan according to current regulatory guidance were conducted.”
✓ VerifiedEMA assessment report, p. 33Source ↗ “In view of the fact that treosulfan is mutagenic, cytotoxic, carcinogenic and toxic to reproduction, and in view of its established clinical use for decades as well as the extensive experience with other alkylating agents, further non-clinical studies are not warranted.”
✓ VerifiedEMA assessment report, p. 37Source ↗ GLPAcceptedBeyond the letter
Package largely published literature and brief summaries of 1970s-1980s studies; only recent studies GLP
Why: Known mutagenic, cytotoxic, carcinogenic, reprotoxic profile; decades of clinical use; experience with other alkylating agents · Human data · Class precedent
“Most of the study results are derived from the published literature whilst other studies are presented as brief summaries of studies conducted in the 1970s and 1980s.”
✓ VerifiedEMA assessment report, p. 37Source ↗ “In view of the fact that treosulfan is mutagenic, cytotoxic, carcinogenic and toxic to reproduction, and in view of its established clinical use for decades as well as the extensive experience with other alkylating agents, further non-clinical studies are not warranted.”
✓ VerifiedEMA assessment report, p. 37Source ↗ GenotoxicityAcceptedBeyond the letter
Original submission lacked convincing evidence of DNA alkylation or genotoxicity; new Ames and chromosomal aberration studies required
“During the review of the NDA, it was determined that the nonclinical data for treosulfan submitted to the NDA in studies or literature for which the Applicant has the right to reference did not provide convincing evidence of DNA alkylation and breaks as the mechanism of action (MOA) of treosulfan or to address genotoxicity potential of the drug.”
✓ VerifiedFDA multi-discipline review, p. 111Source ↗ “To address this issue, the Applicant conducted genetic toxicology studies, and submitted the results to demonstrate the genotoxicity of treosulfan.”
✓ VerifiedFDA multi-discipline review, p. 111Source ↗ Safety marginVerdict not stated
No NOAEL in most repeat-dose studies; adverse effects at the lowest dose tested
“In the other repeat-dose studies, adverse effects were observed at the lowest dose tested.”
✓ VerifiedEMA assessment report, p. 31Source ↗