Evidence from Animal Studies
Lurbinectedin, an alkylating agent used in cancer treatment, shows clear embryo-fetal toxicity in preclinical research. In rats and rabbits, intravenous doses at or below human equivalents (about 0.4 times the recommended human dose) caused embryo-fetal death, reduced fetal weight, and skeletal abnormalities like delayed ossification and malformations (e.g., fused ribs, misshapen vertebrae). These effects occurred during organogenesis, with no live fetuses at higher doses in rabbits.[1][2]
Human Pregnancy Data
No adequate studies exist in pregnant women, but lurbinectedin is classified as Pregnancy Category D by some regulators—positive evidence of human fetal risk from animal data, though controlled trials are absent. Case reports are limited, but alkylating agents like it increase risks of miscarriage, birth defects, and fetal growth restriction. It's advised to avoid during pregnancy, with recommendations for contraception use in patients and partners.[1][2]
Mechanism of Impact
Lurbinectedin traps DNA-topoisomerase I complexes, blocking replication and transcription—highly disruptive to rapidly dividing fetal cells. This leads to cytotoxicity in developing embryos, mirroring effects of similar chemotherapies (e.g., trabectedin, from which it's derived).[3]
Clinical Recommendations and Risks
Labeling warns of fetal harm, mandating pregnancy testing before starting and effective contraception for at least 6 months post-treatment (men) or until resolution (women). Lactation is contraindicated due to potential secretion. Discontinue if pregnancy occurs.[1][2] No data on long-term offspring effects post-exposure.
Sources
[1] FDA Label for Zepzelca (lurbinectedin), 2020
[2] EMA Product Information for Zepzelca, 2020
[3] Trigo et al., Lancet Oncology (lurbinectedin mechanism review), 2020