Does Lurbinectedin Cross the Placenta?
Lurbinectedin, sold as Zepzelca, is a chemotherapy agent that crosses the placenta in animal studies. In pregnant rats and rabbits, radiolabeled lurbinectedin reached fetal tissues after intravenous administration, with fetal exposure levels similar to maternal plasma concentrations.[1][2] Human data is limited, but its low molecular weight (around 700 Da) and moderate lipophilicity suggest it likely crosses the human placenta via passive diffusion, as seen with many small-molecule chemotherapies.[3]
Fetal Risks from Placental Transfer
Exposure in animal models caused embryo-fetal toxicity, including post-implantation loss, decreased fetal weight, skeletal abnormalities, and reduced ossification at doses below human equivalents (about 0.4 times the clinical dose in rats; 0.1 times in rabbits). These effects indicate high teratogenic potential, with risks of miscarriage, birth defects, and growth restriction.[1][2] No human pregnancy studies exist, but category D classification (positive evidence of human fetal risk) applies based on mechanism and animal data.[4]
Recommendations for Pregnant Patients
Lurbinectedin is contraindicated in pregnancy. Women of childbearing potential must use effective contraception during treatment and for 6 months after the last dose; males must use contraception for 4 months post-treatment. Verify pregnancy status before starting therapy. If exposure occurs, discuss risks with an obstetrician and consider pregnancy termination counseling.[1][2]
Comparison to Similar Chemotherapy Drugs
Like other alkylating-like agents (e.g., cyclophosphamide), lurbinectedin targets DNA and causes fetal harm via placental transfer. Cisplatin and doxorubicin also cross the placenta, leading to similar outcomes: 10-20% malformation rates in first-trimester exposures across chemotherapies. Second/third-trimester risks focus more on intrauterine growth restriction and preterm birth.[3][5]
What If Exposed Unintentionally?
Report inadvertent exposure to the Zepzelca Pregnancy Exposure Registry (1-888-661-7284). Fetal ultrasound and amniocentesis may assess development, but no antidote exists. Outcomes depend on gestational age: highest risks in the first trimester.[2][4]
Sources
[1] Zepzelca (lurbinectedin) FDA Label
[2] Zepzelca EMA Product Information
[3] Placental Transfer of Anticancer Drugs (Rev Obstet Gynecol, 2018)
[4] Drugs.com Pregnancy Categories
[5] Chemotherapy in Pregnancy (Lancet Oncol, 2015)