Is Loncastuximab Tesirine safe while breastfeeding?
Here is what LactMed, the Drugs and Lactation Database published by the U.S. National Institute of Child Health and Human Development (NICHD), reports about Loncastuximab Tesirine. The text below is quoted from that source — it is not our own verdict.
Summary of use during breastfeeding
No information is available on the clinical use of loncastuximab tesirine during breastfeeding. Because loncastuximab is a large protein molecule with a molecular weight of about 151,000 Da, the amount in milk is likely to be very low.[1] It is also likely to be partially destroyed in the infant's gastrointestinal tract and absorption by the infant is probably minimal.[2] However, loncastuximab is conjugated with SG3249, a small-molecule alkylating agent that might enter milk and be absorbed by the infant. Because of the potential for serious adverse reactions in the breastfed infant, the manufacturer recommends that women not breastfeed during treatment and for 3 months after the final dose.
Effects on the breastfed infant
Relevant published information was not found as of the revision date.
Effects on milk supply
Relevant published information was not found as of the revision date.
Levels in milk
Maternal Levels. Relevant published information was not found as of the revision date.
Infant Levels. Relevant published information was not found as of the revision date.
“No published information” means the studies do not exist yet — not that Loncastuximab Tesirine is known to be harmful, and not that it is known to be safe. Your prescriber or pharmacist can weigh your baby's age and whether a better-studied alternative would do the same job. Worth asking before stopping a medicine you need.
Source: Drugs and Lactation Database (LactMed), National Institute of Child Health and Human Development (NICHD), via NCBI Bookshelf, record “Loncastuximab Tesirine” (loncastuximab_tes). LactMed on NCBI Bookshelf. LactMed is a registered trademark of the U.S. Department of Health and Human Services.
Educational summary of an authoritative source — not medical advice. Never start, stop, or change a medicine while breastfeeding without confirming with your doctor.