No information is available on the clinical use of dostarlimab during breastfeeding. Because dostarlimab is a large protein molecule with a molecular weight of about 144,000 Da, the amount in milk is likely to be very low. It is also likely to be partially destroyed in the infant's gastrointestinal tract and absorption by the infant is probably minimal. Because of the potential for serious adverse reactions in the breastfed infant, the manufacturer recommends that women not breastfeed during treatment and for 4 months after the final dose.