No information is available on the clinical use of atezolizumab during breastfeeding. Because atezolizumab is a large protein molecule with a molecular weight of 145,000 Da, the amount in milk is likely to be very low and absorption is unlikely because it is probably destroyed in the infant's gastrointestinal tract. Waiting for at least 2 weeks postpartum to resume therapy may minimize transfer to the infant.[1] Until more data become available, atezolizumab should be used with caution or avoided during breastfeeding, especially while nursing a newborn or preterm infant. The manufacturer recommends that breastfeeding be discontinued during atezolizumab therapy and for at least 5 months after the last dose.