Recombinant immunoglobulin G4 monoclonal antibody which is indicated in certain cases of melanoma. At latest update no published data on excretion into breast milk were found. Its high molecular weight and protein nature make it theoretically impossible any excretion into breastmilk as well as the intestinal absorption by the infant gut: its low oral bioavailability hinders the pass to infant plasma from ingested breastmilk, except in premature and early newborn period, in which there may be an increased intestinal permeability. Although it would be possibly safe during breastfeeding, a long elimination half-life (26,7días) and the likelihood of side effects make prudent to avoid breastfeeding until more published data on this drug is available.The period to “washout" (time-period it takes for the drug to be completely eliminated from the body) that should be expected to resume breastfeeding would be about 134 days (5 half-lives) since the last dose.