A drug used to treat B-cell acute lymphoblastic leukemia (ALL) that has not gotten better with other treatment or has recurred (come back). It is also being studied in the treatment of other types of cancer. Inotuzumab ozogamicin contains a monoclonal antibody that binds to a protein called CD22, which is found on some leukemia cells. It also contains a toxic substance, which may help kill cancer cells. Inotuzumab ozogamicin is a type of antibody-drug conjugate. Also called Besponsa.