The FDA had previously granted Besponsa Priority Review, Breakthrough therapy, and Orphan Drug designation. The U.S. labeling includes a boxed warning on the potential for hepatoxicity, which includes blockage of veins in the liver, known as veno-occlusive disease. If hepatoxicity is observed in patients taking Besponsa, then the treatment should either be stopped or the dose should be lowered. Another boxed warning indicates that there is an increased risk of death in patients taking Besponsa if they receive post–hematopoietic stem cell transplant.. Read about the FDA's approval of Pfizer's Besponsa for treatment of adults with relapsed or refractory B-cell precursor ALL.. The U.S. Food and Drug Administration (FDA) today approved Besponsa (inotuzumab ozogamicin) in the treatment of adults with relapsed or refractory B-cell precursor acute lymphoblastic leukemia .