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 . Besponsa still meets the criteria for designation as an orphan medicinal product and that Besponsa should remain in the Community Register of Orphan Medicinal Produc ts. More information on the COMP assessment can be found in the May 2017. Besponsa is an antibody drug conjugate comprised of a monoclonal antibody targeting CD22, a cell surface antigen expressed on around 90 percent of B-cell malignancies, linked to a cytotoxic agent. When the drug binds to CD22 on malignant B-cells it is taken into the cell, where the cytotoxic agent calicheamicin is released to destroy it.. Besponsa also received Orphan Drug designation, which provides incentives to assist and encourage the development of drugs for rare diseases. The FDA granted the approval of Besponsa to Pfizer Inc.. Besponsa ™ (inotuzumab ozogamicin) – New orphan drug approval • On August 17, 2017, the FDA announced the approval of Pfizer’s Besponsa (inotuzumab ozogamicin) for the treatment of adults with relapsed or refractory B-cell precursor acute lymphoblastic leukemia (ALL).. Designated orphan drugs are eligible for a waiver of their application and evaluation fees, but only if designation is received prior to submitting an application to register an orphan drug on the Australian Register of Therapeutic Goods (ARTG)..