Drugs.com provides accurate and independent information on more than 24,000 prescription drugs, over-the-counter medicines and natural products. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment. Data sources include IBM Watson Micromedex (updated 1 May 2019), Cerner Multum™ (updated 2 May 2019), Wolters Kluwer™ (updated 1 May 2019) and others.. Besponsa Approval History. Company: Pfizer Inc. Besponsa (inotuzumab ozogamicin) is a CD22 monoclonal antibody and calicheamicin cytotoxic agent conjugate for the treatment of adults with relapsed or refractory B-cell precursor acute lymphoblastic leukemia (ALL).. BESPONSA is a type of medicine called an antibody-drug conjugate. BESPONSA is designed to find and attach to a specific protein, called CD22, found on leukemia cells BESPONSA is designed to find and attach to a specific protein, called CD22, found on leukemia cells.