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 (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). Development History and FDA Approval Process for Besponsa. The FDA approval of BESPONSA was based on results from the clinical trial that showed BESPONSA improved the rate of CR, the median length of CR, and the rate of MRD-negative CR versus chemotherapy. What were the results with BESPONSA compared to chemotherapy?.