Besponsa is given as an infusion into the vein. Common included low blood counts, fatigue, severe bleeding, fever, nausea, headache, abdominal pain, abnormal liver tests, and high levels of bilirubin in the blood. Other serious side effects included increased risk of severe liver damage in patients who receive Besponsa after certain kinds of stem cell transplant, infusion-related reactions, and heart problems. Women who are pregnant or breastfeeding should not take Besponsa because it may cause harm to a developing fetus or a newborn baby.. Besponsa is a kind of targeted therapy called an antibody-drug conjugate, a monoclonal antibody linked to a chemotherapy drug. It’s thought to work by attaching to B-cell ALL cancer cells that express the CD22 protein, blocking the growth of cancer cells. It is intended to target and kill only the cancer cells and spare healthy cells.. Immunotherapy is the use of medicines to help a patient’s own immune system recognize and destroy cancer cells more effectively. Some types of immunotherapy are now being used to treat acute lymphocytic leukemia (ALL) in certain situations..