The FDA has approved Arzerra for the treatment of patients with chronic lymphocytic leukemia (CLL) that is refractory to fludarabine and alemtuzumab. Arzerra is a monoclonal antibody that causes the body’s immune response to fight against normal and cancerous B-cells. Arzerra attaches to the small and large loop epitopes on a molecule called CD20, which is found on the surface of B-cells, the type of cell which becomes cancerous in CLL.