Drug therapy using monoclonal antibodies can be an effective treatment. A monoclonal antibody is an immune protein made in a laboratory. It’s designed to target a specific molecule on the surface of Chronic lymphocytic leukemia (CLL) cells. The monoclonal antibody aims for the molecule and attaches itself to the cell, causing the cell to die. Monoclonal antibody therapies can cause side effects, but they’re generally milder than chemotherapy’s side effects. Because they’re designed to target and attack specific substances, they tend to leave normal cells unharmed.