Immunotherapy for leukemia
Leukemia was traditionally treated by aggressive chemotherapy causing severe side effects and an overall bad outcome for most patients. Chemotherapy is still the main therapy in most acute leukemias with stem cell transplantation a viable option especially in young patients. The role of immunotherapy in leukemia is stimulating the immune system to attack and destroy abnormal white blood cells circulating in the blood, and in this sense, stem cell transplantation is considered an immunotherapy. When bone marrow is transplanted, it produces new, healthy white blood cells that can target cancer cells and destroy them. There are four main types of leukemia which are: acute lymphoblastic, acute myeloid, chronic lymphocytic and chronic myelocytic leukemias.
Several other monoclonal antibodies and antibody-drug complexes are now employed in cases of leukemia. They target specific CD markers on the surface of cancer cells like CD20, CD53, CD33 and CD22. These markers are identified by doing a bone marrow biopsy then running histochemical investigations on the specimen to make sure that those markers are present before initiating therapy.
Common monoclonal antibodies in use include:
- Rituximab (Rituxan): A monoclonal antibody that targets CD20.
- Ofatumumab (Arzerra): A monoclonal antibody that targets CD20 and is mainly used in Chronic lymphocytic leukemia. Chronic lymphocytic leukemia is considered resistant to chemotherapy making Ofatumumab its first-line drug.
- Inotuzumab (Besponsa): An antibody-drug complex targeting CD22 and used in patients with acute lymphoblastic leukemia.
- Alemtuzumab (Campath): Which is a monoclonal antibody that targets CD53 in chronic lymphocytic leukemia.
- Gemtuzumab (MyloTarg): An antibody-drug complex in use in cases of CD33 acute lymphoblastic leukemia, especially in children.
Interferons are one of the most critical chemical mediators secreted by our bodies in inflammation, viral infections, and cancer. They are used as medications in many conditions including viral infections such as hepatitis. In leukemia, they were used especially in CD20 positive chronic myeloid leukemia. Its use has, however, greatly decreased following the introduction of Imatinib, which is a potent anti-leukemia drug that targets the main genetic abnormality in chronic myeloid leukemia (The Philadelphia chromosome).