“With advances in science we’re discovering new mutations all the time, and many of them are targetable.”
Treatments for blood cancer, including leukemia, are continuously improving and changing, resulting in better outcomes and allowing people to live long, good-quality lives. In fact, since 1960, the five-year survival rate for leukemia has quadrupled, according to the Leukemia and Lymphoma Society—jumping from 14 percent to an overall rate of 64 percent between 2007 and 2013.
Treatment for leukemia varies greatly—it depends on the type of blood cancer you have, your disease subtype and phase, your health and age (treating leukemia in children is often different from treating leukemia in adults), and many other factors.
One of the newer leukemia treatments available is called targeted therapy.
What Is Targeted Therapy?
Targeted therapies are drugs that specifically target changes inside cells that cause them to become cancer. “With advances in science we’re discovering new mutations all the time, and many of them are targetable,” says hematologist and oncologist Michal Bar-Natan Zommer, MD.
Unlike chemotherapy, these drugs attack one or more specific targets on or in the leukemia cells. Targeted therapies tend to spare healthy cells, so they often have different side effects than chemotherapy.
Targeted therapies can sometimes work when chemotherapy doesn’t, or be used along with chemotherapy to enhance the effectiveness of treatment.
Targeted therapies can be useful for treating certain cases of leukemia, including:
- Acute myeloid leukemia (AML)
- Chronic myeloid leukemia (CML)
- Acute lymphocytic leukemia (ALL)
- Chronic lymphocytic leukemia (CLL)
- And small lymphocytic lymphoma (SLL)
How Targeted Therapies Treat Certain Types of Leukemia
Treating leukemia with targeted therapy depends on the genetic makeup of the leukemia cells. Targeted therapies “target” certain genetic mutations within the cancer cell that help it grow.
Acute myeloid leukemia
Acute myeloid leukemia (AML) is a type of leukemia that starts in the bone marrow and often spreads into the blood. It often develops in cells that become white blood cells.
People with AML may have a mutation in the FLT3 gene, or the IDH1 or IDH2 gene. Targeted therapies to treat AML include FLT3 inhibitors, which target the FLT3 gene, and IDH inhibitors, which either target the IDH1 gene or IDH2 gene.
In about 90 percent of AML cases, patients may also have a protein called CD33, which serves as a “target” for targeted therapies. Scientists created a targeted therapy that uses a monoclonal antibody (a man-made immune protein) to attach to CD33 proteins, and acts as a signal, bringing the chemo drug to the leukemia cells.
Chronic myeloid leukemia
Chronic myeloid leukemia (CML) is a type of leukemia that occurs when a genetic change happens to immature myeloid cells, forming an abnormal BCR-ABL gene. This gene makes a protein, BCR-ABL, known as a tyrosine kinase, which causes CML grow and reproduce rapidly. Tyrosine kinase inhibitors are drugs that target BCR-ABL.
Acute lymphoblastic lymphoma
Acute lymphoblastic lymphoma (ALL) is a type of leukemia that starts in early forms of lymphocytes in the bone marrow. Because it’s acute, it can progress quickly and spread rapidly if not treated.
According to the American Cancer Society, in about 1 out of 4 adult patients with ALL, the leukemia cells have the Philadelphia chromosome. The Philadelphia chromosome is an abnormal chromosome formed by the swapping of genetic material between chromosomes 9 and 22, which forms the gene BCR-ABL.
Because some patients with ALL have an abnormal BCR-ABL gene, tyrosine kinase inhibitors can be used to treat this type of leukemia as well.
Chronic lymphocytic leukemia and small lymphocytic lymphoma
Chronic lymphocytic leukemia (CLL) is the most common type of leukemia in adults. This cancer begins in the lymphocytes, but since it’s chronic it tends to build up more slowly than ALL (although some patients have CLL that grows faster).
Small lymphocytic lymphoma (SLL) and CLL are the same disease, but with SLL, the cancer cells are primarily in the lymph nodes.
Targeted therapies have changed the way CLL and SLL are treated, because these drugs can often control the cancer so people don’t need to start chemo right away.
People with CLL or SLL may have mutations that create Bruton’s tyrosine kinase (BTK), PI3K, and BCL-2 proteins. Bruton’s tyrosine kinase and PI3K are both kinases, which are proteins in cancer cells that help the cells grow. Kinase inhibitors are targeted therapies that block these proteins.
When learning about and choosing the right leukemia treatment, it’s important to remember that today’s scientific research is continuously evolving. Treatment options may change as new treatments are discovered and current treatments are improved. That’s why it’s critical that patients check with their physician about any new treatment options so they can be sure they’re getting the best treatment available.
Acute myeloid leukemia: Treatment and outcomes in older adults. UpToDate. (Accessed on November 19, 2018 at https://www.uptodate.com/contents/acute-myeloid-leukemia-treatment-and-outcomes-in-older-adults)
Overview of the treatment of chronic myeloid leukemia. UpToDate. (Accessed on November 19, 2018 at https://www.uptodate.com/contents/overview-of-the-treatment-of-chronic-myeloid-leukemia)
Overview of the treatment of chronic lymphocytic leukemia. UpToDate. (Accessed on November 19, 2018 at https://www.uptodate.com/contents/overview-of-the-treatment-of-chronic-lymphocytic-leukemia)
Targeted Therapy for Acute Lymphocytic Leukemia (ALL). American Cancer Society. (Accessed on November 19, 2018 at https://www.cancer.org/cancer/acute-lymphocytic-leukemia/treating/targeted-therapy.html)
Targeted Therapies for Chronic Myeloid Leukemia. American Cancer Society. (Accessed on November 19, 2018 at https://www.cancer.org/cancer/chronic-myeloid-leukemia/treating/targeted-therapies.html)
Targeted Therapies for Chronic Lymphocytic Leukemia. American Cancer Society. (Accessed on November 19, 2018 at https://www.cancer.org/cancer/chronic-lymphocytic-leukemia/treating/targeted-therapy.html)