Using the Body's Immune System to Defeat B-Cell Leukemia in Children
What Is B-Cell Leukemia?
Acute lymphocytic leukemia (ALL) is the most frequently occurring cancer in children, and it arises because of a problem with the bone marrow. The white blood cells of the immune system are made by the bone marrow, and the first step in the process involves production of bone marrow stem cells. These cells then follow two pathways, one of which is differentiation into lymphoid stem cells. The lymphoid cells produce B-lymphocytes, also called B-cells, and T-lymphocytes or T-cells both of which are white blood cells that serve to protect your body from invading microorganisms.
In a child with acute lymphocytic leukemia, abnormal (cancerous) B-cells or T-cells proliferate wildly. As their numbers increase, they begin to crowd out the healthy white blood cells in addition to the red blood cells and platelets. Since the abnormal B-cells or T-cells are unable to protect against infection, the child easily gets sick. Lack of sufficient platelets and red blood cells means that the child may suffer from anemia and may bleed or bruise easily. An acute lymphocytic leukemia that involves proliferation of abnormal B-cells is referred to as B-cell leukemia.
Immunotherapy: Mobilizing the Immune System Against Cancer
For quite some time now, scientists have tried to discover ways to program the immune system to recognize cancer cells as foreign invaders and then attack and destroy them. In the beginning, the efforts of even the best medical researchers met with failure. Over the last 15 years, however, immunotherapy drugs such as monoclonal antibodies have been approved by the FDA for cancers that include colon cancer, chronic lymphocytic leukemia, breast cancer, lung cancer and a few others. One way that monoclonal antibodies work is by attaching to proteins on the surface of cancer cells thereby allowing cells of the immune system to recognize the cancer cells as invaders.
A Novel Immunotherapy Approach to B-Cell Leukemia
In the April 18, 2013 issue of "The New England Journal of Medicine," scientists from The Children''s Hospital of Philadelphia and the University of Pennsylvania will describe how they broke new ground in the field of immunotheapy by genetically programming T-cells to attack and destroy cancerous B-cells in two young girls with acute lympocytic leukemia. Instead of modifying the cancer cell as is the case with monoclonal antibodies, this new approach modifies the T-cell.
During the spring of 2012, a girl 10 years old and another aged 7, both ALL patients at The Children's Hospital of Philadelphia, participated in a clinical trial of a new approach to treating B-cell leukemia. As a result of the treatment, both girls experienced complete remission of the cancer. The younger girl had previously been treated with standard chemotherapy, but this treatment failed to rid her of the cancer.
The treatment begins when researchers take blood from the patient and remove the T-cells. Then, the T-cells are genetically engineered so that they express a protein that binds to the CD19 protein on the surface of the cancerous B-cells. Thus, the patient's T-cells are now programmed to seek out and destroy cancerous B-cells. The altered T-cells are then injected back into the patient's body where they proliferate rapidly and travel through the bloodstream in a concerted attack on the cancerous B-cells.
Three weeks after the treatment, the 7-year-old girl was in complete remission. Six months later, a check on her bone marrow revealed no cancerous cells, and there were still modified T-cells circulating in her blood. The 10-year-old girl also went into remission directly after the treatment, but two months later the researchers found the cancerous B-cells had returned. These cancer cells did not have the CD19 protein on their surface, and so the modified T-cells did not kill them. The scientists concluded that for some patients it may be necessary to modify the T-cells to seek out molecules other than the CD19 protein on the surface of the cancerous B-cells.
This hub was written for the sole purpose of providing information to the reader. It is not intended to be a source of any kind of medical advice or instruction, and it should not be used in the diagnosis of any illness, disease or condition. You should consult your doctor if you have questions about a specific medical problem.