Researchers are conducting clinical trials in many parts of the country. Clinical trials test an intervention such as a drug, therapy, medical device, or behavior in many people to see if it is safe and effective. Clinical trials already have led to advances, and researchers continue to search for more effective ways to treat and diagnose leukemia. They are studying various drugs, immunotherapy, stem cell transplantation, and other types of treatments. They are also studying the effectiveness of using combinations of treatments.
Most importantly, researchers are gaining a greater understanding of the genes that are mutated in many types of leukemia and are developing targeted treatments to directly attack the mutations. One prime example is in acute myeloid leukemia (AML) where researchers have identified several genes that predict better or worse outcomes and are working to develop drugs targeted at these genes.
The drug imatinib (Gleevec®) is important in the treatment of chronic myeloid leukemia. Imatinib targets an abnormal protein that is present in most leukemia cells. By blocking the abnormal protein, imatinib kills the leukemia cells, but it does not kill normal cells. However, imatinib stops working in some people with leukemia because the cells become resistant.
Fortunately, two drugs, dasatinib (Sprycel®) and nilotinib (Tasigna®), are now used to treat people who stop responding to imatinib. These drugs work against the same abnormal protein targeted by imatinib, but in different ways.
Immunotherapy is a treatment that uses immune cells or antibodies to fight leukemia or stop it from getting worse. The idea is to zero in on leukemia cells so the treatment is less toxic to normal cells.
Leukemia vaccines are not vaccines in the way that most people think of them. Unlike most vaccines, which help prevent diseases, leukemia vaccines are used to treat someone who already has cancer.
A vaccine introduces a molecule called an antigen into the body. The immune system recognizes the antigen as a foreign invader and attacks it. Researchers are studying a vaccine in which the antigen is the same abnormal protein that imatinib targets. The vaccine causes immune cells to destroy leukemia cells that contain this protein.
Gene therapy -- replacing, manipulating, or supplementing nonfunctional genes with healthy genes -- is being explored for treatment of leukemia. It is being studied as a way to stimulate a patient's immune system to kill leukemia cells and also to interfere with the production of proteins that cause cells to become cancerous.
Stem Cell Transplantation
Researchers also are investigating ways to improve current stem cell transplant techniques, such as more precise matching of donors to patients and better ways to prepare the patient's immune system to accept the transplanted cells.
A modified form of stem cell transplant, called a mini-transplant, has been developed. Compared with standard stem cell transplants, this technique requires less intensive radiation and chemotherapy before a patient is given donor cells. This approach has made stem cell transplants a treatment option for older adults and others who may not be able to tolerate high doses of radiation or chemotherapy.
Because leukemia is a complicated disease, using more than one type of treatment may be beneficial. Combining therapies can complement and enhance the effects of each. For example, patients receiving a stem cell transplant also undergo chemotherapy or radiation to prepare their body for the new stem cells.
A clinical trial at the National Cancer Institute is taking this combination treatment one step further. The researchers are looking at giving drugs to patients before and after the transplant so that the patient's immune system will stop attacking the transplanted cells.