Acute lymphoblastic leukemia (ALL) has cure rates of 80 to 90 percent for children, but adults usually suffer relapses within three to seven years. The difference is attributed to multiple factors, including less tolerance for chemotherapy as well as more incidence of aggressive subtypes of ALL in adults. However, recent studies offer more hope for effective treatment in adults. Predicted survival at 10 years has been increased for all age groups, as follows:
1. Age 15 – 19: From 30-60 percent
2. Age 20 – 29: From 25-40 percent
3. Age 30 – 44: From 10-30 percent
4. Age 45 – 59: From 10-20 percent
While these rates are still disappointing, the trend of increasing survival time is very positive. One change is the use of more intense chemotherapy regimens, to more closely match the successful treatment for children. Initial results indicate this is a promising approach.
Immunotherapy treatments for leukemia offer other options. As background data, Reference 2 offers an interesting historical perspective. As far back as the 1700's, doctors noted that some cancer patients who acquired bacterial infections and then recovered also experienced regression of their tumors. The first application of immunotherapy in cancer is credited to William Coley in 1891. He successfully treated adult cancers with “Coley's toxins” derived from streptococcus erysipelatis and bacillus prodigious.
Patients with organ transplants also provide data for the role of the immune system in cancer. Transplant patients are reported to have a seven-fold increased incidence of cancer in general. The blood cancers leukemia and lymphoma have the highest increased risk of 26-fold.
Immunotherapies include monoclonal antibodies, cancer vaccines, and natural killer cell therapies. The monoclonal antibody approach is the most developed, with two approved for leukemia:
1. Rituximab (Rituxan), http://www.rituxan.com/
2. Alemtuzumab (Campath), http://www.campath.com/
Two other monoclonal antibodies used for blood cancer are Ibritumomab tiuxetan (Zevalin), http://www.zevalin.com/, and Tositumomab (Bexxar), http://www.drugs.com/bexxar.html.
A fifth drug in this class, Gemtuzumab ozogamicin, is restricted because of a safety alert. See http://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm216458.htm.
Bone marrow transplantation is sometimes considered a form of immunotherapy as well. Advances in technique have improved the success rate.
Reference 1 reports that as success rates improve for both drugs and bone marrow transplants, doctors face more uncertainty about the optimum treatment for adults with ALL. The authors suggest that we need more patients in clinical trials. See http://clinicaltrials.gov/.
References:
1. Litzow MR, “Evolving paradigms in the therapy of Philadelphia chromosome-negative acute lymphoblastic leukemia in adults”, Hematology Am Soc Hematol Educat Program. 2009: 362-9.
2. Leung W, “Immunotherapy in acute leukemia”, Semin Hematol. 2009 Jan; 46(1): 89-99.
Linda Fugate is a scientist and writer in Austin, Texas. She has a Ph.D. in Physics and an M.S. in Macromolecular Science and Engineering. Her background includes academic and industrial research in materials science. She currently writes song lyrics and health articles.