Jan. 30, 1997
Contact:
Julie Penne, (713) 792-0662
Michael Courtney, (713) 792-003
M. D. Anderson Team Opens New Era in Pediatric Leukemia Research
Researchers at The University of Texas M. D. Anderson Cancer Center have shined a bold new light on the future treatment of childhood leukemia.
Results of a study published in the Jan. 30 issue of the New England Journal of Medicine not only refute a 30-year-old dogma universally held by the medical community, but also open new doors to a better understanding of acute lymphoblastic leukemia (ALL), the most common form of childhood cancer.
Using two sensitive assays, M. D. Anderson researchers found that up to thousands of leukemia cells may remain in a patient long after successful treatment.
The first step in the quantitation assay was to amplify to measurable levels, a leukemia-specific DNA sequence in cells from bone marrow samples. This amplification is a molecular technique previously developed in California. The adaptation of this technique by M. D. Anderson specifically for this study allowed for the determination of the number of leukemia cells in bone marrow samples. It can detect one leukemia cell in up to 200,000 normal cells; a microscope can detect only one leukemia cell in 20 normal cells. The second assay was developed by Dr. Zeev Estrov prior to his coming to M. D. Anderson, and was used by him to grow leukemia cells in laboratory dishes.
The study was led by Dr. Theodore Zipf, chief of pediatric leukemia and lymphoma, and Dr. Mark Roberts. Their collaborators include Dr. Estrov, Dr. Dennis A. Johnston, Maia V. Ouspenskaia, Viktor Papusha and Dr. Kenneth L. McClain.
"These findings have brought pediatric leukemia research into a whole new light," said Dr. Zipf. "We now know that it is not necessary to kill every leukemia cell with chemotherapy to have a successful outcome. We previously believed that the leukemia had to be completely eradicated to achieve cure, but we now see that this is not necessary. With the capability to obtain new information such as this, we can now learn more about how chemotherapy cures leukemia."
In the five-year study of 24 patients, M. D. Anderson researchers found traces of leukemia remaining even in those patients who were considered cured or in remission. Of the patients studied, seven patients relapsed and 17 remained in remission after completion of therapy. Of the 17 who remained in long-term remission, 15 patients showed signs of residual leukemia.
According to Dr. Zipf, the findings will begin a new generation of research into predicting relapse, determining how chemotherapy works and how it changes cells, and determining what role the immune system has in fighting the disease.
Drs. Zipf and Roberts hope that the research will ultimately lead to a test that can predict relapse of ALL. Should such a test be developed, new therapies could be developed or treatments altered to respond more effectively -- and earlier -- to possible relapse.
"Though we are far from developing a test, we could improve our cure rate if we could test for relapse, then treat accordingly. By predicting relapse, we could tailor risk-directed therapies to patients who face relapse or possibly look for a milder form of therapy for those who are not going to relapse," said Dr. Roberts.
Such developments in future decades could help improve the present 75 percent cure rate for ALL, particularly among those patients who relapse. Though three of four children with ALL are cured, more than 500 children in the United States die annually from ALL.
Of the 25 percent who do not survive, most die as a result of their disease recurring. Currently, 10 to 20 percent of children who relapse survive.
While cancer kills more children than any other disease in the United States, the future for young patients looks encouraging. The cure rate for all pediatric cancers is approximately 70 percent and improving. With the improving cure rate, patient-focused care has sought to minimize learning disabilities and other long-term treatment effects.
For information about M. D. Anderson's pediatric or adult patient services, individuals may call The M. D. Anderson Information Line at 1-800-392-1611 (Option 3) during regular business hours Monday through Friday. - 30 -
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