Arsenic Compound Effective in Treating Form of Leukemia
It isn’t often that the results of a phase III cancer clinical trial are so promising that the National Institutes of Health requests that the findings be made available to patients and physicians prior to the study results being published.
Such was the case of the North American Acute Promyelocytic Leukemia Study sponsored by the National Cancer Institute and led by the cooperative group Cancer and Leukemia Group B (CALGB). Principal investigator of the national study was Bayard Powell, M.D., clinical director of the Comprehensive Cancer Center at Wake Forest University Baptist Medical Center.
The results showed that adult patients with previously untreated acute promyelocytic leukemia (APL) who had standard chemotherapy to induce remissions, and then received the chemotherapy drug arsenic trioxide to maintain remission, had a significantly better event-free survival and better overall survival than those who received only standard chemotherapy.
“The positive result in this clinical trial of arsenic trioxide is very exciting,” said Powell. “The willingness of patients with leukemia and their physicians to participate in this important clinical trial has markedly improved the outcome for these and future patients with APL.”
APL, an uncommon subtype of acute myeloid leukemia (AML), accounts for approximately 10 percent of AML cases, or about 1,500 cases per year, in the United States. It is most often diagnosed in young and middle aged adults, but it also occurs in children and older adults. This type of leukemia is often accompanied by life-threatening bleeding at diagnosis that typically worsens, even after initial treatment is begun.
Standard chemotherapy regimens produce complete remission rates of approximately 70 percent and show a five-year survival without recurrence of disease in 35 to 45 percent of patients.
Between June, 1999 and March, 2005, 582 patients enrolled in this study. The percentage of adult patients who remained alive and in remission three years after diagnosis was 77 percent on the treatment arm that included arsenic trioxide compared to 59 percent on the standard treatment arm.
Results of the study were slated to be published later this year but the National Institutes of Health requested the results be announced in January so other patients could benefit from the treatment.
“The positive results of this clinical study underscore the overall benefits and importance of clinical trials,” said Powell. “Patients are benefiting from a treatment regimen that might not have been available to them for years, or possibly ever, if studies like this one didn’t exist.”
Powell was invited to be a plenary speaker at the annual American Society of Clinical Oncologists (ASCO) meeting this June to discuss the study.