Background: It was assessed whether addition of vincristine (VCR) to remission induction therapy would increase the complete remission (CR) rate, and, secondarily, whether 12 courses of maintenance-intensification therapy would produce longer survival than 4 courses in adult acute myeloid leukemia (AML).
Methods: A randomized comparison of individualized induction therapy was conducted between daunorubicin, behenoyl cytarabine, 6-mercaptopurine, and prednisolone with or without VCR. After 3 courses of intensive consolidation therapy, maintenance-intensification therapy was randomized to 4 or 12 courses given every 6 weeks.
Results: Of 265 patients registered, 252 were evaluable. CR was obtained in 78%; 80% in 205 patients of age younger than 60 years, and 65% in 47 of age 60 years or older. Addition of VCR reduced the CR rate significantly (84% to 70%, P = 0.007). Predicted 4-year survival, continuing CR, and disease-free survival (DFS) rates of 196 CR patients are 45%, 41%, and 35%, respectively. Patients receiving 12 courses of maintenance-intensification showed better DFS. By multivariate analyses, significant factors for achievement of CR were performance status 0 to 2, age younger than 60 years, and no VCR; and those for longer DFS were achievement of CR by one course, age younger than 50 years, and French-American-British (FAB) classification M3 or M5. Among 131 patients randomized to the maintenance, the administration of 12 courses was the most important factor (P = 0.0040) for longer DFS, followed by FAB M3 or M5, and by achievement of CR by one course.
Conclusions: Addition of VCR in remission induction therapy was harmful, and longer intensive maintenance therapy prolonged DFS in adult AML.