Long-term results of reinforcement therapy in children with acute leukemia.

A total of 180 children with acute leukemia was randomized to one of two induction regimens: vincristine plus prednisone, or 6-mercaptopurine plus prednisone. Of 170 patients evaluable for induction therapy, a hematologic remission was achieved in 83% (72/87) on vincristine plus prednisone, and in 93% (77/83) on 6-mercaptopurine plus prednisone. When hematologic remission was achieved, patients were randomized to one of three maintenance schedules: 6-mercaptopurine alone, 6-mercaptopurine plus prednisone for 4 weeks every 3 months, or 6-mercaptopurine plus prednisone plus vincristine for 4 weeks every 3 months. The durations of hematologic remission were compared from the achievement of hematologic remission to bone marrow relapse. The survival data were presented as an overview of the effect of this initial therapy on duration of survival. There was no statistical difference between the two induction regimens. The most important finding in the comparison of the three maintenance schedules was that reinforcement of 6-mercaptopurine maintenance therapy with either prednisone or prednisone plus vincristine resulted in significantly longer durations of remission. Vincristine added to prednisone for reinforcement after induction of remission by vincristine plus prednisone did not increase the duration of hematologic remission or survival over prednisone reinforcement alone.