Preliminary results of a multicenter randomized study on the treatment of acute promyelocytic leukemias

AIM: To study efficacy of maintenance therapy of patients with acute promyelocytic leukemia (APL) in the APL treatment Russian multicenter trial. MATERIAL AND METHODS: The trial was made with participation of 18 hematological departments of clinics in Russia. A total of 68 APL patients entered the trial. The maintenance therapy consisted of 5-day courses of cytostatic drugs which alternated or did not alternate with 5-day courses of ATRA. Cytogenetic tests were made in 31 patients, t(15;17) was detected in 26 of them. Molecular examination conducted in 28 patients discovered chimeric transcript PML/RARa in 26 of them. Of 20 patients examined in Hematological Research Center, 7 (35%) had a bcr 1/2 variant of the transcript PML/RARa, 13 (65%)--bcr 3 variant. RESULTS: 65 patients were eligible for assessment. A complete remission was achieved in 90% cases. No resistance was observed. In follow-up within 30 months the recurrence rate was similar on both treatments. The results of the induction therapy and survival in patients with different variants of the transcripts were also similar. Overall 2.5 year survival for all the patients was 77%, recurrence-free--80%. The survival analysis in patients with leukocytosis higher and lower 10 x 10(9)/l found no statistical differences by the survival. Patients with hyperleukocytosis had higher early lethality than patients with leukocytes under 10 x 10(9)/l (25% vs 5.3%, p = 0.03). CONCLUSION: The APL 06.01 protocol showed high efficacy of the relevant maintenance which provides a complete molecular remission in the majority of patients with probable recurrence-free 2.5 year survival 80%.