Objective: To investigate all-trans retinoic acid (ATRA) and As2O3 which were found to be able to selectively induce differentiation and apoptosis in acute promyelocytic leukemia (APL) and recently became standard treatment for de novo or relapsed APL. The results of long-term follow up in 72 APL patients were presented and prognostic factors discussed.
Methods: Seventy-two newly-diagnosed patients with APL entering CR with ATRA were consolidated with chemotherapy alone (31 patients), ATRA + chemotherapy (30 patients) and ATRA alone (11 patients). Univariate analysis was done to identify the potential prognostic factors. A total of 40 cases of patients relapsed after their first complete remission, including 3 groups of patients: group A, patients treated with ATRA and chemotherapy after relapse (8 patients); group B patients treated with As2O3 alone for 2nd CR and consolidation (21 patients); group C patients treated with As2O3 for 2nd CR and both As2O3 and chemotherapy for consolidation (11 patients). Univariate analysis was also done to identify the potential prognostic factors.
Results: With a median follow-up of 45 months (5-75 months), the median event-free survival was 21 months and median overall survival was not achieved. The estimated 3- and 5-year event-free survival (EFS) and over-all survival (OS) were 32.5 +/- 10.5%, 18.4 +/- 7.5% and 73.8 +/- 17.5%, 58.5 +/- 15.2%. In denovo patients, the combination of ATRA and chemotherapy in both induction and post-remission treatment was found to be statistically significant for EFS (P = 0.023), and initial peripheral leukocyte count was significantly related to OS. In relapsed patients, only the treatment of As2O3 with or without chemotherapy in consolidation after relapse was statistically significant for CR and both EFS (P = 0.0061) and OS (P = 0.0013).
Conclusion: ATRA is an effective induction therapy and can be considered as first choice of treatment in denovo APL. Addition of chemotherapy in both induction and post-remission therapy can delay or decrease the possibility of relapse compared to ATRA alone. As2O3 is an effective agent for relapsed APL and remains an important prognostic factor for relapsed APL.