OBJECTIVETo investigate the efficacy and treatment outcome of different induction regimens, and different post-remission therapies for adult acute promyelocytic leukemia (APL).

METHODSThe outcome of 73 patients with newly diagnosed APL were retrospectively analyzed. According to the induction regimens, the patients were divided into three groups: chemotherapy-only (14 cases group I), all-trans retinoic acid (ATRA) or combined with chemotherapy (33 cases group II), and ATRA combined with arsenic trioxide (As(2)O(3)) (26 cases group III). The complete remission (CR) rate and the time to CR (TTC) were analyzed. After CR, the patients were divided into 2 groups for post-remission therapies: one with sequential treatment of chemotherapy/ATRA/As(2)O(3) and the other with alternative treatment of chemotherapy/ATRA. The overall survival (OS), disease free survival (DFS) and relapse rate were compared between these two groups. Patients induced CR with both ATRA and As(2)O(3), and then sequentially treated with chemotherapy/ATRA/As(2)O(3) (group A), and those induced CR with ATRA or As(2)O(3) alone and then with non-chemotherapy/ATRA/As(2)O(3) sequentially (group B) were also analyzed and compared for CR, OS and DFS.

RESULTS(1) For induction treatment, the CR rate in ATRA and As(2)O(3) combination group was 100%, in ATRA combined with chemotherapy group was 78.8%, and in chemotherapy-only group was 57.1% (P = 0.030). The median TTC in ATRA with As(2)O(3) combination group was 26 (13 - 40) days being the shortest among the three groups. (2) For the post-remission treatment, 3-year OS rates in group I and group II were (95.7 ± 4.3)% and (68.6 ± 11.2)% (P < 0.05), and 3-year DFS rates were (79.0 ± 9.5)%, and (32.9 ± 15.5)%, respectively (P < 0.01). The relapse rate was 14.8% in group I, and 50.0% in group II (P = 0.011). (3) The CR, 3-year OS and DFS rates in group A were all 100%. The CR rate in ATRA or As(2)O(3) alone induced group was 72.9%, and 3-year OS was (72.3 ± 9.1)% (P < 0.05).

CONCLUSIONSFor adult APL induction with ATRA and As(2)O(3) combination can obtain a higher CR rate, and shorter TTC. The post-remission treatment with sequential chemotherapy, ATRA and As(2)O(3) results in a lower relapse rate, and significantly improves OS and DFS. The ATRA and As(2)O(3) combination induction with the sequential post-remission therapy is the best strategy for APL treatment.