RESUMEN
Background: The current recommendations for treatment of patients with newly diagnosed acute promyelocytic leukemia (APL) include all-trans-retinoic acid (ATRA) and anthracycline based chemotherapy. Aim: To evaluate the results of the Chilean protocol following the LPA99 regimen of the Spanish PETHEMA group, except for the replacement of Idarubicin by Daunorubicin. Patients and Methods: Induction consisted of Daunorubicin 45 mg/m² on days 2, 4, 6 and 8 plus ATRA 45 mg/m² daily until complete remission. Patients in complete remission (CR) received three monthly chemotherapy courses: Daunorubicin 45 mg/m²/d/4days i.v. and ATRA 45 mg/m²/d/15 days p.o. (course no. 1); Mitoxantrone 10 mg/m²/d/5 days i.v. and ATRA 45 mg/m²/d/15 days p.o. (course no. 2); Daunorubicin 60 mg/m²/d/ day 1 i.v. in the low risk group, and 1 and 2 in the intermediate-high risk groups and ATRA 45 mg/m²/d/15 days p.o. (course no. 3). Maintenance therapy consisted of mercaptopurine 90 mg/m²/d p.o., methotrexate 15 mg/m²/wk p.o. and, ATRA intermittently, 45 mg/m²/d p.o. for 15 days every three months. Results: Between January 2000 and December 2005, 56 patients with newly diagnosed APL from 10 centers were enrolled. A total of 46 patients achieved CR (85%), 8 (15%) died of early complications, seven patients relapsed, with a 16% relapse risk at three years. The 5-year Kaplan-Meier estimates of overall survival and relapse-free survival were 64% and 84% respectively. Conclusions: These data indicate that this protocol has a good antileukemic effect but further reduction of early death and relapse, especially in the high risk group is needed.