[Acute promyelocytic leukemia: results of the Chilean protocol LPA2000]

The current recommendations for treatment of patients with newly diagnosed acute promyelocytic leukemia (APL) include all-trans-retinoic acid (ATRA) and anthracycline based chemotherapy.

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.

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.

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.

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.