Treatment of acute promyelocytic leukemia with PETHEMA LPA 99 protocol: a Tunisian single center experience

Acute promyelocytic leukemia (APL) has now become the most curable of all subtypes of acute myeloid leukemia. A cure rate of 75-80% can be anticipated with a combination of all-trans retinoic acid (ATRA) and anthracyclines. In Tunisia, the ATRA era began in 1998 with the use, consecutively, of two regimens of a combination of ATRA with anthracycline and cytarabine (APL93), and without cytarabine (LPA99). From 2004, 39 patients with confirmed APL either by t(15;17) or PML/RARA were treated by the PETHEMA LPA 99 trial. The rationale of this protocol by avoiding cytarabine is to reduce death in complete remission (CR) without increasing the incidence of relapse. Thirty-three patients achieved CR (84·6%). The remaining six patients were considered as failure due to early death: three caused by differentiation syndrome (DS) and three died from central nervous system hemorrhage. Baseline blood cell count (WBC) >10 × 10 9 /l (P=0·26) and creatinine >1·4 mg/dl (P=0·42) were not predictive of mortality. DS was observed in 11 patients (30·5%) with a median onset time of 12 days (range: 3-23 days) and median WBC of 29 × 10 9 /L (range: 1·2 × 10 9 -82·7 × 10 9 /l). DS was severe in seven cases, moderate in four, and fatal in three cases. Body mass index ≥30 (P=0·044) and baseline WBC ≥20 × 10 9 /l (P=0·025) are independent predictors of DS. The median follow-up of this study is 36 months. Thirty patients are alive in continuous complete remission; two patients died in CR from septic shock and secondary myelodysplastic syndrome respectively; one patient died 47 months after achieving two relapses. Event free survival from diagnosis was 80% and overall survival was 82%. Our results are quite acceptable and can be improved by reducing mortality rate.