Early Mortality of Newly Diagnosed Adult Acute Promyelocytic Leukemia Treated with the AIDA Protocol.

APL represents a particular subtype of acute myeloid leukemia with characteristic clinical features, as well as specific immunophenotypic, cytogenetic and molecular findings owing to the chromosomal translocation t(15;17). Anthracycline-based chemotherapy and All-Trans Retinoid Acid (ATRA) became the cornerstone of APL treatment by improving significantly the long term outcome of patients, even though there is some controversy regarding the impact of this combination on the mortality of the induction phase. Herein, we analysed retrospectively the outcome of 16 consecutive adult APL patients who were diagnosed and treated in our Unit from 12/1998 to 10/2004. The analysis focuses more on the parameters of treatment-related mortality, cause of death and disease-free survival post AIDA chemotherapy. All patients were suffering from the classical form of APL and were homogeneously treated as follows: induction consisted of ATRA p.o. and idarubicin i.v. at conventional doses of 45mg/m²/d, from D1 to CR and 12mg/m²/d, D2,4,6,8 (total of 4 infusions), respectively. Dose modifications for elderly individuals were not allowed. Complete remitters were consolidated with 3 courses of chemotherapy without ATRA, where as non-remitters were taken off protocol and received other therapy. Patients in continuing hematological and molecular remission at the end of consolidation were administered maintenance therapy for 2 years with oral 6-MP at 90mg/m²/d, oral MTX weekly at 15mg/m² and ATRA for 15 days every 3 months. In all cases, the morphological diagnosis of APL was confirmed by chromosome and immunophenotypic analysis of blasts in addition to molecular studies. The median age of our cohort was 55 years (range 31–78) and the male/female ratio was 12/4. Three patients (3/16, 19%) were ≥ 65 years at diagnosis. Two cases (2/16, 12%) presented with a leukocyte count of ≥10 x 10³/mm³ while the median Wbc at presentation was 6.5 x 10³/mm³. All cases had either clinical (haemorrhagic) or laboratory evidence of disseminated intravascular coagulation. Six patients (6/16, 37%) deceased during the induction phase from pulmonary bleeding (2 cases,days 8 and 13 respectively), intracerebral bleeding (1 case,day 6), myocardial infarction-cardiac arrest (1 case,day 5), respiratory distress syndrome secondary to ATRA syndrome (1 case, day 17), and sepsis-induced hemophagocytosis syndrome (1 case, day 38). All ten out of the 16 (63%) surviving patients achieved hematological and molecular CR and remain to date relapse-free in excellent clinical condition. The median overall survival and disease-free survival for the whole group is 25 months but the same parameters for the surviving patients is better at 42 months. Our results corroborate that in APL the AIDA protocol together with maintenance treatment is highly effective in producing sustained haematological and molecular remission. Despite this excellent antileukaemic activity, early mortality (37% in our cohort) caused chiefly by fatal bleeding and thrombotic events (four patients) limits considerably patient survival and deserves further research in order to improve long-term outcome.