High Incidence and Curability of Patients with Acute Myeloblastic Leukemia (AML) and t(8;21) Treated On a Uniform Protocol in Casablanca, Morocco.
Authors: Quessar Asmaa , Lamchahab Mouna , Cherkaoui Siham , Hda Nazha , Howard Scott C , Rachid Mohamed , Madani Abdellah , Matthay Katherine K. , Ribeiro Raul C , Benchekroun Said 
Published: October 2019

Abstract
Abstract 4713

Background
AML with t(8;21) is known to have a more favorable outcome when treated with adequate chemotherapy and supportive care. There have been minimal data on the characteristics and outcome of AML with this translocation in low-income countries.

Aim
We analyze the clinical and biological characteristics of a large population of children and adults with AML in Casablanca who had t(8;21) in relation to response, event-free (EFS) and overall survival (OS).

Methods
From 4/1/03 to 3/31/09, eligible patients were treated on the AML-MA2003 protocol at a single center. For patients presenting with WBC>50,000, hydroxyurea (HU) was given for 4 days prior to initiation of standard induction. Treatment included two induction courses of cytarabine, 200 mg/m2/d (days 1-7) and daunomycin 50 mg/m2/d (days 1-3); consolidation was stratified by age: those '20 years had two courses of Capizzi high-dose cytarabine, 2 g/m2 q 12h (days 1-4) with L-asparaginase, 6000 units/m2 day 4; those >20 years had one or two courses of high-dose cytarabine, 1 g/m2 q 12h (days 1-4) with daunomycin 50 mg/m2/d (day 1-3), and maintenance with oral 6-mercaptopurine 60 mg/m2/d and weekly sc cytarabine 40 mg/m2 for 18 months. Events included death, relapse, progression, and abandonment.

Results
85 of 535 (15.8%) patients with karyotype results had t(8;21), including 40 with only t(8;21), 25 with additional loss of a sex chromosome, 5 with del (9), and 15 with other cytogenetic abnormalities. Characteristics of the t(8;21) group are shown in the Table. Five adults were ineligible for protocol therapy, due to secondary AML (n=1), refused (n=1) and early death (n=3). Of 33 children (age < 20 years), 28 completed all 4 courses of planned therapy. Five deaths occurred on therapy (1 failure, 4 toxicity) and 11/28 relapsed later, 8-14 months after end therapy. Of 47 adults who received the first induction course, 35 went on to 2nd induction, 34 received 1st consolidation, 22 completed both courses of induction and consolidation, and 20 completed maintenance. There were 12 deaths on therapy and 12 relapses after therapy completion. Overall, 30/80 patients did not complete prescribed therapy: 14 deaths, 1 failure, 4 abandonment, 11 complete remission). 7/8 children and 4/4 adults with t(8;21) had an early response (50% decrease in blasts) to HU. The complete remission rate (CR) after two courses of induction therapy was 91% for children and 72.5% for adults. The 2-year EFS and OS for the patients with t(8;21) was 32% (standard error [SE] 6.3%) and 59% (SE 7.3%) respectively. There was not a significant difference in 2-year EFS by sex (p=0.18), age ' 20 years vs older (p= 0.08), or presence of additional cytogenetic abnormalities accompanying the t(8;21) (p=0.98)

Conclusions
t(8;21) in Morocco occurred in 15.8% of cases, more frequently than the 7 to12% reported. It was associated with a high incidence of extramedullary disease, FAB M2, frequent deletion of a sex chromosome, preponderance of males, and young age. A third of these favorable-risk AML patients survive event-free 2 years from diagnosis despite the problem of abandonment of therapy and suboptimal supportive care.

Disclosures:
No relevant conflicts of interest to declare.