Treatment of Acute Promyelocytic Leukemia (APL) At Tawam Hospital UAE

Abstract 4347

Acute Promyelocytic Leukemia (APL) is a unique sub-type of Acute Myeloid leukemia associated with a balanced reciprocal translocation between chromosomes 15 and 17 and 80% of the cases present with bleeding diathesis caused by severe coagulopathy. The translocation generates a fusion transcript joining the PML(promyelocyte) and RAR-α (retinoic acid receptor-α) genes. The therapy of APL has been revolutionized by the introduction of differentiating agents All Trans Retinoic Acid (ATRA) and Arsenic Trioxide.

All patients were treated as per Pethema protocol. Initially LPA99 (Sanz MA. Blood. 1999 Nov 1;94(9):3015-21) and since January 2012 a risk adapted therapy based on LPA2005 (Sanz MA et al. Blood June 24, 2010 vol. 115 no. 25 5137–5146). Treatment included induction followed by 3 cycles of consolidation and two years of maintenance.

Nineteen patients were diagnosed with APL between January 2009 and June 2012. Three patients are excluded from the analysis as karyotyping and/or PCR did not confirm the diagnosis. The median age was 35 years (range 22–53 years). Male to female ratio was 4:1. Nine (56%) patients were stratified as high risk (WBC ≥ 10 ×10⁹/l) while, seven (44%) as intermediate risk and low risk (WBC < 10 ×10⁹/l). Three (19%) patients had early death despite treatment and supportive care. The cause of death was intracranial hemorrhage (1) pulmonary hemorrhage (1) and multi-organ failure (1). Thirteen patients achieved a complete morphological and molecular remission (80%). There has been only 1 case of treatment failure (high risk at presentation). This patient was successfully re-induced with arsenic trioxide and achieved second molecular complete remission. Unfortunately he relapsed a second time and is currently alive in third morphological remission but remains PCR positive for PML/RARα 33 months after diagnosis.

Our limited experience shows favorable outcome (CR 80%) for the treatment of APL using the Pethema protocol compared to published data (Tallman MS. Blood 2002;99(3):759–767). Early death rate remains high despite intensive supportive care. The only variable is the availability and initiation of ATRA at the clinical suspicion of diagnosis both at the referring hospitals and treatment center.