P538: TREATMENT PATTERNS AND CLINICAL OUTCOMES IN ACUTE PROMYELOCYTIC LEUKEMIA: REAL-WORLD DATA

Abstract

Background: All-trans retinoid acid (ATRA) and arsenic trioxide (ATO) have changed the treatment paradigm of acute promyelocytic leukemia (APML). Current therapeutic strategies are based on the risk stratification at diagnosis and molecular response at the end of consolidation.We report our experience of treatment patterns and clinical outcomes of newly diagnosed APML patients. Aims: The primary objective of our study was to evaluate event-free survival in all risk categories of APML.Secondary objectives include disease-free survival, overall survival, rates of complete remission (CR) at the end of induction, rates of molecular CR at the end of consolidation. Methods: We included treatment-naïve APML patients age>14 years who were treated between May 2014 to May 2018.The diagnosis of APML was established by peripheral blood/bone marrow morphology and flow cytometry (FCM) and confirmed by fluorescent in situ hybridization (FISH) and reverse-transcriptase polymerase chain reaction (RT-PCR) for PML-RARA.The details of patients were retrieved from electronic medical records.Patients with low/intermediate risk were treated with ATO-ATRA based induction and consolidation,where as patients with high risk were treated with varying combination of ATO/ATRA/chemotherapy with or without maintenance. Results: We registered 149 patients during the study period.The median age was 37 years(range 15-72 years, male 56.6%, female-37%).93 patients (62.4%) were stratified as low risk and 56 patients (37.5%) as high risk based on Sanz’s score.The induction therapy for high risk APML was single agent ATO (42.8%),ATO/ATRA/anthracycline (26.7%),ATO/anthracycline (25%),and ATO/ATRA (5%).The consolidation for high risk APML includes ATRA/daunorubicin (50%),ATO/ATRA (26.8%),HIDAC (4%) and APL 2000 in one patient.All low-risk APML patients received ATO-ATRA in induction and consolidation.Anthracycline was added to three patients in induction to decease white cell count.The proportion of deaths that occurred in first week include 6.5% in low risk and 9% in high risk group.The median follow up was 42 months.The hematological CR at the end of induction was 85%.(128/149 patients,expired during induction-14,lost to follow up-7).The rate of end of consolidation PCR negativity was 83%.Differentiation syndrome occurred in 75% of patients.For the overall patient population, the 3-year probability for OS, EFS, DFS was 88.1% (95% C.I, 82.9 93.6), 75.9% (95% C.I, 68.9-83.5), 81.4% (95% C.I, 75-88.4) respectively. The 3-year survival probability for OS, EFS, and DFS for low risk APML was 90% (95% C.I, 84.1-96.4), 80.1% (95% C.I, 72-89.1), 84.5% (95% C.I, 76.9-92.7) respectively whereas for high risk APML was 84.7% (95% C.I, 75.3-95.2), 68.6% (95% C.I, 56.9-82.9), 76.1% (95% C.I-65-89) respectively.The total number of relapses were 11.The median time to relapse for low risk and high risk was 23months(18-32months) and 20months(range 5-39months) respectively. Image:Summary/Conclusion: Treatment with ATO and ATRA based regimen are effective in real world setting.The emphasis should be to reduce the early death rate due to bleeding and infectious complications.