Acute Promyelocytic Leukemia: A Decade Long Experience with Evolving Treatment Strategies

Aims: To study the characteristics and outcome of Acute promyelocytic leukemia (APL) patients.

Study Design: Retrospective analysis of APL patients (n=106) treated at the Department of Hematology, NRS Medical College, Kolkata over a period of more than 10 years from October 2009 to September 2020 was done.

Methodology: Patients were treated with ATO, ATRA+ATO and ATRA+ Anthracycline depending on their Sanz risk stratification. Presenting symptoms, clinical spectrum, events (relapse, death, dropout, and refractory disease), and response to treatment was analyzed. Overall survival (OS), event free survival (EFS) and relapse free survival (RFS) were calculated.

Results: Median age was 26.5 (range, 2-71) years with M:F ratio of 1.7:1. Majority presented with bleeding (91.3%) followed by anaemia (84.4%) and fever (78%). Median hemoglobin, TLC and platelet count were 95gm/L, 6.15 x 109/L and 52 x 109/L, respectively. As per Sanz risk criteria Low risk (45.3%) was the commonest followed by Intermediate risk (29.2%) and high risk (25.5%). About half of the cases had BCR1, while BCR 3 (41.5%) and BCR 2 (7.55%). ZBTB/RARA t (11;17) was detected in 2 cases (1.9%) and were treated with AML like therapy. Patients with BCR3 transcript was significantly associated with low platelet count(p=0.009), low Hb (p=0.02) and high TLC (p=0.01) at presentation (p<0.05). Induction mortality was 16.9% and it was significantly associated with low Hb and low platelet count (P<0.05). Most common cause of death was hemorrhagic death. Children (≤18yr) had significantly more differentiation syndrome (DS) than adults (>18yr) (p=0.007). Remission was attained in 83% patients. Median OS, EFS and RFS were not reached. At 10-year OS was 79.1%, EFS was 63.5% and RFS was 78.3%. OS in ATRA+ chemotherapy arm was significantly inferior than ATO (p=0.01) and ATRA+ATO arm (p=0.008), while there was non-significant difference in OS between Vesanoid vs generic ATRA, with or without maintenance.

Conclusion: Bleeding was the commonest presentation. Low risk category was commonest.

Low Hemoglobin and low platelet were significantly associated with Induction mortality and BCR3 transcript. OS in ATRA chemotherapy was significantly inferior to ATO and ATRA+ATO arm ; without any significant difference in OS between original ATRA vs generic ATRA, with or without maintenance, risk categories, or children vs adults.