Acute promyelocytic leukemia: long-term outcomes from the HARMONY project

• The HARMONY APL project confirms that ATRA/ATO combination significantly improves outcome, regardless of patient age and Sanz risk score.

• Reducing the risk of early death still represents an unmet need, particularly in older patients and in high-risk APL.

Treatment outcomes for acute promyelocytic leukemia (APL) have improved with the widespread use of targeted therapy with all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). Our study aimed to validate these data in a large patient cohort, and to redefine prognostic factors. Leveraging the HARMONY Platform, we analyzed 1438 newly diagnosed patients with APL, diagnosed between 1999 and 2022. Patient data derived from the 2 international multicenter Gruppo Italiano Malattie EMatologiche dell’Adulto (GIMEMA)-APL0406 and National Cancer Research Institute (NCRI)-AML17 trials and 4 European registries: the Haemato Oncology Foundation for Adults in the Netherlands, Belgium and Luxembourg (HOVON), AML Study Group (AMLSG), Swedish AML Registry, and Study Alliance Leukemia (SAL). The study cohort included 721 males and 717 females, with a median age of 50.5 years (range, 16-94 years). Of 1309 patients starting therapy, 562 received ATRA-ATO, and 747 idarubicin-based chemotherapy (AIDA-like CHT). Early death (ED) occurred in 85 of 1438 patients (5.9%) at a median of 9 days after APL diagnosis and was independently associated with increasing age and high Sanz risk score (odds ratio [OR], 1.06; 95% confidence interval [CI], 1.04-1.08; and OR, 4.65; 95% CI, 2.55-8.51, respectively). The median follow-up was 5.5 years (interquartile range, 3.2-7.5 years). ATRA-ATO regimen was associated with the best outcome, reaching 91% 7-year overall survival (vs 81% for AIDA-like CHT; hazard ratio [HR], 2.14; 95% CI, 1.51-3.05), 89% event-free survival (vs 71% for AIDA-like CHT; HR, 2.72; 95% CI, 2.01–3.69), and 3% relapse (vs 13% for AIDA-like CHT; HR, 4.19; 95% CI, 2.38-7.39; P < .001 for all outcomes). The survival advantage of ATRA/ATO was independent of patients’ age, Sanz risk score, and treatment scenario. Our study confirms the superiority of ATRA-ATO over ATRA-chemotherapy in patients with APL. Reducing the risk of ED still represents an unmet medical need, in particular in older patients and in high-risk APL.