United Arab Emirates first population-based acute leukemia registry Free

Compared to Western registries, limited data exist on acute leukemia in rapidly developing Middle Eastern nations with diverse expatriate populations. In Abu Dhabi, where the population is young and multiethnic, Understanding the patterns of leukemia presentation and response to therapy in this setting may identify unique challenges and opportunities for improving care.

This single-center retrospective study analyzed 114 adult patients diagnosed with acute leukemia and treated in Abu Dhabi. Men were more frequently affected (69/114), and the most common nationalities represented were Emirati (28), Indian (14), Filipino (11), Pakistani (9), and Bangladeshi (7). Patients were followed from diagnosis until either death or their last documented clinical follow-up.

Acute myeloid leukemia (AML) formed the majority of cases, with 49 patients diagnosed with de novo AML and 15 classified as secondary AML. Nine patients had acute promyelocytic leukemia (APL), predominantly low-risk (8 low risk, 1 high risk). The lymphoid group included 27 B-ALL, 4 Philadelphia chromosome–positive B-ALL, 9 T-ALL, and 3 mixed phenotype acute leukemias. The median age was 37 years, notably younger than Western populations where median ages often exceed 60 years for AML and 40 years for ALL [https://doi.org/10.1182/blood.2022016867. Patients with secondary AML had a median age of 58 years, while T-ALL patients were the youngest, with a median age of 25 years.

Molecular profiling played a critical role in AML prognostication. We grouped results from next-generation sequencing (NGS), fluorescence in situ hybridization (FISH), and multiplex PCR (MDx leukemia screen) into four categories: favorable (PML-RARA), poor (FLT3-ITD, BCR-ABL, TP53, complex karyotype), mixed, and indeterminate. Only 6 patients had favorable markers, while 62 were in the poor-risk group. Notably, 19 of the 27 total deaths occurred among patients with poor-risk profiles. These patients had a median survival of 2.6 months. Conversely, only one death occurred among those with favorable molecular markers, consistent with international literature showing that APL with PML-RARA fusion achieves remission rates of up to 90% and cure rates near 80% [https://doi.org/10.1182/blood.2020007841]. The frequency of poor-risk mutations in our cohort, particularly FLT3-ITD, reflects the aggressive disease biology observed locally, where FLT3-ITD is well established as an adverse prognostic marker [https://doi.org/10.1056/NEJMoa1516192].

Primary AML had a median survival of 3.1 months, with 14 deaths recorded. Secondary AML demonstrated a similar survival trend, with 4 deaths. APL patients showed better outcomes: six of eight low-risk patients remained alive, and the high-risk patient also survived, with a median survival of approximately 16 months. Among lymphoid leukemias, median survival was 8.7 months in B-ALL (two deaths), 14.9 months in T-ALL (one death), and 40.6 months in Philadelphia-positive B-ALL (no deaths). Mixed phenotype acute leukemias had a median survival of 5.4 months. Half of secondary AML patients died, while others had short follow-up durations.

Overall, 27 patients (median age 48) died during the study period. The highest mortality occurred among primary AML (14), secondary AML (4), and APL low-risk (2). Other deaths included two in B-ALL, one in T-ALL, and one in mixed phenotype. Notably, 70% of all deaths were associated with poor-risk genomic findings. The two APL deaths occurred early in treatment, reinforcing that hemorrhagic complications remain a major cause of early mortality in APL, despite its otherwise favorable prognosis [https://doi.org/10.1056/NEJMoa1300874].

This study reflects the wide clinical and genetic variability of acute leukemias seen in a diverse, predominantly young patient population treated in the UAE. While outcomes for APL were encouraging and aligned with global expectations, many patients with AML carried poor-risk molecular features that contributed to early disease progression and limited survival. What stands out is the contrast between the younger age of our patients and the aggressive biology of their disease. These findings highlight the importance of timely molecular testing and individualized treatment planning. In a region with a unique demographic profile, there is a real opportunity to refine strategies that better match the biology of disease and improve outcomes across the spectrum of acute leukemias.