BACKGROUND: Different criteria have been used to diagnose mixed-phenotype acute leukemia (MPAL), which has impacted the number of individuals diagnosed with this pathology. Better outcomes have been reported when using acute lymphoblastic leukemia (ALL)-type chemotherapy in the treatment of MPAL. METHODS: We compared the outcome of 4 groups of patients with MPAL. Group 1 included patients diagnosed using the 2008/2016 World Health Organization (WHO) classification; group 2 included patients diagnosed using the European Group for the Immunological Characterization of Leukemias (EGIL) criteria; group 3 included patients diagnosed using either the EGIL or the 2008/2016 WHO criteria; and group 4 was comprised of patients diagnosed with MPAL using the EGIL classification only. RESULTS: We found a significantly worse disease-free survival (groups 1-4) and overall survival (OS) (groups 2 and 3) when comparing MPAL patients to other acute leukemia (AL) patients. A significantly better OS was obtained in patients (groups 2-4) treated with ALL-type chemotherapy compared to acute myeloid leukemia (AML)-type regimens. CONCLUSION: In light of these results, and because a trend (P=0.06) was found with regard to a better OS in group 4 when compared to other AL patients, an argument can be made that the 2008/2016 WHO classification is underpowered to diagnose all MPAL cases, potentially resulting in the suboptimal treatment of some individuals with AL.
Classification* ; Disease-Free Survival ; Drug Therapy ; Humans ; Leukemia* ; Leukemia, Myeloid, Acute ; Pathology ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; World Health Organization

Background: Acute lymphoblastic leukemia (ALL) is a malignant clonal bone marrow disorder with a high mortality rate during the initial therapy. This retrospective study aimed to describe and analyze the risk factors and causes of induction-related mortality (IRM) in an adolescent and adult ALL population treated in a low- and middle-income country. Methods: From 2009 to 2016, a total of 167 patients were included, of which 50.9% were male with a median age of 28 years. B-immunophenotype represented 97.6%, and high-risk cytogenetics were present in 23.3%. During induction therapy, 91% had at least 1 complication, most of which were infectious, with an IRM of 12%. Results: Factors associated with increased mortality rate were central nervous system (CNS) status [CNS-3: hazard ratio (HR) 3.029; 95% confidence interval (CI), 0.79‒11.49; P =0.103 and CNS-2: HR, 9.98; 95% CI, 2.65‒37.65; P =0.001] and dialysis requirement (HR, 9.15; 95% CI, 2.44‒34.34; P =0.001). Conclusion Our study confirms that ALL patients treated in resource-constrained settings have high rates of IRM, mainly attributed to advanced disease and high tumor burden at diagnosis.