ALL-350 Characterization of Acute Lymphoblastic Leukemia in the Pediatric Mexican Mestizo Population

Abstract

Acute lymphoblastic leukemia (ALL) is the most common neoplasm of lymphoid progenitor cells in pediatric populations. ALL cases can be broadly classified as B-cell or T-cell. B-cell ALL (B-ALL) has many genetic subtypes characterized by major chromosomal alterations. Flow cytometry and biomarkers identification provide information about the subtype of ALL and can be correlated with the patient's prognosis. Based on reactivity with antigens present on the surface or in the cytoplasm of leukemia cells, B-ALL can be divided into 4 subtypes according to its stage of differentiation: pro-B, common B, pre-B, and immature B subtypes. This study aims to establish the association of the molecular biomarkers TCF3-PBX1 t(1;19), rearrangement of MLL t(4;11), BCR-ABL1 t(9;22), and ETV6-RUNX1 t(12;21) with ALL subtypes according to its stage of differentiation. The study includes a retrospective analysis of laboratory data results from the Mexican mestizo pediatric population diagnosed with ALL during a 3-year period (2018-2021), referred to Mendel laboratories from different health institutions. Ninety ALL cases, age range 0-17 years, were classified by immunophenotype and tested by PCR for the biomarkers TCF3-PBX1, rearrangement of MLL, BCR-ABL1, and ETV6-RUNX1. The biomarkers tested were expected to be present in most of the cases (>50%) regardless of the differentiated ALL subtype. B-cell ALL represented 92.2% of the cases (83); the prevailing subtype was pre-B with 51.1% of all cases. The biomarkers TCF3-PBX1, rearrangement of MLL, BCR-ABL1, and ETV6-RUNX1 were present in at least one case in the subtype pro-B. ETV6-RUNX1 was identified as the only marker in common B-ALL. Seventy-one percent of the cases showed no presence of the 4 biomarkers tested and correspond to quadruple negative cases. The biomarkers TCF3-PBX1, rearrangement of MLL, BCR-ABL1, and ETV6-RUNX1 are decisive in establishing the prognosis of patients with any of the ALL-B subtypes and enable the definition of a stratified treatment. The absence of these markers prevails in the study population, so it is essential to include other recently described mutations in laboratory determinations. Laboratorios MENDEL, Morelia Michoacán. México.