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Background: The published literature on hematological, clinical, flowcytometric‐immunophenotyping, and minimal residual disease outcomes of the prognostically important genetic subtypes of acute lymphoblastic leukemia (ALL) is scarce from low‐income countries. For newer classifications such as BCR::ABL1‐like ALLs, the scarcity of patient‐level data is even more pronounced. Methods: The authors performed comprehensive detection of recurrent gene fusions and BCR::ABL1‐like ALL cases followed by immunophenotypic profiling and obtained clinical outcome parameters for a large cohort (n = 1021) of patients from India. This cohort included a significant number of patients with BCR::ABL1‐like ALL subtype and other genetic subtypes of ALL. Results: Patients with BCR::ABL1‐positive and BCR::ABL1‐like ALL were significantly older, had male preponderance, and expressed a higher white blood cell count than BCR::ABL1‐negative cases (p <.05). Logistic regression modeling of B‐lineage‐ALL (B‐ALL) subtypes revealed that cluster of differentiation (CD)36 is a strong statistically significant predictive marker of BCR::ABL1‐like ALL (p <.05). Furthermore, patients with BCR::ABL1‐like ALLs show a significantly higher frequency of CD36 expression compared to BCR::ABL1‐negative ALLs (p <.05). In terms of clinical symptoms, lymphadenopathy is a strong statistically significant predictive marker in BCR::ABL1‐like ALLs compared to BCR::ABL1‐negative ALL cases (p <.05). In terms of treatment outcomes, minimal residual disease (MRD) positivity in BCR::ABL1‐positive ALL cases were statistically significant (p <.05), and BCR::ABL1‐like ALL cases had high MRD‐positivity as compared to BCR::ABL1‐negative ALL cases but did not show statistical significance. Conclusions: The findings evince the use of novel therapies and personalized treatment regimens to improve the overall survival of the newer incorporated entities in B‐ALLs. This is the first report characterizing the hematological, clinical, flowcytometric‐immunophenotyping, and minimal residual disease outcomes of the prognostically significant subtypes of ALLs in patients from India. Plain Language Summary: Characterizing the hematological, clinical, flowcytometric‐immunophenotyping, and minimal residual disease outcomes of the prognostically significant subtypes (n = 1021) of acute lymphoblastic leukemia (ALLs) in patients from India.We have made two independent logistic regression models of cluster of differentiation (CD) markers and clinical symptoms to differentiate prognostically significant subtypes of ALLs.Logistic regression analysis of CD markers revealed CD36 as a strong predictor in BCR::ABL1‐like ALL cases compared to BCR::ABL1‐negative ALL cases.Logistic regression analysis of clinical symptoms revealed lymphadenopathy significantly predicts BCR::ABL1‐like ALLs (p <.05).In terms of treatment outcomes, BCR::ABL1‐positive ALL had statistically significant minimal residual disease (MRD) (p <.05), and BCR::ABL1‐like ALL cases had high MRD‐positivity but did not show statistical significance as compared to BCR::ABL1‐negative ALLs. This study characterizes prognostically significant genetic subtypes of B‐acute lymphoblastic leukemia (B‐ALL). Logistic regression modeling of cluster of differentiation markers and clinical symptoms is used to predict various genetic subtypes of B‐ALL. [ABSTRACT FROM AUTHOR]

Objective: Based on the immunophenotype, acute lymphoblastic leukemia (ALL) can be categorized into B-cell or T-cell lineages. B-cell precursor ALL (BCP-ALL) cases show various genetic/molecular abnormalities, and varying frequencies of chimeric fusion transcripts in BCP-ALL cases are reported from different parts of the world. We studied the immunophenotypic aberrancy profiles of a large number of BCP-ALL cases with respect to various common chimeric fusion transcripts. Materials and Methods: Flow cytometric immunophenotyping and multiplex reverse-transcription polymerase chain reaction assays were performed for 986 BCP-ALL cases. Results: Among 986 BCP-ALL cases, the incidence of various fusion transcripts was 38.36% in adult cases and 20.68% in pediatric cases. Adult BCP-ALL patients with t(9;22)(BCR-ABL1) fusion transcripts and expression of aberrant myeloid markers were significantly older at presentation (p=0.0218) with male preponderance (p=0.0246) compared to those without aberrant myeloid expression. In pediatric patients with the t(12;21)(ETV6-RUNX1) chimeric fusion transcript, aberrant expression of CD13 was observed in 39.13%, CD33 in 36.95%, and CD117 in 8.69% of patients, respectively. Pediatric BCP-ALL patients with the ETV6-RUNX1 fusion transcript and expression of aberrant myeloid markers were not significantly different compared to those without with respect to demographic and clinical/hematological characteristics (p=0.5955). Aberrant myeloid markers were rarely or never expressed in pediatric and adult BCP-ALL patients with the t(4;11)(KTM2A-AF4) and t(1;19)(TCF3-PBX1) fusion transcripts. Conclusion: Aberrant myeloid markers were frequently expressed among BCP-ALL patients with the t(9;22)(BCR-ABL1) and t(12;21) (ETV6-RUNX1) fusion transcripts. However, BCP-ALL patients with the t(4;11)(KTM2A-AF4) and t(1;19)(TCF3-PBX1) fusion transcripts rarely or never expressed aberrant myeloid markers. Aberrant myeloid CD markers can be used in predicting chimeric fusion transcripts at baseline so as to plan appropriate tyrosine kinase inhibitor therapy in cases of BCP-ALL with specific chimeric fusion transcripts. This study has delineated the relationship of chimeric fusion transcripts with the aberrant expression of myeloid markers in a large cohort of BCP-ALL cases. [ABSTRACT FROM AUTHOR]