Prevalence, Clinical And Hematological Profile And Outcome Of Bcr-Abl1-Like Acute Lymphoblastic Leukaemia In Indian Children: A Prospective Observational Study

Introduction: BCR-ABL1-like acute lymphoblastic leukaemia (ALL) represents a perplexing subclass of ALL mainly due to genomicheterogeneity and non-availability of standardized diagnostic tests.The data on prevalence, clinical-hematological profile and outcome are limited from low-middle income countries.We studied prevalence, clinical & hematological profile and outcome of BCR-ABL1-like ALL in Indian ethnicity.Methodology: This prospective observational study enrolled children<14 years with B-ALL.Recurrent genetic/chromosomal aberrations were excluded.BCR-ABL1-like aberrations were analyzed using Polymerized chain reaction(PCR) or Next-generation sequencing(NGS).Two groups with/without BCR-ABL1-like ALL (Mut+/Mut-) were compared.Results: Out of 214 eligible children; 75 with "B-other ALL" were analyzed for BCR-ABL1-like aberrations.Their prevalence was 34/214(15.8%) in B-ALL and 34/75(45.3%) in "B-other" ALL (PCR:33.3% and NGS:53.3%).Majority aberrations were JAK2E16 and ILR7e5/ILR7e6 with PCR and RAS pathway and PAX5 fusion with NGS.Baseline demographic, clinical and laboratory parameters including aberrant flow cytometry were comparable in Mut+ and Mut-groups.Children with day-8 absolute blast count(ABC) were higher in Mut+ group.High endinduction minimal residual disease(MRD) was comparable in two groups.Number of NCI-standard risk(SR) at diagnosis with high D-8 ABC or high MRD was higher in Mut+ group.Similar results were found when aberrations were analyzed by NGS alone.