부산대학교 도서관

Simple Summary: B-cell acute lymphoblastic leukemia is genetically diverse, with one of the most commonly altered genes being PAX5. Recently, alterations in PAX5 have been identified not merely as secondary events, but also as the oncogenic drivers, with newly defined genetic subtypes like PAX5alt and PAX5 P80R. Studying a consecutive cohort of 99 B-ALL patients, we found PAX5 alterations in over a third of patients, mostly involving copy number variations. Seven of our patients exhibited the PAX5alt genetic profile and one carried the P80R variant, and these patients showed intermediate outcomes. We also discovered that patients within the hyperdiploid group that carried extra copies of PAX5 did not respond as well to the treatment. Overall, our study highlights widespread PAX5 alterations affecting treatment response, particularly in specific genetic subtypes, underlining the need to identify these alterations for improved treatment strategies. In this study, we aimed to identify patients within our B-ALL cohort with altered PAX5. Our objective was to use a comprehensive analysis approach to characterize the types of genetic changes, determine their origin (somatic/germline), and analyze the clinical outcomes associated with them. A consecutive cohort of 99 patients with B-ALL treated at the Children's Hospital of the UMC Ljubljana according to the ALL IC-BFM 2009 protocol was included in our study. We used RNA sequencing data for gene expression analysis, fusion gene detection and single nucleotide variant identification, multiplex-ligation dependent probe amplification for copy number variation assessment, and Sanger sequencing for germline variant detection. PAX5 was impacted in 33.3% of our patients, with the genetic alterations ranging from CNVs and rearrangements to SNVs. The most common were CNVs, which were found in more than a third of patients, followed by point mutations in 5.2%, and gene rearrangements in 4.1%. We identified eight patients with a PAX5-associated genetic subtype that were previously classified as "B-other", and they showed intermediate outcomes. We showed higher minimal residual disease values at the end of induction and poorer event-free survival in hyperdiploid cases carrying duplications in PAX5 compared to other hyperdiploid cases. We also report an interesting case of a patient with PAX5::FKBP15 and a pathogenic variant in PTPN11 who underwent an early relapse with a monocytic switch. In conclusion, this study provides valuable insights into the presence, frequency, and prognostic significance of diverse PAX5 alterations in B-ALL patients, highlighting the complexity of genetic factors and their impact on patient outcomes. [ABSTRACT FROM AUTHOR]