Comparative Analysis of 12 Flow Cytometry-Based Markers in B-Lymphoblastic Leukemia/Lymphoma and Their Utility in Detecting Minimal/Measurable Residual Disease.

[INTRODUCTION] Minimal/measurable residual disease (MRD) is a key prognostic factor in B-lymphoblastic leukemia/lymphoma (B-ALL/LBL), commonly assessed via multiparametric flow cytometry (MFC). This study evaluated 12 leukemia-associated immunophenotype (LAIP) markers-CD81, CD86, CD123, CD58, CD9, CD73, CD13/CD33, CD44, CD97, CD66c, CD49f, and CD304-to determine their suitability for MRD detection.

[METHODS] Marker expression was analyzed in 103 B-ALL cases at diagnosis, and 54 post-therapy follow-up samples, including 16 MRD-positive cases. Additionally, 25 non-B-ALL bone marrow samples were examined for marker expression in hematogones. Clinical and genetic correlation was also performed.

[RESULTS] Median age of patients was 9 years (range: 0.3-89), with male: female ratio of 1:1. We found that CD97, CD73, CD86, and CD58 are excellent markers for MRD analysis in B-ALL, as they are expressed in more than 85% of cases at baseline, and their expression is preserved in more than 75% of cases post-therapy. Two other extremely promising markers are CD81 and CD49f, both of which are expressed as LAIP in more than 50% of B-ALL cases, with retention of expression in more than 85% of cases post-therapy, and importantly, expression as LAIP in some post-therapy samples despite their absence at baseline. Hyperdiploidy was significantly associated with expression of CD86, CD97, CD123, CD66c, and CD9; BCR::ABL1 fusion was associated with CD49f, CD81, and CD66c.

[CONCLUSION] CD97, CD73, CD86, and CD58 are the best amongst newer markers in B-ALL MRD assessment. Our findings support integrating these into MRD panels to enhance post-therapy MRD detection, thus improving prognostication and guiding treatment decisions.