VpreB surrogate light chain expression in B-lineage ALL: a report from the Children’s Oncology Group

Winter SS, McCaustland A, Qu C, Simeona N, Heerema NA, Carroll AJ, Wood BL, Gheorghe G, Mullighan CG, Wilson BS. VpreB surrogate light chain expression in B-lineage ALL: a report from the Children’s Oncology Group. Blood Adv. 2022 Jan 25;6(2):585-589. doi: 10.1182/bloodadvances.2021005245. PubMed PMID: 34662891; PubMed Central PMCID: PMC8791581.

Immunotherapies directed against B-cell surface markers have been a common developmental strategy to treat B-cell malignancies. The immunoglobulin heavy chain surrogate light chain (SLC), comprising the VpreB1 (CD179a) and Lamda5 (CD179b) subunits, is expressed on pro- and pre-B cells, where it governs pre–B-cell receptor (BCR)-mediated autonomous survival signaling. We hypothesized that the pre-BCR might merit the development of targeted immunotherapies to decouple “autonomous” signaling in B-lineage acute lymphoblastic leukemia (B-ALL). We used the Children’s Oncology Group (COG) minimal residual disease (MRD) flow panel to assess pre-BCR expression in 36 primary patient samples accrued to COG standard- and high-risk B-ALL studies through AALL03B1. We also assessed CD179a expression in 16 cases with day 29 end-induction samples, preselected to have ≥1% MRD. All analyses were performed on a 6-color Becton-Dickinson flow cytometer in a Clinical Laboratory Improvement Amendment/College of American Pathologist–certified laboratory. Among 36 cases tested, 32 cases were at the pre-B and 4 cases were at the pro-B stages of developmental arrest. One or both monoclonal antibodies (mAbs) showed that CD179a was present in ≥20% of the B-lymphoblast population. All cases expressed CD179a in the end-induction B-lymphoblast population. The CD179a component of the SLC is commonly expressed in B-ALL, regardless of genotype, stage of developmental arrest, or National Cancer Institute risk status.