In a patient with biclonal Waldenstrom macroglobulinemia only one clone expands in three-dimensional culture and includes putative cancer stem cells

Abstract

A small percentage of cases of Waldenstrom macroglobulinemia (WM) present with biclonality, defined here as the rearrangement of two distinct VDJ gene segments. Here we investigated the expansion of two clones from a patient with WM expressing molecularly detectable clonotypic gene rearrangements, one V(H)3 and one V(H)4. Biclonality was determined in blood and bone marrow mononuclear cells using real-time quantitative PCR (RQ-PCR). V(H)4 expressing cells but not V(H)3 expressing cells underwent clonal expansion in 3-D culture of reconstructed WM bone marrow. After 3-D culture, secondary culture in a colony forming unit assay, and RQ-PCR, only the V(H)4 clone was shown to harbor a subpopulation with characteristics of cancer stem cells, including proliferative quiescence, self-regeneration, and the ability to generate clonotypic progeny, suggesting that the V(H)4, but not the V(H)3, clone is clinically significant. Enrichment of potential WM stem cells in 3-D cultures holds promise for monitoring their response to treatment and for testing new therapies.

Clonal Relationship and Mutation Analysis in Lymphoplasmacytic Lymphoma/Waldenström Macroglobulinemia Associated With Diffuse Large B-cell Lymphoma

“…However, in 2 patients the IG‐NGS deep‐sequencing approach provided evidence of >1 malignant B‐cell clone in LPL, showing biclonal LPL as well as dynamic clonal heterogeneity represented possibly by at least 3 malignant B‐cell clones in LPL at distinct anatomical sites. Our findings of detecting multiple B‐cell clones in LPL confirm the observations of others performing clonotypic V(D)J analysis in LPL/WM patients 12–14 . The presence of clonal diversity represented by unrelated B‐cell clones has been observed in several other B‐cell malignancies, including classic Hodgkin lymphoma, 25 multiple myeloma, 44 and chronic lymphocytic leukemia 45 …”

“…Our findings of detecting multiple B-cell clones in LPL confirm the observations of others performing clonotypic V(D)J analysis in LPL/WM patients. [12][13][14] The presence of clonal diversity represented by unrelated B-cell clones has been observed in several other B-cell malignancies, including classic Hodgkin lymphoma, 25 multiple myeloma, 44 and chronic lymphocytic leukemia. 45 To establish the clonal relationship of the consecutive LPL and DLBCL presentations in our LPL/WM cohort, the clonotypes of the malignant B-cell clones identified in the corresponding B-cell lymphomas were compared to each other.…”

“…Our findings of detecting multiple B-cell clones in LPL confirm the observations of others performing clonotypic V(D)J analysis in LPL/WM patients. 12–14 The presence of clonal diversity represented by unrelated B-cell clones has been observed in several other B-cell malignancies, including classic Hodgkin lymphoma, 25 multiple myeloma, 44 and chronic lymphocytic leukemia. 45…”

“…Besides transformation, the occurrence of clonally unrelated DLBCL has been reported in LPL/WM. [7][8][9][10][11] Clonotypic V(D)J analysis has also demonstrated biclonality in a subset of LPL/WM, [12][13][14] but it is still unclear whether these patients are at increased risk of DLBCL development.…”