Visualization of leukemic B cell clonal dynamics during therapy using tSNE.

Abstract

Abstract Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of CD19+ CD5+ clonal B lymphocytes in the blood, bone marrow, and peripheral lymphoid organs. Many patients with CLL never receive treatment for the leukemia and therapy is typically only initiated upon progression of disease-related clinical complications. Treatment options for progressing patients range from chemoimmunotherapy (CIT) to small molecule inhibitors that target pro-survival signaling pathways in leukemic B cells, such as the BTK inhibitor ibrutinib. Although therapy regimens have improved, there is still no cure for CLL, in part due to clonal evolution of the leukemic B cell. The goal of this study is to document the clonal dynamics of CLL B cells at baseline and at response evaluation(s) for alterations in clonal architecture and expression of cell surface markers associated with therapy resistance using the single cell flow cytometry analysis tool, t-distributed stochastic neighbor embedding (t-SNE). Biobanked peripheral blood mononuclear cells were obtained from patients that underwent frontline CIT or ibrutinib, or secondary ibrutinib therapy. Fourteen parameter flow cytometry was performed and subjected to tSNE analysis to document CLL B cell clonal architecture and evolution in patients undergoing the various therapies. Profound differences in treatment responses and leukemic cell clonal dynamics were observed which may inform the discovery of novel biomarkers associated with therapy resistance.