Diversification and shared features of tumor-binding antibody repertoires in tumor, sentinel lymph node and blood of three patients with breast cancer

Abstract

Objectives: B cell-mediated immunity can be associated with favorable clinical outcomes in cancer patients. However, the mechanism and features of anti-tumor immune responses are not well understood. In particular, how B cells expressing tumor-specific antibodies are distributed (in the tumor vs. the circulation) has not been well defined. Methods: We performed an in-depth analysis of B cell antibody repertoires derived from the tumor, sentinel lymph nodes and peripheral blood of three treatment-naïve patients with breast cancer. We integrated transcriptional analysis, next-generation sequencing of immunoglobulin heavy-chain gene rearrangements and phage display to define B cell responses and clonal architecture in the tumor microenvironment, and to identify antibodies against autologous tumor tissues. Results: B cell clonal lineage mapping across sequencing libraries generated from the tumor, sentinel lymph node and blood revealed that some expanded B cell clones overlap between tumor and lymph node, and fewer clones overlapped with the peripheral blood. Notably, tumor-associated or tumor-binding clones recovered in the phage panning and tracked back through the tissues harboured extensive somatic hypermutations in both the tumor and the lymph node. Conclusions: These findings suggest an evolving humoral immune response that targets the tumor and the possibility of monitoring B cell clones of interest in blood after identifying them in tumor or lymph node samples. Studying the dynamics and specificity of B cell responses may provide insights into the characteristics of successful anti-tumor immunity, provide a means for monitoring therapy and yield novel targets for personalised therapies.