Decoding the clonal architecture and function of humoral immunity after immunotherapy in pancreatic adenocarcinoma

Abstract public domain (NIH RePORTER)

PROJECT SUMMARY While most cancer immunotherapy research has historically centered on T cells, growing evidence indicates that tumor-infiltrating B cells and plasma cells play essential and complementary roles in tumor control. These B cell populations can act as antigen-presenting cells, provide immunomodulatory signals, and organize into tertiary lymphoid structures (TLS) that foster germinal centers. Yet despite these emerging insights, the clonal architecture, antigen specificity, and functional consequences of intratumoral antibody responses remain largely unexplored. Additionally, whether TLS act as independent organizers of adaptive immune responses in tumors or synergize with lymph node immunity remains unknown. These gaps in knowledge are important to resolve in solid tumors such as pancreatic ductal adenocarcinoma (PDAC), one of the deadliest human cancers, which shows poor responses to standard therapies. PDAC is characterized by a tumor microenvironment (TME) with sparse immune cell infiltration and a dense desmoplastic stroma, factors that render it resistant to immunotherapies, including immune checkpoint inhibitors. Rare long-term PDAC survivors exhibit higher intratumoral TLS density, supporting the exploration of therapeutic approaches that induce TLS neogenesis to promote favorable outcomes. Neoadjuvant immunotherapy has been shown to remodel the immunosuppressive PDAC microenvironment by inducing TLS with germinal centers that propagate IgG-expressing B cells and plasma cells in pathologic responders, effectively enriching PDAC with hubs of humoral immunity. The central hypothesis of this project is that immunotherapy-induced TLS amplify tumor-draining lymph node immunity by facilitating the local maturation of B cells that secrete antitumor antibodies. A secondary hypothesis is that TLS- derived antibodies actively remodel the tumor stroma to enhance T cell trafficking and facilitate cancer cell clearance. To test these hypotheses, this project will integrate single-cell RNA sequencing, spatial transcriptomics, and proteome-wide antibody profiling to dissect humoral immunity in PDAC with unprecedented resolution, powered by novel computational tools. By recovering paired heavy and light chain sequences from intratumoral B cell clones, this project will generate recombinant monoclonal antibodies and define their epitope specificities using high-throughput antigen display assays. In doing so, the project will not only map the fundamental spatial architecture of tumor-infiltrating B cells but also directly generate novel therapeutic candidates from intratumoral B cell repertoires. By bridging cutting-edge experimental and computational methods, this work will provide a spatiotemporal atlas of humoral immunity in PDAC, establish TLS as engines of antitumor antibody discovery, and deliver candidate antibodies with translational potential. Beyond PDAC, the insights and open-source tools developed by this project will broadly empower cancer immunologists to interrogate humoral immunity across solid tumors, shifting the field toward a more integrated view of adaptive immunity in cancer.

Public health relevance public domain (NIH RePORTER)

PROJECT NARRATIVE This project aims to study how tumor-infiltrating B cells within tertiary lymphoid structures and tumor-draining lymph nodes generate antibodies that remodel the tumor microenvironment in pancreatic cancer following neoadjuvant immunotherapy. By reconstructing therapeutic antibodies from intratumoral B cell repertoires, this work will yield new treatment strategies and biomarkers for pancreatic cancer and other solid tumors.