{
  "abstract": "Background B cells are emerging as critical mediators of anti-tumor immunity due to their ability to produce antibodies against tumor-associated antigens. However, B cell-based immunotherapies remain underexplored compared to T cells. Tumor-infiltrating B cells can organize into tertiary lymphoid structures (TLS), lymph node-like aggregates associated with improved survival and treatment response in various cancers. Yet, whether TLS directly contribute to tumor control or reflect bystander immune activity is unclear. Our lab recently discovered that co-activation of stimulator of interferon genes (STING) and lymphotoxin beta receptor (LTβR) using agonists induces TLS with germinal center B cell responses across multiple murine tumor models. This study investigates whether TLS-B cells directly mediate anti-tumor immunity and evaluates the therapeutic potential of TLS-derived antibodies.Methods Murine pancreatic ductal adenocarcinoma cells (KPC) were implanted subcutaneously into syngeneic C57BL/6 or CD79a knockout (KO) mice. Tumors were treated with STING agonist ADU-S100 and anti-LTβR antibody. Tumors were resected 14 days post-treatment. Lymphocytes were isolated, and plasma cells were sorted and fused with Sp2/0 myeloma cells using hybridoma technology. Hybridomas were screened for KPC-specific immunoglobulin G (IgG) binding using flow cytometry and immunofluorescence. Tumor-specific cytotoxicity was evaluated using NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC) assays.Results We show that, in wild type mice, the STING activation improved the fitness of LTβR-induced TLS with B cell maturation to IgG + long-lived plasma cells and memory cells. This treatment reduced the tumor size and heightened the efficacy of anti-PD-1 immune checkpoint inhibition, leading to complete cure. When used as neoadjuvant therapy, it prevented tumor recurrence and metastasis with 100% survival post-tumor rechallenge, indicating the effective immunization against tumors. Functional TLS formed in different tumor types and anatomical sites using this approach (figure 1). Hybridoma clones developed from TLS-B cells of these tumors generated monoclonal IgG antibodies targeting mouse pancreatic cancer cells, which effectively induced NK cell-mediated cytotoxicity (figure 2). In contrast, B cell-deficient CD79a KO mice failed to develop TLS, with markedly reduced high endothelial venules(HEV) in primary tumors. T cell infiltration did not appear to be reduced by the B cell deficiency. However, these mice showed significantly reduced survival (to 40%) after tumor rechallenge, underscoring the importance of TLS-B cells for coordinated anti-tumor immune responses.Conclusions Co-targeting STING and LTβR induces functional TLS and HEV that support B cell activation and antibody production within tumors. TLS-derived monoclonal antibodies exhibit potent tumor specificity and cytotoxicity. This approach offers a promising immunotherapy strategy for immune-cold tumors resistant to conventional treatments.Abstract 882 Figure 1STING+LTβR therapy induces intratumoral B cell-rich TLS and HEVs in pancreatic tumors, enhancing antitumor immunity and survival, and supporting TLS-derived IgG binding to KPC tumor cellsAbstract 882 Figure 2STING+LTβR therapy expands intratumoral B cell subsets and Ig isotypes. TLS-derived hybridoma antibodies bind KPC tumor cells, and hybridoma IgG clones show tumor specificity, supporting humoral contributions to antitumor immunity",
  "authors": [
    {
      "affiliations": [
        "Johns Hopkins All Children Hospital, Saint Petersburg, FL, USA",
        "Johns Hopkins School of Medicine, Saint Petersburg, FL, USA"
      ],
      "name": "Maxwell Duah"
    },
    {
      "affiliations": [
        "Johns Hopkins All Children Hospital, Saint Petersburg, FL, USA",
        "Johns Hopkins School of Medicine, Baltimore, MD, USA"
      ],
      "name": "Yasuhiro Kikuchi"
    },
    {
      "affiliations": [
        "Johns Hopkins All Children Hospital, Saint Petersburg, FL, USA",
        "Johns Hopkins School of Medicine, Baltimore, MD, USA"
      ],
      "name": "Fumiaki Kanamori"
    },
    {
      "affiliations": [
        "Johns Hopkins All Children Hospital, Saint Petersburg, FL, USA"
      ],
      "name": "Tomoko Stansel"
    },
    {
      "affiliations": [
        "Johns Hopkins All Children Hospital, Saint Petersburg, FL, USA",
        "Johns Hopkins School of Medicine, Baltimore, MD, USA"
      ],
      "name": "Shahidul Islam"
    },
    {
      "affiliations": [
        "Johns Hopkins All Children Hospital, Saint Petersburg, FL, USA",
        "Johns Hopkins School of Medicine, Baltimore, MD, USA"
      ],
      "name": "Gabrielle Brown"
    },
    {
      "affiliations": [
        "Johns Hopkins All Children Hospital, Saint Petersburg, FL, USA",
        "Johns Hopkins School of Medicine, Baltimore, MD, USA"
      ],
      "name": "Masanobu Komatsu"
    }
  ],
  "title": "882 Intratumoral B cells are essential for anti-tumor immune responses of tertiary lymphoid structures: impact of STING and LTβR activation in pancreatic cancer",
  "uid": "b94a5fc1-bbee-54a1-a374-c7fb2909b96d"
}