{
  "abstract": "Background Adoptive cell therapy using tumor infiltrating lymphocytes (TIL) is approved for treatment of advanced melanoma. However, the success of TIL therapy is dependent on the proliferative potential and tumor-reactivity of TIL and is limited to patients with resectable tumors. Malignant pleural effusions may represent a more accessible source of tumor-reactive T cells. Here, we comprehensively profiled the cellular composition and phenotype of T cells in tumor and in pleural fluid from a patient undergoing TIL therapy.Methods T cells from a pleural metastasis and pleural effusion were synchronously collected from a patient with metastatic cutaneous melanoma, and profiled using spectral flow cytometry, single-cell RNA sequencing (scRNA-seq), and single-cell T cell receptor sequencing (scTCR-seq). Circulating cells were also profiled for comparison ( figure 1).Results CD3 + T cells comprised a higher percentage of CD45+ cells in pleural fluid compared to tumor (70.5% vs 50%) and were enriched for CCR7–CD45RA– effector memory (58.1% of CD8+) and CCR7–CD45RA+ (28.5%) CD8+ T cells. Pleural fluid also had a higher proportion of CX3CR1+KLRG1+ CD8+ T cells compared to tumor (5.65% vs. 2.36%) and lower levels of co-inhibitory receptor (PD-1, TIGIT, TIM3) expression on T cells, suggesting an activated but less terminally exhausted state (figure 1A). By scRNA-seq we analyzed 2,900 high quality T cells from the metastatic deposit, 2,786 from pleural fluid and 2,262 from peripheral blood. The phenotypic composition of T cell states was overall consistent with the immunophenotyping analysis. Pseudo-time trajectory analysis indicated that pleural fluid derived T cells had fewer features of exhaustion than those from tumor (figure 1B). Although T cells from tumor showed a greater degree of clonal expansion, most expanded clonotypes identified in the metastatic sample were also present in the pleural fluid and rarely detected in the blood. Notably, clonally-related, neoantigen-reactive T cells exhibited a less exhausted state in the pleural fluid than the tumor (figure 1C).Conclusions Malignant pleural effusions are enriched for clonally expanded, activated T cells, which highly overlap with predicted neoantigen-reactive T cells in metastases. Importantly, malignant pleural effusion-derived T cells exhibit lower exhaustion signatures and may represent an alternative source for TIL therapies.Ethics Approval The study approved by the Yale Institutional Review Board (IRB #s 0608001773) and participants gave informed consent as required by the IRB.Consent Written informed consent was obtained from the patient for publication of this abstract and any accompanying images. A copy of the written consent is available for review by the Editor of this journalAbstract 381 Figure 1Study design and results",
  "authors": [
    {
      "affiliations": [
        "Yale University, New Haven, CT, USA"
      ],
      "name": "Noam Savion Gaiger"
    },
    {
      "affiliations": [
        "Yale School of Medicine, New Haven, CT, USA"
      ],
      "name": "Jack Coburn"
    },
    {
      "affiliations": [
        "Yale Cancer Center, New Haven, CT, USA"
      ],
      "name": "Lin Zhang"
    },
    {
      "affiliations": [
        "Yale School of Medicine, New Haven, CT, USA"
      ],
      "name": "Natalia Nolan"
    },
    {
      "affiliations": [
        "Yale School of Medicine, New Haven, CT, USA"
      ],
      "name": "Gavitt Woodard"
    },
    {
      "affiliations": [
        "Yale Cancer Center, New Haven, CT, USA"
      ],
      "name": "Harriet M Kluger"
    },
    {
      "affiliations": [
        "Yale Cancer Center, New Haven, CT, USA"
      ],
      "name": "Benjamin Y Lu"
    },
    {
      "affiliations": [
        "Yale Cancer Center, New Haven, CT, USA"
      ],
      "name": "David A Schoenfeld"
    }
  ],
  "title": "381 Tumor reactive T cells may be harvested from malignant pleural effusions",
  "uid": "2018c1da-bc11-5ee1-885e-537625a5365c"
}