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E. Servais

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    O08 - Preclinical Therapeutic Models I (ID 92)

    • Event: WCLC 2013
    • Type: Oral Abstract Session
    • Track: Biology
    • Presentations: 1
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      O08.02 - Critical Role of CD28 Costimulation in Tumor-Targeted T-cell Therapy Clinical Trial for Pleural Malignancies (ID 2995)

      16:15 - 17:45  |  Author(s): E. Servais

      • Abstract
      • Presentation
      • Slides

      Successful translation of adoptive T-cell therapy for solid cancers is predicated on the ability to generate a potent antitumor immune response and establish T-cell persistence. Thoracic malignancies typically lack expression of costimulatory ligands but do express negative regulators of T- cell function—factors that may impede T-cell therapy. We hypothesized that cancer antigen–targeted T cells engineered with activating CD28 costimulatory signaling would eradicate tumor and establish long-term functional persistence.

      Mesothelin-specific chimeric antigen receptors (CARs) were engineered without (Mz) or with (M28z) a CD28 costimulatory domain. CAR-transduced human T cells were evaluated in vitro for cytotoxicity ([51]Cr-release assay), cytokine release (Luminex cytokine-release assay), and proliferation (cell-counting assay). In vivo assessment included monitoring of tumor progression by bioluminescence imaging (BLI), flow cytometric analysis of splenic/peripheral blood T-cell phenotypes, and Kaplan-Meier analysis of median survival, in NOD-scid IL-2Rγ-null mice bearing orthotopically implanted mesothelin-expressing mesothelioma cells (MSTO-211H: CD80/86-, TGF-β+, PD-L1+) and treated with human T cells transduced to express either Mz, M28z, or a control vector.

      In vitro, M28z CAR–transduced T cells exhibited equivalent cytotoxicity but enhanced Th1 cytokine secretion and antigen-specific proliferation, compared with Mz transduced T cells. In vivo, mice treated with a single low dose of M28z CAR–transduced T cells achieved tumor eradication and prolonged survival (median survival not reached; p=0.01), compared with mice treated with an equal dose of Mz-transduced (median survival, 63 days; tumor eradication in 20% of mice) or control CAR–transduced (median survival, 36 days) T cells (Figure 1A, 1B). Furthermore, CD28 costimulation enhanced CD62L[-]CD45RA[-] effector memory T-cell persistence (Figure 1C), leading to a robust T-cell proliferative response and superior control of tumor burden on tumor rechallenge 87 days after T-cell administration (Figure 1D, 1E). Figure 1

      CD28 costimulation plays an important role in achieving long-term antitumor efficacy and functional persistence in mesothelin-targeted T-cell therapy. These data provide the scientific rationale for our upcoming clinical trial for pleural malignancies.

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