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X. Qin



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    OA 13 - Immuno-Biology (ID 677)

    • Event: WCLC 2017
    • Type: Oral
    • Track: Immunology and Immunotherapy
    • Presentations: 1
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      OA 13.01 - CD38-Mediated Immunometabolic Suppression as a Mechanism of Resistance to PD-1/PD-L1 Axis Blockade (ID 10157)

      11:00 - 11:10  |  Author(s): X. Qin

      • Abstract
      • Presentation
      • Slides

      Background:
      Although immune checkpoint inhibitors of the PD-1/PD-L1 axis provide significant clinical benefit for patients with lung cancer, effective use of these agents is encumbered by a high rate of primary or acquired resistance. Strategies for optimal therapeutic application of immunotherapy require a thorough understanding of resistance mechanisms. To date, there have been only a few studies reporting potential mechanisms of resistance to PD-1/PD-L1 blockade.

      Method:
      In multiple immunocompetent syngeneic and spontaneous animal models of K-ras/p53 mutant lung cancer, we explored the resistance mechanisms to PD-1/PD-L1 blockade using both pharmacologic and genetic approaches (therapeutic antibody treatment and CRISPR/Cas9-mediated editing). The molecular and immune profiles of the tumor microenvironment were evaluated. Additionally, to determine the applicability to patients with lung cancer, we analyzed 259 tumor specimens with IHC staining and mRNA expression, and further confirmed the analyses in publically-available TCGA datasets.

      Result:
      In multiple models of antibody blockade and genetic knockout of PD-L1, we identified the up-regulation of CD38 on tumor cells as a marker of treatment resistance. Furthermore, by manipulating CD38 on a panel of lung cancer cell lines we demonstrated in vitro and in vivo that CD38 expression inhibits CD8[+] T cell proliferation, anti-tumor cytokine secretion, and tumor cell killing capability. The T cell suppressive effect is dependent upon the ectoenzyme activity of CD38 that regulates the extracellular levels of adenosine. To test whether CD38 blockade might be therapeutically efficacious to prevent anti-PD-L1/PD-1 resistance, we applied combination therapy with anti-CD38 and anti-PD-L1 and demonstrated dramatic therapeutic benefit on primary tumor growth and metastasis. Additionally, in a set of 259 resected lung cancer specimens, ~15% exhibited positive staining for CD38 on tumor cells, and the expression correlated with cytolytic T cell score and an immune/inflammatory signature across multiple large datasets.

      Conclusion:
      CD38 was found to be a novel mechanism for tumor escape from immune checkpoint PD-1/PD-L1 inhibitor therapy. Targeting this resistance pathway may broaden the benefit of PD-L1/PD-1 axis blockade for lung cancer treatment.

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