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J. Wang



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    OA 07 - Biomarker for Lung Cancer (ID 659)

    • Event: WCLC 2017
    • Type: Oral
    • Track: Biology/Pathology
    • Presentations: 1
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      OA 07.02 - Characteristics of Lung Cancer Cell-Free Tumor DNA (CfDNA) Shedding and Correlation with Tumor Burden as Measured by RECIST (ID 9663)

      15:45 - 17:30  |  Author(s): J. Wang

      • Abstract
      • Presentation
      • Slides

      Background:
      cfDNA is a promising biomarker for early recurrence detection and disease monitoring in the NSCLC curative setting. However, less is known about cfDNA shedding characteristics and correlation with tumor burden in advanced NSCLC.

      Method:
      We reviewed cfDNA results of NSCLC patients tested at our institution between November 2015 and December 2016 with Guardant 360, a comprehensive cfDNA assay that detects genomic alterations in 70-73 cancer genes. 141 cases with evaluable imaging were selected for this analysis, enriching for EGFR and KRAS mutated cases to facilitate comparisons of major genomic subtypes (Table 1). Tumor burden was approximated using the sum of longest diameters (SLD), per RECIST v1.1.

      Result:
      There was a statistically significant correlation of moderate strength between cfDNA maximum variant allele frequency (VAF) detected and SLD (Spearman’s rho = 0.35, p < 0.001). This correlation was strongest in KRAS mutant cases (rho = 0.52, p = 0.001) and weakest in EGFR mutated tumors (rho = 0.21, p < 0.24). Multi-variate regression that included stage, histology, and mutation status confirmed the predictive value of cfDNA VAF for SLD (p = 0.03). TP53 mutants had higher cfDNA VAF (Wilcox p < 0.001), even after accounting for SLD. Increased cfDNA VAF was also seen with EGFR mutants and patients with visceral metastasis, though possibly confounded by concomitant EGFR amplification and increased tumor burden, respectively. CNS metastasis was not associated with differential cfDNA shedding. Figure 1



      Conclusion:
      In this primarily metastatic cohort, cfDNA VAF correlated with radiographic assessment of tumor burden by RECIST. This correlation was partially mediated by the presence of key driver mutations. TP53 and EGFR mutant tumors and the presence of visceral metastasis are associated with higher cfDNA VAF. These findings have potential implications for the use of cfDNA in advanced-stage NSCLC disease monitoring, where RECIST is more clinically applicable than formal volumetrics.

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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 - 12:30  |  Author(s): J. Wang

      • 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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    P2.07 - Immunology and Immunotherapy (ID 708)

    • Event: WCLC 2017
    • Type: Poster Session with Presenters Present
    • Track: Immunology and Immunotherapy
    • Presentations: 1
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      P2.07-062b - DNA Damage Repair Targeting Upregulates PD-L1 Level and Potentiates the Effect of PD-L1 Blockade in Small Cell Lung Cancer (ID 9733)

      09:30 - 16:00  |  Author(s): J. Wang

      • Abstract
      • Slides

      Abstract not provided

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    P2.15 - SCLC/Neuroendocrine Tumors (ID 716)

    • Event: WCLC 2017
    • Type: Poster Session with Presenters Present
    • Track: SCLC/Neuroendocrine Tumors
    • Presentations: 1
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      P2.15-016a - Exploiting G2-M Cell Cycle Checkpoint Dependency in Small Cell Lung Cancer (SCLC) by Targeting Checkpoint Kinase 1 (CHK1) (ID 9680)

      09:30 - 16:00  |  Author(s): J. Wang

      • Abstract

      Abstract not provided

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    P3.03 - Chemotherapy/Targeted Therapy (ID 719)

    • Event: WCLC 2017
    • Type: Poster Session with Presenters Present
    • Track: Chemotherapy/Targeted Therapy
    • Presentations: 1
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      P3.03-027 - LKB1 Loss Is Associated with Resistance to Anti-Angiogenic Therapy in Non-Small Cell Lung Cancer Mouse Models (ID 10259)

      09:30 - 16:00  |  Author(s): J. Wang

      • Abstract

      Background:
      LKB1 is a protein kinase that is mutated and down-regulated in 20-30% of non-small cell lung cancer (NSCLC). LKB1 mutations co-occur with KRAS alterations in 7%-10% of NSCLC, resulting in an aggressive phenotype with short survival. Because LKB1 activates AMPK, the master sensor of cellular energy, many of the best known functions of LKB1 are attributed to its ability to control metabolic alterations in the cells. However LKB1 also plays an important role in regulating angiogenesis, likely as a strategy to overcome energetic depletion of tumor microenvironment. Bevacizumab, the human anti-VEGF antibody, improves the PFS and OS of NSCLC patients combined with chemotherapy, but often the benefit is transient and therapeutic resistance occurs. Our laboratory has previously identified alterations in cell metabolism and in vasculature of LKB1-deficient tumors when compared to LKB1 wild type in NSCLC.

      Method:
      LKB1 KO murine NSCLC cell lines were generated using CRISPR/Cas9 system in a KRAS[G12D] mutant background (LKR10 & LKR13). Syngeneic NSCLC models were established via s.c. injection of LKB1 intact and KO murine cells in immunocompetent mice. After tumors reached 150 mm[3] mice were randomly assigned to treatment groups consisting of vehicle, mouse anti-VEGF and nintedanib. Tumor volumes were measured and compared using student’s t test and samples were collected for vasculature analysis. Survival curves will be calculated using log rank test. Hypoxia experiments were preformed and apoptosis was measured using annexin V and 7ADD staining.

      Result:
      Treatment with anti-VEGF or nintedanib significantly inhibited tumor progression in LKB1 wt KRAS[G12D] mutant mouse model (p<0.001) but did not show any therapeutic effect in the LKB1 KO KRAS[G12D] group. Furthermore in the LKB1 wt group, the median survival of anti-VEGF and nintedanib treated mice was 111 days and 84 days respectively and 37 days in the vehicle group. No improvement in survival was detected in the LKB1 KO group after treatment with anti-VEGF. In vitro studies showed that LKB1 loss is associated with a decrease in oxygen consumption and enhanced glycolysis. Furthermore LKB1 KO NSCLC cells showed a decrease in apoptosis under hypoxic and low nutrient conditions compared to LKR13 LKB1 wt cells.

      Conclusion:
      NSCLC LKB1-deficient tumors showed resistance to anti-angiogenic therapy and this effect is driven by the regulation of metabolic adaptations that allow cells to survive under hypoxic and low nutrient conditions.