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Z. Xie



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    JCES01 - Joint IASLC - Chinese Society for Clinical Oncology - Chinese Alliance Against Lung Cancer Session (ID 413)

    • Event: WCLC 2016
    • Type: Joint Chinese / English Session
    • Track:
    • Presentations: 2
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      JCES01.18 - Dual Positive PD-L1 and CD8+ TIL Represents a Predominant Subtype in NSCLC and Correlates with Augmented Immunogenicity (ID 7060)

      Z. Xie

      • Abstract
      • Slides

      Background:
      Recent studies have identified that the degree of tumor infiltrating lymphocyte (TIL) infiltration and PD-L1 expression in the tumor microenvironment (TME) are significantly correlated with the clinical outcomes of anti-PD-1/PD-L1 therapies. Here we conducted this study to verify the distribution of PD-L1/CD8[+] TIL expression and its clinical significance in non-small cell carcinoma (NSCLC). Potential mechanism predicted for PD-1 blockade was explored in depth as well.

      Methods:
      Immunohistochemistry was performed to detect PD-L1 and CD8 expression in NSCLC. The Kaplan–Meier (KM) survival curve was used to estimate disease free survival (DFS) and overall survival (OS). Gene Set Enrichment Analysis (GSEA) was used to determine potentially relevant gene expression signatures.

      Results:
      288 cases with stage I-IIIA NSCLC were evaluated for PD-L1 and CD8+ TIL staining. Dual positive PD-L1 and CD8 (PD-L1+/CD8+) represents a predominant subtype in NSCLC, accounting for 36.5% (105/288), followed by PD-L1-/CD8- (24.3%, 70/288), PD-L1-/CD8+ (26.0%, 75/288) and PD-L1+/CD8- (13.2%, 38/288). Survival analysis of DFS (p=0.031) and OS (p=0.002) showed a significant difference between four subgroups. Furthermore, we analyzed the correlation between expression types of PDL1/CD8 and mutation burden and angtigen presentation. We can identified dual positive PD-L1 and CD8 was significant with increased mutation burden (p<0.001), high frequency of mismatch repair (MMR) related gene mutation. More interestingly, tumor with dual positive PD-L1 and CD8 manifested a remarkable activated angtigen presentation and T cell receptor signature compared with other subgroups.

      Conclusion:
      Dual positive PD-L1 and CD8 was identified as a predominant subtype in NSCLC and correlates with increased immunogenicity. These findings provide the evidence that combined analysis of PD-L1 and CD8 in NSCLC may be a promising way to predict PD-1 blockade immunotherapy.

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      JCES01.24 - Molecular Mechanism of Transformation from Adenocarcinoma to Small-Cell Lung Cancer after EGFR-TKI (ID 7066)

      Z. Xie

      • Abstract
      • Slides

      Background:
      In patients with advanced non–small-cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) activating mutations, EGFR-tyrosine kinase inhibitors (TKIs) are recommended as first-line treatment due to favorable clinical efficacy. However, acquired resistance inevitably develops after median progression-free survival (PFS) of 9-14 months. Among the mechanisms of acquired resistance, small-cell lung cancer (SCLC) transformation was reported to account for nearly 5%. However, the molecular details underlying this histological change and resistance to EGFR-TKI therapy remain unclear.

      Methods:
      15 out of 233 (6.4%) patients were confirmed to develop SCLC transformation after failure to EGFR-TKI. We analyzed the clinical parameters of these patients by using chi-square test and Kaplan-Meier analysis. To explore gene alterations that might contribute to SCLC transformation, next generation sequencing (NGS) was performed on four pairs of matched pre- and post-transformation tumor tissue samples. We further performed NGS on 11 matched circulating tumor DNA (ctDNA) to explore the potential mechanism of resistance to EGFR-TKI.

      Results:
      The median age of SCLC transformed patients was 53 years. 93.3% (14/15) patients harbored EGFR exon19 deletion. The median PFS and overall survival (OS) of SCLC-transformed patients treated with EGFR-TKI compared to those without transformation were 11.7 versus 11.9 months (P=0.473) and 29.4 versus 24.3 months (P=0.664), respectively. All 4 patients developed loss of heterozygosity of TP53/RB1 after transformation. Besides, increased copy number of five proto-oncogenes were identified in post-transformation tissue samples. Three patients developed EGFR T790M mutation in the post-transformation ctDNA rather than their tissue samples.

      Conclusion:
      SCLC transformation was commonly seen in patients harboring EGFR exon 19 deletion. The clinical outcomes of TKI and OS in SCLC transformed patients were similar to non-transformed patients. The loss of heterozygosity of TP53 and RB1along with increased copy number of proto-oncogenes may lead to the SCLC transformation. The mechanisms of acquired resistance to TKI during SCLC transformation might be the emergence of classic drug resistance mutations, which was undetectable due to the intra-tumor heterogeneity.

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