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S. Mori
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P2.04 - Poster Session/ Biology, Pathology, and Molecular Testing (ID 234)
- Event: WCLC 2015
- Type: Poster
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
- Moderators:
- Coordinates: 9/08/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P2.04-072 - Immunohistochemical PDL1 Expression and Clinicopathological Characteristics in 541 Surgically Resected Non-Small Cell Lung Cancers (ID 2737)
09:30 - 09:30 | Author(s): S. Mori
- Abstract
Background:
Immune-checkpoint therapy targeting programmed cell death protein 1 (PD1) and programmed cell death protein ligand1 (PD-L1, PDL1, CD274) has been emerging as a new therapeutic strategy for patients with cancer. PDL1 binding to PD1 expressing on the surface of T-cell suppresses activation and proliferation of T-cell. Many types of cancer frequently overexpress PDL1 and escape the immune system. PDL1 expression of tumors may be a useful marker of responsibility for the immune-checkpoint therapy targeting for PDL1. However, the incidence of PDL1 positive cases and related patients’ characteristics among NSCLC is still unclear. The aim of this study is to clarify these unsolved questions.
Methods:
The 541 surgically resected non-small cell lung cancers (NSCLC) between 1994 and 2014 were recruited as following criteria; including primary lung cancer, excluding pathological incomplete resection, limited resection, in-situ carcinoma, small-sized carcinoma, large cell neuroendocrine carcinoma, pleomorphic carcinoma, synchronous or metachronous multiple cancer and metastatic cancer. Tissue microarrays (TMA) were constructed using formalin-fixed paraffin embedded (FFPE) tumor specimen of each representative histologic area. Patients’ characteristics and outcomes were collected from medical chart. The PDL1 expression was evaluated by immunohistochemistry (IHC) using anti-CD274 (PDL1) antibody (Clone ERP1161 (2), Abcam) as primary antibody on 4-micrometer-thick TMA specimen by an auto-staining machine. The results of IHC were evaluated by microscopy and scored with a combination of intensity and proportion. The intensity was defined as negative: 0, weakly positive: 1+, strongly positive: 2+), the proportion was defined positive cell percentage with 10% increments. Based on PDL1 score defined as ∑ [intensity (0, 1, 2) x proportion of each intensity], the tumors were divided as PDL1 positive group (score >50) and PDL1 negative group (score ≤50). We compared between two groups in clinicopathological characteristics and prognosis.
Results:
541 NSCLCs were classified into PDL1 positive (n = 171, 32%) and negative group (n = 370, 68%). The PDL1 positive group was significantly less differentiated (p < 0.001), higher rate of lymphatic (p = 0.010), vascular invasion (p = 0.036), lymph node metastasis (pN1-3) (p = 0.012), and advanced pStage (p = 0.002) compared to negative group. There were no significant differences in sex, age, smoking habit, tumor size, pT factor, and distribution of histological types between two groups. Although the prognostic analysis showed no difference between PDL1 positive vs negative groups (p = 0.861), the histology-based stratification analysis revealed that PDL1 positive squamous cell carcinoma (SqCC, n=28) showed better overall survival rate compared to PDL1-negative SqCC (n=53) (p = 0.018).
Conclusion:
Our data indicated that the PDL1 positive NSCLCs had worse pathological factors, including tumor differentiation, lymphovascular invasion, pN, and pStage, but did not show a statistically significant difference in terms of overall survival rate compared to PDL1-negative group. It is of interest that PDL1 positive SqCC showed a better prognosis than PDL1 negative SqCC.
