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T. Igarashi
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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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P2.04-070 - Immunological Characterization of PD-L1-Positive Non-Small Cell Lung Cancer Cells (ID 3077)
09:30 - 09:30 | Author(s): T. Igarashi
- Abstract
Background:
The expression of programmed cell death-ligand 1 (PD-L1) on tumor cells plays an essential role in the suppression of anti-tumor immune responses, thus resulting in tumor progression. However, pathological features of PD-L1-positive cancer cells in non-small cell lung cancer (NSCLC) remain unclear.To clarify the characteristics of NSCLCs that are eligible for the-PD-L1-targeted immunotherapy, we examined the immunological feature of PD-L1-positive tumor cells by immunohistochemical analysis.
Methods:
We stained serial sections of formalin-fixed paraffin-embedded NSCLC tissues from 34 patients who had undergone surgery using antibodies to PD-L1 or major histocompatibility complex (MHC) class I. We also identified tumor infiltrated lymphocytes (TIL) in the section, and analyzed the association between PD-L1 expression and MHC class I expression on tumor cells or TIL around tumor cells.
Results:
The patients with median age of 68 years (range, 49-79 years) consisted of 25 males and 9 females. Histological types included 23 adenocarcinomas, 8 squamous cell carcinomas, 2 adeno-squamous cell carcinomas and 1 pleomorphic carcinoma. PD-L1 and MHC class I were expressed on tumor cells in 28 (82.3%) and 29 (85.3%) of 34 cases, respectively. In 18 of 34 cases (52.9%), MHC class I-positive tumor cells were dominant in the tumor; whereas MHC class I-negative tumor cells were dominant in 16 of 34 cases (47.1%). PD-L1 expression was observed in 14 of 18 (77.7%) NSCLCs that are dominant with MHC class I-positive tumor cells, whereas it was detected in 4 of 16 (25.0%) those mainly containing MHC class I-negative tumor cells. There was a significant association between PD-L1 and MHC class I expressions on NSCLC cells (p=0.0045). We next examined the association between the co-expression of PD-L1 and MHC class I on tumor cells and the number of TIL, and found that the incidence of PD-L1[+ ]MHC class I[+ ]tumor cells was likely to associate with the large number of TIL (r=0.42). The frequency of PD-L1-positive cells in MHC class I-positive tumor cells was also associated with the large number of TIL (r=0.33).
Conclusion:
MHC class I expression on tumor cells may be required for their expression of PD-L1, probably through the cell-to-cell interaction with TIL. Further study is warranted, however, the patient with the co-expression of PD-L1 and MHC class I on larger number of tumor cells is likely to be a suitable candidate for PD-L1-targeted immunotherapy.
