59P - Characterization of PD-L1 expression in Chinese non-small cell lung cancer patients with PTEN IHC as a means for sample quality screening

Date 17 December 2016
Event ESMO Asia 2016 Congress
Session Poster lunch
Topics Lung and other Thoracic Tumours
Presenter Xu-chao Zhang
Citation Annals of Oncology (2016) 27 (suppl_9): ix9-ix18. 10.1093/annonc/mdw574
Authors X. Zhang1, C. Sun2, Z. Xie1, X. Cao2, J. Guo2, J. Yang3, X. Yang1, H. Dai4, J. Lee4, F. Xu4, Y. Zuo4, M. Chen4, J. He5, A. Kiermaier6, D. Shames7, G. Cheng2, Y. Wu1
  • 1Guangdong Lung Cancer Institute, Guangdong General Hospital, 510080 - Guangzhou/CN
  • 2Oncology Biomarker Development, Genentech, Inc., 201203 - Shanghai/CN
  • 3Guangdong Lung Cancer Institute, Guangdong General Hospital, 510000 - Guangzhou/CN
  • 4Roche Product Development In Asia Pacific, Roche (China) Holding, Ltd., 201203 - Shanghai/CN
  • 5Oncology Product Development, Genentech, Inc., 94080 - San Francisco/US
  • 6Oncology Biomarker Development, Genentech, Inc., 4070 - Basel/CH
  • 7Oncology Biomarker Development, Genentech, Inc., 94080 - San Francisco/US

Abstract

Background

Cancer immunotherapy agents blocking the receptor and/or ligand of the programed death-1 (PD-1) pathway have demonstrated encouraging clinical utility in patients with non-small cell lung cancer (NSCLC). This study aimed to evaluate PD-L1 prevalence and its association with major clinical characteristics in Chinese patients with NSCLC.

Methods

Formalin-fixed, paraffin-embedded (FFPE) surgical NSCLC samples from ∼300 Chinese patients (the exploratory cohort) were assembled into tissue microarray format. These samples were first stained for PTEN expression through immunohistochemistry (IHC) which serves as a surrogate for tissue quality. Only the ones with at least moderate staining intensity on internal positive control cells (e.g., stromal cells) were considered qualified for PD-L1 IHC with Clone SP142. PD-L1 expression was evaluated on both tumor cells (TCs) and immune cells (ICs). The results were correlated to baseline characteristics and clinical outcomes on standard-of-care treatment regimen.

Results

PTEN IHC showed that ∼110 samples in the exploratory cohort qualified for PD-L1 IHC. With the TC1/IC1 (≥ 1% of all TCs or all ICs express PD-L1) cut-off, 41.7% of these samples were PD-L1+. Clinical characteristics including gender, age, smoking status and disease stage do not correlate with PD-L1 expression. However, EGFR mutant patients seem to have lower PD-L1 level than wild-type patients (18.8% vs. 44.0%, p = 0.083). Moreover, PD-L1 level seems to be a favorable prognostic factor for both overall survival (OS) [HR = 0.58, 95% CI (0.33, 1.03)] and recurrence-free survival (RFS) [HR = 0.55, 95% CI (0.32, 0.93)]. The PTEN-IHC-disqualified samples showed much lower PD-L1 positive rate (12.5%). The correlation between PD-L1 level and EGFR mutation status, OS or RFS was also significantly diminished.

Conclusions

In this study, PD-L1 expression was detected in ∼40% of PTEN-IHC-qualified Chinese NSCLC patient samples and negatively correlated with EGFR mutation. PD-L1 level was found to be a favorable prognostic factor for both OS and RFS. These findings are being verified in a separate cohort of ∼150 Chinese NSCLC samples (the validation cohort).

Clinical trial indentification

Legal entity responsible for the study

Guangdong General Hospital

Funding

Roche (China) Holding, Ltd.

Disclosure

All authors have declared no conflicts of interest.