Multiplex immunohistochemistry/immunofluorescence (mIHC/IF) for PD-L1 testing in triple-negative breast cancer: a translational assay compared with conventional IHC. Issue 9 (22nd January 2020)

• Record Type: Journal Article
• Authors: Yeong, Joe; Tan, Tira; Chow, Zi Long; Cheng, Qing; Lee, Bernett; Seet, Amanda; Lim, Johnathan Xiande; Lim, Jeffrey Chun Tatt; Ong, Clara Chong Hui; Thike, Aye Aye; Saraf, Sahil; Tan, Benjamin, Yong Cheng; Poh, Yong Cheng; Yee, Sidney; Liu, Jin; Lim, Elaine; Iqbal, Jabed; Dent, Rebecca; Tan, Puay Hoon
• Is Part Of: Journal of clinical pathology. Volume 73:Issue 9(2020)
• Page Start: 557
• Page End: 562
• Publication Date: 2020-01-22
• Subjects: breast pathology -- immunohistochemistry -- immunopathology; Pathology -- Periodicals; Pathology, Molecular -- Periodicals; 616.0705
• DOI: 10.1136/jclinpath-2019-206252
• Languages: English
• ISSNs: 0021-9746

Abstract

Abstract : Background: Programmed death-ligand 1 (PD-L1) monoclonal antibody therapy has recently gained approval for treating metastatic triple-negative breast cancer (TNBC) -, in particular in the PD-L1 + patient subgroup of the recent IMpassion130 trial. The SP142 PD-L1 antibody clone was used as a predictive assay in this trial, but this clone was found to be an outlier in previous harmonisation studies in lung cancer. Aims: To address the comparability of PD-L1 clones in TNBC, we evaluated the concordance between conventional immunohistochemistry (IHC) and multiplex immunohistochemistry/immunofluorescence (mIHC/IF) that allowed simultaneous quantification of three different PD-L1 antibodies (22C3, SP142 and SP263). Methods: Our cohort comprised 25 TNBC cases, 12 non-small-cell lung carcinomas and 8 other cancers. EpCAM labelling was used to distinguish tumour cells from immune cells. Results: Moderate-to-strong correlations in PD-L1 positivity were found between results obtained through mIHC/IF and IHC. Individual concordance rates in the study ranged from 67% to 100%, with Spearman's rank correlation coefficient values up to 0.88. Conclusions: mIHC/IF represents a promising tool in the era of cancer immunotherapy, as it can simultaneously detect and quantify PD-L1 labelling with multiple antibody clones, and allow accurate evaluation of tumour and immune cells. Clinicians and pathologists require this information to predict patient response to anti-PD-1/PD-L1 therapy. The adoption of this assay may represent a significant advance in the management of therapeutically challenging cancers. Further analysis and assay harmonisation are essential for translation to a routine diagnostic setting.