Multiplex immunohistochemistry/immunofluorescence (mIHC/IF) for PD-L1 testing in triple-negative breast cancer: a translational assay compared with conventional IHC

Abstract

BackgroundProgrammed 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.AimsTo 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).MethodsOur 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.ResultsModerate-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.ConclusionsmIHC/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.

Multiomic analysis and immunoprofiling reveal distinct subtypes of human angiosarcoma

“…On the other hand, by using mIHC/IF, we validated our genetic findings at the protein level by quantifying immune cell subsets such as CD8 + T cells, CD68 + macrophages, FOXP3 + Tregs, and CD15 + neutrophils in the angiosarcoma tissue samples in this cohort. In a direct correlation with the Nano Stringderived data sets, all immune cell subsets were enriched in cluster 3 compared with clusters 2 and 1. mIHC/IF is a powerful tool to study the spatial tumor microenvironment of limited tissue specimens (25)(26)(27)(28)(29)(30)(31) and has shown great potential in clinical and translational applications (32,33). mIHC/IF, which allows for staining of up to 6 markers on a single slide, allows a broader range of analysis compared with IHC.…”

Proteomics of REPLICANT perfusate detects changes in the metastatic lymph node microenvironment

“…Unlike TIL distribution, PD-L1 expression appeared to be uniform in each of the compartments analysed. This may be related to the PD-L1 antibody that we used however 45,46 . Although this clone has been used previously to assess PD-L1 expression in primary and metastatic BC 47 , it is not used routinely for diagnosis.…”

Multiplex immunofluorescence to measure dynamic changes in tumor-infiltrating lymphocytes and PD-L1 in early-stage breast cancer

“…Pre-operative I-O clinical trials in ESBC provide the opportunity to efficiently compare pharmacodynamic activity using serial tissue-based comparative biomarkers, while also providing pathologic outcomes as a meaningful surrogate of disease-free recurrence [34]. mIF has been proposed as a promising biomarker, as it has been shown to be concordant with clinical PD-L1 assays in ESBC [35], and in a recent meta-analysis outperformed clinical PD-L1 testing, quantification of tumor mutational burden, or gene expression profiling in predicting immunotherapy response [36]. Here, we provide additional guidance on how mIF can be used as a pharmacodynamic biomarker in the context of ESBC I-O pre-operative clinical trials.…”