Use of the 22C3 anti-PD-L1 antibody to determine PD-L1 expression in multiple automated immunohistochemistry platforms.

Marius Ilie,Lingkang Huang,Christiane Copie-Bergman,Paul Hofman,Veronique Hofman,Shirin Khambata-Ford,Jonathan Juco,Giancarlo Troncone

doi:10.1371/journal.pone.0183023

Abstract

BackgroundFor non–small cell lung cancer (NSCLC), treatment with pembrolizumab is limited to patients with tumours expressing PD-L1 assessed by immunohistochemistry (IHC) using the PD-L1 IHC 22C3 pharmDx (Dako, Inc.) companion diagnostic test, on the Dako Autostainer Link 48 (ASL48) platform. Optimised protocols are urgently needed for use of the 22C3 antibody concentrate to test PD-L1 expression on more widely available IHC autostainers.MethodsWe evaluated PD-L1 expression using the 22C3 antibody concentrate in the three main commercially available autostainers Dako ASL48, BenchMark ULTRA (Ventana Medical Systems, Inc.), and Bond-III (Leica Biosystems) and compared the staining results with the PD-L1 IHC 22C3 pharmDx kit on the Dako ASL48 platform. Several technical conditions for laboratory-developed tests (LDTs) were evaluated in tonsil specimens and a training set of three NSCLC samples. Optimised protocols were then validated in 120 NSCLC specimens.ResultsOptimised protocols were obtained on both the VENTANA BenchMark ULTRA and Dako ASL48 platforms. Significant expression of PD-L1 was obtained on tissue controls with the Leica Bond-III autostainer when high concentrations of the 22C3 antibody were used. It therefore was not tested on the 120 NSCLC specimens. An almost 100% concordance rate for dichotomized tumour proportion score (TPS) results was observed between TPS ratings using the 22C3 antibody concentrate on the Dako ASL48 and VENTANA BenchMark ULTRA platforms relative to the PD-L1 IHC 22C3 pharmDx kit on the Dako ASL48 platform. Interpathologist agreement was high on both LDTs and the PD-L1 IHC 22C3 pharmDx kit on the Dako ASL48 platform.ConclusionAvailability of standardized protocols for determining PD-L1 expression using the 22C3 antibody concentrate on the widely available Dako ASL48 and VENTANA BenchMark ULTRA IHC platforms will expand the number of laboratories able to determine eligibility of patients with NSCLC for treatment with pembrolizumab in a reliable and concordant manner.

Highlights

Pembrolizumab is a humanised monoclonal antibody that targets programmed death 1 (PD1), a negative co-stimulatory receptor expressed on the surface of activated T cells that can be exploited by tumours to evade T-cell–induced anti-tumour activity [1,2,3]
An almost 100% concordance rate for dichotomized tumour proportion score (TPS) results was observed between TPS ratings using the 22C3 antibody concentrate on the Dako Autostainer Link 48 (ASL48) and VENTANA BenchMark
Pembrolizumab is currently approved as a monotherapy in >60 countries for one or more of the following indications: unresectable or metastatic melanoma; metastatic non–small cell lung cancer (NSCLC) with programmed death ligand 1 (PD-L1) expression and disease progression on or after platinum-containing chemotherapy; metastatic NSCLC with high PD-L1 expression and no prior systemic chemotherapy; recurrent or metastatic head and neck squamous cell carcinoma with disease progression on or after platinum-containing chemotherapy; adult and paediatric refractory classical non-Hodgkin’s lymphoma; cisplatin-ineligible metastatic urothelial carcinoma; and microsatellite-instability–high solid tumours

Summary

Introduction

Pembrolizumab is a humanised monoclonal antibody that targets programmed death 1 (PD1), a negative co-stimulatory receptor expressed on the surface of activated T cells that can be exploited by tumours to evade T-cell–induced anti-tumour activity [1,2,3]. Pembrolizumab is currently approved as a monotherapy in >60 countries for one or more of the following indications: unresectable or metastatic melanoma; metastatic NSCLC with PD-L1 expression and disease progression on or after platinum-containing chemotherapy; metastatic NSCLC with high PD-L1 expression and no prior systemic chemotherapy; recurrent or metastatic head and neck squamous cell carcinoma with disease progression on or after platinum-containing chemotherapy; adult and paediatric refractory classical non-Hodgkin’s lymphoma; cisplatin-ineligible metastatic urothelial carcinoma; and microsatellite-instability–high solid tumours It is approved in combination with pemetrexed and carboplatin as a first-line treatment for patients with metastatic non-squamous NSCLC [5,6]. Optimised protocols are urgently needed for use of the 22C3 antibody concentrate to test PD-L1 expression on more widely available IHC autostainers

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Results

Conclusion