Training and interpretation

Programmed cell death ligand-1 (PD-L1) testing and scoring of tumour cells (TCs) and tumour infiltrating immune cells (ICs) should be performed by trained pathologists.1-3

It is expected that pathologists undertake relevant training on the diagnostic PD-L1 immunohistochemistry (IHC) assay and understand the expected staining profile.4, 5 Inter-observer variability in PD-L1 staining interpretation should be strictly monitored; it is recommended that a minimum concordance rate of 90% is achieved.4, 5


The issue of borderline PD-L1 expression interpretation

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Professor Keith Kerr (University of Aberdeen, Aberdeen, UK) discusses the interpretation of borderline PD-L1 assay outcomes.

When performing PD-L1 testing, always refer to the relevant diagnostic interpretation manual:

Training tools, programmes and videos

PD-L1 e-trainer tool

The PD-L1 e-trainer tool below is an interactive application designed to allow pathologists to understand PD-L1 scoring and interpretation of tumour samples (non-small cell lung cancer [NSCLC] and urothelial carcinoma [UC]) that have been stained with approved PD-L1 IHC assays.

Also refer to the associated fact sheet for further information on the tool.

Registration is required to access the full PD-L1 e-trainer tool; please contact your local AstraZeneca representative for more information on current and future training opportunities.

To view the PD-L1 e-trainer tool in a new window, please click here

Training programmes

The VENTANA Pathology Education portal contains various online courses to aid in the interpretation of PD-L1 sections stained with the SP142 and SP263 assays.

Targos, a company dedicated to developing biomarker standardisation practices, offer advanced training and consulting for pathologists and technicians.

The PD-L1 IHC 22C3 pharmDx Interpretation Training Program provides information on understanding the core principles of PD-L1 pathology, evaluating and scoring stained samples for PD-L1 expression.

PD-L1 IHC 28-8 pharmDx Interpretation Training involves the use of a virtual microscope to evaluate samples (non-small cell lung cancer [NSCLC], squamous cell carcinoma of the head and neck and urothelial carcinoma) stained with PD-L1 IHC 28-8 pharmDx.

Training videos

VENTANA PD-L1 (SP263) NSCLC Assay Overview

Video runtime: 0.31 secs

In this introductory educational module, Dr Dorothy Hayden (Pathologist, Roche Companion Diagnostics), provides an overview of the VENTANA SP263 assay for staining NSCLC samples.

VENTANA PD-L1 (SP263) NSCLC Assay Evaluation

Video runtime: 0.31 secs

This module provides more detail on NSCLC sample evaluation following staining with the VENTANA PD-L1 SP263 assay.

VENTANA PD-L1 (SP263) NSCLC Assay Guided Digital Case Review

Video runtime: 0.31 secs

In this concluding module, Dr Hayden provides an in-depth, guided digital case review of samples stained with the VENTANA PD-L1 SP263 assay.

  1. Roche. VENTANA PD-L1 (SP263) Assay package insert. 2020. Available from: Accessed: 5 October 2020
  2. Roche. VENTANA PD-L1 (SP142) Assay package insert (FDA). 2016. Available from: Accessed: 15 May 2020
  3. Dako. PD-L1 IHC 22C3 pharmDx package insert (FDA). 2018. Available from: Accessed: 15 May 2020


  1. Cree IA, Booton R, Cane P, et al. PD-L1 testing for lung cancer in the UK: recognizing the challenges for implementation. Histopathology 2016;69:177–186
  2. Cheung CC, Barnes P, Bigras G, et al. Fit-for-purpose PD-L1 biomarker testing for patient selection in immuno-oncology: guidelines for clinical laboratories from the Canadian Association of Pathologists-Association Canadienne Des Pathologistes (CAP-ACP). Appl Immunohistochem Mol Morphol 2019;27:699–714