PD-L1 testing and squamous cell carcinoma of the head and neck: A multicenter study on the diagnostic reproducibility of different protocols

Simona Crosta, Renzo Boldorini, Francesca Bono, Virginia Brambilla, Emanuele Dainese, Nicola Fusco, Andrea Gianatti, Vincenzo L’Imperio, Patrizia Morbini, Fabio Pagni

Research output: Contribution to journalArticlepeer-review

Abstract

Immune checkpoint inhibitors for blocking the programmed cell death protein 1 (PD- 1)/programmed death-ligand 1 (PD-L1) axis are now available for squamous cell carcinoma of the head and neck (HNSCC) in relapsing and/or metastatic settings. In this work, we compared the resulting combined positive score (CPS) of PD-L1 using alternative methods adopted in routine clinical practice and determined the level of diagnostic agreement and inter-observer reliability in this setting. The study applied 5 different protocols on 40 tissue microarrays from HNSCC. The error rate of the individual protocols ranged from a minimum of 7% to a maximum of 21%, the sensitivity from 79% to 96%, and the specificity from 50% to 100%. In the intermediate group (1 ≤ CPS < 20), the majority of errors consisted of an underestimation of PD-L1 expression. In strong expressors, 5 out of 14 samples (36%) were correctly evaluated by all the protocols, but no protocol was able to correctly identify all the “strong expressors”. The overall inter-observer agreement in PD-L1 CPS reached 87%. The inter-observer reliability was moderate, with an ICC of 0.774 (95% CI (0.651; 0.871)). In conclusion, our study showed moderate interobserver reliability among different protocols. In order to improve the performances, adequate specific training to evaluate PD-L1 by CPS in the HNSCC setting should be coordinated.

Original languageEnglish
Article number292
Pages (from-to)1-10
Number of pages10
JournalCancers
Volume13
Issue number2
DOIs
Publication statusPublished - Jan 2 2021

Keywords

  • Head and neck carcinoma
  • HNSCC
  • PD-L1
  • Pembrolizumab

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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