Interobserver Variation of PD-L1 SP142 Immunohistochemistry Interpretation in Breast Carcinoma: A Study of 79 Cases Using Whole Slide Imaging

• DOI: 10.5858/arpa.2020-0451-oa
• Publication Date: 2021-01-14T00:19:29Z
• Authors: Raza S. Hoda; Edi Brogi; Timothy M. D'Alfonso; Anne Grabenstetter; Dilip Giri; Matthew G Hanna; M. Gabriela Kuba; Melissa P. Murray; Christina E. Vallejo; Hong Zhang; Jorge S. Reis-Filho; Hannah Y. Wen
• Keywords: Atezolizumab; Companion diagnostic; Breast carcinoma

Context.— The Ventana programmed death ligand-1 (PD-L1) SP142 immunohistochemical assay (IHC) is approved by the US Food and Drug Administration as companion diagnostic to identify patients with locally advanced or metastatic triple-negative breast cancer for immunotherapy atezolizumab, a monoclonal antibody targeting PD-L1. Objective.— To determine interobserver variability in PD-L1 IHC interpretation invasive carcinoma. Design.— pathology database was interrogated all diagnosed primary invasive, recurrent, carcinoma on which performed from November 2018 June 2019 at our institution. A subset of cases selected using computerized random-number generator. evaluated stromal tumor-infiltrating immune cells IMpassion130 trial criteria, positive defined immunoreactivity 1% more tumor area. interpreted whole slide images staff pathologists expertise. Interobserver calculated unweighted κ. Results.— total 79 were assessed 8 pathologists. agreement substantial (κ = 0.727). There complete among 62% (49 79) cases, 7 84% (66 6 92% (73 cases. In 4% (3 small biopsies, pathologists' interpretations evenly split between scores negative. Conclusions.— findings show assessment single Further study warranted define basis discrepant results.