Examination of Low ERBB2 Protein Expression in Breast Cancer Tissue

Aileen I. Fernandez, Matthew Liu, Andrew Bellizzi, Jane Brock, Oluwole Fadare, Krisztina Hanley, Malini Harigopal, Julie M. Jorns, M. Gabriela Kuba, Amy Ly, Mirna Podoll, Kimmie Rabe, Mary Ann Sanders, Kamaljeet Singh, Olivia L. Snir, T. Rinda Soong, Shi Wei, Hannah Wen, Serena Wong, Esther YoonLajos Pusztai, Emily Reisenbichler, David L. Rimm

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


Importance: Trastuzumab deruxtecan (T-DXd) has shown efficacy in patients with breast cancer with ERBB2 immunohistochemistry (IHC) scores of 1+ or 2+ but not 0 as read in central pathology laboratories. The drug is currently being tested in large randomized clinical trials with registration intent for this patient population. Objective: To determine the suitability of the current standard ERBB2 IHC assays to select patients with low ERBB2 positivity for treatment with T-DXd. Design and Setting: Assessment of data from College of American Pathologists surveys and assessment of analytic data from a Yale University-based study of concordance of 18 pathologists reading 170 breast cancer biopsies. Results: The total survey data set included scores over 2 years from 1391 to 1452 laboratories of 40 ERBB2 cores from each laboratory (20 cores twice a year for a total of 80). College of American Pathologists surveys show that 19% of cases read by the laboratories generate results with less than or equal to 70% concordance for IHC ERBB2 score 0 vs 1+. When 18 pathologists read the scanned slides from a selected set of breast cancer biopsies using a 4-point scale, there was only 26% concordance between 0 and 1+ compared with 58% concordance between 2+ and 3+. Conclusions and Relevance: In this study using a current standard ERBB2 IHC assay, the scoring accuracy for ERBB2 IHC in the low range (0 and 1+) was poor. This inaccuracy in the real world could lead to misassignment of many patients for treatment with T-DXd..

Original languageEnglish (US)
Pages (from-to)1-4
Number of pages4
JournalJAMA Oncology
Issue number4
StatePublished - Apr 2022

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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