The HER-2/neu oncogene encodes a transmembrane tyrosine kinase receptor with extensive homology to the epidermal growth factor receptor. In this review, the association of HER-2/neu gene and protein abnormalities with prognosis and response to therapy with trastuzumab and to other therapies in breast cancer is presented. By considering a series of 80 published studies encompassing more than 25,000 patients, the relative advantages and disadvantages of Southern blotting, polymerase chain reaction amplification, andThe Oncologist 2003;8:307-325 www.TheOncologist.comCorrespondence: Jeffrey S. Ross, M.D., Albany Medical College, Department of Pathology, Mail Code 81, 47 New Scotland Avenue, Albany, New York 12208, USA. Telephone: 518-262-5461; Fax: 518-262-8092; e-mail: rossj@mail.amc.edu Received February 5, 2003; accepted for publication April 28, 2003. ©AlphaMed Press 1083-7159/2003 The Oncologist ® LEARNING OBJECTIVESAfter completing this course, the reader will be able to:1. Define the historical background and biological basis of the discovery of the HER-2/neu gene and its first use as a prognostic factor in breast cancer.2. Recall the uses of HER-2/neu testing prior to the approval of trastuzumab including the impact on anthracycline adjuvant and first-line chemotherapy responses.3. Explain the basic principles of all the HER-2/neu tests in clinical practice: IHC, FISH, Southern blot, PCR, tissue ELISA, and serum ELISA.4. Contrast the pros and cons and uses and limitations of the IHC versus the FISH approach to HER-2/neu testing.5. Critique the most recent data comparing IHC with FISH for the prediction of response to single-agent trastuzumab and trastuzumab in combination with standard chemotherapy for advanced metastatic breast cancer.6. Describe the HER-2/neu expression patterns in all types of breast conditions, including in situ carcinoma, lobular versus ductal carcinoma, Paget's disease, male breast cancer, breast sarcomas, and benign breast disorders.Access and take the CME test online and receive one hour of AMA PRA category 1 credit at CME.TheOncologist.com CME CME This material is protected by U.S. Copyright law. Unauthorized reproduction is prohibited. For reprints contact: Reprints@AlphaMedPress.com Ross, Fletcher, Linette et al. 308 HER-2/NEU GENE (C-ERBB-2)The human epidermal growth factor receptor 2 (HER-2)/neu (c-erbB-2) gene is localized to chromosome 17q and encodes a transmembrane tyrosine kinase receptor protein that is a member of the epidermal growth factor receptor (EGFR) or HER family ( Fig. 1) [1]. This family of receptors is involved in cell-to-cell and cell-to-stroma communication primarily through a process known as signal transduction, in which external growth factors, or ligands, affect the transcription of various genes by phosphorylating or dephosphorylating a series of transmembrane proteins and intracellular signaling intermediates, many of which possess enzymatic activity. Signal propagation occurs as the enzymatic activity of one protein turns on the enzymat...

Purpose Three programmed death-1/programmed death-ligand 1 (PD-L1) inhibitors are currently approved for treatment of non-small-cell lung cancer (NSCLC). Treatment with pembrolizumab in NSCLC requires PD-L1 immunohistochemistry (IHC) testing. Nivolumab and atezolizumab are approved without PD-L1 testing, though US Food and Drug Administration-cleared complementary PD-L1 tests are available for both. PD-L1 IHC assays used to assess PD-L1 expression in patients treated with programmed death-1/PD-L1 inhibitors in clinical trials include PD-L1 IHC 28-8 pharmDx (28-8), PD-L1 IHC 22C3 pharmDx (22C3), Ventana PD-L1 SP142 (SP142), and Ventana PD-L1 SP263 (SP263). Differences in antibodies and IHC platforms have raised questions about comparability among these assays and their diagnostic use. This review provides practical information to help physicians and pathologists understand analytical features and comparability of various PD-L1 IHC assays and their diagnostic use. Methods We reviewed and summarized published or otherwise reported studies (January 2016 to January 2017) on clinical trial and laboratory-developed PD-L1 IHC assays (LDAs). Studies assessing the effect of diagnostic methods on PD-L1 expression levels were analyzed to address practical issues related to tissue samples used for testing. Results High concordance and interobserver reproducibility were observed with the 28-8, 22C3, and SP263 clinical trial assays for PD-L1 expression on tumor cell membranes, whereas lower PD-L1 expression was detected with SP142. Immune-cell PD-L1 expression was variable and interobserver concordance was poor. Inter- and intratumoral heterogeneity had variable effects on PD-L1 expression. Concordance among LDAs was variable. Conclusion High concordance among 28-8, 22C3, and SP263 when assessing PD-L1 expression on tumor cell membranes suggests possible interchangeability of their clinical use for NSCLC but not for assessment of PD-L1 expression on immune cells. Development of LDAs requires stringent standardization before their recommendation for routine clinical use.