| [1] | Oh DY, Bang YJ. HER2-targeted therapies - a role beyond breast cancer. Nat Rev Clin Oncol, 2020; 17, 33−48. doi: 10.1038/s41571-019-0268-3 |
| [2] | Moasser MM. The oncogene HER2: its signaling and transforming functions and its role in human cancer pathogenesis. Oncogene, 2007; 26, 6469−87. doi: 10.1038/sj.onc.1210477 |
| [3] | Wolff AC, Hammond MEH, Allison KH, et al. Human epidermal growth factor receptor 2 testing in breast cancer: American society of clinical oncology/college of American pathologists clinical practice guideline focused update. Arch Pathol Lab Med, 2018; 142, 1364−82. doi: 10.5858/arpa.2018-0902-SA |
| [4] | Loibl S, Gianni L. HER2-positive breast cancer. Lancet, 2017; 389, 2415−29. doi: 10.1016/S0140-6736(16)32417-5 |
| [5] | Rubin I, Yarden Y. The basic biology of HER2. Ann Oncol, 2001; 12, S3−8. |
| [6] | Barzaman K, Karami J, Zarei Z, et al. Breast cancer: biology, biomarkers, and treatments. Int Immunopharmacol, 2020; 84, 106535. doi: 10.1016/j.intimp.2020.106535 |
| [7] | Fehrenbacher L, Cecchini RS, Geyer CE Jr, et al. NSABP B-47/NRG oncology phase III randomized trial comparing adjuvant chemotherapy with or without trastuzumab in high-risk invasive breast cancer negative for HER2 by FISH and with IHC 1+ or 2. J Clin Oncol, 2020; 38, 444−53. |
| [8] | Narayan P, Osgood CL, Singh H, et al. FDA approval summary: fam-trastuzumab deruxtecan-nxki for the treatment of unresectable or metastatic HER2-positive breast cancer. Clin Cancer Res, 2021; 27, 4478−85. doi: 10.1158/1078-0432.CCR-20-4557 |
| [9] | Ferraro E, Drago JZ, Modi S. Implementing antibody-drug conjugates (ADCs) in HER2-positive breast cancer: state of the art and future directions. Breast Cancer Res, 2021; 23, 84. doi: 10.1186/s13058-021-01459-y |
| [10] | Rinnerthaler G, Gampenrieder SP, Greil R. HER2 directed antibody-drug-conjugates beyond T-DM1 in breast cancer. Int J Mol Sci, 2019; 20, 1115. doi: 10.3390/ijms20051115 |
| [11] | Modi S, Jacot W, Yamashita T, et al. Trastuzumab deruxtecan in previously treated HER2-low advanced breast cancer. N Engl J Med, 2022; 387, 9−20. doi: 10.1056/NEJMoa2203690 |
| [12] | Narayan P, Dilawari A, Osgood C, et al. US food and drug administration approval summary: fam-trastuzumab deruxtecan-nxki for human epidermal growth factor receptor 2-low unresectable or metastatic breast cancer. J Clin Oncol, 2023; 41, 2108−16. doi: 10.1200/JCO.22.02447 |
| [13] | Tarantino P, Hamilton E, Tolaney SM, et al. HER2-low breast cancer: pathological and clinical landscape. J Clin Oncol, 2020; 38, 1951−62. doi: 10.1200/JCO.19.02488 |
| [14] | Marchiò C, Annaratone L, Marques A, et al. Evolving concepts in HER2 evaluation in breast cancer: heterogeneity, HER2-low carcinomas and beyond. Semin Cancer Biol, 2021; 72, 123−35. doi: 10.1016/j.semcancer.2020.02.016 |
| [15] | Peiffer DS, Zhao FY, Chen N, et al. Clinicopathologic characteristics and prognosis of ERBB2-low breast cancer among patients in the national cancer database. JAMA Oncol, 2023; 9, 500−10. doi: 10.1001/jamaoncol.2022.7476 |
| [16] | Li YQ, Abudureheiyimu N, Mo HN, et al. In real life, low-level HER2 expression may be associated with better outcome in HER2-negative breast cancer: a study of the national cancer center, China. Front Oncol, 2022; 11, 774577. doi: 10.3389/fonc.2021.774577 |
| [17] | Tarantino P, Jin QC, Tayob N, et al. Prognostic and biologic significance of ERBB2-low expression in early-stage breast cancer. JAMA Oncol, 2022; 8, 1177−83. |
| [18] | Hein A, Hartkopf AD, Emons J, et al. Prognostic effect of low-level HER2 expression in patients with clinically negative HER2 status. Eur J Cancer, 2021; 155, 1−12. doi: 10.1016/j.ejca.2021.06.033 |
| [19] | Shu L, Tong YW, Li ZX, et al. Can HER2 1+ breast cancer be considered as HER2-low tumor? A comparison of clinicopathological features, quantitative HER2 mRNA levels, and prognosis among HER2-negative breast cancer. Cancers (Basel), 2022; 14, 4250. doi: 10.3390/cancers14174250 |
| [20] | Gilcrease MZ, Woodward WA, Nicolas MM, et al. Even low-level HER2 expression may be associated with worse outcome in node-positive breast cancer. Am J Surg Pathol, 2009; 33, 759−67. doi: 10.1097/PAS.0b013e31819437f9 |
| [21] | Tarantino P, Viale G, Press MF, et al. ESMO expert consensus statements (ECS) on the definition, diagnosis, and management of HER2-low breast cancer. Ann Oncol, 2023; 34, 645−59. doi: 10.1016/j.annonc.2023.05.008 |
| [22] | Schettini F, Chic N, Brasó-Maristany F, et al. Clinical, pathological, and PAM50 gene expression features of HER2-low breast cancer. NPJ Breast Cancer, 2021; 7, 1. doi: 10.1038/s41523-020-00208-2 |
| [23] | Idossa D, Borrero M, Blaes A. ERBB2-Low (also known as HER2-low) breast cancer. JAMA Oncol, 2023; 9, 576. doi: 10.1001/jamaoncol.2022.6889 |
| [24] | Allison KH, Hammond MEH, Dowsett M, et al. Estrogen and progesterone receptor testing in breast cancer: ASCO/CAP guideline update. J Clin Oncol, 2020; 38, 1346−66. doi: 10.1200/JCO.19.02309 |
| [25] | Schmid P, Im SA, Armstrong A, et al. BEGONIA: Phase 1b/2 study of durvalumab (D) combinations in locally advanced/metastatic triple-negative breast cancer (TNBC)—Initial results from arm 1, d+paclitaxel (P), and arm 6, d+trastuzumab deruxtecan (T-DXd). J Clin Oncol, 2021; 39, 1023−1023. doi: 10.1200/JCO.2021.39.15_suppl.1023 |
| [26] | Xu B, Shen JG, Shen J, et al. Prognostic impact of HER2-low expression in HER2-negative breast cancer under different hormone receptor status. Int J Clin Oncol, 2023; 28, 543−9. doi: 10.1007/s10147-023-02303-3 |
| [27] | Dai LJ, Ma D, Xu YZ, et al. Molecular features and clinical implications of the heterogeneity in Chinese patients with HER2-low breast cancer. Nat Commun, 2023; 14, 5112. doi: 10.1038/s41467-023-40715-x |
| [28] | Fernandez AI, Liu M, Bellizzi A, et al. Examination of Low ERBB2 protein expression in breast cancer tissue. JAMA Oncol, 2022; 8, 1−4. |
| [29] | Alhamar M, Alkamachi B, Mehrotra H, et al. Clinical significance of quantitative categorization of HER2 fluorescent in situ hybridization results in invasive breast cancer patients treated with HER2-targeted agents. Mod Pathol, 2021; 34, 720−34. doi: 10.1038/s41379-020-00728-z |
| [30] | Horisawa N, Adachi Y, Takatsuka D, et al. The frequency of low HER2 expression in breast cancer and a comparison of prognosis between patients with HER2-low and HER2-negative breast cancer by HR status. Breast Cancer, 2022; 29, 234−41. doi: 10.1007/s12282-021-01303-3 |
| [31] | Mutai R, Barkan T, Moore A, et al. Prognostic impact of HER2-low expression in hormone receptor positive early breast cancer. Breast, 2021; 60, 62−9. doi: 10.1016/j.breast.2021.08.016 |
| [32] | Xu HC, Han YQ, Wu Y, et al. Clinicopathological characteristics and prognosis of HER2-low early-stage breast cancer: a single-institution experience. Front Oncol, 2022; 12, 906011. doi: 10.3389/fonc.2022.906011 |
| [33] | Won HS, Ahn J, Kim Y, et al. Clinical significance of HER2-low expression in early breast cancer: a nationwide study from the Korean breast cancer society. Breast Cancer Res, 2022; 24, 22. doi: 10.1186/s13058-022-01519-x |
| [34] | Tan RSYC, Ong WS, Lee KH, et al. HER2 expression, copy number variation and survival outcomes in HER2-low non-metastatic breast cancer: an international multicentre cohort study and TCGA-METABRIC analysis. BMC Med, 2022; 20, 105. doi: 10.1186/s12916-022-02284-6 |
| [35] | Sanomachi T, Okuma HS, Kitadai R, et al. Low HER2 expression is a predictor of poor prognosis in stage I triple-negative breast cancer. Front Oncol, 2023; 13, 1157789. doi: 10.3389/fonc.2023.1157789 |
| [36] | Almstedt K, Heimes AS, Kappenberg F, et al. Long-term prognostic significance of HER2-low and HER2-zero in node-negative breast cancer. Eur J Cancer, 2022; 173, 10−9. doi: 10.1016/j.ejca.2022.06.012 |
| [37] | Massarweh S, Schiff R. Resistance to endocrine therapy in breast cancer: exploiting estrogen receptor/growth factor signaling crosstalk. Endocr Relat Cancer, 2006; 13, S15−24. doi: 10.1677/erc.1.01273 |
| [38] | Agostinetto E, Rediti M, Fimereli D, et al. HER2-low breast cancer: molecular characteristics and prognosis. Cancers (Basel), 2021; 13, 2824. doi: 10.3390/cancers13112824 |
| [39] | Viganò L, Locatelli A, Ulisse A, et al. Modulation of the estrogen/erbB2 receptors cross-talk by CDK4/6 inhibition triggers sustained senescence in estrogen receptor- and ErbB2-positive breast cancer. Clin Cancer Res, 2022; 28, 2167−79. doi: 10.1158/1078-0432.CCR-21-3185 |
| [40] | Miglietta F, Griguolo G, Bottosso M, et al. Evolution of HER2-low expression from primary to recurrent breast cancer. NPJ Breast Cancer, 2021; 7, 137. doi: 10.1038/s41523-021-00343-4 |
| [41] | Almstedt K, Krauthauser L, Kappenberg F, et al. Discordance of HER2-low between primary tumors and matched distant metastases in breast cancer. Cancers (Basel), 2023; 15, 1413. doi: 10.3390/cancers15051413 |
| [42] | Ocaña A, Amir E, Pandiella A. HER2 heterogeneity and resistance to anti-HER2 antibody-drug conjugates. Breast Cancer Res, 2020; 22, 15. doi: 10.1186/s13058-020-1252-7 |
| [43] | Seol H, Lee HJ, Choi Y, et al. Intratumoral heterogeneity of HER2 gene amplification in breast cancer: its clinicopathological significance. Mod Pathol, 2012; 25, 938−48. doi: 10.1038/modpathol.2012.36 |
| [44] | Tarantino P, Gandini S, Nicolò E, et al. Evolution of low HER2 expression between early and advanced-stage breast cancer. Eur J Cancer, 2022; 163, 35−43. doi: 10.1016/j.ejca.2021.12.022 |