{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T23:06:07Z","timestamp":1790723167833,"version":"4.1.0"},"reference-count":21,"publisher":"American Society of Clinical Oncology (ASCO)","issue":"3","content-domain":{"domain":["ascopubs.org"],"crossmark-restriction":true},"short-container-title":["JCO Precis Oncol"],"published-print":{"date-parts":[[2026,3]]},"abstract":"<jats:sec>\n                    <jats:title>PURPOSE<\/jats:title>\n                    <jats:p>To describe and compare patient characteristics, treatment patterns, and survival outcomes of patients with human epidermal growth factor receptor 2 (HER2)\u2013low and HER2 immunohistochemistry 0 (IHC 0) stage IV breast cancer<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>METHODS<\/jats:title>\n                    <jats:p>A retrospective study was conducted across three academic centers in the United States. Adult patients diagnosed with stage IV breast cancer between 1-1-2010 and 12-31-2020 and classified as having either HER2-low (immunohistochemistry 1+\/2+ with negative fluorescence in situ hybridization) or HER2 IHC 0 disease were followed through 12-31-2021. Patient characteristics, treatments received, and treatment discontinuation were analyzed and survival analyses were conducted using Kaplan-Meier methods.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>RESULTS<\/jats:title>\n                    <jats:p>\n                      Among 501 eligible patients, 385 were classified as HER2-low (76.8%) and 116 as HER2 IHC 0 (23.2%). No statistically significant differences were found for demographic characteristics, but\n                      <jats:italic toggle=\"yes\">PTEN<\/jats:italic>\n                      mutations (11.6%\n                      <jats:italic toggle=\"yes\">v<\/jats:italic>\n                      0%,\n                      <jats:italic toggle=\"yes\">P<\/jats:italic>\n                      = .02) were more common, while germline\n                      <jats:italic toggle=\"yes\">BRCA1<\/jats:italic>\n                      mutations (1.9%\n                      <jats:italic toggle=\"yes\">v<\/jats:italic>\n                      8.6%,\n                      <jats:italic toggle=\"yes\">P<\/jats:italic>\n                      = .04) were less prevalent in the HER2-low subgroup compared with those with HER2 IHC 0 disease. Treatment patterns in both subgroups were largely similar. In the overall cohort, 20%-30% of patients who discontinued treatment did not proceed to a subsequent line of therapy. Median overall survival trended shorter in the HER2 IHC 0 subgroup than the HER2-low subgroup, but 95% confidence intervals overlapped. For both subgroups, progression-free survival (PFS) decreased substantially at 2L and 3L compared with previous line of therapy.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>CONCLUSION<\/jats:title>\n                    <jats:p>Patient characteristics were similar between HER2-low and HER2 IHC 0 subgroups except for some differences in genetic alterations. Deterioration of PFS in later lines of therapy highlights a potential unmet need. Given the high patient attrition, the most effective treatments should be used as early as indicated as some patients may not proceed to subsequent lines of therapy.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1200\/po-25-00814","type":"journal-article","created":{"date-parts":[[2026,3,25]],"date-time":"2026-03-25T19:59:09Z","timestamp":1774468749000},"update-policy":"https:\/\/doi.org\/10.1200\/crossmark","source":"Crossref","is-referenced-by-count":1,"title":["Real-World Study Assessing Characteristics and Treatment Patterns of Patients With Human Epidermal Growth Factor Receptor 2 Immunohistochemistry 0 and Human Epidermal Growth Factor Receptor 2\u2013Low Stage IV Breast Cancer: A Multicenter Retrospective Study"],"prefix":"10.1200","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2452-0556","authenticated-orcid":true,"given":"Chia Jie","family":"Tan","sequence":"first","affiliation":[{"name":"Pharmacotherapy Outcomes Research Centre, University of Utah, Salt Lake City, UT"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7895-2747","authenticated-orcid":true,"given":"Connor","family":"Willis","sequence":"additional","affiliation":[{"name":"Pharmacotherapy Outcomes Research Centre, University of Utah, Salt Lake City, UT"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0149-0115","authenticated-orcid":true,"given":"Trang","family":"Au","sequence":"additional","affiliation":[{"name":"Pharmacotherapy Outcomes Research Centre, University of Utah, Salt Lake City, UT"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3241-3216","authenticated-orcid":true,"given":"Matthew B.","family":"Schabath","sequence":"additional","affiliation":[{"name":"H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2778-5149","authenticated-orcid":true,"given":"Chenghui","family":"Li","sequence":"additional","affiliation":[{"name":"Division of Pharmaceutical Evaluation and Policy, University of Arkansas for Medical Sciences, Little Rock, AR"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2310-510X","authenticated-orcid":true,"given":"Kristen","family":"Kelley","sequence":"additional","affiliation":[{"name":"Huntsman Cancer Institute, Salt Lake City, UT"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8209-6963","authenticated-orcid":true,"given":"Xiaoqing","family":"Xu","sequence":"additional","affiliation":[{"name":"AstraZeneca Oncology Outcomes Research, Gaithersburg, MD"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Leah","family":"Park","sequence":"additional","affiliation":[{"name":"AstraZeneca Oncology Outcomes Research, Gaithersburg, MD"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Clara","family":"Lam","sequence":"additional","affiliation":[{"name":"AstraZeneca Oncology Outcomes Research, Gaithersburg, MD"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sandhya","family":"Mehta","sequence":"additional","affiliation":[{"name":"Daiichi Sankyo, Basking Ridge, NJ"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jackie","family":"Kwong","sequence":"additional","affiliation":[{"name":"Daiichi Sankyo, Basking Ridge, NJ"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6637-6359","authenticated-orcid":true,"given":"Diana","family":"Brixner","sequence":"additional","affiliation":[{"name":"Pharmacotherapy Outcomes Research Centre, University of Utah, Salt Lake City, UT"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1831-285X","authenticated-orcid":true,"given":"David","family":"Stenehjem","sequence":"additional","affiliation":[{"name":"Pharmacotherapy Outcomes Research Centre, University of Utah, Salt Lake City, UT"},{"name":"Department of Pharmacy Practice and Pharmaceutical Sciences, College of Pharmacy, University of Minnesota, MN"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"233","reference":[{"key":"e_1_3_6_2_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.semcancer.2017.08.010"},{"key":"e_1_3_6_3_2","doi-asserted-by":"publisher","DOI":"10.1200\/JOP.18.00206"},{"key":"e_1_3_6_4_2","doi-asserted-by":"publisher","DOI":"10.5858\/arpa.2023-0187-ED"},{"key":"e_1_3_6_5_2","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa2203690"},{"key":"e_1_3_6_6_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.annonc.2022.03.187"},{"key":"e_1_3_6_7_2","doi-asserted-by":"publisher","DOI":"10.1200\/JCO.2022.40.17_suppl.LBA1001"},{"key":"e_1_3_6_8_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41591-023-02478-2"},{"key":"e_1_3_6_9_2","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa2407086"},{"key":"e_1_3_6_10_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.annonc.2023.05.008"},{"key":"e_1_3_6_11_2","doi-asserted-by":"publisher","DOI":"10.1186\/s12916-022-02346-9"},{"key":"e_1_3_6_12_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.prp.2024.155550"},{"key":"e_1_3_6_13_2","first-page":"1177","article-title":"Prognostic and biologic significance of ERBB2-low expression in early-stage breast cancer","volume":"8","author":"Tarantino P","year":"2022","unstructured":"Tarantino P, Jin Q, Tayob N, et al: Prognostic and biologic significance of ERBB2-low expression in early-stage breast cancer. 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