Biomarker testing in advanced or metastatic hormone receptor-positive, human epidermal growth factor receptor 2 negative breast cancer: expert recommendations.

Authors

Tomás Reinert, Ahmed S Alshehri, Amr Shafik, Ching-Hung Lin, Gonzalo Gomez Abuin, Gyungyub Gong, Kyung Hae Jung, Mora Amat, Nirmala Pathmanathan, Samuel G W Ow, Samuel Rivera-Rivera, Shyam Aggarwal, Stephen J Luen, Timothy Kwang Yong Tay

Published in

Therapeutic advances in medical oncology. Volume 18. Pages 17588359261472325. Epub Aug 16, 2026.

Abstract

Biomarker testing is central to precision oncology, enabling effective use of targeted therapies in hormone receptor-positive (HR+), human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer (mBC). Recommendations for current and future biomarker testing and diagnostic workflows were developed using a three-step approach: pre-meeting survey, descriptive analysis, and steering committee discussion. A panel of 14 experts from Latin America, Asia Pacific, the Middle East, and Africa developed recommendations using an expert opinion-based approach without a formal consensus methodology. Recommendations with >90% agreement were considered panel recommendations. Some recommendations are expert-driven and not yet standard-of-care. High agreement was observed for biomarker testing at diagnosis for estrogen receptor (ER), progesterone receptor (PR), HER2, and BReast CAncer gene (BRCA)1/2. For endocrine-resistant patients, phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) testing is recommended at diagnosis; otherwise, during or after first-line treatment. AKT serine/threonine kinase 1 (AKT1) and phosphatase and tensin homolog (PTEN) testing can occur either during first-line treatment or at progression, while estrogen receptor 1 (ESR1) testing is advised at progression. Tumor tissue (preferably from a re-biopsy) is the preferred sample for PIK3CA, AKT1, and PTEN testing; if unavailable, primary tissue or circulating tumor DNA (ctDNA) may be considered. Blood is recommended for germline BRCA1/2 or PALB2 testing, while ctDNA is preferred for ESR1 detection. Next-generation sequencing (NGS) is the preferred method for most biomarkers, with polymerase chain reaction as an alternative where NGS is unavailable; PTEN may also be assessed using immunohistochemistry. Above 90% of experts proposed future biomarker testing at diagnosis for ER, PR, HER2, germline BRCA1/2, PALB2, PIK3CA, AKT1, PTEN, mismatch repair, microsatellite instability, tumor mutational burden, and neurotrophic tyrosine receptor kinase in all patients with HR+, HER2-negative mBC. This article offers a practical guide for biomarker testing in HR+, HER2-negative mBC.

PMID:
42609450
Bibliographic data and abstract were imported from PubMed on 18 Aug 2026.

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