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News|Articles|December 19, 2025

The Need for Ongoing Research in HR+, HER2+ Metastatic Breast Cancer

Key Takeaways

  • HR+, HER2+ metastatic breast cancer (MBC) is a subtype which presents its own specific challenges in patient care
  • Additional research is needed in the effort to further understand the triple-positive subtype
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Understanding a Distinct Subtype of Metastatic Breast Cancer

Approximately 10% of all breast cancers are hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-positive (HER2+), a subtype often referred to as double-positive or triple-positive breast cancer.

HR+, HER2+ metastatic breast cancer (MBC) has a unique tumor biology and is associated with bidirectional crosstalk between the HR and HER2 signaling pathways, which can lead to single pathway resistance, resulting in disease progression. This biological complexity distinguishes HR+, HER2+ MBC from other subtypes and presents unique challenges.

Historically, little research has been specifically focused on the HR+, HER2+ subtype.

The Challenge of Crosstalk in HR+, HER2+ MBC

Crosstalk between the HR and HER2 pathways can lead to continued tumor proliferation if only 1 pathway is blocked because the other pathway can compensate. Therefore, crosstalk may result when both receptors are upregulated.

According to Rashmi Murthy, M.D., Associate Professor in Houston, Texas, “While we’ve seen progress in the management of HR+, HER2+ metastatic breast cancer, research is ongoing in the hope of finding new strategies.”

Dedicated Research and Unmet Needs

With HR+, HER2+ MBC survival rates that remain around 46% at 5 years after diagnosis, additional research is needed for patients with HR+, HER2+ MBC.

Pfizer is one company focused on MBC research, including HR+, HER2+. "Pfizer has deep scientific expertise to tackle the complex challenges of MBC," says Christina Derleth, M.D., MSCI, Development Head, Breast Disease Area, Pfizer Oncology. “We are committed to advancing scientific understanding of HR+, HER2+ MBC and aim to help address the unmet needs of this patient population.”

To learn more about HR+, HER2+ MBC and to hear expert perspectives on crosstalk and disease challenges, visit stepsforher.com.

© 2025 Pfizer Inc. All rights reserved. December 2025. PP-IBR-USA-7181

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