Understanding why some breast cancers resist hormone treatment

Regulation of the tumor microenvironment by DNA damage repair proteins

NIH-funded research San Diego State University · NIH-11125766

This project aims to discover why a common type of breast cancer, called ER+ breast cancer, sometimes stops responding to standard hormone therapy.

Quick facts

Grant typeR37 grant
Study typeNIH-funded research
Funding institutionSan Diego State University NIH-funded
Lab location1 site (San Diego, United States)
Project IDNIH-11125766 on NIH RePORTER

What this research studies

Many people with ER+ breast cancer receive hormone therapy, but some tumors eventually become resistant. We know that when a protein called MLH1 is missing in certain ER+ breast cancer cells, it can activate another protein called HER2, which then leads to resistance to standard treatments. Our goal is to uncover the exact steps by which MLH1 loss causes HER2 to become active, making these cancers harder to treat. We believe that MLH1 loss changes how cancer cells communicate with each other, leading to HER2 activation and continued tumor growth. This work uses laboratory models to explore these cellular changes.

Who could benefit from this research

Good fit: This foundational research is not directly recruiting patients but focuses on understanding mechanisms relevant to patients with ER+ breast cancer that has become resistant to endocrine therapy.

Not a fit: Patients whose breast cancer is not ER+ or does not involve MLH1 loss may not directly benefit from the specific findings of this particular research.

Why it matters

Potential benefit: If successful, this work could uncover new ways to overcome treatment resistance in ER+ breast cancer, potentially leading to more effective therapies for patients.

How similar studies have performed: This project builds upon previous findings from the research team, which showed a link between MLH1 loss and HER2 activation in endocrine therapy resistance.

Where this research is happening

San Diego, United States

Researchers

About this research

  1. This is an active NIH-funded research project — typically early-stage science, not a clinical trial accepting patient enrollment.
  2. Some NIH-funded labs run parallel clinical studies or seek volunteers for related work. To check, contact the principal investigator or institution listed above.
  3. For full project details, budget, and progress reports, visit the official NIH RePORTER page below.
Conditions Breast CancerBreast Cancer CellBreast Cancer Cell Differentiation Factor P45Cancer InductionCancers
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.