Overcoming Hormone Therapy Resistance in Metastatic Breast Cancer

When hormone therapy ceases to be effective for ER-positive, HER2-negative metastatic breast cancer, care teams should assess how the cancer cells have adapted and how to treat them accordingly, an expert said.

Over time, cancer cells can evolve and adapt, finding ways to grow and proliferate independently of hormone signals. To address this resistance, healthcare providers may recommend a reevaluation of the cancer, including additional testing to identify any changes in the tumor's biology.

According to the National Cancer Institute, estrogen receptor positive refers to cells that have a protein that binds to the hormone estrogen and require estrogen to grow. HER2 negative refers to cells that minimal to no amount of the protein HER2 on them, and may grow more slowly than those that are considered HER2 positive.

CURE spoke with Dr. Malinda West, who recently co-moderated the CURE® Educated Patient® Updates in Metastatic Breast Cancer event in Madison, Wisconsin. She discussed what are the potential next steps for patients with ER-positive, HER2-negative breast cancer whose disease stops responding to hormone therapy. West is an assistant professor of oncology at University of Wisconsin Carbone Cancer Center in Madison.

Transcript:

Yeah, that's a really tough question, because we try to maximize using endocrine therapy or these targeted therapies based on the cancer DNA, you know, try to leverage these things for as long as we possibly can, because in general, they're less toxic than chemo. Chemo being — it works, it's just nonspecific. So that's where you get all those — you know, get loads of side effects from.

But eventually the natural course of a hormone receptor-positive and HER2-negative breast cancer is eventually, over time and over exposure to treatments, the breast cancer becomes more dysregulated. It becomes where it finds a way to upregulate different cell signaling inside the cancer cell that doesn't rely on the estrogen receptor. And so it becomes tough, but that's exactly you know, — like Dr. [Rubina] Qamar, [the other co-moderator of the event] was saying about retesting the biomarkers and repeating the receptor testing. Sometimes when things just aren't progressing like you would normally expect and it's like this pattern is a little strange, it's a good indication to reevaluate.

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