New 3-Part Molecule Targets HER Family in Breast Cancer

A novel chimera targets the growth factors responsible for certain types of breast cancer.

Human epidermal growth factor receptor 2 (HER2), human epidermal growth factor receptor 3 (HER3), and epidermal growth factor receptor (EGFR) are 3 growth factors that are overexpressed in some cancers.

Researchers have designed a 3-part molecule that could reduce the expression of these growth factors in order to target certain types of breast cancer, according to the authors of a study published by

Molecular Therapy: Nucleic Acid.

The chimera disrupts the signaling of HER2 and HER3, resulting in the termination of cancer cells, according to the study.

"As a bioengineer, I am developing the materials for cancer-targeted treatment,” said lead author Hongyan Liu, PhD. "I have experience building multifunctional chimeras to target different types of genes associated with cancer cells."

HER2 overexpression accounts for 20% to 30% of breast cancers, according to the authors. The growth factor allows cancer cells to grow and divide faster, resulting in a cancer that is more aggressive and harder to treat.

The authors noted that when HER growth factors are blocked by a drug with a single target, other HER family members can replace them. As a result, the research team designed a molecule that targets HER2, HER3, and EGFR simultaneously.

"When HER2 is expressed in a cell, you'll usually find high expression of HER3, too,” Dr Liu said.

All 3 parts of the molecule have forceful anti-tumor properties, according to the authors. The EGFR-targeted component is placed between the HER2 and HER3 targeted components, making up the HER2 aptamer-EGFR siRNA-HER3 aptamer chimera.

The molecule was specifically designed to allow the EGFR-targeting portion to reach its target within HER2 and HER3 expressing cells, according to the authors. The novel molecule can resist renal depletion, allowing for a longer circulation time and overall increased efficiency.

The non-toxic chimera is easier to produce and more affordable than other treatment options, according to the authors.

The authors are continuing to test the efficacy of the molecules in treating breast cancers that are resistant to Herceptin, a drug that targets HER2.

"We need to prove that this molecule will work on Herceptin-resistant breast cancer patients," Dr Liu said.

Because cancers, such as head and neck cancer, and lung cancer, are also linked to a HER family overexpression, the chimera could potentially benefit many other patients, the authors concluded.