ABY-025 affibody SPECT highlights HER2 status in breast cancer

First-in-human trial of Indium-111 ABY-025 affibody molecule SPECT imaging safely points out human epidermal growth factor receptor type 2 (HER2) expression in metastatic breast tumors, according to preliminary research published online March 24 in the Journal of Nuclear Medicine.

A team of researchers including Jens Sorensen, MD, PhD, from the departments of nuclear medicine and PET and radiology, oncology and radiation sciences at Uppsala University in Uppsala, Sweden, evaluated the safety and efficacy of In-11 ABY-025 for HER2 imaging. Findings of the study showed that the agent was an effective agent for telltale HER2 expression and no limitations were found.

“In-111 ABY-025 appears safe for use in humans and is a promising noninvasive tool for discriminating HER2 status in metastatic breast cancer, regardless of ongoing HER2-targeted antibody treatment,” wrote the authors.

This agent may prove to be an improvement over previous trastuzumab imaging because affibody molecules are about 23 times smaller in molecular weight. There was a limitation with a previous affibody agent, ABY-002, which tested effective for HER2 imaging, but high liver uptake obscured imaging of potential liver metastases. ABY-025 did not seem to have the same limitation and highest uptake was seen in the kidneys.

“Fast blood clearance allowed high-contrast HER2 images within 4–24 hours,” wrote Sorenson et al. “No anti–ABY-025 antibodies were observed. When metastatic uptake at 24 h was normalized to uptake at four hours, the ratio increased in HER2-positive metastases and decreased in negative ones.”

HER2 status was imaged with sensitivity in a number of the seven patients and one patient in particular with an HER2-positive primary tumor revealed HER2-negative metastases. This agent is not yet approved for general clinical use and further study is required to demonstrate its effectiveness for advanced breast cancer imaging.