Antibody Fluorescent Imaging Approach Safe During Glioblastoma Surgery

New data presented at the American College of Surgeons Clinical Congress 2017 suggests that using an antibody for imaging is safe among patients with glioblastoma.

The authors found that the antibody cetuximab was safe and facilitated infrared fluorescent imaging of tumors during glioblastoma surgery.

These findings are the first to show that antibody-based infrared fluorescent imaging is able to differentiate cancerous tissue from healthy tissue, according to the authors.

Infrared fluorescent imaging is typically used to chart lymphatic and blood flow during surgery. With this type of imaging, a fluorescent molecule attached to an antibody can better target and illuminate cancer cells during surgery, according to the authors.

Cetuximab is a monoclonal antibody that targets the epidermal growth factor receptor (EGFR) and has been approved to treat patients with head and neck cancers and colorectal secondary cancers.

In the study, the authors examined the ability of infrared imaging with the fluorescently-labeled cetuximab to highlight cancerous tissue in 3 patients receiving glioblastoma surgery. This surgery is typically very complicated due to the aggressive and invasive nature of glioblastoma.

“The tumor strays into normal brain tissue, and its edges are incredibly difficult to see,” said principal author Eben L. Rosenthal, MD, FACS. “If surgeons can specifically identify the extent of the tumors, they may be able to remove more cancerous tissue, and thus more complete resection of tumors tends to correlate with better progression-free survival.”

The patients were injected with a high-dose or low-dose of cetuximab-IRDye800 between 2 to 5 days prior to surgery.

Resected tissue was also imaged prior to pathological processing and tumor-to-background ratios were calculated, according to the study.

The authors discovered that they were able to clearly distinguish cancer cells from healthy tissue during surgery due to the antibody-based technique.

Overall, the antibody-based infrared fluorescence technique resulted in a highly-specific method for tumor detection in glioblastoma, as healthy brain tissue produced minimal fluorescence, according to the study. The tumor-to-background ratio was nearly 3 times higher in cancerous tissue compared with healthy tissue.

Additionally, high-dose cetuximab resulted in a significantly higher tumor-to-background fluorescence compared with the lower dose. The higher dose also showed tumors as small as 10-mg, according to the study.

“The study is interesting for two reasons. First, we show that the antibodies can be used for imaging the brain. It remains controversial whether antibodies can penetrate the brain because of the blood brain barrier,” Dr Rosenthal said. “Our study shows that this antibody not only passes through tumor and -disrupts blood brain barrier, it also highly specifically binds to brain tumor. Secondly, it represents an opportunity for surgeons to visualize brain tumors more clearly while they are operating.”

The study also joins an FDA-approved antibody and a standard imagining technique to improve patient care.

“In this study, we are taking something that has been used in thousands of patients safely and effectively, rather than creating a new probe that has potential unknown toxicity and is more expensive to bring through toxicity studies,” Dr Rosenthal said. “We also repurpose imaging devices that are common in the operating room. The imaging technique we describe is therefore highly cost effective, and it’s safer than introducing a new agent for imaging.”