A novel imaging technique that uses a synthesized form of scorpion venom to light up brain tumors has shown promise in a clinical trial. The imaging system enables neurosurgeons to better see malignant growths that often are difficult to fully eliminate.
The multi-institutional clinical trial was led by investigators from Cedars-Sinai and sponsored by Blaze Bioscience Inc. The new imaging technique that was studied uses a special high-sensitivity near-infrared camera developed at Cedars-Sinai, along with the imaging agent tozuleristide, or BLZ-100, developed by Blaze. The agent contains a synthetic version of an amino acid compound found in scorpion venom.
Like the natural form of the compound, the synthetic version is not toxic and binds to tumor cells. It is attached to a fluorescent dye that glows when stimulated by a near-infrared laser. Viewed through the camera, the imaging agent might allow neurosurgeons to detect the boundaries between tumors and healthy brain tissue during surgery, improving the opportunity for surgeons to remove tumor cells while sparing normal brain tissue.
"With this fluorescence, you see the tumor so much clearer because it lights up like a Christmas tree," said Adam Mamelak, MD, senior author and investigator in the trial.
That is important because of the sprawling nature of gliomas, the type of brain tumors imaged during the trial. Gliomas are highly lethal and comprise about 33% of all brain tumors. They can infiltrate brain tissue with tentacle-like structures, making them difficult to distinguish from normal brain tissue. They typically do not respond to traditional therapies such as chemotherapy and radiation. The key to extending patient survival depends on a surgeon's ability to detect and remove all parts of the tumor.
In the clinical trial, 17 adult patients with brain tumors were given varying doses of BLZ-100 before surgery. Despite the varying amounts of the drug given, the majority of tumors fluoresced, including both high- and low-grade gliomas. After surgery, patients were monitored for 30 days. Investigators found that none of the patients had any serious adverse responses to the drug, and that the imaging system was safe and could be useful for imaging the brain tumors during surgery.
More clinical trials are needed to further evaluate the safety of the imaging system and demonstrate the system's effectiveness before BLZ-100 can gain approval from the FDA, and the camera used in the trial must be refined before it can be used seamlessly in an operating room. But Mamelak said the clinical trial results were promising. "For a surgeon, this seamless integration of fluorescence imaging into the surgical microscope is very appealing."