Study finds imaging agent helps to remove lung cancer tumors

INDIANA: Surgery, especially surgery to remove cancerous tumours, depends on a variety of instruments and methods in addition to the surgeon's ability. The new imaging agent Cytalux will now improve the accuracy of lung cancer tumour removal surgery.

The inside of the human body famously looks nothing like an anatomy textbook, lacking the bright color coding to differentiate between tissues and organs. Based on foundational intellectual property developed at Purdue University and released by On Target Laboratories, Cytalux helps make tumors more easily and immediately identifiable by illuminating them and making them glow against healthy, noncancerous tissue like beacons against a night sky. Philip Low (rhymes with "now"), Purdue's Presidential Scholar for Drug Discovery and the Ralph C. Corley Distinguished Professor of Chemistry in the College of Science, is an inventor of the drug.

"Non-small cell lung cancer is one of the deadliest cancers," Low said. "The only absolute cure for lung cancer is to surgically remove all of the malignant tissue out of the patient. If it has metastasized, it's generally lethal."

Lung cancer is the second most commonly diagnosed cancer in the world and accounts for more than a quarter of all cancer deaths in the U.S. every year. When a patient is diagnosed with non-small cell lung cancer, the prognosis is often bleak: Only 7% have a chance of living another five years.

The importance of removing all the malignant tissue, the difficulty in distinguishing cancerous tissue from healthy tissue and the widespread nature of this type of lung cancer make the use of Cytalux in lung cancer surgery a welcome development. Low, a chemist by trade, attacks these issues using his expertise in chemical reactions. Cytalux exploits the unique chemistry of cancer cells to light up the tumors. Cancer cells divide rapidly, much faster than normal cells.

To do this, they need folate, a type of B vitamin -- and lots of it. The genius of Cytalux is that, after being administered intravenously to a patient before surgery, it tags that folate compound with a fluorescent dye. The cancer cells grab for the folate but end up flagged with the fluorescent dye, too. During surgery, these cells then fluoresce under near-infrared light.

Low explains further how the drug works in this YouTube video. The newly authorized use of Cytalux, which was initially developed to target ovarian cancer, has the potential to improve the outcomes of thousands of patients, helping surgeons to visualize otherwise undetected cancer tissue in 24% of lung cancer patients in a clinical trial.

"Cancer cells have an enormous appetite for this vitamin, and we have exploited their greed for folic acid by attaching a fluorescent dye to it," Low said.

"The drug not only allows the surgeon to see the cancer but may also help surgeons avoid removing tissue. Being able to avoid cutting healthy tissue can be as important as removing unhealthy tissues." Low and his team continue to develop imaging agents to make cancer tumors easier to detect and remove. He hopes that in the future all solid-tumor cancers will have a targeted fluorescent marker to light the way for surgeons.

"We're leading the way in this effort," Low said. "We are pioneers. We were not only the first tumor-targeted fluorescent dye to be approved by the FDA, but we developed a second one close on its heels. We are also working on other tumor-targeted fluorescent dyes to target many other types of cancer."