The imaging agent, a tracer called F-MPG, can find a specific protein mutation found in non-small cell lung cancer, binds to it and emit gamma rays in PET scans. The tracer can also reveal weak spots in the cancer where therapeutic drugs can counteract mutations. Specifically, the F-MPG tracer floats throughout the body and detects whether tumor cells contain a mutated version of the epidermal growth factor protein, which can spur cell division.
Patients who don't emit a signal while undergoing the scan likely don't have a mutation and can be spared additional treatment, according to the news release.
“If the PET scan shows a high signal from the tracer in a patient’s lung cancer, that’s predictive of someone who is going to respond well to the specific epidermal growth factor therapy,” said Sanjiv Gambhir, MD, PhD, professor and chair of radiology at Stanford, in a prepared statement. “For those who show low signals, they’re likely not going to respond, so you need to look into other treatment options. One way to think about this imaging technique is like it’s taking a biopsy of the entire body and that gives a much more complete picture of the mutational status of the primary tumor, which allows you much better information to treat the cancer."
The clinical trial was conducted at Harbin Medical University in Heilongjiang, China, with contributions made by Fudan University in Shanghai. Currently, the tracer has only been approved for use in China and, according to Gambhir, this is the first clinical trial using the tracer in humans.
Researchers at the university utilized the tracer and PET scans on 75 study participants. According to results, more than 80 percent of participants whose tumors were identified with the tracer received positive responses from a targeted lung cancer drug. However, only 6 percent of participants who lacked PET scan evidence of the epidermal growth factor protein mutation benefited from the drug.
“We’d like to continue to build our collaboration with the terrific group at Harbin, and work toward a clinical trial network in China for testing many different tracers,” Gambhir said in the news release.
Xilin Sun, MD, a former trainee in Stanford's molecular imaging program and now an associate professor of radiology at Harbin Medical University in China, led the study, published online March 7 in Science Translation Medicine.