University of Alberta researchers have developed a new molecular imaging test that could lead to improved diagnosis of lung cancer and better monitoring of treatment.
The innovation involves pairing panitumumab, a humanized antibody already used clinically for cancer treatments, with copper-64, a radioactive isotope that can be used in PET scans.
The new technique combines the antibody's ability to home in on specific targets with the unrivalled sensitivity of radioisotope detection, offering an opportunity for earlier and more accurate detection and treatment response monitoring of lung cancer, which is still among the leading causes of cancer deaths in Canada as it often remains undetected until later, more aggressive stages.
Panitumumab targets the epithelial growth factor receptor, a protein found on the surface of many cancer cells. This receptor is particularly prevalent in non-small-cell lung cancer — the type the researchers examined in their study recently published in Molecular Pharmaceutics — making it an ideal target for anti-cancer drugs. Meanwhile, radioisotope copper-64, attached to panitumumab, allows researchers and clinicians to follow the "metabolic fate" of the antibody, including accumulation and retention in cancer cells.
"Instead of exposing the patient to an invasive biopsy, they can go and get an injection and then we can use a PET scan to help see the tumour and help physicians to determine the best course of therapy," says study co-author Afsaneh Lavasanifar, professor in the Faculty of Pharmacy and Pharmaceutical Sciences.
"With our tools, imaging biomarkers like radiolabelled panitumumab and non-invasive PET imaging technology, we can provide valuable information to clinicians about the molecular footprint of cancer cells," adds Frank Wuest, oncology professor in the Faculty of Medicine & Dentistry.
To test their imaging agent, researchers used several preclinical lung cancer models in mice, including a metastasis model to detect distant lung cancer lesions in the liver and other organs and tissues.
"We showed that this targeted imaging modality not only lights up the tumour in the lungs, but it also lights up the tumour in the liver," says Lavasanifar.
This ability to identify primary tumours and metastases while providing valuable molecular information about the cancer cells addresses significant limitations of other currently used diagnostic imaging techniques. For example, CT scans sometimes fail to detect smaller tumours or cells in hard-to-visualize areas like soft tissues, and do not provide information on the molecular characteristics of cancer cells.
The new PET imaging test can also be a valuable tool to track the growth and spread of cancer over time, says Wuest.
"Clinicians can use the technology to better monitor the patient's response to a treatment at an early stage, which is a critical part of current cancer therapy to improve outcomes."
The researchers now plan to explore pairing panitumumab with copper-67, a complementary isotope that can deliver targeted radiation doses to kill cancer cells. Working together, the panitumumab and copper-67 could find cancerous cells and destroy them while leaving the surrounding healthy tissue untouched.
Lavisanifar and Wuest also note that other antibody drugs could be paired with radioisotopes like copper-64 and copper-67 to detect and treat cancer cells more effectively, ultimately enhancing patient care and outcomes.
The study was supported by funding from the Canadian Institutes of Health Research, the Nanomedicines Innovation Network, Alberta Innovates, the Natural Sciences and Engineering Research Council of Canada's CREATE program, and the Dianne and Irving Kipnes Foundation. Lavasanifar and Wuest are members of the Cancer Research Institute of Northern Alberta, the Women and Children's Health Research Institute and both recently received funding from CIHR.
