Patients likely to respond to cancer therapies that target the PD-1 and PD-L1 proteins can be identified using PET scans. PET scanning is an accurate and non-invasive way to detect cancer in the body. Using PET scan will help doctors to determine the level and stage of cancer and provide the appropriate therapy for patients who respond to the PD-1 targeted cancer therapy. Bristol-Myers Squibb developed the PET scan approach. This scan allows scientists to identify tumors that have PD-L1, which is a biomarker of response to therapies recognized as PD-1 and PD-L1 immune checkpoint inhibitors.
The programmed death protein (PD-1) and the ligand PD-L1 play significant roles in a checkpoint pathway that cancer cells exploit to evade the immune system. To optimize drug therapy, it is essential to have a single PET imaging agent to measure the PD-L1 status in both primary and metastatic lesions. Here is how PD-1 receptors function:
- PD-1 receptors are found on the surface of immune T-cells. PD-1 is bound to the ligand PD-L1 to help regulate the immune response and minimize the possibility of an acute development of an autoimmune disease.
- T-cells travel to tumor locations to kill cancer cells under normal conditions. When responding to immune activity, tumor cells use high levels of PD-L1 to bind to PD-1 on the T-cells to deactivate them.
- The interaction between PD-1 and PD-L1 is called a checkpoint pathway that helps cancer cells to evade the immune response of the body.
In his study, Bristol-Myers used a radioligand that uses radioactive fluorine-18 (18F), an element of PET imaging to target the PD-L1. Researchers used adnectin with 18F to produce a tracer known as 18F-BMS-986192 that was tested on mice that had subcutaneous tumors. The results indicated that 18F-BMS-986192 binds to tumors that contain PD-L1. Therefore, the radioactive tracer was safe for use on humans.
The new approach gives physicians an opportunity to non-invasively assess all tumors for PD-L1 expression using one PET scan and a timely readout. The single PET scan will guide doctors in making treatment decisions, provide right doses, and monitor the response of the patients. PET/CT Las Colinas and other cancer centers continue to conduct more clinical trials on 18F-BMS-986192 are being carried out to understand the PD-L1 expression and checkpoint pathway in human tumors.