June 15, 2021 – A variety of imaging tracers are being developed to evaluate, interrogate, and probe different components of the immune system and the subsequent responses to immuno-oncology therapies.
Imaging Endpoints’ Chief Medical Officer Ron Korn, MD, PHD, says some have great promise, including “ImaginAb’s zirconium labeled PET minibody tracer that’s very specific for identifying the CD8+ cell in the tumor microenvironment and other lymphoid tissues. This tracer appears to be leading the industry in fundamentally changing the way we can evaluate the immune system. And since the CD8+ T cell is central to effective immunotherapy, its use in clinical trials may help to provide earlier and better evidence of whether new drugs, products, device and/or treatment strategies are altering the immune system by promoting CD8 T cell infiltration and killing tumors.”
Dr. Korn says there are a variety of other potential agents that are being considered for clinical use.
In particular, he points to “PET agents that bind to specific molecular targets on the tumor cell surface such as PD-1/PD-L1 or that identify some of the cytokine components that are involved in immune response like IL-2. Early experience with these agents suggests that they are very informative in characterizing the immune state of a tumor but don’t necessarily predict which patients will respond to therapy.”
Dr. Korn says the more familiar PET agents that have been used for over 50 years now such as FDG, measure increased tumor and inflammatory metabolism. However, FDG PET remains too non-specific for immune system imaging and has limited applications at this time.
Elsewhere, investigators have been interested in developing PET tracers to detect and identify whether patients would likely respond to a particular drug or product. Best known is the development of radio-labeled checkpoint inhibitor molecules for PET imaging that are being explored to define the context of tumor vulnerability for specific treatments.
“In the end, I believe that this is all good news especially for patients who are being considered for immune therapies to treat their cancer,” he says.