New whole body positron emission tomography (PET) imaging techniques are allowing scientists to actually watch as immune system cells find and respond to tumors or infection. Compared to the snapshot views of the immune system from tumor biopsies or blood assays, this whole body imaging allows scientists to track how the immune response changes, and the tumor or infection responds, throughout the different phases of immune response and over long periods of time.
At present, this exciting approach is limited to studies of very small animals like mice. Dr. Owen Witte, a leading cancer biologist and immunologist and Howard Hughes Medical Institute investigator at the University of California, Los Angeles, says the real excitement will come as we are able to adapt and modify whole body imaging of immune response to use with humans. He says that thanks to collaboration between clinicians and scientists from a wide variety of disciplines, the time may not be that far away.
Speaking June 15 at the annual meeting of the American Society for Biochemistry and Molecular Biology (ASBMB)/8th International Union of Biochemistry and Molecular Biology Conference (IUBMB) in Boston, Dr. Witte describes how bringing together multiple imaging techniques and modalities from multiple disciplines and laboratories across the country is allowing him and other scientists to better understand the different phases of the immune response.
Using a host of imaging strategies such as radioactively-labeled T cells or cells modified to express jellyfish-like bioluminescence, it is already possible to visualize populations of immune system killer cells as they hone in on and attack solid tumors or blood cells responding to local inflammation.
As this happens, Dr. Witte and other scientists are beginning to glimpse the future and how these techniques will change how the immune response is evaluated during therapy. He is now working with clinical colleagues to plan the use of molecular imaging in future tumor immunology settings, such as clinical trials.
Dr. Witte describes himself as the "conductor" or "choreographer" in these discussions. "I'm not the scientist developing these techniques and modalities," he says. "My contribution is seeing particular biological problems to which they can be applied and how, down the road, this would work in humans."
Dr. Witte is best known for his contributions to understanding the cause of certain blood cancers and immune disorders, findings that have led to the development of improved therapies for patients, including a widely used molecularly targeted therapy for chronic myeloid leukemia (CML).
But now, combining his experience as a cancer biologist and immunologist with that of a broadly interdisciplinary group of colleagues (chemists, engineers, physicists, mathematicians, nuclear medicine, and others), he is looking for targets within the immune response - and targets that he will be able to track using this new technology.
"When a new tool comes into biology, it always accelerates our understanding of a problem," says Dr. Witte. "Over the coming years, we are going to see a greater and greater reliance on whole body molecular imaging techniques to evaluate any treatment, whether chemotherapy or antibody, in preclinical and clinical trials."