A symposium presented at the American Association for Cancer Research Annual Meeting 2016 offers updated results on the ongoing phase 1b clinical trial of anti-PDL1 immunotherapy atezolizumab in advanced stage colorectal cancer patients. Treated at the University of Colorado Cancer Center, one of the earliest trial participants is Rodney Bearfoot, who remains on trial with stable disease three years after being diagnosed with stage 4 colon cancer.
“We believe that tumor shrinkage isn’t the only measure of successful cancer immunotherapy. In this case and others, the long term control of advanced colorectal cancer is a goal unto itself,” says S. Gail Eckhardt, MD, FASCO, associate director for translational research at the University of Colorado Cancer Center.
The drug works by reinitiating the immune system’s ability to recognize and destroy tumor tissue.
Specifically, atezolizumab is one in a promising class of drugs known as PDL1 inhibitors. When the PDL1 receptor on a tumor cell’s surface binds the protein PD-1, the interaction results in signaling that protects the cell against destruction by the immune system’s T lymphocytes. Atezolizumab binds to PDL1 receptors, blocking the receptors’ ability to bind PD-1 and thus reopening cells to immune system attack.