ON CO L OG Y Immunotherapy Heralds a New Age of Treatments for Cancers A recently approved drug for patients with metastatic melanoma represents a significant shift in the way the cancer is treated and may herald a new era in which the body’s immune system is increasingly directed to attack certain cancers. Pembrolizumab, co-developed by Antoni Ribas, MD, PhD, at the UCLA Jonsson Comprehensive Cancer Center, is a protein that works by blocking the immune system’s “brakes,” allowing it to recognize and attack cancer cells. Studies by Dr. Ribas and researchers from 16 countries in patients with metastatic melanoma found that the new drug resulted in less severe side effects, T-lymphocytes, or T cells (round), play an important role in the body’s immune system, tracking down and destroying foreign bodies and infected cells. Now, the evolving science of immunotherapy seeks to unleash the power of T cells against cancer. UCLAHEALTH.ORG 1-800-UCLA-MD1 (1-800-825-2631) improved tumor responses, longer duration of responses and extended survival compared to the standard treatment. “For many decades, cancer biologists have thought that if we can vaccinate for mumps or rubella, maybe we can also vaccinate for cancer,” Dr. Ribas says. “The idea of using the immune system to fight against cancer has been tested with many vaccines, but until recently, the benefits have been anecdotal, and overall the results have been disappointing.” The problem, Dr. Ribas notes, is that the immune system evolved to fight foreign invaders and infection, not cancer cells. But in recent years, as researchers began to better understand how the immune system is activated, it became clear that an important system of checks and balances is in place to keep the healthy immune system from attacking organs. These safeguards, which were also preventing the immune system from attacking cancer cells, are known as checkpoints. “We realized that the key to successful immunotherapy was not just to turn on the immune system against cancer, but to take away the brakes that were turning it off,” Dr. Ribas explains. More than a decade ago, Dr. Ribas and others began developing the first generation of