In the past, many patients with advanced cancers had limited treatment options. If removing the cancer surgically didn’t work, and then chemotherapy or radiation didn’t kill the cancer, patients were left with few choices. Today, however, a type of treatment called immunotherapy, which uses our own immune systems to fight cancer cells, is offering effective results for these patients and changing how we think about cancer care. The concept of using our own immune systems to fight cancer has been around for a long time. For the last century, doctors and researchers have been working to develop a way to harness the power of our own bodies in this fight. Specifically in the last 30 years, lots of research has focused on this concept, and today we are well on our way to understanding the best way to enhance our immune systems’ abilities to fight cancer. Now, a substantial percentage of cancer patients with an increasing number of cancer types are seeing an impact with new immunotherapies. Immunotherapies improve symptoms and quality of life, have few side effects, and, most importantly, extend survival—they’re changing the paradigm. The History of Immunotherapy In general, immunotherapy is a way to modify and activate the patient’s own immune system to fight foreign invaders and eliminate them. When you have a cold, your immune system identifies the invading cold cells and fights them off. However, we don’t see this exact process occur when the body tries to fight cancer cells. Experts first believed this was because the immune system wasn’t working hard enough, so for many years, patients were put on medications that helped their immune systems work harder. However, while this worked for a small percentage of patients, the majority didn’t benefit at all—plus the side effects were hard to tolerate. In the late 1990s, a scientist named James Allison, Ph.D., theorized that the problem may not have anything to do with boosting the immune system. He found that the immune system was already quite stimulated in cancer patients; however, its ability to fight invaders was being blocked by cancer cells. This ability to “blockade” or “inhibit” the immune system from fighting is actually normal. When your immune system fights and destroys invaders, it releases molecules that shield your own tissues from these attacks. This way, the immune system’s army knows what to fight and what to protect. But Dr. Allison and his colleagues found that cancer cells use this strategy for their benefit. They use these molecules themselves to hide from the immune system, so immune cells don’t know to fight the cancer. This discovery led to the development of one kind of immunotherapy, a class of drugs called checkpoint inhibitors, that block the cancer cells from hiding. This way, the immune system recognizes cancer as a foreign substance and destroys it. Research has led to the development of several other types of immunotherapies, but today, checkpoint inhibitors are the leading type due to their success rates and low side effects. The Impact of Checkpoint Inhibitors Today, there are four checkpoint inhibitors approved by the U.S. Food and Drug Administration (FDA): ipilimumab (Yervoy), pembrolizumab (Keytruda), nivolumab (Opdivo), and atezolizumab (Tecentriq). These drugs treat many different types of cancer, mostly (but not always) when they’ve reached advanced stages. They’ve been shown to eliminate cancer from the body entirely in some cases, with results lasting years. Many patients are now living cancer-free five and even 10 years after starting treatment. However, checkpoint inhibitors aren’t a magic bullet for all patients. Currently, they only work in 30 to 40% of patients. Our goal now is to find out why these therapies only work for some patients, and how to extend their effects. Lots of researchers are studying these questions. But for the patients who respond, immunotherapies give them a second chance at life. The Future of Immunotherapy Initially, checkpoint inhibitors were approved only to treat patients with advanced cancers. However, some have now been approved as a first-line treatment for melanoma, and more approvals are sure to come. Additionally, experts are looking at the benefits of combining two immunotherapies at once—we’re seeing longer-lasting cancer-free survival in more patients, but also more difficult side effects. It’s an exciting time for cancer research. Immunotherapies are being studied to treat every type of cancer—even the rarest tumor types. And patients are comforted by the concept of using their own bodies to help fight their cancers. It’s a powerful idea, to know that something within yourself is going to fight this foreign thing called cancer. And immunotherapy is a powerful treatment that we’re learning more about every day.