Skip to 0 minutes and 14 secondsYou may have read articles over recent times about how a new approach to treating cancer, termed immunotherapy, has the potential to greatly impact survival rates. As you might guess from its name, the basic principle of immunotherapy is that it works by utilising the immune system to fight cancer. The hope is that this will offer a longer-term therapy with fewer side effects and that it will be effective against a wide range of cancers. But how do they work? Well, in normal life, our immune system has an array of different cells at its disposal. These look out for and then destroy foreign invaders, such as viruses or bacteria. If we didn't detect and destroy them, they would cause us serious problems.
Skip to 1 minute and 3 secondsThe immune system also has the ability to tell the difference between our own cells and these foreign invaders. If we didn't have this ability, we would destroy our own tissues. We know a little about how this is achieved, especially regarding a specific immune cell called the T cell. These cells are continuously circulating in our body and, on encountering another cell, there are a number of molecules on the surface of both cells which interact and essentially let the T cell work out whether these are friend or foe, i.e. whether these cells should be destroyed or not. Cancer cells, as we've seen already in the course, have become drastically altered and should therefore trigger T cells to destroy them.
Skip to 1 minute and 50 secondsBut for some reason, cancer manages to trick the immune system into effectively leaving it alone to continue to grow and invade. This is one of the key mysteries of cancer and trying to elucidate what this signal is that allows immune evasion has been a major area of research for many years. Two molecules in particular have been the focus of a lot of research-- PD-1 and PD-L1, which both exist on the T cell and the tumour cell, respectively, and act as a molecular handshake, allowing cancer cells to exist in the presence of T cells.
Skip to 2 minutes and 29 secondsSince the discovery of these molecules, the aim of many groups all over the world has been to develop a strategy to disrupt this handshake and allow the immune system to see cancer for what it really is. Now we are beginning to see the results of all this hard work. Recent reports suggest that some of these new approaches may be very successful. At the American Society for Clinical Oncology Conference in May, 2015, several exciting studies were presented. One of these compared one of these anti-PD-1 drugs, Nivolumab, to chemotherapy for patients with advanced lung cancer. Those receiving the immunotherapy treatments survived for several months longer than those on chemotherapy and with fewer side effects.
Skip to 3 minutes and 18 secondsThese are really promising results for lung cancer patients, offering real progress for cancer that currently has very few treatment options. Another study which received worldwide media attention used a combination of immunotherapy drugs to treat patients with advanced melanoma. In this case, Nivolumab was combined with another drug known as ipilimumab, which works in a slightly different way-- it releases the brakes on the immune system. This one-two punch meant that well over half, 57% of patients in the study responded to the treatment, as opposed to only 1/5, 19%, who were given the ipilimumab alone. But on the downside, there were also far more severe side effects as a result of the combination of treatments.
Skip to 4 minutes and 9 secondsMany more studies looked into various combinations of immunotherapy treatments in several cancer types. For example, head and neck cancers, liver cancer, and certain types of bowel cancer. It's been clear for some time that immunotherapy treatments are slowly coming of age, but this news is a big step forward. There are now clear signs that in some cases they can extend survival and even shrink tumours entirely. Next, we need to work out which patients will get the most benefit from these treatments, figure out how we can manage the side effects, and determine what combination will have the most impact. This is especially true given that these drugs are not going to be cheap.
Skip to 4 minutes and 55 secondsBut it's clear that immunotherapy will be playing a key role in the future of cancer treatment.
In this video, Dr Leah Marks discusses recent highlights in the immunotherapy approach to treating cancer
© University of Glasgow and Cancer Research UK