Immunotherapy: Supercharging the Immune System to Fight Cancer

Cancer is one of the leading causes of death worldwide, accounting for approximately 10 million deaths in 2020. Whilst traditional cancer treatments, such as chemotherapy and radiation therapy, have paved the way as the most effective treatments for cancer, in recent years, a new approach to treating cancer has emerged: immunotherapy.

The immune system is designed to detect and destroy abnormal cells, which prevents the growth of many cancers. However, in some cases, cancer cells will evolve ways to avoid detection by the immune system and avoid being destroyed. The goal of immunotherapy is to boost the ability of the immune system to recognise and attack such cancer cells.

The concept of using the immune system to treat cancer has its beginnings in 1981, when William Coley (who is widely recognised as one of the founding fathers of cancer immunotherapy), attempted to harness the power of the immune system for treating cancer. His studies involved injecting bacteria into patient tumours with the hope of triggering an immune response to the infection that would also attack the tumour. Coley achieved some remarkable results, with tumour regression seen in several patients. Despite this, the risks associated with deliberately infecting patients with bacteria meant that surgery and radiotherapy were accepted as the standard treatments for cancer in the 20^th century. However, in recent years, immunotherapy has been revolutionised by several advances, particularly with the development of CAR-T cell therapies.

CAR-T cell therapy involves the removal of immune cells (T cells) from a patient’s blood, genetically engineering them to recognise and attack cancer cells, then infusing the modified cells back into the patient’s blood. The biggest advantage of this treatment is that it is personalised to each patient, as the therapy is tailored to target the unique genetic mutations and characteristics of the patient’s cancer.

CAR-T therapy has produced considerable success in clinical trials for several types of blood cancers. For example, CAR-T cell therapy has produced response rates of up to 90% in patients with relapsed or refractory B-cell lymphomas, which is significantly higher than conventional treatments. Such positive clinical trials have led to the approval of certain immunotherapies for treatment, with the FDA approving CAR-T cell therapy to treat a form of leukaemia in 2017.

Despite this, immunotherapy is still relatively new, meaning that more research is needed to determine its effectiveness for a wide range of cancers and to fully understand its potential side effects. Furthermore, immunotherapy itself still only remains an option for treatment after all other options have been exhausted.

Despite its limitations, immunotherapy is likely to become a staple in the clinician’s toolbox for treating cancer. Crystal Mackall is a researcher at Stanford University, hoping to develop CAR-T cell therapy to treat brain tumours. In a report to Nature, she recognised that immunotherapy still presents considerable challenges, stating “we clearly have a long way to go”. Despite this, Mackall has hope for the future of immunotherapy, predicting that immunotherapy will “go way beyond cancer in the years to come”, suggesting that it may become a treatment for a wide range of conditions.