Immunotherapy medications are revolutionizing cancer treatment. They work by ‘repurposing’ the immune system to fight cancer. Unfortunately, when the immune system is turned on to fight cancer, it can also lead to autoimmune diseases such as arthritis, skin rashes, endocrine disorders, and bowel inflammation. Because these autoimmune diseases are caused by the immune activation as a result of medication they are called, immune-related adverse events (irAE). Those specific to rheumatic disease are often termed rheumatic-irAE or Rh-irAE.

Since immunotherapy medications have been introduced only recently, there are no standardized guidelines on how to best treat these autoimmune side effects. Patients are highly motivated to continue their immunotherapy, as it works well for treating cancer, yet we don’t know if these autoimmune side effects are transient or if they will become chronic in nature. Furthermore, if we treat their autoimmune side effects with medications which suppress the immune system, it is possible that this will negate the beneficial anti-cancer immunotherapy effects and make the cancer worse?

Finally, patients with pre-existing autoimmune conditions have been generally excluded from the cancer studies evaluating these new therapies. As such, we don’t have information on how to manage their underlying disease, and whether immunotherapy is safe in these patients.

Understanding the mechanisms behind these immune side effects may help us identify strategies to reduce them and allow patients to continue on these life-saving drugs. It also may help us better understand traditional auto-immune diseases not caused by the immunotherapy.