Checks and Balances

In recent years, immune checkpoint inhibitors have been shown to be effective tools in treating multiple types of cancer. In a healthy person, immune checkpoint molecules function to remove self-reactive T cells. However, cancer cells may also use these same pathways to suppress T cells. Checkpoint inhibition brings about non-specific T cell activation, which allows for a tumor-specific immune response. However, an infrequent, but potentially severe, complication of checkpoint inhibitor therapies is the formation of autoimmune conditions. Cases of new or worsened autoimmune conditions have been reported in many organ systems. In the nervous system, central and peripheral processes, as well as disorders of the neuro-muscular junction or muscle, have been identified. Treatment is targeted towards the acute episode. Chronic immunosuppression is usually not initiated because stopping the checkpoint inhibitor therapy will typically abort the autoimmune process. In the future, more of these drugs are likely to be used to treat cancer, and thus more must be known about the mechanisms that induce autoimmunity in this setting and the best strategies to treat them.