Duration of Anti-PD-1 Therapy in Metastatic Melanoma

The standard or usual treatment for this disease is to receive treatment with a class of agents known as PD-1 inhibitors, or also with the names anti-PD-1 therapy, immunotherapy and checkpoint inhibitors. PD-1 inhibitors turn on the immune system, so that it can fight the cancer cells in the body. Clinical trials have shown that PD-1 inhibitors (such as pembrolizumab and nivolumab) can shrink tumours and extend the life of patients with melanoma. To-date, PD-1 inhibitors have been given to patients with melanoma continuously (non-stop), for as long as they remain beneficial, for up to a total duration of 2 years. The 2 year duration was chosen because doctors thought it was reasonable, and has been adopted as the standard or usual duration because it was shown to work in clinical trials. However, some recent observations suggest that PD-1 inhibitors may work just as well if they are given for a shorter time and/or in an intermittent schedule. Intermittent means to take breaks from receiving the drug when, and for as long as, the melanoma is better. The investigators doing this study are interested to find out whether patients with melanoma live as long when the PD-1 inhibitors are given continuously (non-stop) or in an intermittent schedule (taking breaks). If the two ways of giving the treatment were to be shown to be just as good, benefits of an intermittent schedule may include less clinic visits and side effects, better quality of life, and less cost over time for the Health Care System. However, this is not known at present.