The development of extremely efficient immune checkpoint inhibition, especially anti-Programmed Death 1 receptor (PD-1) treatment, has transformed systemic therapy for metastatic melanoma during the last decade. Despite the fact that one-third of patients will have a long-term response to single-agent or combination therapy, the ideal length of treatment is uncertain. It is critical to determine the appropriate length of therapy since exposure to anti-PD-1 therapy raises the risk of developing immune-mediated toxicities, which can cause substantial morbidity and, in some cases, death. It has long been recognised that patients who respond completely to high-dose interleukin-2 and ipilimumab typically maintain their responses after a brief treatment course; thus, it is critical to better understand the data in order to help understand the optimal management of melanoma patients treated with anti-PD-1 therapy. 

The clinical results with anti-PD-1-based therapy, as well as published data on the length of therapy, show that patients may not require the entire 2 years of anti-PD-1 therapy and that the risk of toxicity may be reduced by better understanding the mechanisms and kinetics of response to therapy. Although novel indicators to aid in treatment decision making are being researched, there is a continuous need to enhance our tools for monitoring therapy response and disease activity.