IL2 and metastatic melanoma: Before the introduction of immune checkpoint inhibitors (ICIs), the standard of care for most patients with metastatic melanoma was dacarbazine administered as single-agent therapy or part of combination therapy.1,2 Immunotherapy with high-dose interleukin 2 showed durable response in a few patients but was associated with significant toxic effects2,3; however, immunotherapeutic agents in the form of ICIs, including ipilimumab, nivolumab, and pembrolizumab, have substantially improved outcomes and become the standard of care for metastatic melanoma during the past decade.4