AbstractIntroductionCheckpoint blockade has improved the response rate and survival in metastatic melanoma. Elective treatment discontinuation appears to be reasonable in most patients who have achieved a confirmed complete remission. It seems crucial to understand whether restarting immune checkpoint inhibitor therapy can induce additional responses or remissions in rare patients who relapse.MethodsA retrospective analysis identified only 10 patients who relapsed after elective treatment discontinuation after a radiologically confirmed remission. These patients were retreated with single-agent PD-1 or combined CTLA-4 plus PD-1-directed monoclonal antibodies.ResultsWe found an initial complete response rate of 20% (2 patients) following retreatment. With a median follow-up of 26 months, the addition of individualized salvage therapies converted an additional 4 patients to a 2nd remission. All 6 of these patients have again discontinued therapy. Three patients have died of metastatic melanoma, while another is receiving salvage therapy. Six of our 10 patients experienced grades 2-3 retreatment-related toxicity. There were no hospitalizations or fatalities.DiscussionRetreatment of relapsing patients resulted in 20% complete responses with checkpoint inhibitors. The planned addition of other treatment modalities converted another 4 patients (40%) to a durable 2nd remission. This sequential approach merits further exploration in prospective clinical trials.