A little less than one-third of patients with stage III/IV melanoma treated with a single-agent PD-1 drug at Memorial Sloan Kettering Cancer Center from 2009 to 2018 experienced disease relapse at 3 years after discontinuing treatment as a result of a complete response.1

The retrospective study analyzed 396 patients with melanoma treated at the institution who stopped treatment and had at least 3 months of follow-up. Of these patients, 25.8% had a complete response to single-agent anti–PD-1 therapy.

“There are many factors contributing to the desire to discontinue therapy, including risk of significant late toxicity, economic burden of long-term treatment, and quality-of-life concerns,” the researchers wrote. “A significant minority of patients who experience a complete response will ultimately relapse.”

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With a median follow-up of 21.1 months from the time of complete response, the probability of being alive and not needing additional therapy at 3 years was 72.1%. The estimated 3-year overall survival from time of complete response was 82.7%.

The median duration of treatment for the patients who had complete response was 9.4 months. The median duration of treatment after complete response was 0 months, with a range of -12 to 26 months.

Researchers found that complete response was associated with M1b disease and cutaneous compared with mucosal or acral primary tumors.

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The researchers also retreated several patients who had disease progression after treatment discontinuation. Response was seen in 5 of 34 patients retreated with single-agent PD-1 and 11 of 44 patients given anti–PD-1 plus ipilimumab.

In an editorial published with the study, Michael A. Davies, MD, PhD, of University of Texas MD Anderson Cancer Center, wrote that based on these data and data from other studies looking at treatment cessation, criteria for stopping treatment “could be improved and merits additional investigation.”2

“In the absence of prospective trial data, the available data support discussions with patients who achieve complete response about the potential risks and benefits of treatment cessation after 6 to 12 months of treatment and with continued treatment until the complete response is confirmed,” he wrote.


  1. Betof Warner A, Palmer JS, Shoushtari AN, et al. Long-term outcomes and responses to retreatment in patients with melanoma treated with PD-1 blockade [published online February 13, 2020]. J Clin Oncol. doi: 10.1200/JCO.19.01464
  2. Davies M. Is it safe to stop anti-PD-1 immunotherapy in patients with metastatic melanoma who achieve a complete response? [published online February 13, 2020]. J Clin Oncol. doi: 10.1200/JCO.20.00136