Patients with high-risk melanoma who had a course of pembrolizumab had longer recurrence-free survival than patients who received either ipilimumab or high-dose interferon after surgery. These findings of a large SWOG Cancer Research Network clinical trial, S1404, were presented by Grossmann et al during the 2021 ASCO Annual Meeting (Abstract 9501).
Researchers also measured overall survival and found no statistically significant difference in overall survival rates between the two groups of patients at 3.5 years after the last patient enrolled to the trial. They did find, however, that patients taking pembrolizumab had fewer serious side effects than those treated with either high-dose interferon or ipilimumab.
Kenneth F. Grossmann, MD, PhD, of the Huntsman Cancer Institute at the University of Utah Medical Center and Chair of SWOG's Melanoma Committee, was the lead investigator on the study. He commented, "The recurrence-free survival advantage and improved safety profile over the previous standard of care make [pembrolizumab] a continued standard for treating patients with high-risk resected melanoma."
Noting that overall survival measures were not significantly different between the two arms, Dr. Grossmann said, "The overall survival analysis was performed at a predefined time point with only approximately 50% of events needed for a fully powered analysis. We suspect that effective use of PD-1 blockade and other improved therapies for stage IV disease improved outcomes of relapsing patients on the control arm such that overall survival was not different between the two groups."
The recurrence-free survival advantage and improved safety profile over the previous standard of care make [pembrolizumab] a continued standard for treating patients with high-risk resected melanoma.— Kenneth F. Grossmann, MD, PhD
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The study randomly assigned 1,345 adult patients with stage III or IV melanoma who had undergone surgery to remove their tumors to the pembrolizumab arm or the control arm. Those on the control arm decided with their physicians whether to follow a course of high-dose interferon or a course of ipilimumab, both of which are approved by the U.S. Food and Drug Administration for use in treating these patients.
Pembrolizumab, a PD-1 inhibitor, was chosen for the trial because of its comparatively low toxicity and its activity in metastatic disease. Another trial has also since shown a recurrence-free survival benefit for the drug when compared to a placebo. High-dose interferon and ipilimumab, which were standard-of-care treatments for these patients at the start of the study, often come with serious side effects.
As the S1404 researchers had expected, toxicity was lower in patients on the pembrolizumab arm. Among patients taking high-dose interferon, roughly 72% had grade 3 or worse adverse events. The rate of such side effects was about 58% for those on ipilimumab, but it was only about 32% for patients on pembrolizumab.
Dr. Grossmann added that further data to come from this trial will include studies to evaluate pretreatment predictors of whether patients are likely to benefit from treatment and quality-of-life studies to better understand the impact of relapse in patients with high-risk resectable melanoma.
Disclosure: For full disclosures of the study authors, visit coi.asco.org.
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