TUESDAY, Feb. 3, 2026 (HealthDay News) -- For patients with desmoplastic melanoma, neoadjuvant treatment with pembrolizumab, a programmed death-1 (PD-1) immune checkpoint inhibitor, results in a pathological complete response rate of 71 percent, according to a study published online Jan. 29 in Nature Cancer.

Kari L. Kendra, M.D., Ph.D., from The Ohio State University Wexner Medical Center, and colleagues reported the results of one cohort of the phase 2 SWOG S1512 trial, which assessed the pathological complete response rate of neoadjuvant PD-1 blockade in surgically resectable desmoplastic melanoma. Twenty-eight eligible patients received intravenous pembrolizumab 200 mg for three treatments every three weeks, followed by excision. Tissue samples were obtained prior to treatment, at three to five weeks, and at the time of surgery.

The researchers found pathological complete response occurred in 20 of 28 patients (71 percent) in the intent-to-treat population. Overall, 79 percent of patients reported treatment-related adverse events of any grade, and two patients experienced grade 3 treatment-related adverse events (7 percent). The three-year recurrence-free survival rate was 74 percent among patients who underwent surgical resection, and the three-year overall survival rate was 87 percent. Four patients had died at three years of follow-up, none from melanoma or adverse events.

"Giving pembrolizumab before surgery led to very high rates of tumor clearance, few serious side effects, and excellent three-year survival for patients with this rare and difficult-to-treat cancer," senior author Antoni Ribas, M.D., from the David Geffen School of Medicine at UCLA, said in a statement.

Several authors disclosed ties to the biopharmaceutical industry; Merck provided investigational agents for the study.

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