A research team led by Dr. Kari L. Kendra, MD, PhD, from The Ohio State University Wexner Medical Center in the United States, reported data from one cohort of the Phase II SWOG S1512 clinical trial. This trial was designed to assess the pathological complete response of neoadjuvant PD-1 blockade therapy in patients with resectable desmoplastic melanoma. Twenty-eight eligible patients received intravenous pembrolizumab at a dose of 200 mg every 3 weeks for 3 cycles, followed by surgical resection. Researchers collected tissue samples from patients before treatment, 3 to 5 weeks after treatment initiation, and at the time of surgery.

In the intent-to-treat population, 20 out of 28 patients achieved pathological complete response, representing a 71% response rate. Overall, 79% of patients experienced treatment-related adverse events of any grade, with 2 patients (7%) developing Grade 3 treatment-related adverse events. Among patients who underwent complete surgical resection, the 3-year relapse-free survival rate was 74% and the 3-year overall survival rate was 87%. A total of 4 patients died during the 3-year follow-up period, and all deaths were unrelated to desmoplastic melanoma or treatment-related adverse events.

Dr. Antoni Ribas, MD, the senior author of the study from the David Geffen School of Medicine at the University of California, Los Angeles, stated in a press release: "For this rare and refractory cancer, preoperative administration of pembrolizumab achieves an exceptionally high tumor clearance rate, a low incidence of severe adverse reactions, and excellent 3-year survival outcomes for patients."

Several study authors disclosed financial relationships with biopharmaceutical companies. Merck & Co., Inc. provided the investigational drug for this study.