Pembrolizumab monotherapy may be the first-line treatment of choice for most patients with unresectable desmoplastic melanoma, according to a presentation at the AACR Annual Meeting 2023.

The presentation showed that pembrolizumab produced an overall response rate of 89% in patients with unresectable desmoplastic melanoma in a phase 2 trial. 

“Patients with desmoplastic melanoma are exceptional responders to single-agent PD-1 blockade with pembrolizumab,” said study presenter Kari Kendra, MD, PhD, of The Ohio State University Comprehensive Cancer Center in Columbus.

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Dr Kendra and colleagues evaluated pembrolizumab in a phase 2 trial (S1512; Identifier: NCT02775851) that included 2 cohorts of patients with desmoplastic melanoma. Dr Kendra presented results from cohort B, which included patients with unresectable disease. 

There were 27 patients with unresectable desmoplastic melanoma. Their median age was 75 years (range, 59-90), and 93% were men. The primary site of disease was the head or neck in 63% of patients.

The patients were given pembrolizumab at 200 mg every 3 weeks for up to 2 years. They received a median of 15 cycles. 

The complete response rate was 33%, and the overall response rate was 89%. The primary endpoint was met, as the complete response rate exceeded 20%.

The 2-year progression-free survival rate was 74%, and the 2-year overall survival rate was 89%.

Any-grade treatment-related AEs (TRAEs) were reported in 93% of patients. Grade 3 TRAEs were reported in 30%, and grade 4 TRAEs were reported in 7%. There were no grade 5 TRAEs. The most common TRAEs were fatigue (56%), diarrhea (33%), and maculopapular rash (30%). 

“Based on this data, single-agent anti-PD-1 immunotherapy should be considered the first-line treatment of choice for most patients with unresectable desmoplastic melanoma,” Dr Kendra said.

Disclosures: This research was supported by Merck Sharp & Dohme LLC. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.


Kendra K, Bellasea S, Eroglu Z, et al. S1512: High response rate with single agent anti-PD-1 in patients with metastatic desmoplastic melanoma. AACR 2023. April 14-19, 2023. Abstract CT009.