Multicenter phase 2 trial of pembrolizumab for unresectable desmoplastic melanoma

Desmoplastic melanoma has a high tumor mutational burden, which could result in high response rates with anti-PD-1 therapy. The multicenter phase 2 SWOG S1512 evaluated pembrolizumab monotherapy for desmoplastic melanoma. Results of cohort B, recruting patients with unresectable tumors, have now been published. Complete response rate was 37% and objective response rate was 89%. Three-year rates of progression-free survival, overall survival, melanoma-specific progression-free survival, and melanoma-specific survival were 72%, 84%, 84%, and 96%, respectively. Grade 3 or 4 adverse events were reported for 37%, and discontuation due to AE for 33%. The authors conclude that patients with unresectable desmoplastic melanoma have a high response rate to pembrolizumab monotherapy, but also a high frequency of toxicities.