Pembrolizumab in soft-tissue sarcomas with tertiary lymphoid structures

Immune checkpoint inhibitors show limited clinical activity in patients with advanced soft-tissue sarcomas (STSs). Retrospective analysis suggests that intratumoral tertiary lymphoid structures (TLSs) are associated with improved outcomes in these patients. The French PEMBROSARC trial is a multicohort phase 2 study of pembrolizumab combined with low-dose cyclophosphamide in patients with advanced STSs. Among all-comer cohorts the 6-month non-progression rate was 4.9% and the overall response rate was 2.4%. In the cohort of patients selected based on presence of TLSs (n=30) the 6-month NPR was 40% (95% CI 22.7-59.4) and the ORR was 30% (95% CI 14.7-49.4). The authors conclude that TLS presence in advanced STS is a potential predictive biomarker to improve patient selection for pembrolizumab treatment.