Tertiary lymphoid structures correlate with better prognosis in patients with retroperitoneal sarcoma: A retrospective study

Abstract B cells are recognized as components of the tumor immune microenvironment in various cancer types, including soft-tissue sarcomas. Recent studies on sarcomas have suggested that tertiary lymphoid structures (TLSs) are associated with B cell expression and immunotherapy efficacy. We evaluated the relationship between the presence of a TLS at the primary site and the prognosis of patients with retroperitoneal sarcoma. TLSs were observed in 17 of 29 patients (59 %). TLSs were observed in 2 of 3 patients (67 %) with well-differentiated liposarcoma, 14 of 16 patients (88 %) with dedifferentiated liposarcoma, and 1 of 2 patients (50 %) with undifferentiated pleomorphic sarcoma. The number of tumor-infiltrating CD8+ T cells was higher in the TLS-positive group than in the TLS-negative group (p = 0.01). Disease-specific survival was significantly longer in patients with TLS-positive tumors than in those with TLS-negative tumors. When patients were divided into groups according to the density of TLSs, the disease-specific curve showed the highest survival in the TLS ≥10 (/100 mm2) group and the lowest survival in the TLS-negative group. When the analysis focused on patients with dedifferentiated liposarcoma, survival was classified according to the density, as in the overall analysis. Negative TLS, positive resection margins, and a lack of systemic therapy at recurrence were independent prognostic predictors. One patients with TLS-positive undifferentiated pleomorphic sarcoma had a microsatellite-unstable tumor and long-term survival with complete disappearance of all metastatic lesions with pembrolizumab, suggesting a prognostic role of TLSs and their predictive role in immunotherapy efficacy.