137P Predicting survival outcomes in solitary fibrous tumours: A retrospective clinicopathological and molecular cohort study

Methods:We conducted a retrospective study of 102 patients with advanced STS treated with pazopanib at a single center between 2010 and 2025.Demographic, clinical, efficacy, and toxicity data were collected.Primary endpoints were progression-free survival (PFS), overall survival (OS), objective response rate (ORR), and disease control rate (DCR).Secondary endpoints included safety and the identification of prognostic factors using a risk score model. Results:The most common histological subtypes were leiomyosarcoma (25.5%), synovial sarcoma (15.7%), and undifferentiated pleomorphic sarcoma (12.7%).Pazopanib was administered as third-line or later therapy in 33.8% of patients, and 17.7% had ECOG 2.Subsequent treatment was used in 61.8%, mainly gemcitabinedacarbazine (37.1%) and trabectedin (33.9%).Median PFS and OS were 4.0 and 10.0 months, respectively, with DCR 43% and ORR 13%; corresponding values in PALETTE were 4.6 months, 12.5 months, 73%, and 6%.Grade 3 adverse events occurred in 18.3% vs 38%, dose reductions in 15.7% vs 39%, and treatment discontinuation in 12.7% vs 14%.Four adverse factors were identified: hypoalbuminemia (<3.5g /dL), anemia (<11 g/dL), bad peformance status, and neutrophil-to-lymphocyte ratio >5.A prognostic score for OS was developed based on the weighted contribution of each variable, stratifying patients into high-(median OS 3 months), intermediate-(7 months), and low-risk groups (12 months) (p<0.0001).Conclusions: Pazopanib demonstrated real-world outcomes comparable to the pivotal trial.While disease control was modest, toxicity was lower, supporting pazopanib as a valid option after anthracycline failure.The prognostic score may aid in refining risk stratification of patients eligible for pazopanib.