Real world effectiveness of immunotherapy combined with anti-angiogenic therapy in patients with anthracycline-resistant soft tissue sarcomas.

e23543 Background: Soft tissue sarcomas are a heterogeneous group of malignant tumors of mesenchymal origin with more than 50 histologic subtypes. They have distinct molecular, genetic and clinical features and account for 1% of adult malignancies, the most common being liposarcoma, undifferentiated pleomorphic sarcoma and leiomyosarcoma. Immune checkpoint inhibitors (ICIs) have limited efficacy in sarcomas compared to other solid tumors; however, they have shown some activity in certain subtypes. The use of immunotherapy in sarcoma faces many challenges due to tumor heterogeneity, scarcity of therapeutic antibodies and chimeric antigen receptors to target antigens in sarcoma subtypes. However, combining ICIs with other therapies seems to improve the therapeutic efficacy to some extent. Antiangiogenic targeted therapy has been recommended by major guidelines as the treatment of choice for second-line soft tissue sarcomas. However, there are limited results from large clinical studies on whether immunotherapy combined with antiangiogenic therapy improves the efficacy. Methods: In this real-world single-center retrospective cohort study conducted at the First Affiliated Hospital of Zhejiang University School of Medicine, the efficacy of immunotherapy combined with antivascular therapy was assessed by progression-free survival (PFS) and overall survival (OS). Safety was assessed using the Common Terminology Criteria for Adverse Events version 5.0. Results: In this study, we enrolled a total of 21 eligible patients, of which 6 were liposarcoma, 4 were leiomyosarcoma, 4 were rhabdomyosarcoma, and 7 were other types. The immunotherapy used in all patients was anti-PD-1 antibody, with bevacizumab as the antivascular therapy drug in four of them and antiangiogenic tyrosine kinase inhibitors in the others. 12(57%) patients had received one-line therapy, 9 (43%) had received ≥ second-line therapy. Median progression-free survival (mPFS) was 5.5 months and median overall survival (mOS) 16.1 months in the total population. mPFS was significantly longer in 2nd-line V.S. ≥3rd-line patients (9.6 months V.S. 3.1 months, P = 0.0007), with a tendency to be prolonged mOS in 2nd-line treatment (16.1 months V.S. 9.3 months), but with no statistically significant difference. The most common grade ≥3 adverse events were hypertension, hand-foot syndrome, and abnormal thyroid function. Conclusions: This study confirms that immunotherapy combined with antiangiogenic therapy is effective and tolerable in anthracycline-resistant soft tissue sarcomas in the real world.It is possible that use in the second line may lead to better efficacy than use in multiple lines, and more clinical studies are expected.