A Retrospective Study to Evaluate the Safety and Efficacy of Anlotinib Plus Camrelizumab in Management of Advanced Retroperitoneal Sarcoma.

e23545 Background: Several studies have demonstrated the antitumor activity of single-agent anlotinib in the treatment of soft tissue sarcoma (STS). However, the most effective results were from cases of alveolar soft part sarcoma (ASPS), which was a rare subtype in retroperitoneal sarcoma (RPS). The therapy of RPS is still dismal. Thus, we evaluated the effectiveness and safety of anlotinib plus camrelizumab for the treatment of RPS. Methods: We retrospectively reviewed the data of 36 patients with advanced/metastatic RPS in Sarcoma Centre of Peking University Cancer Hospital from July 2019 to February 2021. Anlotinib was given 12mg Qd 2 weeks on and 1 week off, and camrelizumab was transfused 200mg at Q3w. Patients that underwent at least 4 cycles of therapy were enrolled in this study. The primary endpoint is objective response rate (ORR) and evaluated according to the irRECIST 1.1 criteria. Results: The pathologic subtypes of enrolled cases include liposarcoma (LP) (n = 16), leiomyosarcoma (LMP) (n = 5), uncertain differentiation sarcoma (n = 7), fibroblastic and myofibroblastic tumours (n = 4), rhabdomyosarcoma (n = 2) and malignant peripheral nerve sheath tumour (MPNST) (n = 2). Two patients (5.6%) achieved CR and 9 patients (25.0%) achieved PR, with an ORR of 30.6%. Eighteen patients (50.0%) achieved SD and 7 patients (19.4%) were evaluated as PD, with the disease control rate (DCR) of 80.6%. The progression-free rate (PFR) at six months was 60.0%. Five patients underwent further radical surgical resection. The two CR cases were diagnosed as dedifferentiated liposarcoma (DDLP) and MDM2 amplified MPNST respectively, and both patients have been under CR status for over 12 months until now. The only grade 3 or higher treatment related adverse event was hypertension (22.2%). Camrelizumab related reactive cutaneous capillary endothelial proliferation (RCCEP) was not observed in this group of patients. Conclusions: The combination of anlotinib and camrelizumab demonstrated encouraging efficacy and safety in the treatment of RPS. A further clinical study with biomarker exploration should be performed in the future.