The Efficacy and Safety of Apatinib in Advanced Synovial Sarcoma: A Case Series of Twenty-One Patients in One Single Institution.

Background: Synovial sarcoma (SS) is a highly aggressive soft-tissue sarcoma (STS) with poor prognosis. Tyrosine kinase inhibitor (TKI) has shown a promising impact on advanced STS patients. This study aimed to evaluate the efficacy and safety of apatinib, an oral multi-TKI, which especially inhibited vascular endothelial growth factor receptor, as second-line therapy for patients with advanced SS.

Patients And Methods: This retrospective analysis included 21 advanced SS patients, who had a poor response to anthracycline-based chemotherapy alone or combined with ifosfamide at least one cycle. All the patients received an apatinib containing regimen between May 2016 and October 2019 in our institution. Apatinib 500-750 mg (250 mg for patients younger than 10) was given daily. Tumor responses were assessed by response evaluation criteria in solid tumors. Survival analysis was performed by the Kaplan-Meier test, and a safety profile was recorded.

Results: The median follow-up was 15.2 months (95% CI, 12.2-NE). Nine (42.9%) patients had partial response (PR), and eight (38.1%) had stable disease. The median progression-free survival (PFS) was 13.1 months (95% CI, 6.7-NE). The 6- and 12-month PFS rates were 76.2% (95% CI, 60.0-96.8) and 55.4% (95% CI, 37.3-82.3), respectively. Additionally, the median overall survival (OS) was 15.5 months (95% CI, 10.7-NE). The 6- and 12-month OS rates were 81.0% (95% CI, 65.8, 99.6) and 64.9% (95% CI, 46.9-90.0), respectively. Moreover, the objective response rate was 42.9% (9/21) for advanced SS patients. The disease control rate was 81.0% (17/21). For the nine patients with the best response of PR, the median duration of response was 7.7 months.

Conclusion: Apatinib was proved to be a potential second-line treatment option for advanced SS patients with chemo-resistance. Apatinib showed promising efficacy and acceptable safety profile in advanced SS, with considerable OS and particularly PFS. Indeed, further multicenter studies with a longer follow-up time are needed to fully determine the clinical application of apatinib in advanced SS.