Efficacy and Safety of Pazopanib for Recurrent or Metastatic Solitary Fibrous Tumor.

OBJECTIVE: To investigate the efficacy and safety of pazopanib for recurrent or metastatic solitary fibrous tumor (SFT) in first- and second-line settings.

METHODS: Patients histologically diagnosed with SFT at our hospital who received pazopanib monotherapy for inoperable disease between January 2013 and November 2016 were eligible. We retrospectively investigated treatment outcomes according to the treatment lines and assessed adverse events.

RESULTS: Nine patients were eligible. The median age was 67 years (range 42-81), and 6 patients (66.7%) were male. Four patients (50%) received pazopanib as second-line treatment. According to the RECIST and Choi criteria, the respective response rates were 0 and 50%, while the respective disease control rates were 88.9 and 75%. The median progression-free survival (PFS) was 6.2 months (95% confidence interval 3.2-8.8). Treatment line and high frequency of mitosis were not predictive of PFS (p = 0.67, 0.92). Two patients (22.2%) experienced elevated liver enzymes of grade 3 or higher.

CONCLUSION: Pazopanib is an effective treatment option for recurrent or metastatic SFT in first- and second-line settings. Liver injury is a major adverse event and adequate treatment withdrawal and dose reduction should be considered when necessary.