Real-World Outcome and Prognostic Factors of Pazopanib in Advanced Soft Tissue Sarcoma

Pazopanib has been approved for treating soft tissue sarcomas (STS) after chemotherapy. We aimed to evaluate the prognostic factors, clinical outcomes, and tolerability of pazopanib in patients with STS.

Forty-five patients treated between June 2015 and August 2019 were reviewed. Clinical outcome was measured by assessing the disease control rate (DCR) using Response Evaluation Criteria in Solid Tumors (version 1.1). Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan-Meier method. Adverse effects were assessed using the Common Terminology Criteria for Adverse Events (version 5.0).

The median age of patients at diagnosis was 28 (interquartile range (IQR), 23-45) years. Pazopanib was used as the second-line treatment in 46.7% and the subsequent line in 53.3% of patients. The overall DCR was 55.6%, and at 8 and 12 weeks, it was 52.3% and 35.5%, respectively; the median duration of response was 7 (IQR: 2-18) months. Pazopanib-induced hypothyroidism was associated with DCR, with an odds ratio of 7 (95% confidence interval [95% CI: 1.7-27.5], p<0.01). The median PFS and OS were 4.1 (95% CI: 0.85-7.42) and 12.4 months (95% CI: 6.5-18.36), respectively. Hypothyroidism and response to pazopanib, better ECOG PS, histological subtypes desmoid tumor/aggressive fibromatosis (DT/AF), and alveolar soft part sarcoma (ASPS) were favorable prognostic factors for PFS. Hypothyroidism and response to pazopanib were significant favorable factors for OS. There was no statistical difference in the OS between patients using pazopanib as the second-line therapy and those using it as the subsequent-line therapy.

Pazopanib is an effective treatment for STS. However, it showed variability in the clinical outcome in favor of ASPS and an outstanding response in the DT/AF subtype. Pazopanib-induced hypothyroidism is a good prognostic factor for disease control and is associated with prolonged PFS and OS.