Martin-Broto J, et al. - In a cohort of patients with malignant or dedifferentiated solitary fibrous tumour, researchers tested the activity of pazopanib. In this first trial ever addressing this topic, activity of pazopanib was evident in this patient group. Pazopanib displayed a manageable toxicity profile and activity, indicating that it could serve as an option for systemic treatment of advanced malignant solitary fibrous tumour.

Methods

• This was a single-arm, phase 2 trial.
• Partiipants included adult patients (aged ≥ 18 years) with histologically confirmed metastatic or unresectable malignant or dedifferentiated solitary fibrous tumour at any location, who had progressed (by RECIST and Choi criteria) in the previous 6 months and had an ECOG performance status of 0–2, were enrolled at 16 third-level hospitals with expertise in sarcoma care in Spain, Italy, and France.
• Until progression or intolerance was noted, pazopanib 800 mg once daily, taken orally without food, at least 1 h before or 2 h after a meal, was continued.
• Using the subset of the intention-to-treat population (patients who received at least 1 month of treatment with at least one radiological assessment), overall response measured by Choi criteria was assessed as primary endpoint.
• Safety analyses were performed incluing all patients who received at least one dose of the study drug.

Results

• A total of 40 patients were assessed, of whom, 36 were enrolled (34 with malignant solitary fibrous tumour and two with dedifferentiated solitary fibrous tumour) from June 26, 2014, to Nov 24, 2016.
• These subjects were followed-up for a median duration of 27 months (IQR 16–31).
• Partial responses were seen in 18 (51%) of 35 evaluable patients, stable disease in nine (26%), and progressive disease according to Choi criteria in 8 (23%), based on central radiology review.
• In a planned interim analysis, detection of early and fast progressions was followed by cessation of further enrolment of patients with dedifferentiated solitary fibrous tumour.
• Achievement of an overall response, according to Choi criteria, was noted in 51% (95% CI 34–69) of 35 patients.
• Death of 10 (29%) of 35 patients was reported.
• Deaths related to adverse events were nil and hypertension (11 [31%] of 36 patients), neutropenia (four [11%]), increased concentrations of alanine aminotransferase (four [11%]), and increased concentrations of bilirubin (three [8%]) were documented as the most frequently experienced grade 3 or higher adverse events.