Clinical Activity of Pazopanib in Patients with Advanced Desmoplastic Small Round Cell Tumor

Background. Desmoplastic small round cell tumor (DSRCT) is an aggressive, often fatal soft tissue sarcoma that lacks an optimal salvage regimen. We retrospectively reviewed data from 29 pretreated DSRCT patients who received pazopanib at MD Anderson Cancer Center after failure of standard chemotherapies. Subjects, Materials, and Methods. Medical records of patients treated from January 2012 to December 2016 were reviewed and regression analyses were performed. Median progressionfree survival (PFS) and overall survival (OS) were estimated using the Kaplan-Meier method and differences in survival were assessed by a log-rank test. A landmark statistical analysis was used to assess OS at a predefined 12-week time point following pazopanib initiation. Results. The mean age at pazopanib treatment was 27.5 years (range, 6.3-50.1 years). According to RECIST 1.1 criteria, 16 patients (55%) had stable disease, 1 patient (3%) had partial response, 1 patient (3%) had complete response, and 11 patients (38%) had progressive disease. Estimated median PFS was 5.63 months (95% confidence interval [CI]: 3.23-7.47). Median OS was 15.7 months (95% CI: 10.3-32.4). As of December 2016, 11 patients (38%) were still alive, with a median follow-up time of 16.8 (range 3.8-30.1) months. Doses between 400 and 800 mg were included. Pazopanib was well tolerated and 23 (79%) of the patients continued it until progression or death, 4 discontinued because of side effects, and 2 were still on pazopanib at the time of data analysis. Conclusion. In the largest study conducted to date in DSRCT, pazopanib was well tolerated and clinically active in heavily pretreated patients who otherwise lack good treatment options.