Phase Ii Clinical Trial Of Pazopanib For Patients With Unresectable Or Metastatic Malignant Peripheral Nerve Sheath Tumors.

e23569 Background: Malignant peripheral nerve sheath tumor (MPNST) is a malignant soft tissue tumor that does not respond well to chemotherapy and often develops on the basis of neurofibromatosis type 1 (NF1). The purpose of this study was to examine the effects of pazopanib on MPNST. Methods: This study was designed as a physician-initiated phase II clinical trial of pazopanib in patients with MPNST with unresectable or distant metastases. Eleven large hospitals were selected from the Japanese Musculoskeletal Oncology Group (JMOG), and patients were registered between July 2016 and August 2018. The primary endpoint was set to clarify the clinical benefit rate (CBR, including complete or partial response and stable disease) at 12 weeks for pazopanib according to Response Evaluation Criteria in Solid Tumors (RECIST1.1). Progression-free survival and overall survival were set as secondary endpoints along with the safety of this treatment. The clinical benefit rate based on Choi evaluation at week 12 was also set as the secondary endpoint. Results: The study enrolled twelve patients with MPNST. Grade 2 was 7 and grade 3 was 5 by according to the FNCLCC evaluation. Median follow-up period was 10.60 (1.74-22.85) months. Six were male, and six were female. Median age was 49 (20-76). After 12 weeks of pazopanib treatment, CBR was 50.0% (6 of 12 patients) and 50.0% (6 of 12 patients) at RECIST and Choi criteria, respectively. The median progression-free survival was 5.4 months for both RECIST and Choi. Interestingly, the median progression-free survival was 2.9 months for patients with FNCLCC Grade 2 and 10.2 months for Grade 3 for both RECIST and Choi. The median overall survival was 10.6 months. The adverse events of Grade 4 was neutropenia in one person and lipase elevation in one person. Grade 3 adverse events observed in ≥10% of patients were increase of AST and ALT, and decrease of white blood cells. Conclusions: The results of this pazopanib clinical trial were comparable to those of previous doxorubicin-based chemotherapy, and better than those of other molecular targeted therapy. Although accumulation of cases is necessary, pazopanib treatment for MPNST might be a safe and promising treatment, particularly for grade 3 MPNST. Clinical trial information: UMIN000019303 .