Surufatinib in advanced well-differentiated neuroendocrine tumors: a multicenter, single-arm, open-label, phase Ib/II trial

Purpose: No anti-angiogenic treatment is yet approved for extrapancreatic neuroendocrine tumors (NETs). Surufatinib (HMPL-012, previously named sulfatinib) is a small molecule inhibitor targeting vascular endothelial growth factor receptors, fibroblast growth factor receptor 1 and colony stimulating factor 1 receptor. We conducted a single-arm phase Ib/II study of surufatinib in advanced NETs. Experimental Design: Patients with histologically well-differentiated, low or intermittent grade, inoperable or metastatic NETs were enrolled into a pancreatic or extrapancreatic NETs cohort. Patients were treated with surufatinib 300 mg orally, once daily. The primary endpoints were safety and objective response rate (ORR) according to Response Evaluation Criteria in Solid Tumors (version 1.1). Results: Of the 81 patients enrolled, 42 had pancreatic NETs, and 39 had extrapancreatic NETs. Most patients had radiological progression within one year prior to enrollment (32 patients in each cohort). In the pancreatic and extrapancreatic NETs cohorts, ORRs were 19% (95% CI 9-34) and 15% (95% CI 6-31), disease control rates were 91% (95% CI 77-97) and 92% (95% CI 79-98), and median progression-free survival was 21.2 months (95% CI 15.9-24.8) and 13.4 months (95% CI 7.6-19.3), respectively. The most common grade ≥3 treatment-related adverse events were hypertension (33%), proteinuria (12%) hyperuricemia (10%), hypertriglyceridemia and diarrhea (6% for each), and increased alanine aminotransferase (5%). Conclusions: Surufatinib showed encouraging anti-tumor activity and manageable toxicities in patients with advanced NETs. Two ongoing phase III studies, validating the efficacy of surufatinib in patients with NETs, will contribute to the clinical evidence.