What this Trial Is About

The incidence rate of pancreatic neuroendocrine neoplasms (pNENs) is increasing year by year. According to the statistical results of the SEER (Surveillance, Epidemiology, and End Results) database, the incidence rate of pNENs increased from 0.27/100000 to 1/100000 from 2000 to 2016, with a median overall survival time of 68 months. The 5-year overall survival rates of localized, locally advanced, and metastatic pNENs were 83%, 67%, and 28%, respectively. pNENs are gradually gaining attention and importance from the medical community. The existing therapeutic drugs for neuroendocrine tumors include somatostatin analogues, recombinant human interferon injections, chemotherapy drugs, and molecular targeted drugs. Although these drugs can prolong patients' PFS to some extent, there is a common problem of low objective response rates. In recent years, sunitinib and everolimus have been approved for targeted therapy in patients with pancreatic neuroendocrine neoplasms , but their clinical efficacy is still limited. The study by Panzuto et al. showed that the median PFS for first-line treatment of advanced well differentiated pancreatic neuroendocrine neoplasms was 13.9 months, with an ORR of 14.9%. After imaging progression of the disease, the median PFS after second-line treatment was 15 months, and the ORR of only 5.5%. There is currently no effective treatment for patients with disease progression or drug resistance after undergoing existing treatment ways. Therefore, there is a huge clinical demand for the treatment of pNEN patients worldwide, and effective drugs are urgently needed to benefit these patients. Our previous research found that pathways in tumor were significantly affected in pNENs and liver metastases and EGFR tyrosine kinase inhibitor resistance and transcriptional dysregulation in tumor were unique to liver metastasis through KEGG pathway analysis; Meanwhile, GO Biological Processes analysis emphasizes those signaling pathways closely related to tyrosine phosphorylation, DNA repair, and cell cycle regulation, especially in liver metastases. Xiao et al. found that epidermal growth factor receptor (EGFR) was enriched in high glycosylation pNENs using RNA-seq. EGFR was expressed in 21.2% of pNENs using immunohistochemistry and associated with poor overall survival. Therefore, the study from Xiao et al. demonstrates that EGFR may be a potential therapeutic target for pNENs. This is consistent with our previous findings that the EGFR signaling pathway plays an important role in pNENs with liver metastases. Due to the heterogeneity and complexity of tumors, the efficacy of monotherapy or blocking a single signaling pathway may be limited or this treatment method may easily develop drug resistance. The existing anti-tumor targeted drugs block tumor angiogenesis by inhibiting vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF). Colony-stimulating factor 1 receptor (CSF1R) is an important signaling pathway associated with the survival and function of tumor associated macrophages (TAMs). Inhibiting CSF1R can regulate the activity of macrophages, improve the immune microenvironment, promote immune response, and activate the body's immune function. Sofantinib is a novel oral tyrosine kinase inhibitor which exerts dual effects of anti-tumor angiogenesis and immune regulation by targeting VEGFR, FGFR1, and CSF1R, resulting in synergistic anti-tumor activity. In December 2020 and June 2021, sorafenib was approved in China as a monotherapy for unresectable locally advanced or metastatic, well differentiated extrapancreatic and pancreatic neuroendocrine neoplasms. However, in a multicenter, single blind, open label, phase Ib/II clinical trial, the objective response rate for pNENs patients was only 19%. There is currently no effective treatment available for patients with disease progression or drug resistance after undergoing existing treatment regimens. Therefore, there is an urgent need to seek new treatment methods to improve the therapeutic effect of pNENs. Based on our previous research results and relevant literature reports, we speculate that the combination of sorafenib and EGFR inhibitor gefitinib may improve the therapeutic effect of pNENs patients.

A Clinical Study of Sorafenib Combined With Gefitinib for the Treatment of pNET