Phase I trial of sorafenib and gemcitabine in advanced solid tumors with an expanded cohort in advanced pancreatic cancer

Background: With its potent inhibitory effects against Raf-1 kinase and vascular endothelial growth factor receptor-2, sorafenib is a novel oral anticancer agent targeting signal transduction and angiogenic pathways. This study is designed to combine sorafenib and gemcitabine due to their compatibility in preclinical models and nonoverlapping clinical toxicities. Experimental Design: An initial dose-escalation part of the study enrolled patients with advanced solid tumors, followed by an expanded cohort at the recommended dose for patients with advanced unresectable or metastatic pancreatic cancer. Sorafenib is administered continuously, whereas gemcitabine is given at 1,000 mg/m(2) weekly x 7 followed by 1 rest week, then weekly x 3 every 4 weeks. Results: Forty-two patients have been enrolled overall, including 19 in the dose-escalation part and 23 in the extended pancreatic cancer cohort. Demographics were as follows: male-to-female ratio = 26:16; median age = 61 years (range 39-83 years); Eastern Cooperative Oncology Group performance status 0:1:2 ratio = 16:21:5. The recommended dose of this combination is sorafenib 400 mg twice daily and gemcitabine 1,000 mg/m(2). The most frequent grade 3 or 4 adverse events of all causalities were thrombocytopenia (28.6%), lymphopenia (21.4%), lipase elevation (19%), neutropenia (16.7%), and fatigue (14.3%). Antitumor activity was observed in both groups, with 2 (10.5%) confirmed partial responses in ovarian cancer and 12 patients (63.2%) with disease stabilization in the dose-escalation part; 13 patients (56.5%) achieved disease stabilization in the pancreatic cohort. There was no consistent pharmacokinetic drug-to-drug interaction between sorafenib and gemcitabine. Conclusions: Sorafenib and gemcitabine are well tolerated in combination; further evaluations in pancreatic and ovarian cancers are warranted.