Phase I Trial of Anti-MET Monoclonal Antibody in MET-Overexpressed Refractory Cancer

In this study, we conducted a first-in-human trial using mesenchymal epithelial transition factor (MET)-targeted monoclonal antibody in MET-overexpressed solid tumor. All patients were heavily pretreated before study entry and all patients except for 1 patient were colorectal cancer (CRC) patients. We found a dramatic responder in MET-overexpressed CRC patients in whom all available standard chemotherapy had failed. The overall response rate was 6.3% (n = 1 partial response) and there were 4 patients with stable disease (n = 4; 25.0%) and 6 with progressive disease (n = 6; 37.5%). On the basis of this study, the dose of 3.69 mg/kg was determined to be the maximum tolerated dose for phase II. Background: Samsung Advance Institute of Technology-301 (SAIT301) is a human immunoglobulin G2 antibody that can specifically target mesenchymal epithelial transition factor (c-MET). This novel antibody has higher priority over hepatocyte growth factors when binding to the Sema domain of c-MET and accelerates the internalization and degradation of c-MET, proving its powerful antitumor activities in intra- as well as extracellular areas. Materials and Methods: SAIT301 was administered intravenously once every 3 weeks in c-MET overexpressed solid tumor patients, focusing on metastatic colorectal cancer (CRC) according to common clinical phase I criteria. Dose escalation was performed according to a modified Fibonacci design, following the conventional 3+3 design. The purpose of this phase I study was to assess the safety profile, to establish the recommended dose for clinical phase II studies and to assess potential anticancer activity of the compound. Results: Sixteen patients with a median age of 56 (range, 39-69) years were enrolled in the study. The most common adverse events were decreased appetite (50.0%), hypophosphatemia, fatigue and dizziness (25.0%, respectively), and diarrhea, blood alkaline phosphatase increased and dyspnea (18.8%, respectively). For tumor response, no patients achieved complete response. One (9.1%) CRC patient had a partial response in the 1.23 mg/kg group, 4 (36.4%) patients achieved stable disease (2 in the 0.41 mg/kg group, 2 in the 1.23 mg/kg group, 0 in the 3.69 mg/kg group, and 1 in the 8.61 mg/kg group). Because of the increase in dose-limiting toxicities (DLTs) at 8.61 mg/kg, the 3.69 mg/kg dose was considered the maximum tolerated dose and selected for further assessment in phase II. Conclusion: We successfully completed a phase I trial with MET antibody in a MET-overexpressed patient population focusing on CRC, and found that the DLTs were alkaline phosphatase elevation or hypophosphatemia. The recommended dose of SAIT301 for phase II is the dose of 3.69 mg/kg.