A Study of FOLFIRI Plus OMP-21M18 as 1st or 2nd-line Treatment in Subjects With Metastatic Colorectal Cancer

The purpose of this study is to test the safety and determine the optimal dose of a new drug, OMP-21M18, when given in combination with FOLFIRI, a standard drug treatment for advanced colorectal cancer. Participants must not have had more than one chemotherapy regimen for their metastatic disease. OMP-21M18 is a humanized monoclonal antibody (a protein made in the laboratory) developed to target cancer stem cells. The way the body handles OMP-21M18 will also be investigated. Up to 32 participants, 21 years or older, at up to 6 centres in Australia and New Zealand, will receive intravenous infusions of OMP-21M18 followed by FOLFIRI every two weeks, until disease progression or limited by drug toxicity. After 8 weeks, participants will undergo assessments to determine their disease status. If there is no evidence of disease progression participants will continue to receive infusions of OMP-21M18 and FOLFIRI every second week, until disease progression.