This trial will evaluate Hu5F9-G4 in combination with cetuximab. Hu5F9-G4 is a monoclonal antibody which is designed to block a protein called CD47, which is widely expressed on human cancer cells. Blocking CD47 with Hu5F9-G4 may enable the body's immune system to find and destroy the cancer cells. Cetuximab is a monoclonal antibody drug that is used for treatment of certain types of colorectal cancer as well as head and neck cancer.