Initially , patients were randomly assigned to receive either pemetrexed ( 500 mg/m ( 2 ) ) or docetaxel ( 75 mg/m ( 2 ) ) and then randomly assigned within each group to receive their chemotherapy with or without cetuximab ( 400 mg/m ( 2 ) at first dose and 250 mg/m ( 2 ) weekly thereafter ) until disease progression or unacceptable toxicity .