IRX-2 was previously tested in a study of 13 patients with advanced head and neck cancer who had been previously treated and failed chemotherapy and/or radiation therapy. The trials were specifically designed to test the safety of IRX-2. Researchers found that IRX-2 did not appear to have major side effects. Also, the researchers believed that further study in less advanced head and neck cancer patients could be useful in obtaining more data on the safety of IRX-2 as well as data on possible effects on tumors and on patient survival.