While patients with nasopharyngeal carcinoma (NPC) may be cured by chemotherapy and radiotherapy, the outlook for patients who are resistant to this treatment or who relapse is poor. Almost all patients with undifferentiated nasopharyngeal carcinoma have the EBV virus in their tumors which may be a target for immunotherapy approaches. We have successfully used specialized immune system cells grown in the laboratory and trained to recognize and kill EBV infected cells (EBV-specific cytotoxic T-lymphocytes [EBV-CTL]) to prevent and treat another type of cancer called post transplant lymphoma that occurs after bone marrow transplant. In post transplant lymphoma, the tumor cells have 9 proteins made by EBV on their surface. However in nasopharyngeal carcinoma that develops in patients with a normal immune system, the tumor cells only express 2 EBV proteins that are much harder for the immune system to recognize. In a previous study we made EBV-CTL that recognized all 9 proteins and gave them to patients with NPC. For patients without evidence of active disease at the time of therapy, there disease remains in remission. For those patients with active disease at the time they received CTL, some patients had a partial response to this therapy, and only three patients had a complete response. We think the main reason for this is that many of the T cells reacted with EBV proteins that were not on the tumor cells, and the other is that the infused T cells have not enough space to grow.