Targeting tumor specific antigens immunologically is an attractive approach to the destruction of tumor cells most refractory to chemo and radiotherapy. Epstein-Barr virus (EBV) malignancies offer some interesting opportunities in this regard. Healthy immunocompetent individuals show an intense cytotoxic memory T cell response to EBV latency antigens. However, the immunodominant viral latency antigens are not expressed in most EBV malignancies. Restricted viral antigen expression in tumors, correlates with methylation of transcriptional regulatory elements of the EBV genome. Treatment of Burkitt's cell lines with a demethylating agent (5-azacitidine) leads to: (i) demethylation of these regulatory elements, (ii) a promoter switch, and (iii) expression of the full panel of EBV latency antigens including those frequently targeted by cytotoxic T cells. A comparable effect of this or other pharmacologic agents that alter patterns of viral gene transcription in tumors in vivo might facilitate immune destruction of EBV(+) tumors. In this proposal we are seeking support for the study of this approach to the treatment of EBV(+) malignancies with restricted patterns of antigen expression. We will study patients without history of HIV infection or history of organ transplantation. We will begin by assaying tumors at high risk for EBV-association (Hodgkin's disease, nasopharyngeal carcinoma, undifferentiated gastric cancer) for the presence of EBV in tumor cells. Patients with these tumors will be studied to characterize their conventional therapies will be eligible for enrollment in a trial to determine the effect of pharmacologic manipulation on patterns of viral gene expression in tumor tissue, and/or determining antitumor therapeutic efficacy of such agent. The trials will be conducted under the auspices of the John Hopkins Oncology Center Drug Development Program and will utilize the clinical resources of the General Clinical Research Inpatient and Outpatient Centers. In an initial trial, 5-azacitidine, will be administered to patients with biopsy-accessible disease by 7-day continuous infusion. Patients will undergo biopsy before and after treatment; and tumor tissue will be assayed for patterns of methylation, transcription and antigen expression. This will be followed by the investigation of other agents that may alter patterns of viral gene expression. This will be followed by the investigation of other agents that may alter patterns of viral gene expression including other demethylating agents such as 5-aza- 2'deoxycytidine and phenylbutyrate. Ultimately, such drugs might be used in place of conventional therapy, as """"""""consolidation"""""""" following conventional therapy, or in combination with adoptive cellular immunotherapy to facilitate immune-mediated destruction of residual tumor cells.
