Adoptive transfer of Epstein-Barr virus (EBV)-specific cytotoxic T lymphocytes (CTLs) is effective prophylaxis and treatment of EBV-positive immunoblastic lymphoma in immunocompromised patients. In 50% of patients with Hodgkin's disease, the tumor cells are EBV antigen-positive and may therefore also be suitable targets for treatment with virus-specific CTLs. However, Hodgkin's disease may produce several inhibitory effects on immune induction and effector function in vivo, which may preclude the generation or effector function of CTLs reactive against EBV viral proteins, including those expressed by the tumor cells. We have investigated whether EBV-specific CTLs could be generated ex vivo from 13 patients with Hodgkin's disease: nine with active relapsed disease and four who were in clinical remission after a first or subsequent relapse. CTL lines were successfully generated from nine of 13 patients (five active disease, four remission). Although these lines had an abnormal pattern of expansion comparable to EBV-specific CTLs generated from normal donors, their phenotype was normal except for reduced expression of the zeta chain of the T-cell receptor (TCR). Their cytotoxicity was also compared to EBV-specific lines generated from normal donors and included activity against LMP2a, one of the three weakly immunogenic viral antigens expressed by Hodgkin's tumor cells. To assess the activity of the CTLs in vivo, they were gene-marked and infused into three patients with multiply relapsed disease. The CTLs persisted for more than 13 weeks postinfusion and retained their potent antiviral effects in vivo, thereby enhancing the patient immune response to EBV. This approach may therefore have value in the treatment of EBV-positive Hodgkin's disease.

The hallmark of infection by human herpesviruses, life-long persistence in the host, is unaffected by current antiviral therapies effective against replication of virus. In vitro studies indicated that low concentrations of the ribonucleotide reductase inhibitor, hydroxyurea, completely eliminated Epstein-Barr virus (EBV) episomes from latently infected Burkitt's lymphoma (BL) cell subsets, providing the first example of chemotherapeutic eradication of a latent herpesvirus from any cell population. Unlike parental EBV-positive BL cells, virus-free cell progeny from one treated cell line no longer exhibited the malignant phenotype in tumorigenicity assays. Hydroxyurea-treated primary B lymphocytes immortalized by EBV ceased to proliferate as episomes were lost. The altered growth phenotype of both BL cells and immortalized primary B cells suggests that latent EBV is an appropriate and accessible therapeutic target for treatment of some EBV-induced lymphoproliferations.

We have shown that interleukin-12 (IL-12) generated a strong, albeit transient, anti-tumor response, mostly mediated by natural killer (NK) cell. T cell participation, in addition to NK cells, was essential for persistence of the antitumor response. Ligation of 4-1BB, a co-stimulatory receptor expressed on activated T cells, is known to amplify T cellmediated immunity. In this study, we compared the effect of a systemically delivered agonistic anti-4-1BB monoclonal antibody (anti-4-1BB mAb) with intra-tumoral adenoviralmediated gene transfer of the 4-1BB ligand (ADV/4-1BBL) to liver metastases in a syngeneic animal model of breast cancer. Both treatments induced a dramatic regression of