In vitro activation of hTERT-specific T cell responses in lung cancer patients following chemotherapy.

OBJECTIVE: The aim of this study was to examine chemotherapy concomitant in vitro activation of human telomerase reverse transcriptase (hTERT)-specific T cell responses in peripheral blood mononuclear cell (PBMC) samples of patients with advanced non-small cell lung cancer (NSCLC). METHODS: PBMCs depleted of regulatory T cells were stimulated by peptide loaded dendritic cells (DC) matured either by application of cytokines (cDC) or a Toll-like receptor 7/8-agonist combined with a soluble CD40-ligand (ligDC). The hTERT peptide-specific T cell responses were assessed using flow cytometry for intracellular interferon-γ (IFN-γ). RESULTS: After cDC activation, T cells producing IFN-γ in response to hTERT were found in PBMC samples of 4 patients. In 2 of these patients the hTERT-specific T cell responses were further increased after ligDC application. However, PBMC of 3 other patients showed little or no induction of hTERT-specific T cell responses as a result of the methods applied during this study. CONCLUSIONS: These results indicate, that concomitant to chemotherapy hTERT-specific T cell responses can be activated in PBMC of NSCLC patients in vitro. This activation can be further increased by ligDC though the number of responding patients is still limited.

Quantitative assessment of molecular remission after high-dose therapy with autologous stem cell transplantation predicts long-term remission in mantle cell lymphoma.

To evaluate the prognostic impact of minimal residual disease (MRD), quantitative real-time polymerase chain reaction (RQ-PCR) of clonal IGH rearrangements was performed in 29 patients with mantle cell lymphoma (MCL) treated with high-dose radiochemotherapy and autologous stem cell transplantation (ASCT). Fourteen of 27 patients evaluable for MRD after ASCT achieved complete clinical and molecular remission, whereas 13 patients had detectable MRD within the first year after ASCT. Molecular remission after ASCT was strongly predictive for improved outcome, with a median progression-free survival (PFS) of 92 months in the MRD-negative group compared with 21 months in the MRD-positive group (P < .001). Median overall survival (OS) was 44 months in the MRD-positive group and has not been reached in the MRD-negative group (P < .003). In multivariate analysis, molecular remission and bulky disease were independent prognostic factors for PFS (P = .001 and P = .021, respectively). While cyclophosphamide, doxorubicin, vincristine, prednisolone (CHOP)-like cytoreduction had only modest influence, ara-C-containing mobilization and myeloablative radiochemotherapy significantly reduced MRD. Quantitative MRD measured in the stem cell products of 27 patients was not predictive for molecular remission. We conclude that sequential quantitative monitoring of residual disease after ASCT is a powerful indicator for treatment outcome in MCL and defines subgroups of patients with a significantly different prognosis.

Cytotoxic T lymphocyte therapy for Epstein-Barr virus+ Hodgkin's disease.

Epstein Barr virus (EBV)+ Hodgkin's disease (HD) expresses clearly identified tumor antigens derived from the virus and could, in principle, be a target for adoptive immunotherapy with viral antigen-specific T cells. However, like most tumor-associated antigens in immunocompetent hosts, these potential targets are only weakly immunogenic, consisting primarily of the latent membrane protein (LMP)1 and LMP2 antigens. Moreover, Hodgkin tumors possess a range of tumor evasion strategies. Therefore, the likely value of immunotherapy with EBV-specific cytotoxic effector cells has been questioned. We have now used a combination of gene marking, tetramer, and functional analyses to track the fate and assess the activity of EBV cytotoxic T lymphocyte (CTL) lines administered to 14 patients treated for relapsed EBV+ HD. Gene marking studies showed that infused effector cells could further expand by several logs in vivo, contribute to the memory pool (persisting up to 12 mo), and traffic to tumor sites. Tetramer and functional analyses showed that T cells reactive with the tumor-associated antigen LMP2 were present in the infused lines, expanded in peripheral blood after infusion, and also entered tumor. Viral load decreased, demonstrating the biologic activity of the infused CTLs. Clinically, EBV CTLs were well tolerated, could control type B symptoms (fever, night sweats, and weight loss), and had antitumor activity. After CTL infusion, five patients were in complete remission at up to 40 mo, two of whom had clearly measurable tumor at the time of treatment. One additional patient had a partial response, and five had stable disease. The performance and fate of these human tumor antigen-specific T cells in vivo suggests that they might be of value for the treatment of EBV+ Hodgkin lymphoma.

Identification of a naturally processed HLA-DR-restricted T-helper epitope in Epstein-Barr virus nuclear antigen type 1.

Epstein-Barr virus nuclear antigen type 1 (EBNA1), the only viral protein that is unequivocally expressed in all Epstein-Barr virus (EBV)-associated malignant diseases, is essential for viral DNA replication and maintenance of the viral episome in infected cells. A glycine-alanine repeat domain inhibits antigen processing through the ubiquitin-proteasome pathway for presentation on human leukocyte antigen (HLA) class I molecules. EBNA1 is not protected from the HLA class II processing pathway, and CD4+ HLA class II-restricted T cells recognize the antigen. CD4+ T-helper (Th) cells play critical roles in initiating, regulating, and maintaining immune responses against viral infections and tumors, so that inclusion of EBNA1 as a target antigen may improve immunotherapy for EBV-associated cancers. In this study, the authors used the TEPITOPE software program to predict promiscuous class II epitope candidates. After several HLA-DR-restricted peptides were identified by in vitro analysis of the T-cell response to synthetic peptides, a T-cell clone was established that was specific for one of the peptides. Functional studies were performed with this clone. The CD4+ T helper cells specific for the HLA-DR15-restricted peptide EBNA1(482) (AEGLRALLARSHVER) recognized naturally processed EBNA1 protein. This epitope was presented by several HLA-DR alleles, including DR4, DR7, and DR11. The inclusion of the promiscuous, naturally processed EBNA1(482) epitope in vaccine constructs could enhance immune responses against EBV-positive cancers.

Immunotherapy to reconstitute immunity to DNA viruses.

Defects in cytotoxic T-lymphocyte (CTL) function after hemopoietic stem cell transplantation (HSCT) are associated with an increased frequency and severity of viral diseases. Initial investigations of viral infections in immunosuppressed mice and subsequent clinical studies of cytomegalovirus (CMV) and Epstein-Barr virus (EBV) in human stem cell transplant patients have suggested that adoptive transfer of virus-specific T cells may restore protective immunity and control established infections. Current efforts focus on optimizing adoptive immunotherapy approaches and developing strategies for generating T cells specific for multiple viruses to provide broader protection.