Exploring dendritic cell based vaccines targeting survivin for the treatment of head and neck cancer patients.

BACKGROUND: New treatment modalities are needed for the treatment of cancers of the head and neck region (HNSCC). Survivin is important for the survival and proliferation of tumor cells and may therefore provide a target for immunotherapy. Here we focused on the ex vivo presence and in vitro induction of survivin specific T cells. METHODS: Tetramer staining and ELIspot assays were used to document the presence of survivin specific T cells in patient derived material, and to monitor the presence and persistence of survivin specific T cells after repeated in vitro stimulation with autologous dendritic cells. RESULTS: Ex vivo analysis showed the presence of survivin-specific T cells in the peripheral blood (by tetramer analysis) and in the draining lymph node (by ELIspot analysis) in a HNSCC and a locally advanced breast cancer patient respectively. However, we were unable to maintain isolated survivin specific T cells for prolonged periods of time. For the in vitro generation of survivin specific T cells, monocyte derived DC were electroporated with mRNA encoding full length survivin or a survivin mini-gene together with either IL21 or IL12 mRNA. Western blotting and immunohistochemical staining of dendritic cell cytospin preparations confirmed translation of the full length survivin protein. After repeated stimulation we observed an increase, followed by a decrease, of the number of survivin specific T cells. FACS sorted or limiting dilution cloned survivin specific T cells could not be maintained on feeder mix for prolonged periods of time. Protein expression analysis subsequently showed that activated, but not resting T cells contain survivin protein. CONCLUSIONS: Here we have shown that survivin specific T cells can be detected ex vivo in patient derived material. Furthermore, survivin specific T cells can be induced in vitro using autologous dendritic cells with enforced expression of survivin and cytokines. However, we were unable to maintain enriched or cloned survivin specific T cells for prolonged periods of time. Endogenous expression of survivin in activated T cells and subsequent fratricide killing might explain our in vitro observations. We therefore conclude that survivin, although it is a universal tumor antigen, might not be the ideal target for immunotherapeutic strategies for the treatment of cancer of the head and neck.

Generating HPV specific T helper cells for the treatment of HPV induced malignancies using TCR gene transfer.

BACKGROUND: Infection with high risk Human Papilloma Virus (HPV) is associated with cancer of the cervix, vagina, penis, vulva, anus and some cases of head and neck carcinomas. The HPV derived oncoproteins E6 and E7 are constitutively expressed in tumor cells and therefore potential targets for T cell mediated adoptive immunotherapy. Effective immunotherapy is dependent on the presence of both CD4+ and CD8+ T cells. However, low precursor frequencies of HPV16 specific T cells in patients and healthy donors hampers routine isolation of these cells for adoptive transfer purposes. An alternative to generate HPV specific CD4+ and CD8+ T cells is TCR gene transfer. METHODS: HPV specific CD4+ T cells were generated using either a MHC class I or MHC class II restricted TCR (from clones A9 and 24.101 respectively) directed against HPV16 antigens. Functional analysis was performed by interferon-γ secretion, proliferation and cytokine production assays. RESULTS: Introduction of HPV16 specific TCRs into blood derived CD4+ recipient T cells resulted in recognition of the relevant HPV16 epitope as determined by IFN-γ secretion. Importantly, we also show recognition of the endogenously processed and HLA-DP1 presented HPV16E6 epitope by 24.101 TCR transgenic CD4+ T cells and recognition of the HLA-A2 presented HPV16E7 epitope by A9 TCR transgenic CD4+ T cells. CONCLUSION: Our data indicate that TCR transfer is feasible as an alternative strategy to generate human HPV16 specific CD4+ T helper cells for the treatment of patients suffering from cervical cancer and other HPV16 induced malignancies.

Promiscuous behavior of HPV16E6 specific T cell receptor beta chains hampers functional expression in TCR transgenic T cells, which can be restored in part by genetic modification.

BACKGROUND: T cell receptor gene transfer is a promising strategy to treat patients suffering from HPV induced malignancies. Therefore we isolated the TCRalphabeta open reading frames of an HPV16E6 specific CTL clone and generated TCR transgenic T cells. In general low level expression of the transgenic TCR in recipient human T cells is observed as well as the formation of mixed TCRs dimers. Here we addressed both issues employing three different expression platforms. METHODS: We isolated the HVP16E6 specific TCRalpha and TCRbeta open reading frames and retrovirally transduced human T cells with either wild-type (wt), or codon-modified (cm) chains to achieve enhanced TCR expression levels, or used codon-modification in combination with cysteinization (cmCys) of TCRs to facilitate preferential pairing of the introduced TCRalpha and TCRbeta chains. RESULTS: Careful analysis of recipient T cells carrying the HPV16E6 TCRbeta and endogenous TCR chains revealed the transgenic TCRbeta chain to behave very promiscuously. Further analysis showed that the percentage of tetramer positive T cells in codon-modified/cysteinized TCR transgenic T cells was four-fold higher compared to wild-type and two-fold higher compared to codon-modification only. Functional activity, as determined by IFN-gamma production, was high in cmCysTCR transgenic T cells, where it was low in cm and wt TCR transgenic T cells. Recognition of endogenously processed HPV16E6 antigen by cmCysTCR transgenic T cells was confirmed in a cytotoxicity assay. CONCLUSION: Promiscuous behavior of the HPV16E6 specific TCRbeta chain can in part be forced back into specific action in TCR transgenic T cells by codon modification in combination with the inclusion of an extra cysteine in the TCR chains.

Tumor associated antigen and interleukin-12 mRNA transfected dendritic cells enhance effector function of natural killer cells and antigen specific T-cells.

Immunotherapy aiming at the combined activation of tumor associated antigen (TAA) specific cytotoxic T lymphocytes (CTL) and Natural Killer (NK) cells may be crucial to eradicate both MHC-I positive and negative tumors. Vaccination with mature dendritic cells (DC) transfected with mRNA encoding for TAA and the pro-inflammatory cytokines interleukin (IL)-12 and IL-18 may increase NK cell and TAA specific CTL activity. We demonstrate here that IL-12 over-expressing human DC induces increased NK cell activation and effector function and confirm the increase in TAA specific CTL by TAA/IL-12 double transfected DC. The effects of IL-18 transfection were limited to phenotypic activation and down-regulation of tissue homing receptors and did not add to the effect of IL-12 on NK cell effector function. In conclusion, co-transfection of TAA and IL-12 mRNA into mature DCs offers a vaccine for the induction of an anti-tumor immune response mediated by CTL and NK effector cells.

Inducing antitumor T cell immunity: comparative functional analysis of interstitial versus Langerhans dendritic cells in a human cell line model.

Dendritic cells (DC) are increasingly applied as a cellular adjuvant in immunotherapy of cancer. Two major myeloid DC subsets are recognized: interstitial DC (IDC) that infiltrate connective tissues and Langerhans cells (LC) that line epithelial surfaces. Yet, functional differences between IDC and LC remain to be defined. We recently showed that the CD34(+) acute myeloid leukemia cell line MUTZ-3 supports differentiation of both DC-SIGN(+) IDC and Langerin-positive Birbeck granule-expressing LC. By comparative functional characterization of MUTZ-3 IDC and MUTZ-3 LC, we aimed to elucidate the relative abilities of these two DC subsets to induce a specific T cell response and reveal the more suitable candidate for use as a clinical vehicle of tumor vaccines. Although mature LC and IDC displayed comparable lymph node-homing potential, mature LC showed higher allogeneic T cell stimulatory capacity. Nevertheless, IDC supported the induction of tumor Ag-specific CD8(+) T cells at an overall higher efficiency. This might be related to the observed inability of LC to release T cell stimulatory cytokines such as IL-12p70, IL-23, and IL-15. Although this inability did not result in a detectable deviation in the cytokine expression profile of primed T cells, transduction with IL-12p70 significantly improved priming efficiency of LC, and ensured a functional equivalence with IDC in this regard. In conclusion, except for the inability of LC to release distinct type 1 T cell stimulatory cytokines, in vitro function of LC and IDC suggests comparable abilities of both subsets for the in vivo induction of antitumor T cells.

Constitutively active STAT5b induces cytokine-independent growth of the acute myeloid leukemia-derived MUTZ-3 cell line and accelerates its differentiation into mature dendritic cells.

The CD34(+) human acute myeloid leukemia-derived cell line MUTZ-3 is dependent on hematopoietic growth factors for its proliferation and is able to differentiate into dendritic cells (DCs) in response to the combination of granulocyte-macrophage colony-stimulating factor, interleukin-4, and tumor necrosis factor-alpha. This cell line carries human leukocyte antigen (HLA)-A2.1, HLA-A3, and HLA-B44, which cover most of the caucasian population, and it could therefore be used as an off-the-shelf allogeneic DC-based vaccine. Signal transduction and activation of transcription (STAT) 5b is involved in cytokine signal transduction, particularly of cytokines involved in DC precursor growth and differentiation. The constitutively active form of STAT5b induced cytokine-independent growth of MUTZ-3 cells. Furthermore, STAT5b-transduced cells differentiated into mature DCs in 3 to 4 days after stimulation with DC differentiation-inducing cytokines, reducing the culture period to obtain mature DCs with 5 days compared with unmodified MUTZ-3-derived mature DC cultures. Both DC types expressed DC maturation markers and were equally effective in inducing primary T-cell responses. DCs derived from the STAT5b-transduced cells had a more stable mature phenotype after cytokine deprivation, which was reflected in a better performance in functional assays. In conclusion, these results show that STAT5b-transduced MUTZ-3 can be propagated in cytokine-free medium and rapidly differentiated into functional mature DCs that sustain a mature phenotype over a period of 3 to 5 days in the absence of differentiation-inducing cytokines. The simplified propagation and rapid differentiation into mature DCs may facilitate clinical application of this cell line as an allogeneic DC-based vaccine.

Antigen gene transfer to human plasmacytoid dendritic cells using recombinant adenovirus and vaccinia virus vectors.

Recombinant adenoviruses (RAd) and recombinant vaccinia viruses (RVV) expressing tumour-associated antigens (TAA) are used as anti-tumour vaccines. It is important that these vaccines deliver the TAA to dendritic cells (DC) for the induction of a strong immune response. Infection of myeloid DC (MDC) with RAd alone is relatively inefficient but CD40 retargeting significantly increases transduction efficiency and DC maturation. Infection with RVV is efficient without DC maturation. Plasmacytoid dendritic cells (PDC) play a role in the innate immune response to viral infections through the secretion of IFNalpha but may also play a role in specific T-cell induction. The aim of our study was to investigate whether PDC are better targets for RAd and RVV based vaccines. RAd alone hardly infected PDC (2%) while CD40 retargeting did not improve transduction efficiency, but it did increase PDC maturation (25% CD83 positive cells). Accordingly, specific CTL activation by RAd infected PDC was limited (the number of IFNgamma producing CTL was reduced by 75% compared to stimulation with peptide loaded PDC). RVV infected PDC specifically stimulated CTL but PDC were not activated. These results indicate that PDC are not ideal targets for RAd and RVV based vaccines. However, PDC induced specific CTL activation after pulsing with recombinant protein, indicating that PDC can also cross-present antigens released from surrounding infected cells.

Plasmacytoid dendritic cells are present in cervical carcinoma and become activated by human papillomavirus type 16 virus-like particles.

OBJECTIVES: Plasmacytoid dendritic cells (PDC) play an important role in the innate immune response to viral infections through the secretion of high levels of IFNalpha. We investigated whether PDC play a role in Human Papillomavirus (HPV) associated cervical carcinoma. METHODS: Frozen sections of 18 cervical carcinomas were analyzed for the presence of myeloid and plasmacytoid DC. To study whether the HPV virus can activate PDC, expression of putative VLP receptors (CD49f and CD16) was analyzed on PDC in peripheral blood mononuclear cells of healthy donors. Furthermore, CD83 induction and IFNalpha production by purified blood-derived PDC was measured after incubation with HPV 16 virus like particles (VLP). RESULTS: PDC were detected in 83% of the CxCa cases, primarily in the stroma. PDC express one of the putative VLP receptors (CD49f). IFNalpha production but no CD83 expression was induced in PDC upon incubation with VLP. CONCLUSION: Our data suggest that PDC, which are at hand locally in the cervix, play a role in the natural immune response against HPV and identify PDC as possible targets for VLP-based vaccines.

Preservation and redirection of HPV16E7-specific T cell receptors for immunotherapy of cervical cancer.

Human papilloma virus (HPV) type 16 infections of the genital tract are associated with the development of cervical cancer (CxCa) in women. HPV16-derived oncoproteins E6 and E7 are expressed constitutively in these lesions and might therefore be attractive candidates for T-cell-mediated adoptive immunotherapy. However, the low precursor frequency of HPV16E7-specific T cells in patients and healthy donors hampers routine isolation of these cells for adoptive transfer. To overcome this problem, we have isolated T cell receptor (TCR) genes from four different HPV16E7-specific healthy donor and patient-derived human cytotoxic T lymphocyte (CTL) clones. We examined whether genetic engineering of peripheral blood-derived CD8+ T cells in order to express HPV16E711-20-specific TCRs is feasible for adoptive transfer purposes. Reporter cells (Jurkat/MA) carrying a transgenic TCR were shown to bind relevant but not irrelevant tetramers. Moreover, these TCR-transgenic Jurkat/MA cells showed reactivity towards relevant target cells, indicating proper functional activity of the TCRs isolated from already available T cell clones. We next introduced an HPV16E711-20-specific TCR into blood-derived, CD8+ recipient T cells. Transgenic CTL clones stained positive for tetramers presenting the relevant HPV16E711-20 epitope and biological activity of the TCR in transduced CTL was confirmed by lytic activity and by interferon (IFN)-gamma secretion upon antigen-specific stimulation. Importantly, we show recognition of the endogenously processed and HLA-A2 presented HPV16E711-20 CTL epitope by A9-TCR-transgenic T cells. Collectively, our data indicate that HPV16E7 TCR gene transfer is feasible as an alternative strategy to generate human HPV16E7-specific T cells for the treatment of patients suffering from cervical cancer and other HPV16-induced malignancies.

Interleukin-12 increases proliferation and interferon-gamma production but not cytolytic activity of human antigen-specific effector memory cytotoxic T lymphocytes: power of the effect depends on the functional avidity of the T cell and the antigen concentration.

Cytotoxic T lymphocytes (CTLs) play an important role in the defense against viral infections and malignant diseases. Interleukin (IL)-12 plays a crucial role in induction of antigen-specific primary CTL responses and enhances proliferation, interferon-gamma (IFN-gamma) production, and cytolytic activity of mitogen-stimulated T cells. However, the effects of IL-12 on proliferation and effector functions of previously in vitro or in vivo primed antigen-specific CTLs are less clear. Our results show that IL-12 induces an increase in proliferation of and IFN-gamma production by influenza peptide-specific CTLs, but no increase in cytolytic activity on a per cell basis was observed in bulk cultures. Stimulation of a CTL clone confirmed these results; IL-12 supported an increase in IFN-gamma production, but did not increase cytolytic activity. The extent of the effect of IL-12 on IFN-gamma production differs per CTL clone and depends on the avidity of the clone and the peptide concentration on its target. Our data suggest that IL-12 is a good adjuvant for boosting CTL responses, in terms of proliferation and IFN-gamma production, the latter particularly for CTLs with low to intermediate avidity, such as tumor-associated self-antigen-specific CTLs.

Human telomerase reverse transcriptase-transduced human cytotoxic T cells suppress the growth of human melanoma in immunodeficient mice.

Immunotherapy of melanoma by adoptive transfer of tumor-reactive T lymphocytes aims at increasing the number of activated effectors at the tumor site that can mediate tumor regression. The limited life span of human T lymphocytes, however, hampers obtaining sufficient cells for adoptive transfer therapy. We have shown previously that the life span of human T cells can be greatly extended by transduction with the human telomerase reverse transcriptase (hTERT) gene, without altering antigen specificity or effector function. We developed a murine model to evaluate the efficacy of hTERT-transduced human CTLs with antitumor reactivity to eradicate autologous tumor cells in vivo. We transplanted the human melanoma cell line melAKR or melAKR-Flu, transduced with a retrovirus encoding the influenza virus/HLA-A2 epitope, in RAG-2(-/-) IL-2Rgamma (-/-) double knockout mice. Adoptive transfer of the hTERT-transduced influenza virus-specific CTL clone INFA24 or clone INFA13 inhibited the growth of melAKR-Flu tumors in vivo and not of the parental melAKR melanoma cells. Furthermore, the hTERT-transduced CTL clone INFA13 inhibited tumor growth to the same extent in vivo as the untransduced CTL clone, as determined by in vivo imaging of luciferase gene-transduced melAKR-Flu tumors, indicating that hTERT did not affect the in vivo function of CTL. These results demonstrate that hTERT-transduced human CTLs are capable of mediating antitumor activity in vivo in an antigen-specific manner. hTERT-transduced MART-1-specific CTL clones AKR4D8 and AKR103 inhibited the growth of syngeneic melAKR tumors in vivo. Strikingly, melAKR-Flu cells were equally killed by the MART-1-specific CTL clones and influenza virus-specific CTL clones in vitro, but only influenza-specific CTLs were able to mediate tumor regression in vivo. The influenza-specific CTL clones were found to produce higher levels of IFNgamma on tumor cell recognition than the MART-1-specific CTL clones, which may result from the higher functional avidity of the influenza virus-specific CTL clones. Also, melAKR-Flu tumors were growing faster than melAKR tumors, which may have surpassed the relatively modest antitumor effect of the MART-1-specific CTL, as compared with the influenza virus-specific CTL. Taken together, the adoptive transfer model described here shows that hTERT-transduced T cells are functional in vivo, and allows us to evaluate the balance between functional activity of the CTL and tumor growth rate in vivo, which determines the efficacy of CTLs to eradicate tumors in adoptive transfer therapy.

In vitro generation and life span extension of human papillomavirus type 16-specific, healthy donor-derived CTL clones.

Human papillomavirus (HPV) type 16 infection is strongly associated with the development of cervical carcinoma (CxCa) in women. The HPV16-derived oncoproteins E6 and E7, responsible for both onset and maintenance of malignant transformation, are expressed constitutively in CxCa cells and represent tumor-associated Ags. As a result, E6 and E7 constitute potential targets for adoptive CTL-mediated immunotherapy of CxCa. However, the availability to date of well-characterized HPV16-specific, CxCa-reactive human CTLs is extremely limited. The current study describes the in vitro generation and isolation of HPV16 E7-specific, CxCa-reactive human CTL clones from low-frequency healthy donor-derived CD8beta-positive precursors. For this purpose, an in vitro CTL induction protocol was used involving mature monocyte-derived dendritic cells as stimulator cells loaded with an HLA-A2.1-restricted, E7(11-20)-derived high-affinity altered peptide ligand. A double tetramer-guided isolation procedure and subsequent limiting-dilution cloning resulted in Ag-specific CTL clones. Stringent CTL characterization clearly indicated Ag-specific, HLA-A2.1-restricted reactivity against different HPV16-transformed CxCa cell lines. To allow expansion of E7(11-20)-specific CTL clones to numbers required for prolonged in vitro as well as in vivo application, their life span was significantly extended by ectopic expression of human telomerase reverse transcriptase. Collectively, our results show that optimized CTL induction and stringent CTL selection procedures, followed by human telomerase reverse transcriptase-mediated life span extension will allow continued availability of low-frequency HPV16-specific, CxCa-reactive human CTL clones. This may enhance the prospects of HPV16-specific adoptive CTL immunotherapy in CxCa patients.