Gut microbiota modulate T cell trafficking into human colorectal cancer.

OBJECTIVE: Tumour-infiltrating lymphocytes (TILs) favour survival in human colorectal cancer (CRC). Chemotactic factors underlying their recruitment remain undefined. We investigated chemokines attracting T cells into human CRCs, their cellular sources and microenvironmental triggers. DESIGN: Expression of genes encoding immune cell markers, chemokines and bacterial 16S ribosomal RNA (16SrRNA) was assessed by quantitative reverse transcription-PCR in fresh CRC samples and corresponding tumour-free tissues. Chemokine receptor expression on TILs was evaluated by flow cytometry on cell suspensions from digested tissues. Chemokine production by CRC cells was evaluated in vitro and in vivo, on generation of intraperitoneal or intracecal tumour xenografts in immune-deficient mice. T cell trafficking was assessed on adoptive transfer of human TILs into tumour-bearing mice. Gut flora composition was analysed by 16SrRNA sequencing. RESULTS: CRC infiltration by distinct T cell subsets was associated with defined chemokine gene signatures, including CCL5, CXCL9 and CXCL10 for cytotoxic T lymphocytes and T-helper (Th)1 cells; CCL17, CCL22 and CXCL12 for Th1 and regulatory T cells; CXCL13 for follicular Th cells; and CCL20 and CCL17 for interleukin (IL)-17-producing Th cells. These chemokines were expressed by tumour cells on exposure to gut bacteria in vitro and in vivo. Their expression was significantly higher in intracecal than in intraperitoneal xenografts and was dramatically reduced by antibiotic treatment of tumour-bearing mice. In clinical samples, abundance of defined bacteria correlated with high chemokine expression, enhanced T cell infiltration and improved survival. CONCLUSIONS: Gut microbiota stimulate chemokine production by CRC cells, thus favouring recruitment of beneficial T cells into tumour tissues.

CD40 ligand-expressing recombinant vaccinia virus promotes the generation of CD8(+) central memory T cells.

Central memory CD8(+) T cells (TCM ) play key roles in the protective immunity against infectious agents, cancer immunotherapy, and adoptive treatments of malignant and viral diseases. CD8(+) TCM cells are characterized by specific phenotypes, homing, and proliferative capacities. However, CD8(+) TCM -cell generation is challenging, and usually requires CD4(+) CD40L(+) T-cell "help" during the priming of naïve CD8(+) T cells. We have generated a replication incompetent CD40 ligand-expressing recombinant vaccinia virus (rVV40L) to promote the differentiation of human naïve CD8(+) T cells into TCM specific for viral and tumor-associated antigens. Soluble CD40 ligand recombinant protein (sCD40L), and vaccinia virus wild-type (VV WT), alone or in combination, were used as controls. Here, we show that, in the absence of CD4(+) T cells, a single "in vitro" stimulation of naïve CD8(+) T cells by rVV40L-infected nonprofessional CD14(+) antigen presenting cells promotes the rapid generation of viral or tumor associated antigen-specific CD8(+) T cells displaying TCM phenotypic and functional properties. These observations demonstrate the high ability of rVV40L to fine tune CD8(+) mediated immune responses, and strongly support the use of similar reagents for clinical immunization and adoptive immunotherapy purposes.

FGF2 induces RANKL gene expression as well as IL1ß regulated MHC class II in human bone marrow-derived mesenchymal progenitor stromal cells.

OBJECTIVE: Human bone marrow mesenchymal stromal cells (hBM-MSC) are being applied in tissue regeneration and treatment of autoimmune diseases (AD). Their cellular and immunophenotype depend on isolation and culture conditions which may influence their therapeutic application and reflect their in vivo biological functions. We have further characterised the phenotype induced by fibroblast growth factor 2 (FGF2) on healthy donor hBM-MSC focusing on the osteoimmunological markers osteoprotegerin (OPG), receptor activator of nuclear factor kB (RANK), RANK ligand (RANKL) and HLA-DR and their regulation of expression by the inflammatory cytokines IL1ß and IFNγ. METHODS: RANK, RANKL, OPG and HLA-DR expression in hBM-MSC expanded under specific culture conditions, were measured by RT-PCR and flow cytometry. MAPKs induction by FGF2, IL1ß and IFNγ in hBM-MSC was analysed by immunoblotting and RT-PCR. RESULTS: In hBM-MSC, OPG expression is constitutive and FGF2 independent. RANKL expression depends on FGF2 and ERK1/2 activation. IL1ß and IFNγ activate ERK1/2 but fail to induce RANKL. Only IL1ß induces P38MAPK. The previously described HLA-DR induced by FGF2 through ERK1/2 on hBM-MSC, is suppressed by IL1ß through inhibition of CIITA transcription. HLA-DR induced by IFNγ is not affected by IL1ß in hBM-MSC, but is suppressed in articular chondrocytes and lung fibroblasts. CONCLUSIONS: RANKL expression and IL1ß regulated MHC-class II, both induced via activation of the ERK1/2 signalling pathway, are specific for progenitor hBM-MSC expanded in the presence of FGF2. HLA-DR regulated by IL1ß and ERK1/2 is observed on hBM-MSC during early expansion without FGF2 suggesting previous in vivo acquisition. Stromal progenitor cells with this phenotype could have an osteoimmunological role during bone regeneration.

Enhanced chondrocyte proliferation and mesenchymal stromal cells chondrogenesis in coculture pellets mediate improved cartilage formation.

In this study, we aimed at investigating the interactions between primary chondrocytes and mesenchymal stem/stromal cells (MSC) accounting for improved chondrogenesis in coculture systems. Expanded MSC from human bone marrow (BM-MSC) or adipose tissue (AT-MSC) were cultured in pellets alone (monoculture) or with primary human chondrocytes from articular (AC) or nasal (NC) cartilage (coculture). In order to determine the reached cell number and phenotype, selected pellets were generated by combining: (i) human BM-MSC with bovine AC, (ii) BM-MSC from HLA-A2+ with AC from HLA-A2- donors, or (iii) human green fluorescent protein transduced BM-MSC with AC. Human BM-MSC and AC were also cultured separately in transwells. Resulting tissues and/or isolated cells were assessed immunohistologically, biochemically, cytofluorimetrically, and by RT-PCR. Coculture of NC or AC (25%) with BM-MSC or AT-MSC (75%) in pellets resulted in up to 1.6-fold higher glycosaminoglycan content than what would be expected based on the relative percentages of the different cell types. This effect was not observed in the transwell model. BM-MSC decreased in number (about fivefold) over time and, if cocultured with chondrocytes, increased type II collagen and decreased type X collagen expression. Instead, AC increased in number (4.2-fold) if cocultured with BM-MSC and maintained a differentiated phenotype. Chondro-induction in MSC-chondrocyte coculture is a robust process mediated by two concomitant effects: MSC-induced chondrocyte proliferation and chondrocyte-enhanced MSC chondrogenesis. The identified interactions between progenitor and mature cell populations may lead to the efficient use of freshly harvested chondrocytes for ex vivo cartilage engineering or in situ cartilage repair.

Preventing vaccinia virus class-I epitopes presentation by HSV-ICP47 enhances the immunogenicity of a TAP-independent cancer vaccine epitope.

Herpes simplex virus protein ICP47, encoded by US12 gene, strongly downregulates major histocompatibility complex (MHC) class-I antigen restricted presentation by blocking transporter associated with antigen processing (TAP) protein. To decrease viral vector antigenic immunodominance and MHC class-I driven clearance, we engineered recombinant vaccinia viruses (rVV) expressing ICP47 alone (rVV-US12) or together with endoplasmic reticulum (ER)-targeted Melan-A/MART-1(27-35) model tumor epitope (rVV-MUS12). In this study, we show that antigen presenting cells (APC), infected with rVV-US12, display a decreased ability to present TAP dependent MHC class-I restricted viral antigens to CD8+ T-cells. While HLA class-I cell surface expression is strongly downregulated, other important immune related molecules such as CD80, CD44 and, most importantly, MHC class-II are unaffected. Characterization of rVV-MUS12 infected cells demonstrates that over-expression of a TAP-independent peptide, partially compensates for ICP47 induced surface MHC class-I downregulation (30% vs. 70% respectively). Most importantly, in conditions where clearance of infected APC by virus-specific CTL represents a limiting factor, a significant enhancement of CTL responses to the tumor epitope can be detected in cultures stimulated with rVV-MUS12, as compared to those stimulated by rVV-MART alone. Such reagents could become of high relevance in multiple boost protocols required for cancer immunotherapy, to limit vector-specific responsiveness.

MAGE-A10 is a nuclear protein frequently expressed in high percentages of tumor cells in lung, skin and urothelial malignancies.

MAGE-A10 is a highly immunogenic member of the MAGE-A family of cancer/testis tumor-associated antigens (C/T TAAs). Studies performed with broadly reactive antibodies have helped to initially characterize this TAA. However, no specific reagents have been developed so far, thus preventing a thorough analysis of its expression in healthy and tumoral tissues. We have produced MAGE-A10 gene product in soluble recombinant form, and we have used it to generate specific monoclonal antibodies (mAbs). One of these reagents, recognizing an epitope located at the COOH terminus of the MAGE-A10 gene product, was used to stain a multitumor tissue microarray comprising more than 2,500 paraffin-embedded specimens including healthy tissues, benign tumors and malignancies of different histological origin. MAGE-A10 protein was identified as an intranuclear protein of an apparent molecular weight of 70 kDa, expressed in normal spermatogonia and spermatocytes but in no other healthy tissue. Most importantly, this C/T TAA appears to be expressed in high (>50%) percentages of cancer cells from a number of malignancies, including lung, skin and urothelial tumors. Unexpectedly, high expression of MAGE-A10 TAA at the protein level was also detectable in gynecological malignancies and stomach and gall bladder cancers. The characterization of MAGE-A10-specific reagents might set the stage for the development of targeted active immunotherapy by clarifying potential indications and by allowing the selection of patients eligible for treatment and the monitoring of its effectiveness.

Fibroblast growth factor 2 and platelet-derived growth factor, but not platelet lysate, induce proliferation-dependent, functional class II major histocompatibility complex antigen in human mesenchymal stem cells.

OBJECTIVE: To document the specificity and the mechanism of induction of a novel class II major histocompatibility complex (MHC) antigen by mitogenic growth factors in human mesenchymal stem cells (MSCs) expanded in vitro for translational applications. METHODS: Expression of class II MHC molecules was measured in human MSCs and differentiated cells expanded in the presence of fibroblast growth factor 2 (FGF-2), platelet-derived growth factor BB (PDGF-BB), human platelet lysate, or interferon-γ (IFNγ). The roles of cell proliferation and growth factor-induced signaling pathways were investigated as well as the class II MHC assembly machinery and functional capacity. RESULTS: FGF-2 and, to a lesser extent, PDGF-BB induced in adult human MSCs the expression of HLA-DR (normally induced by inflammatory cytokines), which was able to stimulate CD4+ T cells via superantigen binding. In contrast to IFNγ, FGF induced HLA-DR expression only in human MSCs proliferating under its mitogenic effect and not in mouse MSCs or in differentiated human cells. Although it induced cell proliferation, human platelet lysate did not cause HLA-DR expression in human MSCs. HLA-DR expression occurred following FGF-specific binding to its receptor(s), mainly FGF receptor 1, without inducing IFNγ or tumor necrosis factor α expression. Both MAPK/ERK-1/2 and phosphatidylinositol 3-kinase/Akt controlled cell proliferation and HLA-DR expression, but only MAPK/ERK-1/2 controlled the induction of the class II MHC transcription activator protein CIITA, the major determinant of HLA-DR transcription. CONCLUSION: The induction of functional HLA-DR in proliferating progenitor MSCs is a property of human MSCs that have been expanded with mitogenic growth factors. This has potential biologic significance in the regulation and/or protection of progenitor cell subpopulations under sustained mitogenic proliferation and needs to be taken into account when expanding MSCs for use in in vivo applications.

Intranodal immunization with a vaccinia virus encoding multiple antigenic epitopes and costimulatory molecules in metastatic melanoma.

Recombinant vaccinia virus (rVV) encoding tumor-associated antigens (TAAs) and adhesion or costimulatory molecules may represent important immunogenic reagents for cancer immunotherapy. Recently, intranodal (IN) antigen administration was suggested to be more immunogenic than intradermal (ID) vaccination. However, IN rVV administration has not been attempted so far. We used a rVV encoding gp100(280-288), Melan-A/MART-1(27-35) and tyrosinase(1-9) HLA-A0201 restricted epitopes and CD80 and CD86 costimulatory molecules in stage III and IV melanoma patients in a phase 1/2 trial. Of 15 patients initiating treatment, including two cycles of IN immunization, each comprising one rVV administration and three recall injections of the corresponding peptides, accompanied by subcutaneous granulocyte macrophage-colony stimulating factor supplementation, five withdrew due to progressing disease. Of 10 remaining patients seven showed evidence of induction of cytotoxic T lymphocytes (CTLs) directed against at least one epitope under investigation, as detectable by limiting dilution analysis (LDA) of specific precursors and multimer staining. Adverse reactions were mild (National Cancer Institute (NCI) grade 1-2) and mainly represented by fever, skin rashes, and pruritus. These data indicate that IN administration of rVV encoding melanoma-associated epitopes and costimulatory molecules is safe and immunogenic.

Non-replicating recombinant vaccinia virus expressing CD80 to enhance T-cell stimulation.

The following method describes the generation of a recombinant vaccinia virus expressing a costimulatory molecule (human CD80 or B7.1).The procedure first requires the cloning, by classical methods not described here, of the gene of interest, e.g. CD80, into a vaccinia shuttle plasmid under the control of a virus-specific promoter enabling a transcription during the early phase of infection. Flanking the insert, the plasmid contains viral sequences and a selection maker needed for the insertion into the viral genome. The successive plaque isolation of recombinant virus on cell monolayer described here is based on the transient "gpt" selection system which enables other insertions in different loci of the same virus. Finally, after verification amplification and titration of the recombinant vector, replication will be impaired by a psoralen-UV treatment in order to produce a non-replicating virus. Expression and function of inserts, following infection of cells, are verified by specific phenotypic and functional assays.

A replication-incompetent CD154/40L recombinant vaccinia virus induces direct and macrophage-mediated antitumor effects in vitro and in vivo.

CD40 triggering may result in antitumor effects of potentially high clinical relevance. To gain insights important for patient selection and to identify adequate targeting techniques, we investigated CD40 expression in human cancer tissues and generated a replication-incompetent recombinant vaccinia virus expressing CD40 ligand (rVV40L). Its effects were explored in vitro and in vivo upon direct CD40 targeting on malignant cells or macrophage activation. CD40 expression was analyzed by immunohistochemistry in tumor and stromal cells in a multi-tumor array including 836 specimens from 27 different tumor types. Established tumor cell lines were used to explore the capacity of rVV40L to induce malignant cell apoptosis and modulate functional profiles of polarized macrophages. CD40 expression was detectable in significantly higher numbers of stromal as compared to malignant cells in lung and breast cancers. CD40 ligation following rVV40L infection induced apoptosis in CD40(+) cancer cells, but only in the presence of intact specific signal transduction chain. Importantly, rVV40L infection promoted the induction of TNF-α-dependent antitumor activity of M1-like macrophages directed against CD40(-) targets. CD40-activated M1-like macrophages also displayed enhanced ability to CXCL10-dependently recruit CD8+ T cells and to efficiently present cancer cell intracellular antigens through cross-priming. Moreover, rVV-driven CD40L expression partially "re-educated" M2-like macrophages, as suggested by detectable CXCL10 and IL-12 production. Most importantly, we observed that intra-tumoral injection of rVV40L-infected human macrophages inhibits progression of human CD40(-) tumors in vivo. First evidences of anticancer activity of rVV40L strongly encourage further evaluations.

Whole blood assessment of antigen specific cellular immune response by real time quantitative PCR: a versatile monitoring and discovery tool.

BACKGROUND: Monitoring of cellular immune responses is indispensable in a number of clinical research areas, including microbiology, virology, oncology and autoimmunity. Purification and culture of peripheral blood mononuclear cells and rapid access to specialized equipment are usually required. We developed a whole blood (WB) technique monitoring antigen specific cellular immune response in vaccinated or naturally sensitized individuals. METHODS: WB (300 microl) was incubated at 37 degrees C with specific antigens, in the form of peptides or commercial vaccines for 5-16 hours. Following RNAlater addition to stabilize RNA, the mixture could be stored over one week at room temperature or at 4 degrees C. Total RNA was then extracted, reverse transcribed and amplified in quantitative real-time PCR (qRT-PCR) assays with primers and probes specific for cytokine and/or chemokine genes. RESULTS: Spiking experiments demonstrated that this technique could detect antigen specific cytokine gene expression from 50 cytotoxic T lymphocytes (CTL) diluted in 300 microl WB. Furthermore, the high sensitivity of this method could be confirmed ex-vivo by the successful detection of CD8+ T cell responses against HCMV, EBV and influenza virus derived HLA-A0201 restricted epitopes, which was significantly correlated with specific multimer staining. Importantly, a highly significant (p = 0.000009) correlation between hepatitis B surface antigen (HBsAg) stimulated IL-2 gene expression, as detectable in WB, and specific antibody titers was observed in donors vaccinated against hepatitis B virus (HBV) between six months and twenty years before the tests. To identify additional markers of potential clinical relevance, expression of chemokine genes was also evaluated. Indeed, HBsAg stimulated expression of MIP-1beta (CCL4) gene was highly significantly (p = 0.0006) correlated with specific antibody titers. Moreover, a longitudinal study on response to influenza vaccine demonstrated a significant increase of antigen specific IFN-gamma gene expression two weeks after immunization, declining thereafter, whereas increased IL-2 gene expression was still detectable four months after vaccination. CONCLUSION: This method, easily amenable to automation, might qualify as technology of choice for high throughput screening of immune responses to large panels of antigens from cohorts of donors. Although analysis of cytokine gene expression requires adequate laboratory infrastructure, initial antigen stimulation and storage of test probes can be performed with minimal equipment and time requirements. This might prove important in "field" studies with difficult access to laboratory facilities.

Heterologous prime-boost immunotherapy of melanoma patients with Influenza virosomes, and recombinant Vaccinia virus encoding 5 melanoma epitopes and 3 co-stimulatory molecules. A multi-centre phase I/II open labeled clinical trial.

To the exception of early stages of disease, the morbidity and mortality of melanoma is considerable, with no acknowledged therapeutic options beyond surgery. Immunotherapy of melanoma has achieved some success, but further refinements are urgently needed in order to realize its potential. This paper describes a multi-centre phase I/II open labeled, controlled clinical trial investigating 2 innovative immunotherapeutic reagents. Two successive groups of 20 resected AJCC stages IIb-IV melanoma patients will be treated, first with melanoma epitopes included into Influenza virosomes (group 1), and second with a heterologous prime-boost protocol priming with a recombinant Vaccinia virus, and boosting with Influenza virosomes (group 2). Five melanoma epitopes from three different melanoma differentiation antigens were included into Influenza virosomes, that cross-stimulate CD4+ T cells and are endowed with high adjuvant capacity in the generation of CTL. The same five melanoma epitopes, two co-stimulatory molecules CD80 and CD86, and the CD40 ligand, a marker known to play a crucial role in CTL generation and memory maintenance were encoded in a recombinant Vaccinia virus. GM-CSF will be administered as a supporting cytokine. Both Influenza virosomes and octo-recombinant Vaccinia virus are innovative and original constructs assessed for the first time in human. Immunotherapy foresees 12 weekly immunizations for each group. Toxicity and adverse events will be monitored clinically. Immunological efficacy will be assessed dynamically by ex-vivo multimer analysis, Elispot, and quantitative real-time PCR for up to 3 months following completion of immunotherapy schedule. Disease free survival will be assessed by 4-monthly serial clinic visits, including physical and FDG-PET examinations, for a follow-up time of 2 years. Quality of life will be assessed with a dedicated FACT-BRM 4 questionnaire.

MAGE-A Antigens and Cancer Immunotherapy.

MAGE-A antigens are expressed in a variety of cancers of diverse histological origin and germinal cells. Due to their relatively high tumor specificity, they represent attractive targets for active specific and adoptive cancer immunotherapies. Here, we (i) review past and ongoing clinical studies targeting these antigens, (ii) analyze advantages and disadvantages of different therapeutic approaches, and (iii) discuss possible improvements in MAGE-A-specific immunotherapies.

Induction of hypoxia and necrosis in multicellular tumor spheroids is associated with resistance to chemotherapy treatment.

Culture of cancerous cells in standard monolayer conditions poorly mirrors growth in three-dimensional architectures typically observed in a wide majority of cancers of different histological origin. Multicellular tumor spheroid (MCTS) culture models were developed to mimic these features. However, in vivo tumor growth is also characterized by the presence of ischemic and necrotic areas generated by oxygenation gradients and differential access to nutrients. Hypoxia and necrosis play key roles in tumor progression and resistance to treatment. To provide in vitro models recapitulating these events in highly controlled and standardized conditions, we have generated colorectal cancer (CRC) cell spheroids of different sizes and analyzed their gene expression profiles and sensitivity to treatment with 5FU, currently used in therapeutic protocols. Here we identify three MCTS stages, corresponding to defined spheroid sizes, characterized by normoxia, hypoxia, and hypoxia plus necrosis, respectively. Importantly, we show that MCTS including both hypoxic and necrotic areas most closely mimic gene expression profiles of in vivo-developing tumors and display the highest resistance to 5FU. Taken together, our data indicate that MCTS may mimic in vitro generation of ischemic and necrotic areas in highly standardized and controlled conditions, thereby qualifying as relevant models for drug screening purposes.

Characterization of highly frequent epitope-specific CD45RA+/CCR7+/- T lymphocyte responses against p53-binding domains of the human polyomavirus BK large tumor antigen in HLA-A*0201+ BKV-seropositive donors.

Human polyomavirus BK (BKV) has been implicated in oncogenic transformation. Its ability to replicate is determined by the binding of its large tumor antigen (LTag) to products of tumor-suppressor genes regulating cell cycle, as specifically p53. We investigated CD8+ T immune responses to BKV LTag portions involved in p53 binding in HLA-A*0201+ BKV LTag experienced individuals. Peptides selected from either p53-binding region (LTag351-450 and LTag533-626) by current algorithms and capacity to bind HLA-A*0201 molecule were used to stimulate CD8+ T responses, as assessed by IFN-gamma gene expression ex vivo and detected by cytotoxicity assays following in vitro culture. We observed epitope-specific immune responses in all HLA-A*0201+ BKV LTag experienced individuals tested. At least one epitope, LTag579-587; LLLIWFRPV, was naturally processed in non professional antigen presenting cells and induced cytotoxic responses with CTL precursor frequencies in the order of 1/20'000. Antigen specific CD8+ T cells were only detectable in the CD45RA+ subset, in both CCR7+ and CCR7- subpopulations. These data indicate that widespread cellular immune responses against epitopes within BKV LTag-p53 binding regions exist and question their roles in immunosurveillance against tumors possibly associated with BKV infection.

Nonreplicating recombinant vaccinia virus expressing CD40 ligand enhances APC capacity to stimulate specific CD4+ and CD8+ T cell responses.

Recombinant poxviruses expressing immunomodulatory molecules together with specific antigens represent powerful vaccines for cancer immunotherapy. Recently, we and others have demonstrated, in vitro and in vivo, that coexpression of CD80 and CD86 costimulatory molecules enhances the immunogenic capacity of a recombinant vaccinia virus (rVV) encoding different tumor-associated antigens. To further investigate the capacity of these vectors to provide ligands for different costimulatory pathways relevant in the generation of T cell responses, we constructed a recombinant virus (rVV) expressing CD40 ligand or CD154 (CD154rVV). Upon binding the CD40 receptor expressed on antigen presenting cells (APC), this molecule, physiologically expressed on activated CD4+ T cells, increases their antigen presentation and immunostimulatory capacities. Therefore, we evaluated the effects of CD154rVV infection on APC activation and its consequences on T cell stimulation. CD154rVV infection of autologous fibroblasts, monocytes, or iDC promoted the expression of a number of cytokines, including GM-CSF, TNF-alpha, and IL-15 in iDC. Most importantly, IL-12 p40 gene expression and protein secretion were induced by CD154rVV but not by wild-type VV (WT VV) in either CD14+ cells or iDC, and these effects could be blocked by anti-CD40 monoclonal antibodies. Furthermore, phenotypic characterization of CD154rVV infected iDC revealed enhanced expression of CD83 and CD86 surface markers as compared with wild-type vaccinia virus infection. As expected, VV infection triggered cytokines gene expression in cultures including APC and T cells from VV immune donors. However, cytokine genes typically expressed by T cell receptor triggered T cells such as those encoding IL-2 and IFN-gamma, or T cell proliferation, were detectable to a significantly higher extent in CD154rVV infected cultures, as compared with WT VV. Activation of specific CD8+ T cells was then investigated using MART-1/Melan-A(27-35) epitope as the model of tumor-associated antigen (TAA). In the presence of CD154rVV activated APCs, significantly higher numbers of specific cytotoxic CD8+ T cells were detected, as compared with cultures performed in the presence of WT VV or in the absence of virus. Taken together, these data indicate that functional CD154 expression from rVV infected cells promotes APC activation, thereby enhancing antigen-specific T cell generation. Such a recombinant vector might help bypass the requirement for activated helper cells during CTL priming, thus qualifying as a potentially relevant vector in the generation of CD8+ T cell responses in cancer immunotherapy.

Bioreactor-engineered cancer tissue-like structures mimic phenotypes, gene expression profiles and drug resistance patterns observed "in vivo".

Anticancer compound screening on 2D cell cultures poorly predicts "in vivo" performance, while conventional 3D culture systems are usually characterized by limited cell proliferation, failing to produce tissue-like-structures (TLS) suitable for drug testing. We addressed engineering of TLS by culturing cancer cells in porous scaffolds under perfusion flow. Colorectal cancer (CRC) HT-29 cells were cultured in 2D, on collagen sponges in static conditions or in perfused bioreactors, or injected subcutaneously in immunodeficient mice. Perfused 3D (p3D) cultures resulted in significantly higher (p < 0.0001) cell proliferation than static 3D (s3D) cultures and yielded more homogeneous TLS, with morphology and phenotypes similar to xenografts. Transcriptome analysis revealed a high correlation between xenografts and p3D cultures, particularly for gene clusters regulating apoptotic processes and response to hypoxia. Treatment with 5-Fluorouracil (5-FU), a frequently used but often clinically ineffective chemotherapy drug, induced apoptosis, down-regulation of anti-apoptotic genes (BCL-2, TRAF1, and c-FLIP) and decreased cell numbers in 2D, but only "nucleolar stress" in p3D and xenografts. Conversely, BCL-2 inhibitor ABT-199 induced cytotoxic effects in p3D but not in 2D cultures. Our findings advocate the importance of perfusion flow in 3D cultures of tumor cells to efficiently mimic functional features observed "in vivo" and to test anticancer compounds.

Rapid induction of specific cytotoxic T lymphocytes against melanoma-associated antigens by a recombinant vaccinia virus vector expressing multiple immunodominant epitopes and costimulatory molecules in vivo.

A specific cellular immune response directed against a panel of three defined tumor-associated antigen (TAA) epitopes was induced in metastatic melanoma patients by a prime-boost strategy taking advantage of an innovative recombinant vaccinia virus as evaluated by quantitative assessment of cytotoxic T lymphocytes (CTLs) with corresponding specificity. The immunization protocol consisted of the administration of psoralen-UV-treated and replication-incompetent recombinant vaccinia virus encoding the three immunodominant HLA-A*0201-restricted epitopes Melan-A(27-35), gp100(280-288), and tyrosinase(1-9) together with two costimulatory molecules, B7.1 and B7.2, in the context of systemic granulocyte-macrophage colony-stimulating factor (GM-CSF) treatment. Boosts were subsequently applied with corresponding synthetic nonapeptides and GM-CSF. Specific CTL induction was assessed by tetramer staining and CTL precursor (CTLp) frequency evaluation. Within 12 days of injection of the recombinant vector, cytotoxic T cell responses specific for engineered epitopes were detectable in three of three patients. During the vaccination treatment, antigen-specific CTLp frequencies exceeding 1:10,000 peripheral CD8(+) T cells could be observed. Tetramer staining also revealed significant increases in specific CD8(+) T cell numbers. We conclude that active specific antitumor vaccination can raise a concurrent and specific cellular immune response against a panel of molecularly defined antigens, thereby increasing the chance of an immune hit against neoplastic cells with heterogeneous antigen expression. Data from this study emphasize the potency of a recombinant vaccinia virus vector encoding multiple minigenes and costimulatory molecules in the context of exogenously administered GM-CSF. Clinical effectiveness of this immunologically active protocol should therefore be explored in appropriately selected groups of patients.

Cytotoxic T-cell induction in metastatic melanoma patients undergoing recombinant vaccinia virus-based immuno-gene therapy.

In an ongoing phase I/II study, metastatic melanoma patients were treated with a replication-incompetent recombinant vaccinia virus (rVV) encoding Melan-A(27-35), gp100(280-288), and tyrosinase(1-9) HLA-A*201-restricted epitopes together with B7.1 and B7.2 co-stimulatory molecules. rVV was administered in the context of systemic GM-CSF treatment. Boosts were subsequently administered 2 weeks apart with corresponding synthetic nonapeptides and GM-CSF. Two cycles of treatment were administered 2 weeks apart from each other. Specific immune responses were evaluated by quantitative assessment of cytotoxic T-lymphocyte precursor frequency and tetramer staining. By the time the two cycles had been completed, four out of five patients showed significant (greater than threefold) increases in gp100(280-288)-specific and four out of five, in Melan-A(27-35)-specific tetramer staining of CD8+ cells. Frequencies of CTL precursors specific for gp100(280-288), tyrosinase(1-9) and Melan-A(27-35) were also significantly increased in all five, and in four and four of the five patients, respectively, in some cases within 12 days after the first injection of the recombinant vector. Thus, the innovative vector under investigation is able to raise a concurrent and specific cellular immune response against a panel of molecularly defined antigens, thereby increasing the chance of an immune hit against neoplastic cells displaying heterogeneous antigen expression.

GM-CSF Production by Tumor Cells Is Associated with Improved Survival in Colorectal Cancer.

PURPOSE: Colorectal cancer infiltration by CD16(+) myeloid cells correlates with improved prognosis. We addressed mechanistic clues and gene and protein expression of cytokines potentially associated with macrophage polarization. EXPERIMENTAL DESIGN: GM-CSF or M-CSF-stimulated peripheral blood CD14(+) cells from healthy donors were cocultured with colorectal cancer cells. Tumor cell proliferation was assessed by (3)H-thymidine incorporation. Expression of cytokine genes in colorectal cancer and autologous healthy mucosa was tested by quantitative, real-time PCR. A tumor microarray (TMA) including >1,200 colorectal cancer specimens was stained with GM-CSF- and M-CSF-specific antibodies. Clinicopathological features and overall survival were analyzed. RESULTS: GM-CSF induced CD16 expression in 66% ± 8% of monocytes, as compared with 28% ± 1% in cells stimulated by M-CSF (P = 0.011). GM-CSF but not M-CSF-stimulated macrophages significantly (P < 0.02) inhibited colorectal cancer cell proliferation. GM-CSF gene was expressed to significantly (n = 45, P < 0.0001) higher extents in colorectal cancer than in healthy mucosa, whereas M-CSF gene expression was similar in healthy mucosa and colorectal cancer. Accordingly, IL1ß and IL23 genes, typically expressed by M1 macrophages, were expressed to significantly (P < 0.001) higher extents in colorectal cancer than in healthy mucosa. TMA staining revealed that GM-CSF production by tumor cells is associated with lower T stage (P = 0.02), "pushing" growth pattern (P = 0.004) and significantly (P = 0.0002) longer survival in mismatch-repair proficient colorectal cancer. Favorable prognostic effect of GM-CSF production by colorectal cancer cells was confirmed by multivariate analysis and was independent from CD16(+) and CD8(+) cell colorectal cancer infiltration. M-CSF expression had no significant prognostic relevance. CONCLUSIONS: GM-CSF production by tumor cells is an independent favorable prognostic factor in colorectal cancer.