Prognostic Value of "Basal-like" Morphology, Tumor-Infiltrating Lymphocytes and Multi-MAGE-A Expression in Triple-Negative Breast Cancer

"Basal-like" (BL) morphology and the expression of cancer testis antigens (CTA) in breast cancer still have unclear prognostic significance. The aim of our research was to explore correlations of the morphological characteristics and tumor microenvironment in triple-negative breast carcinomas (TNBCs) with multi-MAGE-A CTA expression and to determine their prognostic significance. Clinical records of breast cancer patients who underwent surgery between January 2017 and December 2018 in four major Croatian clinical centers were analyzed. A total of 97 non-metastatic TNBCs with available tissue samples and treatment information were identified. Cancer tissue sections were additionally stained with programmed death-ligand 1 (PD-L1) Ventana (SP142) and multi-MAGE-A (mAb 57B). BL morphology was detected in 47 (49%) TNBCs and was associated with a higher Ki-67 proliferation index and histologic grade. Expression of multi-MAGE-A was observed in 77 (79%) TNBCs and was significantly associated with BL morphology. Lymphocyte-predominant breast cancer (LPBC) status was detected in 11 cases (11.3%) and significantly correlated with the Ki-67 proliferation index, increased number of intratumoral lymphocytes (itTIL), and PD-L1 expression. No impact of BL morphology, multi-MAGE-A expression, histologic type, or LPBC status on disease-free survival was observed. Our data suggest that tumor morphology could help identify patients with potential benefits from CTA-targeting immunotherapy.

Prognostic Significance of Lymphocyte Infiltrate Localization in Triple-Negative Breast Cancer

High infiltration by tumor-infiltrating lymphocytes (TILs) is associated with favorable prognosis in different tumor types, but the clinical significance of their spatial localization within the tumor microenvironment is debated. To address this issue, we evaluated the accumulation of intratumoral TILs (itTILs) and stromal TILs (sTILs) in samples from 97 patients with early triple-negative breast cancer (TNBC) in the center (sTIL central) and periphery (sTIL peripheral) of tumor tissues. Moreover, the presence of primary and secondary lymphoid aggregates (LAs) and the expression levels of the cancer testis antigen (CTA), NY-ESO-1, and PD-L1 were explored. High infiltration by itTILs was observed in 12/97 samples (12.3%), unrelated to age, Ki67 expression, tumor size, histologic type and grade, and LA presence. NY-ESO-1 was expressed in tumor cells in 37 samples (38%), with a trend suggesting a correlation with itTIL infiltration (p = 0.0531). PD-L1 expression was detected in immune cells in 47 samples (49%) and was correlated with histologic grade, sTILs, and LA formation. The presence of primary LAs was significantly correlated with better disease-free survival (DFS) (p = 0.027). Moreover, no tumor progression was observed during >40 months of clinical follow up in the 12 patients with high itTILs or in the 14 patients with secondary LAs. Thus, careful evaluation of lymphoid infiltrate intratumoral localization might provide important prognostic information.

Abstract 2821: Gut commensal bacteria modulate functions of tumor-associated neutrophils in human colorectal cancer

Tumor infiltration by immune cells critically impacts on clinical outcome of human colorectal cancer (CRC). While high densities of CD8+ T cells and T-helper type 1 cells are associated with prolonged patient survival, the role of tumor-associated neutrophils (TANs) is debated.

CRC arise in an environment heavily populated by microrganisms. Upon CRC oncogenesis, gut commensal bacteria translocate into the submucosa where they directly interact with residing immune cells. Neutrophils represent a front-line arm of the immune system in the response to bacteria. However, little is known about their interaction with commensal bacteria within CRC tissues. We investigated the interplay between neutrophils and commensal bacterial species present within the CRC microenvironment.

Using an orthotopic CRC xenograft model, we found that commensal bacteria stimulate CRC cells to produce neutrophil recruiting chemokines. We then compared in vitro chemokine induction capacity of Fusobacterium nucleatum (Fn) and Bacteroides fragilis (Bf), two most abundant bacterial species of CRC microenvironment. Fninduced significantly higher levels of IL-8 by CRC cells than Bf, thus more effectively promoting neutrophil recruitment. Accordingly, in human CRC samples, abundance of Fn, but not Bf, significantly correlated with high infiltration by CD66b+ cells. Functional studies indicate that neutrophils cultured in the presence of Fn, but not Bf, lose their ability to enhance proliferation and cytokine release by CD8+ T cells undergoing antigenic stimulation. Moreover, neutrophils exposed to Fn, but not Bf, stimulate release of IL-6 by tumor-associated stromal cells, leading to enhanced tumor cell proliferation.

Our data cumulatively suggest that distinct bacterial components of the human gut flora might differentially modulate functions of CRC infiltrating neutrophils, thus ultimately influencing their prognostic significance.

Note: This abstract was not presented at the meeting.

Citation Format: Valeria Governa, Eleonora Cremonesi, Diego Calabrese, Valentina Mele, Emanuele Trella, Raoul A. Droeser, Martin Bolli, Serenella Eppenberger-Castori, Salvatore Piscuoglio, Charlotte K. y. Ng, Jesus Francisco Glaus Garzon, Lubor Borsig, Klaus-Peter Janssen, Luigi M. Terracciano, Giulio Cesare Spagnoli, Dimitri Christoforidis, Pietro Edoardo Majno-Hurst, Giandomenica Iezzi. Gut commensal bacteria modulate functions of tumor-associated neutrophils in human colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2821.

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.

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.

Phosphorylated CXCR4 expression has a positive prognostic impact in colorectal cancer

BACKGROUND

The CXCL12-CXCR4 chemokine axis plays an important role in cell trafficking as well as in tumor progression. In colorectal cancer (CRC), the chemokine receptor CXCR4 has been shown to be an unfavorable prognostic factor in some studies, however, the role of its activated (phosphorylated) form, pCXCR4, has not yet been evaluated. Here, we aimed to investigate the prognostic value of CXCR4 and pCXCR4 in a large cohort of CRC patients.

PATIENTS AND METHODS

A tissue microarray (TMA) of 684 patient specimens of primary CRCs was analyzed by immunohistochemistry (IHC) for the expression of CXCR4 and pCXCR4 by tumor cells and tumor-infiltrating immune cells (TICs).

RESULTS

The combined high expression of CXCR4 and pCXCR4 showed a favorable 5-year overall survival rate (68%; 95%CI = 59-76%) compared to tumors showing a high expression of CXCR4 only (48%; 95%CI = 41-54%). High expression of pCXCR4 was significantly associated with a favorable prognosis in a test and validation group (p = 0.015 and p = 0.0001). Moreover, we found that CRCs with a high density of pCXCR4+ tumor-infiltrating immune cells (TICs) also showed a favorable prognosis in a test and validation group (p = 0.054 and p = 0.004). Univariate Cox regression analysis for TICs revealed that a high density of pCXCR4+ TICs was a favorable prognostic marker for overall survival (HR = 0.97,95%CI = 0.96-1.00; p = 0.01). In multivariate Cox regression survival analyses a high expression of pCXCR4 in tumor cells lost its association with a better overall survival (HR = 0.99; 95%CI = 0.99-1.00, p = 0.098).

CONCLUSION

Our results show that high densities of CXCR4 and pCXCR4 positive TICs are favorable prognostic factors in CRC.

Abstract 3695: The interplay between neutrophils &It CDThe interplay between neutrophils and CD8+ cell improves survival in human colorectal cancer

Purpose: Tumor infiltration by different T lymphocyte subsets is known to be associated with favorable prognosis in colorectal cancer (CRC). Still debated is the role of innate immune system. We investigated clinical relevance, phenotypes &it functional features of CRC infiltrating CD66b+ neutrophils &it their crosstalk with CD8+ T cells.

Experimental design: CD66b+ &it CD8+ cell infiltration was analyzed by immunohistochemistry on a tissue microarray including >650 evaluable CRC samples. Phenotypic profiles of tissue infiltrating and peripheral blood CD66b+ cells were evaluated by flow cytometry. CD66b+/ CD8+ cells crosstalk was investigated by in vitro experiments.

Results: CD66b+ cell infiltration in CRC is significantly associated with increased survival. Interestingly, neutrophils frequently co-localize with CD8+ T cells in CRC. Functional studies indicate that although neutrophils are devoid of direct antitumor potential, co-culture with peripheral blood or tumor associated neutrophils (TANs) enhances CD8+ T cell activation, proliferation and cytokine release induced by suboptimal concentrations of anti-CD3 monoclonal antibody (mAb). Moreover, under optimal activation conditions, CD8+ cells initially stimulated in the presence of CD66b+ cells show decreased expression of PD-1 “exhaustion” marker and are significantly less susceptible to apoptosis induced by T- cell receptor triggered re-stimulation. Importantly, combined tumor infiltration by CD66b+ and CD8+ T lymphocytes is associated with significantly better prognosis, as compared to CD8+ T cell infiltration alone.

Conclusions: Neutrophils enhance the responsiveness of CD8+ T cells to TCR triggering. Accordingly, infiltration by neutrophils enhances the prognostic significance of CRC infiltration by CD8+ T cells, suggesting that they might effectively promote antitumor immunity.

Note: This abstract was not presented at the meeting.

Citation Format: Valeria Governa, Emanuele Trella, Valentina Mele, Raul Droeser, Serenella Eppenberger-Castori, Luigi Maria Terracciano, Giandomenica Iezzi, Giulio Cesare Spagnoli. The interplay between neutrophils &It CDThe interplay between neutrophils and CD8+ cell improves survival in human colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3695. doi:10.1158/1538-7445.AM2017-3695

Abstract A123: Modulation of immune cell trafficking into human colorectal cancer by gut microbiota

Colorectal cancer (CRC) is a leading cause of cancer-related death. CRC infiltration by immune cells, including cytotoxic CD8+ T cells (CTLs), IFN-gamma-producing T-helper 1 cells (Th1), Foxp3+ regulatory T cells (Tregs) and CD16+ MPO+ neutrophils, is associated with favorable prognosis. However, chemokines driving these cell populations into the tumor site, their cellular sources and their microenvironmental triggers remain to be elucidated. We investigated the chemokine/chemokine receptor network promoting CRC infiltration by immune cells associated to favorable prognosis. Analysis of freshly excised specimens of CRC and adjacent healthy colonic tissues revealed that tumor infiltration by beneficial immune cells is associated with the expression of four main chemokine patterns: 1) CCL3, CCL5, CCL8, CXCL9, CXCL10, and CXCL12 for CTLs; 2) CCL5, CCL22, CXCL9 and CXCL12 correlating with CRC infiltration by Th1; 3) CCL22 and CXCL12 attracting Tregs; 4) CXCL2 and CXCL5, promoting chemotaxis of CD16+ MPO+ myeloid cells. Most of identified chemokines were found to be expressed, although at different levels, in primary CRC cells purified from tumor specimens and from xenografts generated upon injection of CRC cells in immunodeficient mice. Notably, chemokine expression levels in orthotopic xenografts, developed upon intracecal injection of tumor cells, were significantly higher as compared to those of subcutaneous tumors. Antibiotic treatment of tumor bearing mice drastically reduced chemokine expression in orthotopic xenografts, thus suggesting a role for commensal bacteria in chemokines induction in tumor cells. Importantly, human CRC samples characterized by high expression of chemokine and immune cell markers, displayed significantly higher bacterial loads, as compared to samples showing low chemokine expression and immune cell infiltration. Furthermore, bacterial loads significantly correlated with expression of CCL3 and CCL5, and Th1 infiltration. These data suggest that stimuli derived from gut flora components may trigger chemokine production in CRC tissues thus leading to tumor infiltration by beneficial immune cells.

Note: This abstract was not presented at the conference.

Citation Format: Eleonora Cremonesi, Francesca Amicarella, Jesus Francisco Glaus Garzon, Valeria Governa, Manuele Giuseppe Muraro, Valentina Mele, Elisabetta Padovan, Daniel Oertli, Paul Zajac, Giulio Cesare Spagnoli, Lubor Borsig, Giandomenica Iezzi. Modulation of immune cell trafficking into human colorectal cancer by gut microbiota [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr A123.

Abstract P4-04-19: Primary breast cancer culture in a perfusion-based bioreactor suitable for in vitro testing of immune blockade therapy

Introduction: Interaction between cancer cells and immune system critically affects development, progression and treatment of human malignancies. Two-dimensional (2D) in vitro culture systems and in vivo animal models are the primary tools used to test cancer cell response to drugs but they are not suited for the development of immune-mediated therapies. Here we present an innovative method to culture breast cancer tissue in porous 3D scaffolds by using a perfusion-based bioreactor system that allows the maintenance and expansion of tumor microenvironment.

Experimental procedures: Freshly excised breast cancer specimens were fragmented and cultured in a 3D "sandwich-like format" between two layers of porous collagen scaffold under perfusion flow (U-CUP). DMEM/F12, supplemented with 10% autologous human serum, was used as a culture medium. We assessed the ability of tumor and non-malignant cells to survive and expand into the scaffold in perfusion culture, as well as their capacity to recapitulate features of the original breast cancer tissue. The maintenance of immune-infiltrating cells allowed testing of immune blockade therapy in vitro using anti-PD-L1 and anti-CTLA4 antibodies alone or in combination.

Results: The U-CUP culture system preserved tissue viability better compared to a static culture and promoted the expansion of breast cancer cells from surgical specimens together with accompanying stromal and immune cells into the porous scaffold. Tumor tissues were viable after 21 days and mostly recapitulating the initial histology with formation of glands. Administration of anti-PDL1 antibody, alone or in combination with anti-CTLA4, to the culture medium was associated with increased expression of markers of immune-activation (i.e. IFNg) and decreased expression of immunosuppressive cytokine IL10.

Conclusions: Our results show that culture of breast cancer tissue in a 3D perfusion-based bioreactor might represent a promising system for the pre-clinical evaluation of immune-mediated therapies. Preserving malignant, interstitial and immunocompetent cells comprised in surgically excised breast cancer samples might allow a direct evaluation of the effects of various treatments on the complex tumor microenvironment. This engineered in vitro model could be extended as a platform allowing the testing of innovative approaches for the treatment of human malignancies, possibly in the direction of personalized medicine.

Citation Format: Muraro MG, Muenst S, Mele V, Spagnoli GC, Oertli D, Weber WP, Soysal SD. Primary breast cancer culture in a perfusion-based bioreactor suitable for in vitro testing of immune blockade therapy. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-04-19.

Enhancement of anti-leukemia activity of NK cells in vitro and in vivo by inhibition of leukemia cell-induced NK cell damage

Acute myeloid leukemia (AML) cells induce, in vitro, NK cell abnormalities (NKCAs) including apoptosis and activating receptor down-regulation. The potential negative impact of AML cells on the therapeutic efficacy of NK cell-based strategies prompted us to analyze the mechanisms underlying NKCAs and to develop approaches to protect NK cells from NKCAs. NKCA induction by the AML leukemia cells target a subpopulation of peripheral blood NK cells and is interleukin-2 independent but is abrogated by a long-term culture of NK (LTNK) cells at 37°C. LTNK cells displayed a significantly enhanced ability to damage AML cells in vitro and inhibited the subcutaneous growth of ML-2 cells grafted into CB17 SCID mice. Actinomycin D restored the susceptibility of LTNK cells to NKCAs while TAPI-0, a functional analog of the tissue inhibitor of metalloproteinase (TIMP) 3, inhibits ML-2 cell-induced NKCAs suggesting that the generation of NK cell resistance to NKCAs involves RNA transcription and metalloproteinase (MPP) inactivation. This conclusion is supported by the reduced susceptibility to AML cell-induced NKCAs of LTNK cells in which TIMP3 gene and protein are over-expressed. This information may contribute to the rational design of targeted strategies to enhance the efficacy of NK cell-based-immunotherapy of AML with haploidentical NK cells.

Abstract 2490: CD40 ligand expressing recombinant vaccinia virus (rVV40L) modulation of central memory CD8-mediated immune response

In cancer immunotherapy, induction of tumor-reactive CD8+ T cells displaying phenotypic and functional profile of central memory T cells (TCM) is associated with favorable prognosis. A key element in the generation of TCM CD8+ cells is represented by the help provided by CD4+ T cells during the priming of naïve CD8+ T cells. In particular CD40 ligand (CD40L) expressed and/or secreted by activated CD4+ T cells triggers CD40 receptor expressed on antigen presenting cells (APCs) thereby enhancing their antigen presentation capacity. In order to bypass the requirement of CD4+ T cells we generated a non-replicating recombinant vaccinia virus encoding human CD40L (rVV40L) and compared its ability to shape CD8-mediated immune response to soluble CD40L recombinant protein (sCD40L).

In this regard, our data clearly underline the different biological properties of membrane-bound CD40L, as provided by rVV40L infection, as compared to its soluble form, in CD14+ APCs activation. Notably, considering expression of IL-12p40, IFN-a and -b genes, cytokines of proven relevance for memory T cell induction, rVV40L-infection was much more potent than s40L-treatment alone or combine with WT infection. In parallel, s40L-stimulation induced a much more significant expression of IL-10 and indoleamine-2, 3-dioxygenase (IDO) genes encoding immunosuppressive factors. Considering a panel of molecules involved in the generation of the immunological synapse with T cells on CD14+ cells, rVV40L appeared to promote a less intense up regulation of CD80 co-stimulatory molecules but, most importantly, only a minor increase of programmed death ligand-1 (PD-L1). Therefore, gene expression and phenotypic profiles suggested that rVV40L-infected CD14+ cells might be highly effective APC in the induction of TCM CD8+ cells. Indeed, a single in vitro stimulation of naïve CD8+ T cells by rVV40L-infected CD14+ cells, in the absence of CD4+ T cells, was able to promote the rapid generation of central memory TAA (MAGE and MART-1) specific CD8+ T cells. These TCM were characterized by the typical central memory phenotype, as indicated by co-expression of CD45RO, CD62L and IL-7Ra, and by the high proliferative potential upon antigen recognition.

Collectively our data indicate that rVV40L efficiently modulates the quality of different APC signals delivered during the formation of the immunological synapse with CD8+ T cells. These in-vitro observations validate the strong clinical potential of our recombinant vaccinia virus constructs co-expressing CD40L for cancer immunotherapies.

Citation Format: Emanuele Trella, Evangelos Panopoulos, Nermin Raafat, Chantal Mengus, Emmanuel Traunecker, Swantje Heidtmann, Michael Heberer, Daniel Oertli, Giulio Cesare Spagnoli, Paul Zajac. CD40 ligand expressing recombinant vaccinia virus (rVV40L) modulation of central memory CD8-mediated immune response. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2490. doi:10.1158/1538-7445.AM2015-2490

Co-expression of cancer testis antigens and topoisomerase 2-alpha in triple negative breast carcinomas

Triple negative breast cancers (TNBC) are characterized by aggressive tumor biology, lack of targeted treatments and poor prognosis. Anthracyclins were shown to induce immunogenic death in target cells, potentially leading to "endogenous" vaccination. We comparatively assessed expression of cancer testis antigens (CTA) and topoisomerase 2-alpha (TOPO2A), a well defined molecular target of anthracyclins, in TNBC fully characterized for basal-like (BL) immunophenotype, BL morphology and conventional clinicopathological factors. The study included 83 patients undergoing surgery between January 2003 and December 2009. Tissue sections were stained with CK5/6, CK14, EGFR, Ki-67, TOPO2A, MAGE-A1, MAGE-A10, NY-ESO and multi-MAGE-A specific reagents. Of the 83 TNBC, >66.3% had BL immunophenotype and 48.2% had BL morphology. MAGE-A1 specific staining was most frequently detectable (69.2%), followed by multi-MAGE-A (58%), NY-ESO (27.1%) and MAGE-A10 (16%) specific staining. MAGE-A10 expression significantly correlated with tumor size (p=0.026). Furthermore, MAGE-A1, MAGE-A10 and multi-MAGE-A specific stainings significantly correlated with advanced clinical stage (p=0.024, p=0.041, p=0.031, respectively). We found no significant association between CTA expression and disease free (DFS) or overall survival (OS). Most interestingly, a significant correlation was observed between expression of MAGE-A10 and NY-ESO and expression of TOPO2A (p=0.005, p=0.013). Expression of defined CTA and TOPO2A are significantly correlated in TNBC. Considering the limited therapeutic options for TNBC, these findings might suggest novel forms of combination therapies that should be further explored.

Abstract 1476: Mesenchymal stromal cells induce epithelial-to-mesenchymal transition in human colorectal cancer cells through the expression of surface-bound TGF-β

Mesenchymal stem/stromal cells (MSC) are multipotent precursors endowed with the ability to home to primary and metastatic tumor site. Because of this feature, they are currently being used in preclinical models and in clinical trials as potential vehicles for delivery of targeted anti-cancer therapies. Clinical applications of MSC however, require a deeper understanding of their biology and, in particular, of their interaction with cancer cells. In this study we have investigated the effects mediated by human bone marrow-derived MSC on human colorectal cancer (CRC) cells in vitro and in vivo. We found that MSC induced upregulation of epithelial-to-mesenchymal (EMT)-related genes and downregulation of E-cadherin in tumor cells. These effects required cell-to-cell contact and were mediated by expression of surface-bound TGF-β, induced in MSC upon coculture with tumor cells. CRC cells exposed to MSC formed larger tumor masses in vivo, characterized by higher vessel density and increased mesenchymal marker expression, and displayed enhanced invasive capacity. Thus, by promoting cell expansion, EMT-related phenomena and tumor angiogenesis, MSC appear to favor the acquisition of an aggressive phenotype by CRC cells. These findings raise concerns regarding the safety of MSC administration for clinical purposes in patients with cancer.

Citation Format: Valentina Mele, Manuele Giuseppe Muraro, Diego Calabrese, Nunzia Amatruda, Francesca Amicarella, Dennis Pfaff, Brynn Kvinlaug, Chiara Bocelli-Tyndall, Ivan Martin, Therese J. Resink, Luigi M. Terracciano, Giulio Cesare Spagnoli, Giandomenica Iezzi. Mesenchymal stromal cells induce epithelial-to-mesenchymal transition in human colorectal cancer cells through the expression of surface-bound TGF-β. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1476. doi:10.1158/1538-7445.AM2013-1476

Abstract P4-04-04: Immunohistochemical analysis of Cancer Testis antigens and Topoisomerase 2-alpha expression in triple negative breast carcinomas: a retrospective study

Aim. The aim of this study is to assess the expression of cancer testis (C/T) antigens in the TNBC group, expression of topoisomerase 2-alpha (TOPO2A), basal-like (BL) immunophenotype defined by basal markers (CK5/6, CK14, and EGFR), BL morphology and conventional clinicopathologic factors as well as to demonstrate their prognostic relevance with respect to this group of tumours.

Methods. The study includes 83 patients who underwent surgery between January 2003 and December 2009. Slides were stained immunohistochemically with CK5/6, CK14, EGFR, Ki-67, TOPO2A, MAGE-A1, MAGE-A10, NY-ESO and multi-MAGE. Survival-time and multivariate survival analyses were performed for the purpose of identifying prognostic markers for tumours with more aggressive behaviour.

Results. Of the 83 triple negative tumours, 55 (66.3%) have BL immunophenotype and 40 (48.2%) BL morphology. MAGE-A1 show the most frequent expression (69.0%), followed by multi-MAGE (58.0%), NY-ESO (27.1%) and MAGE-A10 (13, 2%). MAGE-A10 expression is significantly correlated with tumour size (p = 0.026). The expressions of MAGE-A1, MAGE-A10 and multi-MAGE are significantly correlated with clinical stage (p = 0.024, p = 0.041, p = 0.031, respectively). A significant correlation has been found between the expressions of MAGE-A10 and NY-ESO and the expression of TOPO2A (p = 0.005, p = 0.013). There is no significant correlation between the expression of C/T antigens and disease-free survival (DFS) or overall survival (OS).

Conclusions. High expression levels of MAGE and NY-ESO observed in TNBC are of potential clinical relevance, especially in the adjuvant setting of treatment, and may be of therapeutic value as a vaccine-based treatment in the TN group of breast tumours for which therapeutic options are limited.

Key words: triple negative breast cancer, basal-like breast cancer, cancer-testis antigen, topoisomerase 2-alpha, prognosis, survival analysis.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-04-04.

CD133+, CD166+CD44+, and CD24+CD44+ phenotypes fail to reliably identify cell populations with cancer stem cell functional features in established human colorectal cancer cell lines

Increasing evidence that cancers originate from small populations of so-called cancer stem cells (CSCs), capable of surviving conventional chemotherapies and regenerating the original tumor, urges the development of novel CSC-targeted treatments. Screening of new anticancer compounds is conventionally conducted on established tumor cell lines, providing sufficient material for high-throughput studies. Whether tumor cell lines might comprise CSC populations resembling those of primary tumors, however, remains highly debated. We have analyzed the expression of defined phenotypic profiles, including CD133+, CD166+CD44+, and CD24+CD44+, reported as CSC-specific in human primary colorectal cancer (CRC), on a panel of 10 established CRC cell lines and evaluated their correlation with CSC properties. None of the putative CSC phenotypes consistently correlated with stem cell-like features, including spheroid formation ability, clonogenicity, aldehyde dehydrogenase-1 activity, and side population phenotype. Importantly, CRC cells expressing putative CSC markers did not exhibit increased survival when treated with chemotherapeutic drugs in vitro or display higher tumorigenicity in vivo. Thus, the expression of CD133 or the coexpression of CD166/CD44 or CD24/CD44 did not appear to reliably identify CSC populations in established CRC cell lines. Our findings question the suitability of cell lines for the screening of CSC-specific therapies and underline the urgency of developing novel platforms for anticancer drug discovery.

Abstract 3546: IL-17 production by tumor-infiltrating Th17 cells favors inflammation and promotes survival in human colorectal cancer

Background and aims: Evidence from experimental models suggests that IL-17 and T helper (Th)-17 cells may contribute to anti-tumor immune responses. The role played by IL-17 in human cancers remains however, to be clarified. We have investigated phenotypes and prognostic significance of IL-17-producing and IL-17-responsive cells in human colorectal cancer (CRC). Methods: Expression of IL-17 and IL-17 receptors (IL-17R) A and C was investigated on freshly isolated CRC specimens by flow cytometry, in combination with surface molecules identifying specific cell populations. IL-17 and IL-17RA expression was also evaluated by immunohistochemistry on a tissue micro-array (TMA) including 1420 cases of primary CRC with full clinico-pathological data. IL-17R-expressing cell populations were tested for their responsiveness to IL-17 in vitro. In particular, proliferation rates were measured by 3H-thymidine incorporation and production of inflammatory cytokine/chemokines was evaluated at gene and protein level by real-time PCR and ELISA. Results: CRC-infiltrating IL-17-producing cells were exclusively comprised within the lymphocyte population and expressed CD4, but not CD8, and surprisingly, Foxp3 molecules. In contrast, no NK, NKT, gamma-delta T and lymphoid tissue-inducer-like cells were found within the IL-17+ fraction. High infiltration by IL-17 producing cells significantly correlated with low T and N stages, and, most importantly, in the group of mismatch repair (MMR)-proficient CRCs, with prolonged survival time. Interestingly, infiltration by IL-17+ cells was found to be significantly associated to that of CD16+ myeloid cells. On primary CRCs and established cell lines, IL-17RA and C were found to be expressed only on a subpopulation of tumor cells. In contrast, all tumor-associated stromal cells expressed IL-17RC at high levels, and at lower extent, IL-17RA. Conversely, tumor-infiltrating CD16+ myeloid cells exhibited high expression of IL-17RA, but did not express IL-17RC. Prognostic significance of IL-17R expression on primary CRCs is currently being evaluated. In vitro exposure of CRC cells to IL-17 did not significantly enhance tumor cell proliferation, neither promoted the release of inflammatory cytokines, but strongly induced the expression of CXCL1, XCL1 and CXCL16 chemokines. On CD16+ myeloid cells, IL-17 promoted the release of IL-6 and the expression of chemotactic factors, including CXCL1, XCL1, CXCL10, CXCL11, CCL2, CCL3, and CCL20. Finally, IL-17 markedly enhanced IL-6 production by stromal cells. Conclusions: Tumor-infiltrating Th17 cells appear to play a beneficial role in human CRC, possibly by inducing the expression of inflammatory and chemotactic factors by tumor-associated stromal and myeloid cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3546. doi:1538-7445.AM2012-3546

Abstract 1491: Tumor-associated stromal cells increase malignancy of human colorectal cancers through epithelial-to-mesenchymal transition

BACKGROUNDS & AIMS: Exogenously administered mesenchymal stromal cells (MSCs) have been shown to migrate into tumor tissues and contribute to tumor development. Still unclear is however, whether MSCs are actually a component of the stroma associated with primary tumors. The mechanisms underlying this interaction also remain to be characterized. Here we investigated the phenotype and functional properties of tumor-associated stromal cells (TASCs) isolated from human primary colorectal cancers (CRCs) and compared them with those derived from the bone marrow of healthy donors. METHODS: TASCs, isolated from CRC biopsies, and MSCs, derived from the bone marrow of healthy donors, were cultured with CRC cells from established cell lines. Proliferation, expression of epithelial-to-mesenchymal transition (EMT)-related genes and surface markers, and the release of soluble factors were evaluated. Tumorigenicity and invasive potential of CRC cells exposed to stromal cells were also investigated in vivo. RESULTS: TASCs expanded from CRC-associated stroma resembled MSCs in morphology and phenotype. Similar to MSCs, they enhanced tumor cell proliferation through the release of soluble factors, and induced upregulation of EMT-related genes on tumor cells in vitro through the expression of surface-bound TGF-beta. Conditioning by stromal cells resulted in accelerated tumor growth and increased invasiveness of CRC cells in vivo. CONCLUSIONS: The stroma associated to primary CRCs includes MSC-like cells capable of initiating EMT on CRC cells, thus contributing to tumor growth and spreading.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1491. doi:1538-7445.AM2012-1491

Expression of cancer-testis antigens MAGE-A4 and MAGE-C1 in oral squamous cell carcinoma

BACKGROUND

Tumor markers are genes or their products expressed exclusively or preferentially in tumor cells and cancer-testis antigens (CTAs) form a group of genes with a typical expression pattern expressed in a variety of malignant neoplasms. CTAs are considered potential targets for cancer vaccines. It is possible that the CTA MAGE-A4 (melanoma antigen) and MAGE-C1 are expressed in carcinoma of the oral cavity and are related with survival.

METHODS

This study involved immunohistochemical analysis of 23 patients with oral squamous cell carcinoma (SCC) and was carried out using antibodies for MAGE-A4 and MAGE-C1. Fisher's exact test and log-rank test were used to evaluate the results.

RESULTS

The expression of the MAGE-A4 and MAGE-C1 were 56.5% and 47.8% without statistical difference in studied variables and survival.

CONCLUSION

The expression of at least 1 CTA was present in 78.3% of the patients, however, without correlation with clinicopathologic variables and survival.

Abstract 1513: Mesenchymal stromal cells enhance the malignant potential of human colorectal cancer cells by inducing epithelial to mesenchymal transition-related phenomena

Background: Mesenchymal stromal cells (MSCs) are recruited to primary and metastatic sites of several tumour types, including colorectal cancer (CRC), and might contribute to tumour progression. The actual role played by MSCs and the mechanisms underlying MSC-tumour interactions remain to be clarified. We investigated the effects of human bone-marrow-derived MSCs (BM-MSCs) on CRC, in vitro and in vivo.

Material and methods: Human established CRC cell lines were cultured in the presence or absence of BM-MSCs, in direct contact or in transwell plates. After a five day culture, tumour cell proliferation was assessed by differential cell counts, surface molecule expression was analyzed by flow cytometry, and production of soluble factors in culture supernatants was measured by Raybio antibody array® and ELISA. Tumour cells, sorted upon co-culture by flow cytometry, were evaluated for the expression of epithelial to mesenchymal transition (EMT)-related genes by quantitative PCR and for in vitro invasiveness, by chemoinvasion assay. Furthermore, their tumorigenicity was assessed upon injection in NOD/SCID mice and developing tumours were analyzed by immunofluorescence.

Results: MSCs significantly increased tumour cell proliferation and decreased CD44 expression, independently of cell-to-cell contact. Analysis of co-culture supernatants revealed higher amounts of IL-6, MCP-1, RANTES and Angiogenin, in comparison to supernatants derived from single cultures. Moreover increased expression of several EMT-related genes, including SNAI2, TWIST, N-Cadherin, was detected on CRC cells sorted upon co-culture as compared with controls. Importantly, CRC cells co-cultured with MSCs showed higher invasive behaviour in vitro, than CRC cells cultured alone. No significant changes were observed in tumorigenicity. However, tumours originated from tumour cells co-cultured with MSCs showed a significantly higher vessel density as compared to controls.

Conclusions: MSCs reduce adhesiveness, induce expression of EMT-related genes and increase proliferation, invasiveness and angiogenic potential of CRC cells. These effects might contribute to CRC progression and spreading.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1513. doi:10.1158/1538-7445.AM2011-1513

Abstract 784: Prevalence, phenotype and prognostic significance of IL-17-producing cells infiltratinghuman colorectal cancers

Background: Lymphocytic infiltration is known to be associated with a favourable prognosis in human colorectal cancer (CRC). In particular, the presence of CD8+ T cells and, unexpectedly, of Foxp3+ regulatory T cells, has been found to be associated with improved patient survival. Recent evidence suggests that IL-17 and T helper (Th) 17 cells might also have an impact on anti-tumour immune responses. We have investigated prevalence, phenotype and prognostic significance of IL-17-producing cells in human CRC.

Material and Methods: IL-17 expression was evaluated by immunohistochemistry on a tissue micro-array (TMA) including 1420 cases of primary CRC with full clinico-pathological data. Furthermore, gene expression levels were assessed on CRC tissues by quantitative PCR.

Finally, in order to characterize the phenotype of IL-17-positive cells, expression of IL-17, in combination with that of specific surface molecules, was analyzed on freshly excised CRC specimens by flow cytometry.

Results: Frequencies of IL-17-producing cells, as well as IL-17 gene expression levels were significantly increased in tumour tissues as compared to autologous normal mucosa. IL-17-producing cells isolated from clinical specimens were exclusively comprised within the lymphocyte population and expressed CD4, but not CD8, and surprisingly, Foxp3 molecules. Accordingly, mRNA levels of genes encoding for cytokines favouring IL-17 acquisition by Foxp3+ T cells, including IL-6, IL-1beta, TGF-beta and IL-23, were found more elevated in CRC tissues as comparing to corresponding healthy mucosa.

High infiltration by IL-17 producing cells significantly correlated with low T and N stages, and, most importantly, with prolonged survival time in mismatch repair (MMR)- proficient, but not-deficient CRC. Moreover, the simultaneous CRC-infiltration by IL-17+ and Foxp3+ cells was significantly associated with improved survival in both MMR-proficient and -deficient tumours.

Conclusions: Our data suggest that IL-17 produced by tumour-infiltrating either CD4+ or Foxp3+ cells may promote a benign clinical outcome in CRC.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 784. doi:10.1158/1538-7445.AM2011-784

Cancer-testis antigen expression in triple-negative breast cancer

BACKGROUND

cancer-testis (CT) antigens, frequently expressed in human germline cells but not in somatic tissues, may become aberrantly reexpressed in different cancer types. The aim of this study was to investigate the expression of CT antigens in breast cancer.

PATIENTS AND METHODS

a total of 100 selected invasive breast cancers, including 50 estrogen receptor (ER) positive/HER2 negative and 50 triple negative (TN), were examined for NY-ESO-1 and MAGE-A expression by immunohistochemistry.

RESULTS

a significantly higher expression of MAGE-A and NY-ESO-1 was detected in TN breast cancers compared with ER-positive tumors (P = 0.04). MAGE-A expression was detected in 13 (26%) TN cancers compared with 5 (10%) ER-positive tumors (P = 0.07). NY-ESO-1 expression was confirmed in nine (18%) TN tumor samples compared with two (4%) ER-positive tumors.

CONCLUSIONS

MAGE-A and NY-ESO-1 CT antigens are expressed in a substantial proportion of TN breast cancers. Because of the limited therapeutic options for this group of patients, CT antigen-based vaccines might prove to be useful for patients with this phenotype of breast cancer.

Human bone marrow mesenchymal stem cells and chondrocytes promote and/or suppress the in vitro proliferation of lymphocytes stimulated by interleukins 2, 7 and 15

OBJECTIVES

To investigate whether human bone marrow-derived mesenchymal stem cells (BM-MSCs) and articular chondrocytes (ACs) affect the in vitro proliferation of T lymphocytes and peripheral blood mononuclear cells (PBMCs) driven by the homeostatic interleukin (IL)2, IL7 and IL15 cytokines binding to the common cytokine receptor gamma-chain (gamma(c)) in the absence of T cell receptor (TCR) triggering.

METHODS

PBMCs, total T cells and T cell subsets (CD4+ and CD8+) were stimulated with IL2, IL7 or IL15 and exposed to cultured BM-MSCs and ACs at varying cell:cell ratio either in contact or in transwell conditions. Lymphocyte proliferation was measured by (3)H-thymidine uptake or by flow cytometry of carboxyfluorescein succinimidyl ester (CFSE)-labelled lymphocytes.

RESULTS

MSCs and ACs enhanced and inhibited lymphocyte proliferation depending on the extent of lymphocyte baseline proliferation and on the MSC/AC to lymphocyte ratio. Enhancement was significant on poorly proliferating lymphocytes and mostly at lower MSC/AC to lymphocyte ratio. Suppression occurred only on actively proliferating lymphocytes and at high MSC/AC to lymphocyte ratio. Neither enhancement nor inhibition required cell-cell contact.

CONCLUSIONS

There is a dichotomous effect of MSCs/ACs on lymphocytes proliferating in response to the homeostatic IL2, IL7 and IL15 cytokines likely to be encountered in homeostatic and autoimmune inflammatory conditions. The effect is determined by baseline lymphocyte proliferation, cell:cell ratio and is dependent on soluble factor(s). This should be taken into account when planning cellular therapy for autoimmune disease (AD) using stromal-derived cells such as MSCs.

Expression of MAGE-A1, MAGE-A3/4 and NY-ESO-1 cancer-testis antigens in fetal testis

Immunohistochemical expression of MAGE-A1, MAGE-A3/4 and NY-ESO-1/LAGE-1 cancer testis antigens (CTA) was assessed in 24 fetal testes from 15th to 36th week of gestation. Three monoclonal antibodies were used for immunohistochemical staining: 77B recognizing MAGE-A1, 57B recognizing multiple MAGE-A CTA, and D8.38 recognizing NY-ESO-1/LAGE-1. Expression of MAGE-A1 was not observed in fetal testis samples, whereas multi-MAGE-A and NY-ESO-1/LAGE-1 specific reagents stained pro-spermatogonia in all samples with different expression levels during the period of fetal development observed. Significant expression of MAGE-A3/4 and almost continuous expression of NY-ESO-1 in fetal testes after 22nd week of gestation suggested their important role in the development of sex cords and pro-spermatogonia in particular.

Multiple mechanisms underlie defective recognition of melanoma cells cultured in three-dimensional architectures by antigen-specific cytotoxic T lymphocytes

Cancer cells' growth in three-dimensional (3D) architectures promotes resistance to drugs, cytokines, or irradiation. We investigated effects of 3D culture as compared to monolayers (2D) on melanoma cells' recognition by tumour-associated antigen (TAA)-specific HLA-A(*)0201-restricted cytotoxic T-lymphocytes (CTL). Culture of HBL, D10 (both HLA-A(*)0201+, TAA+) and NA8 (HLA-A(*)0201+, TAA-) melanoma cells on polyHEMA-coated plates, resulted in generation of 3D multicellular tumour spheroids (MCTS). Interferon-gamma (IFN-gamma) production by HLA-A(*)0201-restricted Melan-A/MART-1(27-35) or gp 100(280-288)-specific CTL clones served as immunorecognition marker. Co-culture with melanoma MCTS, resulted in defective TAA recognition by CTL as compared to 2D as witnessed by decreased IFN-gamma production and decreased Fas Ligand, perforin and granzyme B gene expression. A multiplicity of mechanisms were potentially involved. First, MCTS per se limit CTL capacity of recognising HLA class I restricted antigens by reducing exposed cell surfaces. Second, expression of melanoma differentiation antigens is downregulated in MCTS. Third, expression of HLA class I molecules can be downregulated in melanoma MCTS, possibly due to decreased interferon-regulating factor-1 gene expression. Fourth, lactic acid production is increased in MCTS, as compared to 2D. These data suggest that melanoma cells growing in 3D, even in the absence of immune selection, feature characteristics capable of dramatically inhibiting TAA recognition by specific CTL.

Local activation of the innate immune system in Buruli ulcer lesions

Buruli ulcer (BU) caused by Mycobacterium ulcerans is a chronic necrotizing disease of the skin and the underlying soft tissue. Fat tissue necrosis accompanied by minimal inflammation is considered the most reliable histopathologic feature of BU. There may be a constant influx of inflammatory cells to the sites of active infection but these are thought to be killed by mycolactone, a polyketide toxin produced by M. ulcerans, through apoptosis and necrosis. Here we describe the spatial correlations between mycobacterial load and the expression of dendritic cell (DC) surface markers (cluster of differentiation (CD)83, CD11c, and CD123), the Toll-like receptor (TLR) 9 and pro- and anti-inflammatory cytokines (IL-8, IL-6, tumor necrosis factor-alpha (TNF-alpha), IFN-alpha, IL-12p40, IL-10, and IFN-gamma) within BU lesions. Although IL-8, IL-6, and TNF-alpha messenger RNA (mRNA) was detectable by real-time PCR in all lesions, the expression of the other cytokines was only found as small foci in some lesions. Correlations of the distribution of mRNA encoding the activation marker CD83 and the DC subset markers CD123 and CD11c indicate that both activated plasmacytoid and myeloid dendritic cells were present in the lesions. Results suggest that M. ulcerans specific immune responses may develop once therapeutic interventions have limited the production of mycolactone.

Immunohistochemical expression of tumor antigens MAGE-A1, MAGE-A3/4, and NY-ESO-1 in squamous cell carcinoma of the penis

OBJECTIVES

To investigate by immunohistochemistry the expression of MAGE-A and NY-ESO-1/LAGE-1, cancer testis antigens (CTAs), in squamous cell carcinoma of the penis.

METHODS

A total of 30 penile carcinoma samples from patients undergoing penile amputation at the Urology Clinics at the Zagreb Clinical Hospital Center and University Hospital "Sestre milosrdnice" from 1997 to 2004 were investigated in this study. Three monoclonal antibodies were used for immunohistochemical staining: 77B specific for MAGE-A1, 57B recognizing multiple MAGE-A CTAs, and D8.38, specific for NY-ESO-1 antigen.

RESULTS

The expression of MAGE-A1 was not observed in the carcinoma samples, but both multi-MAGE-A and NY-ESO-1-specific reagents stained 29 (97%) of 30 samples. Immunohistochemical staining was prevailingly detected in the cytoplasm. A significant heterogeneity was observed within the same specimen, in which areas with strong positivity coexisted with CTA-negative areas. The extent of CTA expression did not correlate significantly with tumor grade.

CONCLUSIONS

The results of this study have documented for the first time the expression of CTAs in squamous cell carcinoma of the penis. Additional research is warranted to explore the potential implications regarding both diagnosis and therapy.

Expression of MAGE-A cancer/testis antigens in esophageal squamous cell carcinomas

BACKGROUND

Although the diagnosis and therapy of esophageal cancer have improved over the past decade, the prognosis remains dismal. Since MAGE-A cancer/testis antigens (CTA) are potential targets for immunotherapy, this study was aimed at evaluating their expression in these patients and its prognostic value.

MATERIALS AND METHODS

Using 57B monoclonal antibody, MAGE-A CTA expression was analyzed in paraffin-embedded tumor specimens of 98 patients with esophageal squamous cell carcinoma or adenocarcinomas who had undergone surgical resection. For all patients, a postoperative follow-up of at least 4 years was available. The expression was quantified using a scoring system considering intensity and homogeneity of the immunostaining. The prognostic relevance of MAGE-A expression was analyzed in univariate analyses as well as Cox proportional hazard regression analysis.

RESULTS

57B positivity could be detected in 38 tumors (38.8%). Positive staining was observed in five out of 32 adenocarcinomas (15.2%) and in 33 out of 66 (50%) squamous cell carcinomas. MAGE-A expression did not correlate with the TNM classification, grading or age of the patients. Both univariate (p=0.88) and multivariate analyses (p = 0.82) revealed that MAGE-A expression lacked prognostic significance in esophageal carcinomas.

CONCLUSION

MAGE-A was expressed in half of the squamous cell carcinomas of the esophagus, but rarely in adenocarcinomas. Although its immunodetection was insufficient for prognostic evaluation, the high expression rate suggests MAGE-A as a potential target for immunotherapy in the first group with the ability for pretherapeutic testing.

Immunohistochemical expression of tumor antigens MAGE-A1, MAGE-A3/4, and NY-ESO-1 in cancerous and benign prostatic tissue

OBJECTIVE

To investigate immunohistochemical expression of MAGE-A and NY-ESO-1/LAGE-1, cancer testis antigens in prostate tissues showing evidence of malignant transformation or benign hyperplasia.

METHODS

112 prostate samples from patients undergoing surgery at the Urology Clinic at the Zagreb Clinical Hospital Center from 1995 to 2003 were investigated in this study. Of these, 92 carcinoma samples were obtained by radical prostatectomy, and 20 benign prostatic hyperplasia samples by transvesical prostatectomy. Three monoclonal antibodies were used for immunohistochemical staining: 77B for MAGE-A1, 57B for multi-MAGE-A and D8.38 for NY-ESO-1 expression.

RESULTS

Expression of MAGE-A1 was observed in 10.8% of carcinoma samples, whereas multi-MAGE-A and NY-ESO-1/LAGE-1 stained 85.9% and 84.8% of samples. Immunohistochemical staining was only detectable in the cytoplasm. A significant heterogeneity could be observed within a same tissue sample where areas with strong positivities coexisted with cancer testis antigens negative areas. Interestingly, a majority of 57B positive cases were also found to be D8.38 positive (correlation coefficient r=0.727 (P<0.01)). Cancer testis antigens expression was neither significantly correlated with PSA values nor with Gleason score. In benign prostatic hyperplasia tissues MAGE-A1 expression was detected in 5%, while 57B and D8.38 staining was observed in 15% samples, and in all cases percentages of positive cells were always <10%.

CONCLUSION

Our data underline the peculiar relevance of cancer testis antigens expression in prostate cancers, with potential implications regarding both diagnosis and therapy.

High-level expression of cancer/testis antigen NY-ESO-1 and human granulocyte-macrophage colony-stimulating factor in dendritic cells with a bicistronic retroviral vector

Tumor-specific genes delivered to dendritic cells (DCs) have been used for the generation of cytotoxic T cells (CTLs), but their application has been limited on the one hand by low viral titers resulting in low transduction efficiency and poor protein production, and on the other hand by immunogenicity of the selectable marker and poor viability of the DCs. We addressed these limitations by creating a multipurpose master vector (pMV) and cloning the tumor gene NY-ESO-1, which is highly expressed in more than 50% of advanced myeloma patients. pMV was constructed from a Moloney murine leukemia virus (Mo-MuLV)-based retroviral backbone with the following features: (1) an extended packaging signal to achieve high viral titers, (2) a splice acceptor region to facilitate protein production, (3) a nonimmunogenic selectable marker, dihydrofolate reductase-L22Y (DHFR(L22Y)), to exclude the generation of CTLs against the selectable marker, (4) an internal ribosomal entry site between the tumor-specific gene (NY-ESO-1) and the selectable marker DHFR(L22Y) for coexpression of two heterologous gene products from a single bicistronic mRNA, minimizing the possibility of differential expression of these two genes, and (5) human granulocyte-macrophage colony-stimulating factor (hGM-CSF) cDNA driven by the human T-lymphotropic virus promoter to enhance DC function and viability. Recombinant virus of pMV-NY-ESO-1 was generated with vesicular stomatitis virus G envelope protein (VSV-G) in the GP2-293 cell line for efficient transduction. We present evidence that the DC phenotype is unaltered after transduction and that more than 85% of DCs express NY-ESO-1, which secrete approximately 40 ng of GM-CSF per 10(6) DCs.

Encapsulation into sterically stabilised liposomes enhances the immunogenicity of melanoma-associated Melan-A/MART-1 epitopes

Tumour-associated antigens (TAA)-specific vaccination requires highly immunogenic reagents capable of inducing cytotoxic T cells (CTL). Soluble peptides are currently used in clinical applications despite an acknowledged poor immunogenicity. Encapsulation into liposomes has been suggested to improve the immunogenicity of discrete antigen formulations. We comparatively evaluated the capacity of HLA-A2.1 restricted Melan-A/MART-1 epitopes in soluble form (S) or following inclusion into sterically stabilised liposomes (SSL) to be recognised by specific CTL, to stimulate their proliferation and to induce them in healthy donors' peripheral blood mononuclear cells (PBMC), as well as in melanoma-derived tumour-infiltrating lymphocytes (TIL). HLA-A2.1⁺, Melan-A/MART-1-NA-8 melanoma cells served as targets of specific CTL in 51Cr release assays upon pulsing by untreated or human plasma-treated soluble or SSL-encapsulated Melan-A/MART-1 27–35 (M27–35) or 26–35 (M26–35) epitopes. These reagents were also used to stimulate CTL proliferation, measured as 3H-thymidine incorporation, in the presence of immature dendritic cells (iDC), as antigen-presenting cells (APC). Induction of specific CTL upon stimulation with soluble or SSL-encapsulated peptides was attempted in healthy donors' PBMC or melanoma-derived TIL, and monitored by 51Cr release assays and tetramer staining. Na-8 cells pulsing with SSL M27–35 resulted in a five-fold more effective killing by specific CTL as compared with equal amounts of S M27–35. Encapsulation into SSL also provided a partial (50%) protection of M27–35 from plasma hydrolysis. No specific advantages regarding M26–35 were detectable in these assays. However, at low epitope concentrations (⩽100 ng ml⁻¹), SSL M26–35 was significantly more effective in inducing CTL proliferation than S M26–35, in the presence of iDC, as APC. Preincubation with iDC for 6 h virtually abolished the capacity of S M26–35 to stimulate specific CTL proliferation, but only partially affected that of SSL M26–35. Most importantly, SSL M26–35 was able to enhance the induction of specific CTL in healthy donors PBMC and in melanoma-derived TIL as compared to S M26–35. Taken together, our data indicate that encapsulation of TAA epitopes into SSL results in effective immunogenic formulations suitable for clinical use in active specific tumour immunotherapy.

Disseminated single tumor cells as detected by real-time quantitative polymerase chain reaction represent a prognostic factor in patients undergoing surgery for colorectal cancer

OBJECTIVE

To evaluate the clinical relevance of real-time quantitative polymerase chain reaction (qPCR) detection of CEA and CK20 transcripts, as potentially related to tumor cell dissemination, in blood and peritoneal lavage from patients undergoing surgery for colorectal cancer.

SUMMARY BACKGROUND DATA

Dissemination of single colorectal cancer cells in the peritoneal cavity, as well as in tumor drainage and peripheral blood vessels, might play a role in the metastasis process, thus affecting the clinical course. However, this phenomenon needs further elucidation.

METHODS

In a prospective study the authors evaluated the potential of qPCR in the detection of CEA and/or CK20 transcripts in the peritoneal lavage fluid and in the peripheral and mesenteric venous blood of 39 patients undergoing curative resection for colorectal cancer. Peritoneal lavage and peripheral blood was sampled before and after tumor resection; mesenteric venous blood was sampled from the major tumor-draining vein immediately before clamping. After RNA extraction and reverse transcription, qPCR was performed using specific cDNA primers and probes for CEA and CK20. The dichotomous results from the qPCR were used as a predictor along with other covariates in Cox proportional hazard regression models of long-term outcome (disease-free survival and overall survival).

RESULTS

Of 39 patients, 11 were positive. The median follow-up at analysis was 31 months for all patients. The dichotomous qPCR covariate was significant, with P =.001 and.0035 for disease-free survival and overall survival, respectively, in the proportional hazard regression models with only qPCR. In seven patients, disseminated colorectal cancer cells were found in the peritoneal lavage fluid but not in blood specimens; five of these patients (71%) had recurrence.

CONCLUSIONS

These data suggest that detection of mRNA coding for CEA and/or CK20 using qPCR has potential clinical utility as a prognostic marker and should be evaluated in larger clinical studies. Identification of patients at high risk for metastatic disease after curative resection of colorectal cancer might be improved by analyzing peritoneal lavage specimens in addition to blood samples. This is based on the observation that in more than half of qPCR-positive patients, disseminated colorectal cancer cells were detected in peritoneal lavage specimens but not in blood samples, and that 71% of them had recurrence.

MAGE-A4, a germ cell specific marker, is expressed differentially in testicular tumors

BACKGROUND

Testicular germ cell tumors are the most common malignancy in young males, and the frequency of these tumors has risen dramatically over the last century. Because it is known that the MAGE genes are expressed in a wide variety of tumors but are expressed only in the mitotic spermatogonia (germ cells) and in the primary spermatocytes in the normal testis, the authors screened the expression of MAGE-A4 in a panel of testicular germ cell tumors.

METHODS

Monoclonal antibody 57B raised against MAGE-A4 was tested immunohistochemically on 12 classical seminomas, 5 anaplastic seminomas, 10 various specimens of nonseminomatous germ cell tumors (NSGCTs), 2 combined tumors containing seminoma components, 1 Sertoli cell tumor, 2 Leydig cell tumors, and 15 carcinomas in situ (CIS). In addition, monoclonal antibody 57B was tested on embryonic gonad (age 8 weeks) and fetal gonads (ages 15 weeks, 17 weeks, and 28 weeks).

RESULTS

Classical seminomas uniformly and specifically expressed MAGE-A4 compared with anaplastic seminomas and NSGCTs, which were negative for this antigen. Specific expression of MAGE-A4 also was seen in subpopulations of CIS cells, providing additional evidence for heterogeneity of the phenotype of these cells, in which it is believed that differentiation and proliferation generate seminomas and NSGCTs. Finally, MAGE-A4 was expressed in the fetal precursors of the stem germ cells from 17 weeks of gestation onward, in accordance the fact that CIS can arise from prespermatogonia in the fetus.

CONCLUSIONS

MAGE-A4 can be considered a potential specific marker for normal premeiotic germ cells and germ cell tumors and can be used to characterize classical seminomas.

Immunogenicity of nonreplicating recombinant vaccinia expressing HLA-A201 targeted or complete MART-1/Melan-A antigen

The effect on immunogenicity of different tumor T cell epitope formulations was evaluated in vitro using nonreplicating recombinant vaccinia vector expressing two forms of the melanoma-associated MART-1/Melan-A antigen. The first recombinant virus expressed a minigene encoding a fusion product between an endoplasmic reticulum (ER)-targeting signal and the HLA-A201 binding 27-35 peptide. The second viral construct encoded the complete MART-1/Melan-A protein. The capacity of HLA-A201 cells infected with either viral construct to generate and to stimulate MART-1/Melan-A 27-35 specific cytotoxic T-lymphocytes (CTL), was comparatively characterized. The results obtained here with a tumor antigen confirmed the capacity of vaccinia virus-encoded ER-minigene to generate a very strong antigenic signal. In cytotoxicity assays, recognition of target cells infected with high amounts of both recombinant viruses with activated specific CTL clones, resulted in similar lytic activity. With regard to calcium mobilization, TCR down-regulation, IFN-gamma release, and T cell proliferation assays, the targeted epitope elicited 10- to 1000-fold stronger responses. Remarkably, the immunogenic difference between the two formulations, in their respective capacity to generate CTL from naive HLA-A2 peripheral blood mononuclear cells in vitro as measured by tetramer detection, was lower (2- to 3-fold). Recombinant vectors expressing complete antigens have demonstrated their capacity to generate specific responses and such vaccines might take advantage of a broader potential of presentation. However, as demonstrated here for the HLA-A201-restricted MART-1/Melan-A immunodominant epitope, nonreplicative vaccinia virus expressing ER-targeted minigenes appear to represent a significantly more immunogenic epitope vaccine formulation.

Expression of MAGE tumour-associated antigens is inversely correlated with tumour differentiation in invasive ductal breast cancers: an immunohistochemical study

MAGE (Melanoma antigen E) family gene products encompass tumour-associated antigens (TAAs) recognised by human leukocyte antigen (HLA)-restricted specific T-cells. Agents inducing DNA demethylation, an event typically detectable in cellular de-differentiation processes, were shown to induce the expression of MAGE genes. By using a monoclonal antibody specific for MAGE family gene products, we have studied the expression of these TAAs in a group of 144 patients with invasive ductal breast cancers. Immunohistochemical data were correlated with tumour differentiation, lymphatic vessel invasion, oestrogen receptor expression, intratumoural necrosis, lymphocytic infiltration, perineural invasion, tumour microcalcifications and axillary lymph node metastases. MAGE immunoreactivity was undetectable in non-neoplastic cells. In poorly differentiated cancers positive staining was observed in 30/63 cases (47.6%) as compared with 13/51 (25.4%) and 5/30 (16.6%) in moderately and well-differentiated tumours, respectively (P<0.05). In addition, MAGE immunoreactivity was significantly correlated with lymphatic vessel invasion and intratumoural necrosis. Moreover, a significant inverse relationship with oestrogen receptor expression was also observed. However, no significant correlation could be established between MAGE immunoreactivity and defined phenotypic characteristics of tumour infiltrating lymphocytes, including expression of CD3, CD4, CD8, CD20 or granzyme B. Thus, expression of MAGE family gene products in invasive ductal breast cancers appears to be associated with poorly differentiated histological phenotypes. These data support the concept of specific immunotherapy in highly aggressive forms of breast neoplasms. Furthermore, they suggest that MAGE immunoreactivity could represent a tumour marker of potential prognostic relevance.

High density oligonucleotide array analysis of interferon- alpha2a sensitivity and transcriptional response in melanoma cells

Interferon alpha (IFN-alpha) represents an adjuvant therapy of proven effectiveness in increasing disease-free interval and survival in subgroups of melanoma patients. Since high doses of cytokine are required, the treatment is often accompanied by toxic side effects. Furthermore, naturally occurring insensitivity to IFN-alpha may hamper its therapeutic efficacy. Clinical, molecular or immunological markers enabling the selection of potential responders have not been identified so far. To explore the molecular basis of IFN-alpha responsiveness, we analysed the expression pattern of about 7000 genes in IFN-alpha sensitive and resistant cell lines and we compared the transcription profiles of cells cultured in the presence or absence of the cytokine using high-density oligonucleotide arrays. Melanoma cell lines were screened for their sensitivity to proliferation inhibition and HLA class I induction upon IFN-alpha treatment by standard 3H-thymidine incorporation and flow-cytometry. The study of 4 sensitive and 2 resistant cell lines allowed the identification of 4 genes (RCC1, IFI16, hox2 and h19) preferentially transcribed in sensitive cells and 2 (SHB and PKC-zeta) preferentially expressed in resistant cells. IFN-alpha stimulation resulted in the expression of a panel of 19 known inducible genes in sensitive but not in resistant cells. Moreover a group of 30 novel IFN-alpha inducible genes was identified. These data may provide a useful basis to develop diagnostic tools to select potential IFN-alpha responders eligible for treatment, while avoiding unnecessary toxicity to non-responders. Furthermore, by extending the knowledge of the polymorphic effects of IFN-alpha on gene expression, they offer novel clues to the study of its pleiotropic toxicity.

A retrogen strategy for presentation of an intracellular tumor antigen as an exogenous antigen by dendritic cells induces potent antitumor T helper and CTL responses

Induction of an effective antitumor response requires CD4+ helper T (Th) cells to recognize antigens on the same dendritic cells (DCs) that cross-present CTL antigens. Such cross-presentation is difficult to achieve by current tumor vaccine strategies. Here, we develop a novel "Retrogen" strategy for DCs to efficiently cross-present an intracellular tumor antigen, MAGE-3, to both MHC class I and MHC class II in a cognate manner. Specifically, the MAGE-3 gene was linked to a leader sequence at its NH2 terminus for secretion and to a cell-binding domain at its COOH terminus for receptor-mediated internalization. DCs transduced with the modified MAGE-3 gene produced and secreted MAGE-3 proteins, which were efficiently taken up by DCs via receptor-mediated internalization and presented as exogenous antigens to class I and class II molecules. Immunization of mice with the transduced DCs expressing the MAGE-3 fusion protein, termed "Retrogen" for its retrograde transport/internalization after secretion, efficiently induced all arms of the adaptive antitumor immune responses. Thus, this retrogen strategy of using a unifying mechanism for DCs to cross-present an intracellular tumor antigen in a cognate manner could be generally used to improve the efficacy of tumor vaccines and immunotherapies.

Modulation of dendritic cell phenotype and mobility by tumor cells in vitro

To gain new insights into the functional interaction between DC and neoplastic cells, we have analyzed the effects of melanoma and colorectal cancer lines on the chemotaxis and the phenotype of monocyte-derived DC in vitro. Both types of tumor cells displayed effective chemoattractive capacity towards immature, but not mature DC. Furthermore, conditioned medium of discrete melanoma lines induced upregulation of CD80, CD86, MHC class I, and MHC class II molecules on immature DC. However, de novo expression of E-cadherin and strong upregulation of CD15 could also be detected in the absence of CD83 expression. Melanoma-conditioned DC exhibited an increased adhesion capacity to a melanoma cell line in vitro and did not migrate in response to SLC chemokine. Tumor-infiltrating CD15(+) cells displaying DC morphology could also be detected by immunohistochemistry in the original tumor specimens from which discrete melanoma cell lines under investigation were derived. Colorectal cancer cell lines, although able to chemoattract immature DC, were apparently unable to modulate their phenotype. Altogether our results suggest that tumor cells can attract immature DC in vitro and, eventually, modulate their phenotype. As a result, DC mobility could be severely impaired.

Expression of MAGE antigens and analysis of the inflammatory T-cell infiltrate in human seminoma

The MAGE gene family encodes antigens that are recognized by cytotoxic T-cells. The expression of MAGE antigens has been linked to tumor stage, and MAGE peptides are under investigation as possible vaccines. Seminomas are tumors that are typically accompanied by a heavy inflammatory infiltrate, but have not been studied with regard to their MAGE antigen expression and its correlation with the inflammatory infiltrate. We investigated, therefore, MAGE protein expression, the amount of cytotoxic T-cells, clonality of the lymphocytic infiltrate, apoptotic activity and occurrence of necrosis. Specimens of 27 patients with classical seminoma were examined by immunohistochemistry for CD4, CD8, CD56, CD45R0, beta2-microglobulin and HLA-DR. MAGE expression was detected with the monoclonal antibody 57B, reactive with MAGE-1, -3, -4, -6 and -12. Clonality of the inflammatory infiltrate was examined by multiplex polymerase chain reaction (PCR) analysis of the T-cell receptor rearrangement. Apoptotic cells were detected by DNA nick-end labeling of fragmented DNA, and the apoptotic index was determined semi-quantitatively. Expression of 57B was found in 19 (70%) of 27 seminomas. In all cases, more than 70% of T-cells expressed CD45R0. In four cases, a predominant infiltration of CD8-positive cytotoxic T-cells (CD4/CD8 ratio < 1) was present. However, 15 seminomas showed a CD4/CD8 ratio > 1. In all cases, infiltration of CD56-positive natural killer cells was only focal. HLA-DR expression was not detectable in tumor tissue; beta2-microglobulin was only focal in three cases. Analysis of the T-cell clonality revealed a polyclonal population. The apoptotic index was not significantly different in 57B-positive seminomas (4.15%) compared with 57B negative seminomas (3.80%). Also, no correlation between the 57B expression and the occurrence of necrosis was found. MAGE antigens are homogeneously expressed in most seminomas, but their presence does not appear to represent a dominant epitope responsible for the lymphocytic infiltrate.

Naturally processed and concealed HLA-A2.1-restricted epitopes from tumor-associated antigen tyrosinase-related protein-2

In this study, a computer-assisted reverse immunology approach was utilized in order to identify potentially antigenic peptides derived from the differentiation antigen TRP-2, a melanosomal protein frequently expressed in melanoma. Among the seven peptides complying with HLA-A2.1-binding motifs, two induced specific CD8(+) cytotoxic T lymphocytes. HLA-A2.1(+) melanoma cells expressing TRP-2 were lysed by clones specific for TRP-2(360-368) (TLDSQVMSL) peptide, thus identifying it as a naturally processed epitope. Other T-cell clones directed against TRP-2(476-484) (VMGTLVALV) were unable to lyse HLA-matched TRP-2(+) cell lines. The role of intracellular proteolytic processing in the generation of this epitope was investigated by transfecting mini-genes encoding the TRP-2(476-484) peptide alone or carrying N- or C-terminal extensions. Specific T-cell clones recognized target cells expressing the cytotoxic T-lymphocyte (CTL)-defined epitope or its C-terminally extended precursor, but failed to recognize cells expressing the N-terminally extended TRP-2(476-484) peptide, suggesting the presence of a negative processing signal (NPS). Regarding C-terminus-flanking regions, mutational analysis indicates that the GLY485 residue plays a key role in the processing of the TRP-2(476-484) epitope. Interestingly, proteasome inhibitors preventing the generation of the MART-1/Melan-A(27-35) immunodominant melanoma tumor-associated antigen (TAA) promoted detectable presentation of TRP-2(476-484) epitope in HLA-A2.1(+) and TRP-2(+) tumor lines, as witnessed by cytokine release by specific T-cell clones.

NY-ESO-1 tumour associated antigen is a cytoplasmic protein detectable by specific monoclonal antibodies in cell lines and clinical specimens

NY-ESO-1 gene encodes a novel member of the cancer/testis (CT) family of human tumour-associated antigens (TAA). Specific monoclonal antibodies (mAb) have identified the corresponding gene product in lysates of tumour cell lines as a 22 kDa protein but no data are available concerning its intracellular location or distribution within neoplastic tissues. We have generated NY-ESO-1 specific mAbs recognizing the target molecule in cytospin preparations and in sections from clinical tumour specimens. These reagents identify NY-ESO-1 TAA in melanoma cell lines expressing the specific gene as a cytoplasmic protein, sharing the intracellular location of most MAGE TAA. In a series of 12 melanoma specimens, specific staining, limited to neoplastic cells, was detectable in the five cases where NY-ESO-1 gene expression was observed. In two of them over 90% of tumour cells showed evidence of positive staining. Lower percentages of positive neoplastic cells ranging between single cells and 50% were observed in the remaining tumours. These data suggest that active specific immunotherapies targeting NY-ESO-1, alone or in combination with other TAA could be of high clinical relevance in sizeable subgroups of melanoma patients.

Monoclonal antibody 57B stains tumor tissues that express gene MAGE-A4

Monoclonal antibody (Mab) 57B, which was raised against a recombinant MAGE-A3 protein, was tested for its ability to stain cells expressing various members of the MAGE-A gene family. COS-7 cells transfected with cDNAs encoding MAGE-A1, A2, A3, A4, A6, or A12 were stained, whereas those transfected with MAGE-A8, A9, A10, or A11 cDNAs were not. However, in tissue sections, we observed a different pattern of staining: the antibody effectively stained the tumors that expressed MAGE-A4 and only these tumors, regardless of the expression of the other MAGE-A genes. It seems, therefore, that at the level of MAGE gene expression found in tumors, a level clearly lower than that observed in transfected COS cells, only the MAGE-A4 protein can be reliably detected. We conclude that the 57B Mab should be useful for tumor diagnosis related to therapeutic vaccination involving MAGE-A4.

Expression of gene MAGE-A4 in Reed-Sternberg cells

Genes of the MAGE-A family are expressed in several types of solid tumors but are silent in normal tissues with the exception of male germline cells, which do not carry HLA molecules.Therefore, peptides encoded by MAGE-A genes are strictly tumor-specific antigens that can be recognized by CTL and constitute promising targets for immunotherapy. The expression of 6 genes of the MAGE-A family was tested with reverse transcriptase-polymerase chain reaction in lymphoma samples. Among 38 samples of non-Hodgkin lymphoma, 1 anaplastic large cell lymphoma expressed genes MAGE-A1, -A2, -A3, -A4, and -A12, and 1 lymphoepithelioid T-cell lymphoma expressed gene MAGE-A4. Five of 18 samples (28%) from patients with Hodgkin disease expressed gene MAGE-A4. In tissue sections, staining by a monoclonal antibody that recognizes the MAGE-A4 protein was observed in 11 of 53 samples (21%) from patients with Hodgkin disease. In the positive samples, the Reed-Sternberg cells were strongly stained whereas the surrounding cells were not. These results indicate that Hodgkin disease may be a target for specific immunotherapy involving MAGE-A4 antigens.

Phase I study in melanoma patients of a vaccine with peptide-pulsed dendritic cells generated in vitro from CD34(+) hematopoietic progenitor cells

Dendritic cells (DCs) are professional antigen-presenting cells (APCs) that can be used for vaccination purposes, to induce a specific T-cell response in vivo against melanoma-associated antigens. We have shown that the sequential use of early-acting hematopoietic growth factors, stem cell factor, IL-3 and IL-6, followed by differentiation with IL-4 and granulocyte-macrophage colony-stimulating factor allows the in vitro generation of large numbers of immature DCs from CD34(+) peripheral blood progenitor cells. Maturation to interdigitating DCs could specifically be induced within 24 hr by addition of TNF-alpha. Here, we report on a phase I clinical vaccination trial in melanoma patients using peptide-pulsed DCs. Fourteen HLA-A1(+) or HLA-A2(+) patients received at least 4 i.v. infusions of 5 x 10(6) to 5 x 10(7) DCs pulsed with a pool of peptides including either MAGE-1, MAGE-3 (HLA-A1) or Melan-A, gp100, tyrosinase (HLA-A2), depending on the HLA haplotype. A total of 83 vaccinations were performed. Clinical side effects were mild and consisted of low-grade fever (WHO grade I-II). Clinical and immunological responses consisted of anti-tumor responses in 2 patients, increased melanoma peptide-specific delayed-type hypersensitivity reactions in 4 patients, significant expansion of Melan-A- and gp100-specific cytotoxic T lymphocytes in the peripheral blood lymphocytes of 1 patient after vaccination and development of vitiligo in another HLA-A2(+) patient. Our data indicate that the vaccination of peptide-pulsed DCs is capable of inducing clinical and systemic tumor-specific immune responses without provoking major side effects.

Phase I study in melanoma patients of a vaccine with peptide-pulsed dendritic cells generated in vitro from CD34(+) hematopoietic progenitor cells

Dendritic cells (DCs) are professional antigen-presenting cells (APCs) that can be used for vaccination purposes, to induce a specific T-cell response in vivo against melanoma-associated antigens. We have shown that the sequential use of early-acting hematopoietic growth factors, stem cell factor, IL-3 and IL-6, followed by differentiation with IL-4 and granulocyte-macrophage colony-stimulating factor allows the in vitro generation of large numbers of immature DCs from CD34(+) peripheral blood progenitor cells. Maturation to interdigitating DCs could specifically be induced within 24 hr by addition of TNF-alpha. Here, we report on a phase I clinical vaccination trial in melanoma patients using peptide-pulsed DCs. Fourteen HLA-A1(+) or HLA-A2(+) patients received at least 4 i.v. infusions of 5 x 10(6) to 5 x 10(7) DCs pulsed with a pool of peptides including either MAGE-1, MAGE-3 (HLA-A1) or Melan-A, gp100, tyrosinase (HLA-A2), depending on the HLA haplotype. A total of 83 vaccinations were performed. Clinical side effects were mild and consisted of low-grade fever (WHO grade I-II). Clinical and immunological responses consisted of anti-tumor responses in 2 patients, increased melanoma peptide-specific delayed-type hypersensitivity reactions in 4 patients, significant expansion of Melan-A- and gp100-specific cytotoxic T lymphocytes in the peripheral blood lymphocytes of 1 patient after vaccination and development of vitiligo in another HLA-A2(+) patient. Our data indicate that the vaccination of peptide-pulsed DCs is capable of inducing clinical and systemic tumor-specific immune responses without provoking major side effects.

Identification of genes differentially expressed in melanoma sublines derived from a single surgical specimen characterised by different sensitivity to cytotoxic T-lymphocyte activity

In this study we used differential display technology in an attempt to obtain an insight into the mechanisms underlying escape of tumour cells to the specific cytotoxic T cell response. A primary tumour cell line and autologous tumour infiltrating lymphocytes were raised from a metastatic melanoma sample (ME15). Upon co-culture of tumour infiltrating lymphocytes with irradiated tumour cells, CTL specific for neoplastic cells were generated and cloned. Using a CTL clone, a cytotoxicity resistant tumour subline (ME15R) was immunoselected. We applied a PCR-based differential display technique to amplify DNA sequences differentially expressed in ME15 sublines sensitive (S) or resistant (R) to specific CTL killing. 10 different sequences whose expression was exclusively detectable in ME15S cells were identified. Five of them matched with known expressed sequence tags encoding products of unidentified function. 2 showed high homology with a mitochondrial mRNA and with the gene encoding the S24 ribosomal protein. Most interestingly, genes coding for glutamine synthetase, TGF-beta-3 and PAX3, a well-characterised transcription factor, were only expressed in ME15S cells. The latter gene was found to be transcribed in all healthy tissues tested, but only in a subgroup of established melanoma cell lines. Taken together, our data underline the relevant potential of differential display technology in the molecular analysis of paired tumour lines endowed with different phenotypic characteristics. Cloning of entire open reading frames and transfection studies are warranted to clarify the role of individual differentially displayed genes in the escape of tumour cells from cellular immune response.

FLT3 ligand gene expression and protein production in human colorectal cancer cell lines and clinical tumor specimens

Dendritic cells (DC) are professional antigen presenting cells (APC) whose proliferation and functional differentiation can be induced by hematopoietic growth factors including GM-CSF and FLT3 ligand (FL). Colorectal cancers are known to be infiltrated by dendritic cells (DC) and neoplastic cells have been shown to produce GM-CSF. In this work we investigated FLT3 ligand (FL) gene expression and protein production in human colorectal cancer cell lines and clinical tumor specimens. Using reverse transcription polymerase chain reaction (RT-PCR), 6 out of 6 established tumor lines were found to express to variable extents FL gene. In 1 of them, SW480, FL immunoreactivity could be observed by taking advantage of specific antibodies. In contrast, soluble FL could not be detected in any culture supernatant. FLT3 receptor (FR) gene was not expressed and exogenous addition to the cultures of recombinant FL (rFL) did not affect the proliferation of the tumor lines. FL gene expression was investigated using a densitometry-assisted, semiquantitative RT-PCR in clinical tumor specimens. Specific FL gene transcripts were amplified from 12 of 12 surgical samples. In these cases, FL gene expression of significantly lower intensity was also detected in healthy mucosa sampled in the vicinity (2 cm) or at a distance (10 cm) from neoplastic outgrowth. Immunohistochemical studies identified FL-positive cancer cells in 5 of 5 cases tested. No positivity was detected in healthy mucosa epithelia at a distance from the tumor or in stromal cells. FL content in preoperative sera from colorectal cancer patients (n = 13) did not exceed the levels detected in healthy donors (</= 100 pg/ml).