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Biomedical subjects

Stephan N Wagner

Publications and source records attributed to Stephan N Wagner.

14 recordsLinked to original sources
PubMed2006

Phase II trial of a toll-like receptor 9-activating oligonucleotide in patients with metastatic melanoma.

PURPOSE: The recent identification of toll-like receptors (TLRs) and respective ligands allows the evaluation of novel dendritic cell (DC) -activating strategies. Stimulation of TLR9 directly activates human plasmacytoid DCs (PDCs) and indirectly induces potent innate immune responses in preclinical tumor models. We performed an open-label, multicenter, single-arm, phase II pilot trial with a TLR9-stimulating oligodeoxynucleotide in melanoma patients. PATIENTS AND METHODS: Patients with unresectable stage IIIb/c or stage IV melanoma received 6 mg PF-3512676 weekly by subcutaneous injection for 24 weeks or until disease progression to evaluate safety as well as clinical and immunologic activity. Clinical and laboratory safety assessments were performed weekly; blood samples for immunological measurements were taken every 8 weeks. Tumor measurements were performed according to Response Evaluation Criteria in Solid Tumors. RESULTS: Twenty patients received PF-3512676 for a mean of 10.9 weeks with a mean of 10.7 injections. Laboratory and nonlaboratory adverse events were limited, transient, and did not result in any withdrawals. Two patients experienced a confirmed partial response; one response is ongoing for 140+ weeks. Three patients experienced stable disease. Immunologic measurements revealed induction of an activated phenotype of PDC, elevation of serum levels of 2',5'-oligoadenylate, a surrogate marker of type I interferon production, and significant stimulation of natural killer cell cytotoxicity (the latter was associated with clinical benefit). CONCLUSION: These results indicate that TLR9-targeted therapy can stimulate innate immune responses in cancer patients, identify biomarkers that may be associated with TLR9-induced tumor regression, and encourage the design of follow-up studies to evaluate the ability of this therapeutic approach to target human cancer.

Adult↗
PubMed2006

Comparative oncogenomics identifies NEDD9 as a melanoma metastasis gene.

Genomes of human cancer cells are characterized by numerous chromosomal aberrations of uncertain pathogenetic significance. Here, in an inducible mouse model of melanoma, we characterized metastatic variants with an acquired focal chromosomal amplification that corresponds to a much larger amplification in human metastatic melanomas. Further analyses identified Nedd9, an adaptor protein related to p130CAS, as the only gene within the minimal common region that exhibited amplification-associated overexpression. A series of functional, biochemical, and clinical studies established NEDD9 as a bona fide melanoma metastasis gene. NEDD9 enhanced invasion in vitro and metastasis in vivo of both normal and transformed melanocytes, functionally interacted with focal adhesion kinase and modulated focal contact formation, and exhibited frequent robust overexpression in human metastatic melanoma relative to primary melanoma. Thus, comparative oncogenomics has enabled the identification and facilitated the validation of a highly relevant cancer gene governing metastatic potential in human melanoma.

Adaptor Proteins, Signal Transducing↗
PubMed2005

Integrative genomic analyses identify MITF as a lineage survival oncogene amplified in malignant melanoma.

Systematic analyses of cancer genomes promise to unveil patterns of genetic alterations linked to the genesis and spread of human cancers. High-density single-nucleotide polymorphism (SNP) arrays enable detailed and genome-wide identification of both loss-of-heterozygosity events and copy-number alterations in cancer. Here, by integrating SNP array-based genetic maps with gene expression signatures derived from NCI60 cell lines, we identified the melanocyte master regulator MITF (microphthalmia-associated transcription factor) as the target of a novel melanoma amplification. We found that MITF amplification was more prevalent in metastatic disease and correlated with decreased overall patient survival. BRAF mutation and p16 inactivation accompanied MITF amplification in melanoma cell lines. Ectopic MITF expression in conjunction with the BRAF(V600E) mutant transformed primary human melanocytes, and thus MITF can function as a melanoma oncogene. Reduction of MITF activity sensitizes melanoma cells to chemotherapeutic agents. Targeting MITF in combination with BRAF or cyclin-dependent kinase inhibitors may offer a rational therapeutic avenue into melanoma, a highly chemotherapy-resistant neoplasm. Together, these data suggest that MITF represents a distinct class of 'lineage survival' or 'lineage addiction' oncogenes required for both tissue-specific cancer development and tumour progression.

Cell Line, Tumor↗
PubMed2005

EMPACT syndrome.

BACKGROUND: Seizure prophylaxis with phenytoin is a common measure in oncologic patients with brain metastases. In these patients, generalized severe adverse drug reactions such as erythema multiforme (EEM) may occur. However, in a subgroup of patients with brain radiation therapy, EEM-like lesions develop particularly in the radiation field. Most recently, the acronym EMPACT (Erythema Multiforme associated with Phenytoin And Cranial radiation Therapy) was proposed to specifically describe this syndrome. PATIENT/METHOD: Here, we report on EMPACT syndrome in a 46-year-old woman. Therapeutic measures included seizure prophylaxis with phenytoin and total brain radiation therapy of brain metastases from bronchial carcinoma. Three weeks after introduction of phenytoin, the patient presented with EEM-like skin lesions restricted to the original radiation field and facial mucocutaneous involvement. After a few days, the rash spread to the upper part of the body. She was also in poor general condition. RESULTS: The immediate cessation of phenytoin therapy, combined with administration of systemic corticosteroids and high dose immunoglobulins along with intensive local treatment and pain medications, resulted in complete resolution of the skin eruption. Patch testing to phenytoin was positive after 72 hours. CONCLUSION: EMPACT should be classified as an specific entity among the EEM-like drug reactions as it only appears after radiotherapy and seizure prophylaxis with the anticonvulsant phenytoin. We propose including specific type IV-sensitization to phenytoin into the definition of EMPACT.

Adrenal Cortex Hormones↗
PubMed2004

A phase I vaccination study with tyrosinase in patients with stage II melanoma using recombinant modified vaccinia virus Ankara (MVA-hTyr).

A significant percentage of patients with stage II melanomas suffer a relapse after surgery and therefore need the development of adjuvant therapies. In the study reported here, safety and immunological response were analyzed after vaccination in an adjuvant setting with recombinant modified vaccinia virus Ankara carrying the cDNA for human tyrosinase (MVA-hTyr). A total of 20 patients were included and vaccinated three times at 4-week intervals with 5x10(8) IU of MVA-hTyr each time. The responses to the viral vector, to known HLA class I-restricted tyrosinase peptides, and to dendritic cells transfected with tyrosinase mRNA, were investigated by ELISpot assay on both ex vivo T cells and on T cells stimulated in vitro prior to testing. The delivery of MVA-hTyr was safe and did not cause any side effects above grade 2. A strong response to the viral vector was achieved, indicated by an increase in the frequency of MVA-specific CD4+ and CD8+ T cells and an increase in virus-specific antibody titers. However, no tyrosinase-specific T-cell or antibody response was observed with MVA-hTyr in any of the vaccinated patients. Although MVA-hTyr provides a safe and effective antigen-delivery system, it does not elicit a measurable immune response to its transgene product in patients with stage II melanoma after repeated combined intradermal and subcutaneous vaccination. We presume that modification of the antigen and/or prime-boost vaccination applying different approaches to antigen delivery may be required to induce an effective tyrosinase-specific immune response.

Adult↗
PubMed2004

Differential downregulation of endoplasmic reticulum-residing chaperones calnexin and calreticulin in human metastatic melanoma.

Characterization of the molecular basis of tumor recognition by T cells has shown that major histocompatibility complex (MHC) class I molecules play a crucial role in presenting antigenic peptide epitopes to cytotoxic T lymphocytes. MHC class Ia downregulation has been repeatedly described on melanoma cells and is thought to be involved in the failure of the immune system to control tumor progression. Proper assembly of MHC class I molecules is dependent on several cofactors, e.g. the chaperones calnexin and calreticulin residing in the endoplasmic reticulum. Alterations in the expression of these chaperones may have important implications for MHC class I assembly, peptide loading, and presentation on the tumor cell surface and thus may contribute to the immune escape phenotype of tumor cells. In the present study, we compared melanoma lesions representing different stages of tumor progression with regard to the expression of calnexin and calreticulin in tumor cells by means of immunohistochemistry. Metastatic melanoma lesions exhibited significant downregulation of calnexin as compared to primary melanoma lesions. In contrast, chaperone calreticulin was expressed in melanoma cells of primary as well as of metastatic lesions. Our data suggest that chaperone-downregulation, particularly calnexin-downregulation, may contribute to the metastatic phenotype of melanoma cells in vivo. Consistently, conserved chaperone expression in metastatic melanoma lesions may be a useful criterion for selection of patients for treatment with T cell-based immunotherapies.

Calnexin↗
PubMed2004

Alterations of DeltaTA-p 73 splice transcripts during melanoma development and progression.

In the last 2 years, it has become apparent that the p53-family members p53 and p73 play fundamentally different roles in human malignancies. In contrast to p53, many studies on cancer patients failed to detect mutational inactivation of p73 and reported overexpression of wild-type p73 instead. A possible explanation was provided by the recent discovery of N-terminal truncated isoforms of p73 (DeltaTA-p73) that act as dominant-negative inhibitors of wild-type p53 and TA-p73 and result in tumor growth in nude mice. We investigated the role of DeltaTA-p73 in the development and progression of human melanomas, which lack p53 mutations. We analyzed 8 benign melanocytic nevi, 8 primary melanomas and 19 melanoma metastases for alterations of TA-p73 and DeltaTA-p73 expression using isoform-specific real-time RT-PCR. Based on our results, p73Deltaex2 and Deltaex2/3 spliced transcripts derived from the first promoter were significantly up-regulated in melanoma metastases, whereas DeltaN-p73 generated from the second promoter was the predominant isoform in benign nevi. Moreover, increased expression of p73Deltaex2 and p73Deltaex2/3 correlated with high-levels of both TA-p73 and E2F1. Our data suggest a potential function of DeltaTA-p73 splice isoforms in melanoma progression.

DNA-Binding Proteins↗
PubMed2004

CpG motifs are efficient adjuvants for DNA cancer vaccines.

DNA vaccines can induce impressive specific cellular immune response (IR) when taking advantage of their recognition as pathogen-associated molecular patterns (PAMP) through Toll-like receptors (TLR) expressed on/in cells of the innate immune system. Among the many types of PAMP, immunostimulatory DNA, so-called CpG motifs, was shown to interact specifically with TLR9, which is expressed in plasmacytoid dendritic cells (pDC), a key regulatory cell for the activation of innate and adaptive IR. We now report that CpG motifs, when introduced into the backbone, are a useful adjuvant for plasmid-based DNA (pDNA) vaccines to induce melanoma antigen-specific protective T cell responses in the Cloudman M3/DBA/2 model. The CpG-enriched pDNA vaccine induced protection against subsequent challenge with melanoma cells at significantly higher levels than its parental unmodified vector. Preferential induction of an antigen-specific, protective T cell response could be demonstrated by (i) induction of antigen-dependent tumor cell protection, (ii) complete loss of protection by in vivo CD4+/CD8+T cell- but not NK cell-depletion, and (iii) the detection of antigen-specific T cell responses but not of relevant NK cell activity in vitro. These results demonstrate that employing PAMP in pDNA vaccines improves the induction of protective, antigen-specific, T cell-mediated IR.

Adjuvants, Immunologic↗
PubMed2003

Association of TAP1 downregulation in human primary melanoma lesions with lack of spontaneous regression.

Spontaneous regression of primary melanoma lesions is regarded as the result of the recognition of melanoma-associated antigen (MAA)-derived peptides by cytotoxic T-lymphocytes and destruction of melanoma cells. The transporter associated with antigen processing (TAP1/2) is likely to play a crucial role in this process since it loads antigen peptides onto MHC class I molecules. To determine the impact of TAP defects on the spontaneous regression of melanoma lesions, we have compared the expression of TAP1 and TAP2 in 39 primary melanoma lesions exhibiting clinical and histological signs of tumour regression and in 35 primary melanoma lesions without regression phenomena. TAP1 expression was significantly associated with regression of melanoma lesions, since the staining pattern with anti-TAP1 antibody was positive in 38 of the 39 lesions exhibiting regression phenomena and in only 24 of the 35 lesions without histopathological signs of tumour regression. In the latter group, six lesions were stained with a heterogeneous pattern and five with a negative pattern. Furthermore, in lesions with a heterogeneous staining pattern, a clear association was found between TAP1 expression in melanoma cells and the presence of tumour-infiltrating lymphocytes. These results suggest that TAP1 plays an important role in the MAA-specific cytotoxic T-lymphocyte response, which has been suggested to underlie the spontaneous regression of primary melanoma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2003

Immunoproteasome subunits LMP2 and LMP7 downregulation in primary malignant melanoma lesions: association with lack of spontaneous regression.

Recently, expression of the immunoproteasome subunits low molecular protein (LMP) 2 or LMP7 was shown to reduce the presentation of certain major histocompatibility complex (MHC) class I-restricted tumour peptide epitopes in renal cell carcinoma and melanoma cells. This may provide the tumour cells with an immune escape mechanism. To test the relevance of this hypothesis, we have taken advantage of the fact that spontaneous regression of human primary melanoma is thought to be the result of a successful peptide-specific cellular immune response in vivo. Immunohistochemical staining with anti-LMP2 and anti-LMP7 xenoantibodies showed a significantly higher expression of these immunoproteasome subunits in primary melanoma lesions exhibiting histological signs of tumour regression than in primary melanoma lesions without regression phenomena. In spontaneously regressing melanoma lesions, LMP2 and LMP7 expression was significantly associated with the presence of tumour-infiltrating lymphocytes. Our results are compatible with the possibility that the expression of the immunoproteasome subunits LMP2 and LMP7 rather than their downregulation in melanoma cells is associated with the presence of a successful anti-melanoma immune response.

Cysteine Endopeptidases↗
PubMed2002

Induction of specific immune responses by polycation-based vaccines.

The s.c injection of tumor Ag-derived, MHC class I-binding peptides together with cationic poly-amino acids (e.g., poly-L-arginine; pR) has been shown to protect animals against a challenge with tumor cells expressing the respective peptide(s). Given our only restricted knowledge about immunogenic tumor-associated peptides, we sought to determine whether this pR-based vaccination protocol would also induce protective cancer immunity if large proteins were used instead of peptide epitopes. We found that the intracutaneous administration of the model Ag beta-galactosidase (beta-gal) together with pR (referred to as pR-based protein vaccine; pR-PV) was significantly more potent in protecting mice against the growth of beta-gal-expressing RENCA cells than the protein alone. Coadministration of pR enhanced both the beta-gal-induced specific humoral and CD8 response. The protective effect required CD8(+), but neither CD4(+) T lymphocytes nor beta-gal-specific Abs. beta-Gal priming of protective CD8(+) T lymphocytes was found to be CD4(+) T cell-independent, to take place within the draining lymph nodes, and to be accomplished by day 5 after vaccination. Ablation of the injection sites as early as 1.5 h after pR-PV administration still led to protection in a large proportion of the animals, indicating that certain protein Ags administered intradermally in the context of polycations are quickly transported to the draining nodes, where they induce molecular and cellular events resulting in the helper-independent priming and expansion of Tc1 cells. However, optimal protection required the prolonged presence of the injection site, suggesting that pR-PV injection facilitates the formation of a cutaneous depot of Ag-charged cells capable of migration and T cell activation.

Adjuvants, Immunologic↗
PubMed2002

Unbalanced overexpression of the mutant allele in murine Patched mutants.

Inherited mutations of Patched (PTCH) in the nevoid basal cell carcinoma syndrome (NBCCS) lead to several developmental defects and contribute to tumor formation in a variety of tissues. PTCH mutations have been also identified in sporadic tumors associated with NBCCS including basal cell carcinoma (BCC) and medulloblastoma. Mice heterozygous for Ptch recapitulate the typical developmental symptoms of NBCCS and develop rhabdomyosarcoma (RMS) and medulloblastoma. PTCH is assumed to act as a tumor suppressor gene although inactivation of both alleles has been demonstrated only in a fraction of tumors. We have investigated the status of Ptch in RMS of heterozygous Ptch neo67/+ mice. Although the wild-type Ptch allele was retained in tumor tissue, the high levels of Ptch mRNA in these tumors result from overexpression of the mutant Ptch transcript. Our results suggest that the wild-type Ptch allele might be selectively silenced in RMS tissue or, alternatively, that haploinsufficiency of Ptch is sufficient to promote RMS formation in mice.

Alleles↗