Journal of the American Society of Nephrology, Sep 1, 2008
Complement activation plays a key role in mediating apoptosis, inflammation, and transplant rejec... more Complement activation plays a key role in mediating apoptosis, inflammation, and transplant rejection. In this study, the role of the complement 5a receptor (C5aR) was examined in human renal allografts and in an allogenic mouse model of renal transplant rejection. In human kidney transplants with acute rejection, C5aR expression was increased in renal tissue and in cells infiltrating the tubulointerstitium. Similar findings were observed in mice. When recipient mice were treated once daily with a C5aR antagonist before transplantation, long-term renal allograft survival was markedly improved compared with vehicle-treatment (75 versus 0%), and apoptosis was reduced. Furthermore, treatment with a C5aR antagonist significantly attenuated monocyte/macrophage infiltration, perhaps a result of reduced levels of monocyte chemoattractant protein 1 and the intercellular adhesion molecule 1. In vitro, C5aR antagonism inhibited intercellular adhesion molecule 1 upregulation in primary mouse aortic endothelial cells and reduced adhesion of peripheral blood mononuclear cells. Furthermore, C5aR blockade markedly reduced alloreactive T cell priming. These results demonstrate that C5aR plays an important role in mediating acute kidney allograft rejection, suggesting that pharmaceutical targeting of C5aR may have potential in transplantation medicine.
Histology and Histopathology Cellular and Molecular Biology, Jun 1, 2007
Immunotherapy of cancer has become a more promising approach in the past decade. Developments in ... more Immunotherapy of cancer has become a more promising approach in the past decade. Developments in both basic immunology and tumor biology have increased our knowledge of the interactions between the tumor cells and the immune system. The molecular identification of tumor-associated antigens and understanding of immunological pathways have cleared the way for development of different strategies for anti-tumor vaccines. The success of any cancer vaccine relies on the induction of an effective tumor-specific immune response to break tolerance and to elicit a long lasting anti-tumor immunity. It is also increasingly clear that the interactions of host-tumor are quite complicated leading to tumor escape mechanisms, which add another level of difficulty to this interaction. This review will summarize the recent developments in tumor immunotherapy as well as the clinical trials addressing novel immunotherapeutic approaches to cancer.
Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of mortality and morbidity. The 5-year... more Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of mortality and morbidity. The 5-year survival rate remains less than 5% and in contrast to other solid tumors, survial has changed only little in the last decade. Overall PDAC treatment shows only limited response to conventional chemotherapeutic agents. Several trials on therapy are ongoing and new targeted agents are in development to improve the treatment outcome of this deadly disease. However, our review presents the current developments of molecular therapies, supports the translational PDAC research and encourage you to take part in further clinical studies.
Co-culturing of immunological effector cells with antigen-pulsed DC leads to an increase of cytot... more Co-culturing of immunological effector cells with antigen-pulsed DC leads to an increase of cytotoxic activity against antigen-expressing tumour cells. Using this approach, we could detect up to 2.8% antigenspecific CTLs after co-culture with antigen-pulsed DC. However, the required high effector cell numbers remain a major obstacle in immunotherapy. In this study, we show an approach for generating activated and antigenspecific effector cells that enables us to decrease effector to target cell ratios. We used an interferon-c secretion assay to enrich activated effector cells after co-culture with antigen-pulsed dendritic cells (DC). Purified immunological effector cells lysed 58.3% of antigenexpressing tumour cells at an effector to target ratio of 1:1. Furthermore, using MHC-IgG complexes, we enriched effector cells expressing antigen-specific T-cell receptor after co-culture with DC. Performing ELISpot, flow cytometry and TCR analysis, we could show a significant increase of activated and specific TCRexpressing effector cells after co-culture with DC.
Hepatocellular carcinoma (HCC) is the second most common cause of cancer-related death. Non-alcoh... more Hepatocellular carcinoma (HCC) is the second most common cause of cancer-related death. Non-alcoholic fatty liver disease (NAFLD) affects a large proportion of the US population and is considered to be a metabolic predisposition to liver cancer. However, the role of adaptive immune responses in NAFLD-promoted HCC is largely unknown. Here we show, in mouse models and human samples, that dysregulation of lipid metabolism in NAFLD causes a selective loss of intrahepatic CD4(+) but not CD8(+) T lymphocytes, leading to accelerated hepatocarcinogenesis. We also demonstrate that CD4(+) T lymphocytes have greater mitochondrial mass than CD8(+) T lymphocytes and generate higher levels of mitochondrially derived reactive oxygen species (ROS). Disruption of mitochondrial function by linoleic acid, a fatty acid accumulated in NAFLD, causes more oxidative damage than other free fatty acids such as palmitic acid, and mediates selective loss of intrahepatic CD4(+) T lymphocytes. In vivo blockade o...
Hepatocellular carcinoma (HCC) is generally difficult to treat. This is primarily due to the redu... more Hepatocellular carcinoma (HCC) is generally difficult to treat. This is primarily due to the reduced liver function of most patients and the low sensitivity of liver cancer cells to chemotherapy. This has been demonstrated in many clinical trials. Molecular therapies might represent an improvement in the systemic treatment of patients with HCC. In addition to anti-angiogenic drugs, compounds which interfere with specific signal transduction cascades have shown promising results in smaller trials. There are only limited numbers of studies about the systemic treatment options for biliary cancers. To date, the best response rates have been achieved with combination chemotherapies containing platinum analogues and gemcitabine. In the absence of larger clinical phase III trials, no standard chemotherapy for biliary cancers exists today.
Background KRAS mutations are clinically important predictors of resistance to EGFR-directed ther... more Background KRAS mutations are clinically important predictors of resistance to EGFR-directed therapies in colorectal cancer (CRC). Oncogenic activation of the RAS/RAF/MEK/ERK signaling cascade mediates proliferation independent of growth factor signaling. We hypothesized that targeting MEK with selumetinib could overcome resistance to cetuximab in KRAS mutant CRC. Methods A phase I study (NCT01287130) was undertaken to determine the tolerability, and pharmacokinetic profiles of the combination of selumetinib and cetuximab, with an expanded cohort in KRAS-mutant CRC. Results 15 patients were treated in the dose escalation cohort and 18 patients were treated in the expansion cohort. Two dose-limiting toxicities were observed. One grade 3 acneiform rash and one grade 4 hypomagnesemia occurred. The most common grade 1 and 2 adverse events included rash, nausea/vomiting, diarrhea, and fatigue. The maximum tolerated dose was established at selumetinib 75 mg PO BID and cetuximab 250 mg/m(2) weekly following a 400 mg/m(2) load. Best clinical response in the dose escalation group included 1 unconfirmed partial response in a patient with CRC and stable disease (SD) in 5 patients (1 squamous cell carcinoma of the tonsil, 1 non-small cell lung cancer, and 3 CRC), and in the KRAS-mutant CRC dose expansion cohort, of the 14 patients who were evaluable for response, 5 patients had SD and 9 patients had progressive disease. Conclusions The combination of selumetinib and cetuximab is safe and well tolerated. Minimal anti-tumor activity was observed in KRAS-mutant refractory metastatic CRC. Further investigations might be warranted in other cancer subtypes.
Journal of the American Society of Nephrology, Sep 1, 2008
Complement activation plays a key role in mediating apoptosis, inflammation, and transplant rejec... more Complement activation plays a key role in mediating apoptosis, inflammation, and transplant rejection. In this study, the role of the complement 5a receptor (C5aR) was examined in human renal allografts and in an allogenic mouse model of renal transplant rejection. In human kidney transplants with acute rejection, C5aR expression was increased in renal tissue and in cells infiltrating the tubulointerstitium. Similar findings were observed in mice. When recipient mice were treated once daily with a C5aR antagonist before transplantation, long-term renal allograft survival was markedly improved compared with vehicle-treatment (75 versus 0%), and apoptosis was reduced. Furthermore, treatment with a C5aR antagonist significantly attenuated monocyte/macrophage infiltration, perhaps a result of reduced levels of monocyte chemoattractant protein 1 and the intercellular adhesion molecule 1. In vitro, C5aR antagonism inhibited intercellular adhesion molecule 1 upregulation in primary mouse aortic endothelial cells and reduced adhesion of peripheral blood mononuclear cells. Furthermore, C5aR blockade markedly reduced alloreactive T cell priming. These results demonstrate that C5aR plays an important role in mediating acute kidney allograft rejection, suggesting that pharmaceutical targeting of C5aR may have potential in transplantation medicine.
Histology and Histopathology Cellular and Molecular Biology, Jun 1, 2007
Immunotherapy of cancer has become a more promising approach in the past decade. Developments in ... more Immunotherapy of cancer has become a more promising approach in the past decade. Developments in both basic immunology and tumor biology have increased our knowledge of the interactions between the tumor cells and the immune system. The molecular identification of tumor-associated antigens and understanding of immunological pathways have cleared the way for development of different strategies for anti-tumor vaccines. The success of any cancer vaccine relies on the induction of an effective tumor-specific immune response to break tolerance and to elicit a long lasting anti-tumor immunity. It is also increasingly clear that the interactions of host-tumor are quite complicated leading to tumor escape mechanisms, which add another level of difficulty to this interaction. This review will summarize the recent developments in tumor immunotherapy as well as the clinical trials addressing novel immunotherapeutic approaches to cancer.
Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of mortality and morbidity. The 5-year... more Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of mortality and morbidity. The 5-year survival rate remains less than 5% and in contrast to other solid tumors, survial has changed only little in the last decade. Overall PDAC treatment shows only limited response to conventional chemotherapeutic agents. Several trials on therapy are ongoing and new targeted agents are in development to improve the treatment outcome of this deadly disease. However, our review presents the current developments of molecular therapies, supports the translational PDAC research and encourage you to take part in further clinical studies.
Co-culturing of immunological effector cells with antigen-pulsed DC leads to an increase of cytot... more Co-culturing of immunological effector cells with antigen-pulsed DC leads to an increase of cytotoxic activity against antigen-expressing tumour cells. Using this approach, we could detect up to 2.8% antigenspecific CTLs after co-culture with antigen-pulsed DC. However, the required high effector cell numbers remain a major obstacle in immunotherapy. In this study, we show an approach for generating activated and antigenspecific effector cells that enables us to decrease effector to target cell ratios. We used an interferon-c secretion assay to enrich activated effector cells after co-culture with antigen-pulsed dendritic cells (DC). Purified immunological effector cells lysed 58.3% of antigenexpressing tumour cells at an effector to target ratio of 1:1. Furthermore, using MHC-IgG complexes, we enriched effector cells expressing antigen-specific T-cell receptor after co-culture with DC. Performing ELISpot, flow cytometry and TCR analysis, we could show a significant increase of activated and specific TCRexpressing effector cells after co-culture with DC.
Hepatocellular carcinoma (HCC) is the second most common cause of cancer-related death. Non-alcoh... more Hepatocellular carcinoma (HCC) is the second most common cause of cancer-related death. Non-alcoholic fatty liver disease (NAFLD) affects a large proportion of the US population and is considered to be a metabolic predisposition to liver cancer. However, the role of adaptive immune responses in NAFLD-promoted HCC is largely unknown. Here we show, in mouse models and human samples, that dysregulation of lipid metabolism in NAFLD causes a selective loss of intrahepatic CD4(+) but not CD8(+) T lymphocytes, leading to accelerated hepatocarcinogenesis. We also demonstrate that CD4(+) T lymphocytes have greater mitochondrial mass than CD8(+) T lymphocytes and generate higher levels of mitochondrially derived reactive oxygen species (ROS). Disruption of mitochondrial function by linoleic acid, a fatty acid accumulated in NAFLD, causes more oxidative damage than other free fatty acids such as palmitic acid, and mediates selective loss of intrahepatic CD4(+) T lymphocytes. In vivo blockade o...
Hepatocellular carcinoma (HCC) is generally difficult to treat. This is primarily due to the redu... more Hepatocellular carcinoma (HCC) is generally difficult to treat. This is primarily due to the reduced liver function of most patients and the low sensitivity of liver cancer cells to chemotherapy. This has been demonstrated in many clinical trials. Molecular therapies might represent an improvement in the systemic treatment of patients with HCC. In addition to anti-angiogenic drugs, compounds which interfere with specific signal transduction cascades have shown promising results in smaller trials. There are only limited numbers of studies about the systemic treatment options for biliary cancers. To date, the best response rates have been achieved with combination chemotherapies containing platinum analogues and gemcitabine. In the absence of larger clinical phase III trials, no standard chemotherapy for biliary cancers exists today.
Background KRAS mutations are clinically important predictors of resistance to EGFR-directed ther... more Background KRAS mutations are clinically important predictors of resistance to EGFR-directed therapies in colorectal cancer (CRC). Oncogenic activation of the RAS/RAF/MEK/ERK signaling cascade mediates proliferation independent of growth factor signaling. We hypothesized that targeting MEK with selumetinib could overcome resistance to cetuximab in KRAS mutant CRC. Methods A phase I study (NCT01287130) was undertaken to determine the tolerability, and pharmacokinetic profiles of the combination of selumetinib and cetuximab, with an expanded cohort in KRAS-mutant CRC. Results 15 patients were treated in the dose escalation cohort and 18 patients were treated in the expansion cohort. Two dose-limiting toxicities were observed. One grade 3 acneiform rash and one grade 4 hypomagnesemia occurred. The most common grade 1 and 2 adverse events included rash, nausea/vomiting, diarrhea, and fatigue. The maximum tolerated dose was established at selumetinib 75 mg PO BID and cetuximab 250 mg/m(2) weekly following a 400 mg/m(2) load. Best clinical response in the dose escalation group included 1 unconfirmed partial response in a patient with CRC and stable disease (SD) in 5 patients (1 squamous cell carcinoma of the tonsil, 1 non-small cell lung cancer, and 3 CRC), and in the KRAS-mutant CRC dose expansion cohort, of the 14 patients who were evaluable for response, 5 patients had SD and 9 patients had progressive disease. Conclusions The combination of selumetinib and cetuximab is safe and well tolerated. Minimal anti-tumor activity was observed in KRAS-mutant refractory metastatic CRC. Further investigations might be warranted in other cancer subtypes.
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Papers by Tim Greten