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Espaço de publicação e discussão sobre oncologia. GBM IMMUNOTHERAPY ONCO-VIRUS ONCOLOGY CANCER CHEMOTHERAPY RADIOTHERAPY


Terça-feira, 21.07.15

Scientists elucidate which mechanisms block natural killer cells and how this could be lifted

 

Scientists elucidate which mechanisms block natural killer cells and how this could be lifted

Published on July 8, 2015 at 12:00 PM 

Natural killer cells of the immune system can fend off malignant lymphoma cells and thus are considered a promising therapeutic approach. However, in the direct vicinity of the tumor they lose their effect. Scientists of Helmholtz Zentrum München have now elucidated which mechanisms block the natural killer cells and how this blockade could be lifted. The results were recently published in the European Journal of Immunology.

Natural killer cells (NK cells) are part of the immune system and provide an innate immunity against exogenous and altered endogenous structures. This also appears to apply to tumor cells, against which the body could develop immunity as it does against pathogens, e.g. against viruses. Tumors of the lymph nodes, called lymphomas, are malignant neoplasms that originate from the B cells or T cells of the lymphatic system. B cell lymphomas are very difficult to treat - which is why innovative approaches to therapy are needed. Earlier studies have shown that NK cells have the potential to attack B lymphoma cells and are therefore considered a possible approach to new treatment strategies. In the living organism, however, tumor control by NK cells has been found to be clearly limited.

NK cells become functionally impaired in the tumor microenvironment

In their experiments, the team led by Prof. Dr. Ralph Mocikat of the Institute of Molecular Immunology (IMI) at Helmholtz Zentrum München, found that the NK cells in the immediate vicinity of the tumor showed reduced function. If the cells were placed in a normal environment, their function could be restored within a few hours. This suggests that the factors responsible for the inactivation of the NK cells derive from the tumor itself.

An inflammatory cytokine inactivates NK cells - altered surface molecules block immune activation

The scientists engaged in the research project identified two important tumor-specific factors that are associated with impaired NK cell function. First, a specific inflammatory cytokine (IL-10) is indirectly involved in the inactivation of NK cells. Second, the tumor cells develop protective mechanisms against the NK cells. Thus, the research group showed that specific surface molecules of the tumor cells (NKG2D ligands) which NK cells could bind are down-regulated. Consequently, the NK cells lack an important activation mechanism and are no longer able to carry out cytotoxic activity. Despite the inhibitory strategies of the tumor cells, at an early stage the NK cells produce the cytokine interferon-gamma (IFN-γ), the scientists reported. IFN-γ is essential to activate further immune responses that support the fight against the tumor.

Immunotherapy possible using NK cells - with optimization potential

"Our results show that the transfer of NK cells is a possible strategic option to treat B cell lymphoma. According to our findings, this therapeutic approach can be optimized when transferred NK cells are already activated in vitro prior to their injection, thus bypassing the missing activation potential in the tumor microenvironment. An additional injection of IFN-γ or of antibodies against IL-10 could further support the immune activity," said study leader Mocikat.

Source:

Helmholtz Zentrum München - German Research Center for Environmental Health

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por cyto às 18:20

Terça-feira, 21.07.15

Patients' own genetically engineered immune cells show significant success against multiple myeloma

 

Patients' own genetically engineered immune cells show significant success against multiple myeloma

Published on July 21, 2015 at 2:37 AM 

In recent years, immunotherapy has emerged as a promising treatment for certain cancers. Now this strategy, which uses patients' own immune cells, genetically engineered to target tumors, has shown significant success against multiple myeloma, a cancer of the plasma cells that is largely incurable. The results appeared in a study published online today in Nature Medicine.

Patients received an infusion of altered immune cells known as T-cells - roughly 2.4 billion of them - after undergoing a stem cell transplantation of their own stem cells. In 16 of 20 patients with advanced disease, there was a significant clinical response. The scientists found that the T-cell therapy was generally well-tolerated and that modified immune cells traveled to the bone marrow, where myeloma tumors typically are found, and showed a long-term ability to fight the tumors. Relapse was generally associated with a loss of the engineered T-cells.

"This study suggests that treatment with engineered T-cells is not only safe but of potential clinical benefit to patients with certain types of aggressive multiple myeloma," says first author Aaron P. Rapoport, MD, the Gary Jobson Professor in Medical Oncology at the University of Maryland School of Medicine. "Our findings provide a strong foundation for further research in the field of cellular immunotherapy for myeloma to help achieve even better results for our patients."

The trial is the first published use of genetically modified T-cells for treating patients with multiple myeloma. The approach has been used to treat leukemia as well as lymphoma, according to Dr. Rapoport, who is the Director of the Blood and Marrow Transplant Program at the University of Maryland Marlene and Stewart Greenebaum Cancer Center.

More than 77,000 people in the United States have multiple myeloma, with about 24,000 new cases diagnosed each year. Patients are treated with chemotherapy and in many cases an autologous stem cell transplant, but long-term response rates are low, and median survival is three to five years.

"The majority of patients who participated in this trial had a meaningful degree of clinical benefit," Dr. Rapoport notes. "Even patients who later relapsed after achieving a complete response to treatment or didn't have a complete response had periods of disease control that I believe they would not have otherwise experienced. Some patients are still in remission after nearly three years."

The research is a collaboration between the University of Maryland School of Medicine, the Perelman School of Medicine at the University of Pennsylvania and Adaptimmune, a clinical stage biopharmaceutical company which owns the core T-cell receptor technology and funded the study. Dr. Rapoport and co-authors Edward A. Stadtmauer, MD, of the University of Pennsylvania Abramson Cancer Center, and Gwendolyn K. Binder-Scholl, PhD, of Adaptimmune, contributed equally to the research. Dr. Rapoport is the study's principal investigator.

In the clinical study, patients' T-cells were engineered to express an affinity-enhanced T-cell receptor (TCR) specific for a type of tumor antigen, or protein, known as a cancer-testis antigen (CT antigen). The target CT antigens were NY-ESO-1 and LAGE-1. Up to 60 percent of advanced myelomas have been reported to express NY-ESO-1 and/or LAGE-1, which correlates to tumor proliferation and poorer outcomes. According to Adaptimmune, the trial is the first published study of lentiviral vector mediated TCR gene expression in humans.

Of the 20 patients treated, 14 (70 percent) had a near complete or complete response three months after treatment. Median progression-free survival was 19.1 months and overall survival was 32.1 months. Two patients had a very good partial response three months post treatment. Half the patients were treated at the University of Maryland Greenebaum Cancer Center and half at the University of Pennsylvania Abramson Cancer Center. Researchers note that the response rate was better than would be expected for a standard autologous stem cell transplant. In addition, patients did not experience side effects which have been associated with another type of genetically engineered T-cells (chimeric antigen receptors, or CARS) used to treat other cancers.

The study was originally developed by Carl H. June, MD, of the University of Pennsylvania Abramson Cancer Center, and Dr. Rapoport, who have been research collaborators for 18 years.

"Multiple myeloma is a treatable but largely incurable cancer. This study reveals the promise that immunotherapy with genetically engineered T-cells holds for boosting the body's ability to attack the cancer and provide patients with better treatments and control of their disease," says E. Albert Reece, MD., PhD, MBA, vice president for medical affairs at the University of Maryland and the John Z. and Akiko K. Bowers Distinguished Professor and dean of the University of Maryland School of Medicine. "This trial is also an excellent example of significant scientific advances that result from collaborations between academic medical institutions and private industry."

Source:

University of Maryland Medical Center

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por cyto às 18:10


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