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Quinta-feira, 23.07.15

New UW-Madison study links two unrelated cancer treatments

 

New UW-Madison study links two unrelated cancer treatments

Published on July 14, 2015 at 5:10 AM 

A new study at the University of Wisconsin-Madison has linked two seemingly unrelated cancer treatments that are both now being tested in clinical trials.

One treatment is a vaccine that targets a structure on the outside of cancer cells, while the other is an altered enzyme that breaks apart RNA and causes the cell to commit suicide. The study was published July 13 in the new journal of the American Chemical Society: ACS Central Science.

The new understanding could help both approaches, says UW-Madison professor of biochemistry Ronald Raines, who has long studied ribonucleases -- enzymes that break apart RNA, a messenger with multiple roles inside the cell. In 1998, he discovered how to alter one ribonuclease to avoid its deactivation in the body. Soon thereafter, he found that the engineered ribonuclease was more toxic to cancer cells than to others.

Raines patented the advance through the Wisconsin Alumni Research Foundation and with UW-Madison chemist Laura Kiessling cofounded Quintessence Biosciences in Madison. They remain shareholders in the firm, which has licensed the patent from WARF and begun early-phase human trials with the ribonuclease at the UW Carbone Cancer Center and MD Anderson Cancer Center in Houston.

The current study began as an effort to figure out why the ribonuclease was selective for cancer cells. To identify which structure on the cell surface helped it enter the cell, Raines screened 264 structures using a specially designed chip. The winner was a carbohydrate called Globo H.

"We were surprised -- delighted -- to see that because we already knew that Globo H is an antigen that is abundant in many tumors," Raines says. Antigens are complex molecules with structures that are recognizable to proteins called antibodies. "Globo H is under development as the basis for a vaccine that will teach the immune system to recognize and kill cancer cells," he says.

Working with Samuel Danishefsky, who solved the difficult problem of synthesizing Globo H at the Memorial Sloan-Kettering Cancer Center in New York, Raines found that reducing the Globo H display on the surface made breast cancer cells less vulnerable to ribonucleases like those that Quintessence is testing. "This was exciting, as we now have a much clearer idea of how our drug candidate is working."

Biochemistry Professor John Markley aided the research with studies of the structure of the molecules in question.

The picture that emerges from the work is of ribonucleases patrolling our bodies, looking for telltales of cancer cells, Raines says. "We are working to demonstrate this surveillance more clearly in mice, but don't have direct evidence yet."

As other scientists test whether using a vaccine will start an immune attack on Globo H, Raines says, "we are probing a different type of immunity. This innate immunity does not involve the immune system. It's a way for our bodies to fight cancer without using white blood cells or antibodies, just an enzyme and a carbohydrate."

Source:

University of Wisconsin-Madison

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por cyto às 22:46

Quinta-feira, 23.07.15

Emory University immunologists identify long-lived antibody-producing cells in bone marrow

 

Emory University immunologists identify long-lived antibody-producing cells in bone marrow

Published on July 16, 2015 at 2:40 AM · 

Immunologists from Emory University have identified a distinct set of long-lived antibody-producing cells in the human bone marrow that function as an immune archive.

The cells keep a catalog of how an adult's immune system responded to infections decades ago in childhood encounters with measles or mumps viruses. The results, published Tuesday, July 14 in , could provide vaccine designers with a goalpost when aiming for long-lasting antibody production.

"If you're developing a vaccine, you want to fill up this compartment with cells that respond to your target antigen," says co-senior author F. Eun-Hyung Lee, MD, assistant professor of medicine at Emory University School of Medicine and director of Emory Healthcare's Asthma, Allergy and Immunology program.

The findings could advance investigation of autoimmune diseases such as lupus erythematosus or rheumatoid arthritis, by better defining the cells that produce auto-reactive antibodies.

Co-senior author of the Immunity paper is Iñaki Sanz, MD, professor of medicine and pediatrics, chief of the Division of Rheumatology, Mason I. Lowance Chair of Allergy and Immunology and a Georgia Research Alliance Eminent Scholar. The research was started when Lee, Sanz and colleagues were investigators at the University of Rochester Medical Center, and continued when they arrived at Emory in 2012. The first author of the paper is Jessica Halliley, MS from Rochester.

As described in part of the Immunity paper, the researchers studied 11 older individuals (aged 43 to 70) who had not been immunized against measles or mumps, but who had antibodies in their blood indicating infection by those viruses in childhood. Measles and mumps vaccines first became available in the 1960s.

Antibodies in the blood have a half-life of just a few weeks, so researchers thought these individuals had long-lived plasma cells, or white blood cells secreting antibodies, dating from the childhood infection.

Examining bone marrow samples obtained from these volunteers, researchers divided plasma cells into four different groups based on the proteins found on their surfaces. Only one group ("subset D", CD19-, CD38high, CD138+) contained the cells that produce antibodies that react with measles or mumps virus.

"I like to call this group of cells the 'historical record' of infection or vaccination," Lee says.

In contrast, cells producing anti-influenza antibodies were found spread across three of the subsets. Because study participants were likely to have been exposed to influenza by annual vaccination or infection more recently than measles or mumps, the researchers inferred that cells specific to recent exposures can reside in multiple subsets while subset D represents the long-lived plasma cells.

In separate experiments, volunteers who were vaccinated against tetanus did have some plasma cells producing anti-tetanus antibodies within three weeks in several subsets, but over time tetanus-specific plasma cells were found in subset D.

The team proved that subset D cells were exclusively responsible for producing the measles- and mumps-specific antibodies in the blood of one of the older volunteers, through proteomics and RNA sequencing techniques.

Compared with other subsets, subset D cells are more quiescent: they displayed less signs of proliferation. In addition, subset D cells have a distinct "fried egg" appearance, containing bubble-like vacuoles or lipid droplets, which are rare in bone marrow cell samples, and a tighter, more condensed nucleus than other white blood cells.

Plasma cells differ from many other cells in the body in that they undergo changes in their DNA -- specifically, their antibody genes. In the patients the researchers examined, antibody genes from subset D are much more diverse than those from other plasma cells. Lee says this finding also reflects subset D's role as an archive, which does not devote too much cellular space to any one vaccination or infection.

Source:

Emory Health Sciences

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por cyto às 22:43

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

Isis Innovation, Ludwig Cancer Research announce launch of new cancer immunotherapy spinout

 

Isis Innovation, Ludwig Cancer Research announce launch of new cancer immunotherapy spinout

Published on July 9, 2015 at 7:30 AM 

Isis Innovation, the University of Oxford's technology commercialisation company, and Ludwig Cancer Research are proud to announce the launch of a new spinout company, iOx Therapeutics. iOx Therapeutics will develop a novel cancer immunotherapy discovered through a collaboration between Ludwig Cancer Research and Professor Vincenzo Cerundolo, the director of the MRC Human Immunology Unit within the University of Oxford's Weatherall Institute of Molecular Medicine.

Since 2003, Professor Cerundolo, supported by funding from Ludwig Cancer Research, has led a research team working in collaboration with Professor Gurdyal Besra and Dr. Liam Cox of the University of Birmingham and Professor Richard Schmidt of the University of Konstanz. This team discovered multiple synthetic lipid compounds, now under development by iOx, which activate iNKT cells. A large body of evidence suggests that iNKT cells play an important role in anti-tumour immune responses and could prove highly effective in combination with other immunotherapies.

"Preclinical studies of our iNKT-activating compounds have been extremely promising," said Professor Cerundolo. "We've been able to show that these molecules can halt the progression of tumours in animal models. I am very excited to see them moving toward the clinic, and gratified that our research could prove to be of benefit to cancer patients."

"The new immune checkpoint inhibitors recently approved by regulatory agencies, such as anti-PD-1 antibodies, sabotage the strategies used by tumour cells to suppress the immune system and so induce potent anti-tumour immune responses in many patients," said Dr. Jonathan Skipper, Ludwig's executive director of technology development. "There is good reason to expect that iOX's iNKT agonists could significantly improve these responses, and we look forward to seeing the results of their clinical evaluation."

The company has discussed plans for a first human trial with the UK Medicines and Healthcare products Regulatory Agency. The trial will be run by Professor Mark Middleton, director of the Oxford Experimental Cancer Medicine Centre at Oxford University Hospitals NHS Trust.

Jim Mellon, an Oxford alumnus, has invested in the company through SalvaRx, an oncology-focused investment vehicle that provides capital and drug development expertise to support emerging technologies and companies.

Isis Innovation Head of Technology Transfer, Life Sciences Dr. Adam Stoten said, "The field of cancer immunotherapy is moving forward with unprecedented momentum and we're delighted to support Professor Cerundolo and his team in their goal of finding new and better cancer treatments."

Source:

Ludwig Institute for Cancer Research

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por cyto às 18:00


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