Study Will Test Transplantation Of Gene-Modified Cells To Explore A Potential Cure For HIV Infection


Whether a stem cell transplant using an HIV-infected person's own genetically modified immune cells can become a cure for the disease is the focus of a new $20 million, five-year research grant award announced today by the National Institutes of Health to Fred Hutchinson Cancer Research Center.

Hutchinson Center researchers will use the grant to lead a multifaceted team of scientists and institutions to study whether a person's own stem cells can be engineered to deny HIV entry into the body's blood cells. The researchers also will work to develop tools to eradicate existing reservoirs of infection in the body.

"Funding for research to find a cure for HIV-infected persons represents a paradigm shift," said Keith Jerome, M.D., Ph.D., an expert in viral infections and co-principal investigator of the grant. "HIV has been an incurable, lifelong infection that at best sentences people to a lifetime of complex drug therapies. Now the research field is shifting to address the possibility of a cure. No one would have talked about this approach five years ago."

Jerome is an associate member of the Hutchinson Center's Vaccine and Infectious Disease Division. The other co-principal investigator is stem cell transplant researcher Hans-Peter Kiem, M.D., a member of the Hutchinson Center's Clinical Research Division and recipient of the Center's Jose Carreras/E. Donnall Thomas Endowed Chair for Cancer Research.

"I am particularly excited that we can explore stem cell-based therapies for the cure of HIV," Kiem said. "It is a perfect fit for our institution, which has such a unique history of pioneering stem cell transplantation and research in HIV."

The Hutchinson Center grant was one of three announced today by the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, to fund research focused on developing strategies for eradicating HIV infection via its Martin Delaney Collaboratory program.

"I applaud the NIAID's efforts to open up new areas of research funding to find a potential cure for HIV," said Larry Corey, M.D., president and director of the Hutchinson Center. "The work to be done in this grant is groundbreaking and the kind of public/private collaboration that is needed to move the science forward."

The research projects will focus on ways around a major obstacle to long-term control and cure of HIV: the persistence of HIV provirus in reservoirs throughout the bodies of infected persons. The infected cells in these reservoirs are long lived and remain a threat during the lifespan of infected persons. Highly active antiretroviral therapy (HAART), although successful at keeping the spread of HIV under control by inhibiting viral replication, does not eliminate these reservoirs. If a patient discontinues HAART, the virus rebounds.

One approach under investigation is autologous stem cell transplantation, in which the infected patient's own immune cells are genetically modified to be resistant to HIV by eliminating one of the receptors, called CCR5, which HIV needs to infect new cells. This method builds on the Hutchinson Center's long-standing expertise in using transplantation to treat and cure blood cancers and some autoimmune diseases, a Nobel Prize-winning accomplishment that has boosted survival rates from nearly zero to 90 percent for certain types of leukemia.

Stem cell transplantation to eliminate HIV infection has one intriguing precedent.

In 2008, a group of German physicians published results of transplanting an American man who had acute myeloid leukemia and HIV. The so-called "Berlin patient" received a new immune system from donor cells that also carried a rare genetic variation that made them resistant to HIV. The man was able to stop HAART and the virus remained undetectable. However, few stem cell donors have this genetic mutation, so a way must be found to modify the patient's own immune cells to be HIV resistant in order for such a transplant to be more widely available.

A second approach to be studied involves developing DNA-targeting proteins to directly attack the reservoirs of HIV provirus without harming the infected cells themselves. This method would complement the stem cell-based approach and could potentially lead to elimination of the HIV provirus.

In addition to better understanding the biology and virology of gene-modified cells, another goal will be to optimize the combination of stem cell protection and HIV reservoir-purging techniques. Researchers expect to have enough data to begin human clinical trials in five years.

The team of scientists and institutions that will conduct the studies includes Sangamo Biosciences of Richmond, Calif., Beckman Research Institute at City of Hope in Duarte, Calif., the University of Washington and Seattle Children's.

Source:
Dean Forbes
Fred Hutchinson Cancer Research Center


The Complexity Of Glue Molecule's Role In Cancer Revealed By Stem Cell Study


A protein molecule that 'glues' cells together and so has a key role in cancer is also responsible for many other important functions of cells, a new study has found.

University of Manchester scientists say their unexpected findings are important because they could lead to a better understanding of why some cancer cells are difficult to eradicate in patients and lead to new cancer treatments.

The research - published in PLoS One - looked at the role of the cell-adhesion molecule E-cadherin in embryonic stem (ES) cells. As well as the expected findings associated with changes in adhesion, the team found that the protein may also regulate up to 25% of the genes within cells.

"E-cadherin is a 'glue' that keeps cells together in the body - without it we would not develop beyond a bundle of cells a few days after conception," said Dr Chris Ward, who led the study in the University's School of Dentistry.

"E-cadherin is also important during cancer progression from benign to malignant states, with loss of this molecule leading to increased movement of the cells which can lead to secondary tumours within the body.

"Whilst E-cadherin has been studied intensively there has been no research that has identified all of the genes that E-cadherin regulates. Our lab has carried out profiling of ES cells lacking E-cadherin and found this protein is responsible for regulating up to 25% of the genes within cells.

"As well as the expected findings associated with changes in cell adhesion, we found that E-cadherin exerts an effect on a diverse range of biological functions within the cell. This unexpected result demonstrates that E-cadherin, often viewed as no more than a cell 'glue', is an important part of regulating the biology of ES cells."

The group found that E-cadherin regulates genes associated with, amongst other things, cell proliferation, cell death, metabolism of fats and sugars and the deciphering of messages received by cells from outside.

Since loss of E-cadherin is implicated in higher death rates in cancer patients and a more aggressive tumour type, the group has suggested that this molecule may have a much more important role to play in preventing tumour development.

Dr Ward added: "Essentially, abnormal regulation of E-cadherin can lead to a significant change in a cell and this may be one of the reasons why such cells are difficult to eradicate in cancer patients. Further investigation of specific changes in these cells may lead to the development of novel treatments for cancer."

Source:
Aeron Haworth
University of Manchester


Study Reveals Cancer Stem Cells Recruit Normal Stem Cells To Fuel Ovarian Cancer



Researchers at the University of Michigan Comprehensive Cancer Center have found that a type of normal stem cell fuels ovarian cancer by encouraging cancer stem cells to grow.

Cancer stem cells are the small number of cells in a tumor that drive its growth and spread. Traditional cancer treatments do not kill these cells, which is why cancer treatments often fail.

In a study published online in the Journal of Clinical Investigation, researchers looked in ovarian tissue at the mesenchymal stem cells, which are normal cells found throughout the body. These cells can form different specialized cells such as fat, bone or cartilage.

Mesenchymal stem cells are known to be helpful with wound healing, which has many scientists conjecturing that they may help combat cancer. In this study, the researchers observed that mesenchymal stem cells in ovarian tumors were different than mesenchymal stem cells from healthy ovaries. And in fact, the mesenchymal stem cells in the ovarian tumors were fueling the cancer.

"Cancer is very good at tricking the mesenchymal stem cells into doing what the cancer likes. The cancer takes the cells hostage and uses them to promote the cancer's growth," says study author Ronald Buckanovich, M.D., Ph.D., assistant professor of internal medicine and of obstetrics and gynecology at the U-M Medical School.

The researchers used mouse models and human tissue samples of both normal ovaries and ovarian cancer, to look at what happened to the mesenchymal stem cells. They also noticed the cancer-associated mesenchymal stem cells increased tumor size, primarily by increasing the number of cancer stem cells.

At the same time, the researchers saw that a type of protein called BMP2 was prevalent in the cancer-associated mesenchymal stem cells. BMP2 is a so-called master regulatory protein, and is carefully regulated in normal cell function. The researchers found more than three times the amount of BMP in the cancer-associated mesenchymal stem cells than in the normal ones. When BMP was added to cancer cells, it led to an increase in cancer stem cells.

The researchers then used a known BMP inhibitor called Noggin, and found that Noggin blocked the mesenchymal stem cells from triggering this cancer stem cell growth.

"High doses of Noggin might not be tolerated in humans," Buckanovich says. "Our next step is to figure out how to target Noggin directly to the vascular niche where the mesenchymal stem cells and cancer stem cells live. This would allow us to make it safer to use Noggin as a potential treatment for ovarian cancer."

This research must continue in the laboratory before it can be advanced to clinical trials in patients. In the meantime, the U-M Comprehensive Cancer Center expects to open two new clinical trials within the next year testing other therapies aimed at attacking ovarian cancer stem cells. For information, contact the Cancer AnswerLine at 800-865-1125.

Notes:

Ovarian cancer statistics: 21,880 Americans will be diagnosed with ovarian cancer this year and 13,850 will die from the disease, according to the American Cancer Society

Additional authors: Karen McLean, Yusong Gong, Junjung Choi, Ning Deng, Kun Yang, Shoumei Bai, Lourdes Cabrera, Evan Keller, Laurie McCauley and Kathleen R. Cho, all from U-M

Funding: Damon Runyon Cancer Research Foundation, National Institutes of Health

Disclosure: None

Reference: Journal of Clinical Investigation, doi:10.1172/JCI45273

Source:
Nicole Fawcett
University of Michigan Health System


 

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