Transplant drug could boost power of brain tumor treatments, study finds

Drs. Maria Castro and Pedro Lowenstein, both of the U-M Department of Neurosurgery, co-led the research. Credit: Image courtesy of University of Michigan Health System

Every day, organ transplant patients around the world take a drug called rapamycin to keep their immune systems from rejecting their new kidneys and hearts. New research suggests that the same drug could help brain tumor patients by boosting the effect of new immune-based therapies.

In experiments in animals, researchers from the University of Michigan Medical School showed that adding rapamycin to an immunotherapy approach strengthened the immune response against brain tumor cells.

What's more, the drug also increased the immune system's "memory" cells so that they could attack the tumor if it ever reared its head again. The mice and rats in the study that received rapamycin lived longer than those that didn't.

Now, the U-M team plans to add rapamycin to clinical gene therapy and immunotherapy trials to improve the treatment of brain tumors. They currently have a trial under way at the U-M Health System which tests a two-part gene therapy approach in patients with brain tumors called gliomas in an effort to get the immune system to attack the tumor. In future clinical trials, adding rapamycin could increase the therapeutic response.

The new findings, published online in the journal Molecular Cancer Therapeutics, show that combining rapamycin with a gene therapy approach enhanced the animals' ability to summon immune cells called CD8+ T cells to kill tumor cells directly. Due to this cytotoxic effect, the tumors shrank and the animals lived longer.

But the addition of rapamycin to immunotherapy even for a short while also allowed the rodents to develop tumor-specific memory CD8+ T cells that remember the specific "signature" of the glioma tumor cells and attacked them swiftly when a tumor was introduced into the brain again.

"We had some indication that rapamycin would enhance the cytotoxic T cell effect, from previous experiments in both animals and humans showing that the drug produced modest effects by itself," says Maria Castro, Ph.D., senior author of the new paper. Past clinical trials of rapamycin in brain tumors have failed.

"But in combination with immunotherapy, it became a dramatic effect, and enhanced the efficacy of memory T cells too. This highlights the versatility of the immunotherapy approach to glioma." Castro is the R.C. Schneider Collegiate Professor of neurosurgery and a professor of cell and developmental biology at U-M.

Rapamycin is an FDA-approved drug that produces few side effects in transplant patients and others who take it to modify their immune response. So in the future, Castro and her colleagues plan to propose new clinical trials that will add rapamycin to immune gene therapy trials like those already ongoing at UMHS.

She notes that other researchers currently studying immunotherapies for glioma and other brain tumors should also consider doing the same. "This could be a universal mechanism for enhancing efficacy of immunotherapies in glioma," she says.

Rapamycin inhibits a specific molecule in cells, called mTOR. As part of the research, Castro and her colleagues determined that brain tumor cells use the mTOR pathway to hamper the immune response of patients.

This allows the tumor to trick the immune system, so it can continue growing without alerting the body's T cells that a foreign entity is present. Inhibiting mTOR with rapamycin, then, uncloaks the cells and makes them vulnerable to attack.

Castro notes that if the drug proves useful in human patients, it could also be used for long-term prevention of recurrence in patients who have had the bulk of their tumor removed. "This tumor always comes back," she says.

Source: University of Michigan Health System

Understanding, improving body's fight against pathogens

Significant reductions in the number of plasma cells in the spleen and bone marrow were observed in the absence of DOK3. Each dot in the figure represents one plasma cell detected. Credit: Image courtesy of A*Star Agency for Science, Technology and Research

Scientists from A*STAR's Bioprocessing Technology Institute (BTI) have uncovered the crucial role of two signalling molecules, DOK3 and SHP1, in the development and production of plasma cells. These discoveries, published in two journals PNAS and Nature Communications, advance the understanding of plasma cells and the antibody response, and may lead to optimisation of vaccine development and improved treatment for patients with autoimmune diseases such as lupus and tumours such as multiple myeloma.

While they exist in small populations in humans, the large amounts of antibodies secreted by plasma cells make them key to the body's immune system and its ability to defend itself against pathogens, such as bacteria and viruses. Proper maintenance of a pool of plasma cells is also critical for the establishment of lifelong immunity elicited by vaccination.

Dysregulation of plasma cell production and maintenance could lead to autoimmune diseases and multiple myeloma. Autoimmune diseases occur when the immune system does not distinguish between healthy tissue and antigens, which are found in pathogens. This results in expansion of plasma cells which produce excessive amounts of antibodies leading to destruction of one's own healthy tissue. The discoveries by scientists in BTI's Immunology Group have improved understanding of the mechanism by which plasma cells are developed from a major class of white blood cells called B cells.

For the first time, the molecule DOK3 was found to play an important role in formation of plasma cells. While calcium signalling typically controls a wide range of cellular processes that allow cells to adapt to changing environments, it was found to inhibit the expression of the membrane proteins essential for plasma cell formation. These membrane proteins include PDL1 and PDL2, and represent some of the key targets for the development of immunotherapy by pharmaceutical companies. DOK3 was able to promote the production of plasma cells by reducing the effects of calcium signalling on these membrane proteins. The absence of DOK3 would thus result in defective plasma cell formation.

In another study, BTI scientists discovered the importance of SHP1 signalling to the long term survival of plasma cells. While the molecule SHP1 has a proven role in prevention of autoimmune diseases, it was found that the absence of SHP1 would result in the failure of plasma cells to migrate from the spleen where they are generated to the bone marrow, a survival niche where they are able to survive for much longer periods. This could result in a reduction of the body's immune response and thus, an increased susceptibility to infections and diseases. The scientists in this study also successfully rectified the defective immune response caused by an absence of SHP1 by applying antibody injections, which might advance the development of therapeutics. On the other hand, targeting SHP1 might be a strategy to treat multiple myeloma where the accumulation of cancerous plasma cells in the bone marrow survival niches is undesirable.

Findings hold potential for improved treatment

The discovery of these new targets for modulating the antibody response allows the development of novel therapeutic strategies for patients with autoimmune diseases and cancer.Understanding the mechanism that governs plasma cell differentiation is also critical for the optimal design of vaccines and adjuvants, which are added to vaccines to boost the body's immune response.

Prof Lam Kong Peng, Executive Director of BTI, said, "These findings allow better understanding of plasma cells and their role in the immune system. The identification of these targets not only paves the way for development of therapeutics for those with autoimmune diseases and multiple myeloma, but also impacts the development of immunological agents for combating infections."

Source: A*Star Agency for Science, Technology and Research

Special delivery: Hitchhiking microparticles deliver drugs directly

Disc-shaped microparticles use monocytes to get to their destination. Credit: Peter Allen illustration

Inflammation is a normal and often beneficial response to injury or infection. The swelling, heat and even pain are the body's attempts to protect its soft tissue, remove offending objects, substances or microbes and initiate healing. However, persistent inflammation is often indicative of more serious conditions and can lead to problems of its own, including impaired healing, loss of function or even tissue death.

"Many diseases result in inflammation," said Samir Mitragotri, professor of chemical engineering at UC Santa Barbara and director of the campus's Center for Bioengineering. Whether inflammation is a byproduct of the disease or the inflammation is the disease, it is a common indicator of a problem with the system. "If we could target the common denominator, whether the inflammation is coming from cancer or arthritis, we could deliver the drug there," said Mitragotri, who specializes in targeted drug delivery.

By taking advantage of natural body processes, researchers at UC Santa Barbara and MIT have developed a method of targeting inflamed tissues, creating a way to treat both the inflammation and its underlying cause.

"It's a cell-mediated approach to targeted drug delivery," said UCSB grad student researcher Aaron Anselmo, lead author of a study in the current issue of the Journal of Controlled Release.

Key to this technology is the utilization of monocytes, the type of white blood cell known for its ability to penetrate into deep sections of tissue. Under normal circumstances, the job of these monocytes is to circulate in the blood and respond to biochemical signals that indicate inflammation -- a sign of injury or infection. Once at the site, these monocytes transform into macrophages, cells that reside in the affected tissues to engulf and digest foreign material.

Working with the expertise of chemical engineering and materials science researchers at MIT, including graduate researcher Jonathan Gilbert and professors Robert Cohen and Michael Rubner, the UCSB researchers developed an approach based on "cellular backpacks" -- flat, disc-shaped polymeric particles that could, in the near future, hold therapeutic agents that can be released at the site of the inflammation. These polymeric discs are coated on one side with a single layer of an antibody that can bind to receptors on the monocyte's surface.

To prevent the cellular backpack from being engulfed and devoured by the very cell that is transporting it, the researchers chose a flexible particle that is nonspherical in shape, which, according to the study, has proved to be more durable and resistant to phagocytosis than a rigid spherical particle. The shape and flexibility gives the backpack the ability to bind strongly while resisting phagocytosis to hitchhike onto monocytes and reach the inflamed tissue.

In-vitro and in-vivo tests have proved that cellular backpacks are successful in attaching to and being transported by monocytes to target areas without impairing the monocytes' natural functions, said Anselmo. Further studies will include research into how much drug can be loaded into the cellular backpacks. Ideally, Anselmo said, the cellular backpacks loaded with drugs would be injected into the bloodstream, whereupon they would attach to these traveling monocytes and hitchhike to the target region. At the inflamed site, the particles would simultaneously degrade and release their drugs.

The development of effective cellular backpacks has broad potential, say the researchers.
"Basically the main benefit is that you can deliver the drug in a more effective dose," Mitragotri said. Take for example the case of chemotherapy, which often has a narrow therapeutic range: Too little and the treatment is not effective, too much and it can be lethal. 
Because chemo travels through the bloodstream and affects all the tissues it comes in contact with, dosages are restricted at least in part based on the deleterious effect it has on other, unafflicted organs and their functions. Not only can targeted therapy ensure other body systems remain unaffected, Mitragotri explained, but it could allow for higher doses of drug to the site, which could decrease treatment time.

Source: University of California - Santa Barbara

Using power of computers to harness human genome may provide clues into Ebola virus

Ramaswamy Narayanan, Ph.D., professor in the Charles E. Schmidt College of Science at Florida Atlantic University.

Ramaswamy Narayanan, Ph.D., professor in the Charles E. Schmidt College of Science at Florida Atlantic University, is working to blend the power of computers with biology to use the human genome to remove much of the guesswork involved in discovering cures for diseases.

In an article titled "Ebola-Associated Genes in the Human Genome: Implications for Novel Targets," published in the current MedCrave Online Journal of Proteomics and Bioinformatics, Narayanan describes how key genes that are present in our cells could be used to develop drugs for this disease.

"Bioinformatics is a powerful tool to help us understand biological data," said Narayanan whose research has focused in this field for more than a decade. "We are mining the human genome for Ebola virus association to develop an understanding of the human proteins involved in this disease for subsequent research and development, and to potentially create a pipeline of targets that we can test and evaluate."

Ebola virus disease is a major healthcare challenge facing the globe today and if left unchecked could become a pandemic. A limited knowledgebase exists about the Ebola virus and companies are hastening to develop vaccines and other forms to treat and cure the virus. There are no FDA-approved drugs, and developing vaccines or antibodies and testing them in clinical trials is an arduous process that takes considerable time. Currently, patients infected with Ebola are only able to receive supportive care such as fluid replacement, nutritional support, pain control, and blood pressure maintenance. In some cases, patients may be fortunate enough to be treated with experimental drugs.

Narayanan's work has helped to identify numerous FDA-approved drugs already used for many other diseases including anti-inflammatory drugs, anticoagulants, cancer, HIV, statins and hormones, which could potentially be used to add to the current supportive care for patients with the Ebola virus.

"With the high mortality rate of this disease, the world urgently needs new ways to treat patients," said Narayanan. "The ability to use drugs that are already approved by the FDA could provide clinicians with more options to treat Ebola patients, rather than just relying on supportive measures like fluid replacement or antibiotics."

According to the World Health Organization (WHO), Ebola virus disease (EVD) is a severe, often fatal illness in humans. The virus is transmitted to people from wild animals and spreads in the human population through human-to-human transmissions. The evolving knowledge of this disease is prompting appropriate attention locally and globally. The 2014 Ebola epidemic has affected multiple countries in West Africa with some cases observed in Europe and the United States.

Source: Florida Atlantic University

Promising compound rapidly eliminates malaria parasite

A new report says that the rapid action of (+)-SJ733 will likely slow malaria drug resistance. Credit: Peter Barta, St. Jude Children's Research Hospital

An international research collaborative has determined that a promising anti-malarial compound tricks the immune system to rapidly destroy red blood cells infected with the malaria parasite but leave healthy cells unharmed. St. Jude Children's Research Hospital scientists led the study, which appears in the current online early edition of the Proceedings of the National Academy of Sciences (PNAS).

The compound, (+)-SJ733, was developed from a molecule identified in a previous St. Jude-led study that helped to jumpstart worldwide anti-malarial drug development efforts. Malaria is caused by a parasite spread through the bite of an infected mosquito. The disease remains a major health threat to more than half the world's population, particularly children. The World Health Organization estimates that in Africa a child dies of malaria every minute.

In this study, researchers determined that (+)-SJ733 uses a novel mechanism to kill the parasite by recruiting the immune system to eliminate malaria-infected red blood cells. In a mouse model of malaria, a single dose of (+)-SJ733 killed 80 percent of malaria parasites within 24 hours. After 48 hours the parasite was undetectable.

Planning has begun for safety trials of the compound in healthy adults.

Laboratory evidence suggests that the compound's speed and mode of action work together to slow and suppress development of drug-resistant parasites. Drug resistance has long undermined efforts to treat and block malaria transmission.

"Our goal is to develop an affordable, fast-acting combination therapy that cures malaria with a single dose," said corresponding author R. Kiplin Guy, Ph.D., chair of the St. Jude Department of Chemical Biology and Therapeutics. "These results indicate that SJ733 and other compounds that act in a similar fashion are highly attractive additions to the global malaria eradication campaign, which would mean so much for the world's children, who are central to the mission of St. Jude."

Whole genome sequencing of the Plasmodium falciparum, the deadliest of the malaria parasites, revealed that (+)-SJ733 disrupted activity of the ATP4 protein in the parasites. The protein functions as a pump that the parasites depend on to maintain the proper sodium balance by removing excess sodium.

The sequencing effort was led by co-author Joseph DeRisi, Ph.D., a Howard Hughes Medical Institute investigator and chair of the University of California, San Francisco Department of Biochemistry and Biophysics. Investigators used the laboratory technique to determine the makeup of the DNA molecule in different strains of the malaria parasite.

Researchers showed that inhibiting ATP4 triggered a series of changes in malaria-infected red blood cells that marked them for destruction by the immune system. The infected cells changed shape and shrank in size. They also became more rigid and exhibited other alterations typical of aging red blood cells. The immune system responded using the same mechanism the body relies on to rid itself of aging red blood cells.

Another promising class of antimalarial compounds triggered the same changes in red blood cells infected with the malaria parasite, researchers reported. The drugs, called spiroindolones, also target the ATP4 protein. The drugs include NITD246, which is already in clinical trials for treatment of malaria. Those trials involve investigators at other institutions.

"The data suggest that compounds targeting ATP4 induce physical changes in the infected red blood cells that allow the immune system or erythrocyte quality control mechanisms to recognize and rapidly eliminate infected cells," DeRisi said. "This rapid clearance response depends on the presence of both the parasite and the investigational drug. That is important because it leaves uninfected red blood cells, also known as erythrocytes, unharmed."

Laboratory evidence also suggests that the mechanism will slow and suppress development of drug-resistant strains of the parasite, researchers said.

Planning has begun to move (+)-SJ733 from the laboratory into the clinic beginning with a safety study of the drug in healthy adults. The drug development effort is being led by a consortium that includes scientists at St. Jude, the Swiss-based non-profit Medicines for Malaria Venture and Eisai Co., a Japanese pharmaceutical company.

Source: St. Jude Children's Research Hospital