Image courtesy St. Jude Children’s Research Hospital
A recent study led by John Hopkins Medicine has found that combining two ‘old therapies’ can offer a surprising new purpose – fighting Medulloblastoma, the most common malignant brain tumor in children. The fast-growing cancerous tumor originates in the brain or spinal cord and has traditionally been treated with surgery to remove the tumor followed by radiation and chemotherapy.
The prospective therapy which comprises of copper ions and Disulfiram (DSF-Cu++), paves the way toward a successful treatment that can be used alone or in conjunction with traditional therapy. “Disulfiram, [is] a medication that’s been used for nearly 70 years to treat chronic alcoholism,” explains Betty Tyler, the study’s senior author and associate professor of neurosurgery at Johns Hopkins. “It has great promise being ‘repurposed’ as an anticancer agent, especially when it is complexed with metal ions such as copper.”
The researchers tested the anticancer activity of DSF-Cu++ and, in their attempts to define what it targeted at the molecular level to achieve these effects, were able to highlight four key findings.
First, the team of researchers found that DSF-Cu++ blocks two biological pathways in medulloblastomas that the cancer cells need in order to remove proteins threatening their survival. With these pathways blocked, these proteins accumulate in the tumor and cause the malignant cells to die, leaving them to eventually be removed by the body’s own immune system.
Second, the researchers discovered that just a few hours of exposure to DSF-Cu++ not only kills medulloblastoma cells but can also effectively reduce the cancer stem cells responsible for their creation.
The third finding in the study revealed that DSF-CU++ keeps cancer cells from recovering. By impairing the ability of medulloblastoma cells to repair the damage done to their DNA, DSF-CU++ enhances the cell killing power of the treatment.
Lastly, the promising combo of DSF-CU++ demonstrated significant increases in prolonging survival days of mice whose brains were implanted with two subtypes of medulloblastoma.
Dr. Tariq Rana (left) and Dr. Jeremy Rich (right) both lead independent teams at UC San Diego that identified a molecule, αvβ5 integrin, as the Zika virus’ key to getting into brain stem cells
Zika virus is caused by a virus transmitted by Aedes mosquitoes. People usually develop mild symptoms that include fever, rash, and muscle and joint pain. However, Zika virus infection during pregnancy can lead to much more serious problems. The virus causes infants to be born with microcephaly, a condition in which the brain does not develop properly, resulting in an abnormally small head. In 2015-2016, the rapid spread of the virus was observed in Latin America and the Caribbean, increasing the urgency of understanding how the virus affected brain development.
Working independently, Dr. Tariq Rana and Dr. Jeremy Rich from UC San Diego identified the same molecule, αvβ5 integrin, as the Zika virus’ key to entering brain stem cells. The two studies, with the aid of CIRM funding, discovered how to take advantage of the molecule in order to block the Zika virus from infecting cells. In addition to this, they were able to turn it into something useful: a way to destroy brain cancer stem cells.
In the first study, Dr. Rana and his team used CRISPR gene editing on brain cancer stem cells to delete individual genes, which was done to see which genes are required for the Zika virus to enter the cells. They discovered that the gene responsible for αvβ5 integrin also enabled the Zika virus.
In a press release by UC San Diego, Dr. Rana elaborates on the importance of his findings.
“…we found Zika uses αvβ5, which is unique. When we further examined αvβ5 expression in brain, it made perfect sense because αvβ5 is the only integrin member enriched in neural stem cells, which Zika preferentially infects. Therefore, we believe that αvβ5 is the key contributor to Zika’s ability to infect brain cells.”
In the second study, Dr. Rich and his team use an antibody to block αvβ5 integrin and found that it prevented the virus from infecting brain cancer stem cells and normal brain stem cells. The team then went on to block αvβ5 integrin in a mouse model for glioblastoma, an aggressive type of brain tumor, by using an antibody or deactivating the gene responsible for the molecule. Both approaches blocked Zika virus infection and allowed the treated mice to live longer than untreated mice.
Dr. Rich then partnered with Dr. Alysson Muotri at UC San Diego to transplant glioblastoma tumors into laboratory “mini-brains” that can be used for drug discovery. The researchers discovered that Zika virus selectively eliminates glioblastoma stem cells from the mini-brains. Additionally, blocking αvβ5 integrin reversed that anti-cancer activity, further demonstrating the molecule’s crucial role in Zika virus’ ability to destroy cells.
In the same UC San Diego press release, Dr. Rich talks about how understanding Zika virus could help in treating glioblastoma.
“While we would likely need to modify the normal Zika virus to make it safer to treat brain tumors, we may also be able to take advantage of the mechanisms the virus uses to destroy cells to improve the way we treat glioblastoma.”
Dr. Rana’s full study was published in Cell Reports and Dr. Rich’s full study was published in Cell Stem Cell.
Glioblastoma is an aggressive form of cancer that invades brain tissue, making it extremely difficult to treat. Current therapies involving radiation and chemotherapy are effective in destroying the bulk of brain cancer cells, but they are not able to reach the brain cancer stem cells, which have the ability to grow and multiply indefinitely. These cancer stem cells enable the glioblastoma to continuously grow even after treatment, which leads to recurring tumor formation.
Dr. Jeremy Rich and his team at UC San Diego examined glioblastomas further by obtaining glioblastoma tumor samples donated by patients that underwent surgery and implanting these into mice. Dr. Rich and his team tested a combinational treatment that included a targeted cancer therapy alongside a drug named teriflunomide, which is used to treatment patients with multiple sclerosis. The research team found that this approach successfully halted the growth of glioblastoma stem cells, shrank the tumor size, and improved survival in the mice.
In order to continue replicating, glioblastoma stem cells make pyrimidine, one of the compounds that make up DNA. Dr. Rich and his team noticed that higher rates of pyrimidine were associated with poor survival rates in glioblastoma patients. Teriflunomide works by blocking an enzyme that is necessary to make pyrmidine, therefore inhibiting glioblastoma stem cell replication.
In a press release, Dr. Rich talks about the potential these findings hold by stating that,
“We’re excited about these results, especially because we’re talking about a drug that’s already known to be safe in humans.”
However, he comments on the need to evaluate this approach further by saying that,
“This laboratory model isn’t perfect — yes it uses human patient samples, yet it still lacks the context a glioblastoma would have in the human body, such as interaction with the immune system, which we know plays an important role in determining tumor growth and survival. Before this drug could become available to patients with glioblastoma, human clinical trials would be necessary to support its safety and efficacy.”
The full results to this study were published in Science Translational Medicine.
How often do you get to ask an expert a question about something that matters deeply to you and get an answer right away? Not very often I’m guessing. That’s why CIRM’s Facebook Live “Ask the Stem Cell Team About Patient Advocacy” gives you a chance to do just that this Thursday, March 14th from noon till 1pm PST.
We have three amazing individuals who will share their experiences, their expertise and advice as Patient Advocates, and answer your questions about how to be an effective advocate for your cause.
The three are:
Gigi McMillan became a Patient Advocate when her 5-year-old son was diagnosed with a brain tumor. That led her to helping develop support systems for families going through the same ordeal, to help researchers develop appropriate consent processes and to campaign for the rights of children and their families in research.
Adrienne Shapiro comes from a family with a long history of Sickle Cell Disease (SCD) and has fought to help people with SCD have access to compassionate care. She is the co-founder of Axis Advocacy, an organization dedicated to raising awareness about SCD and support for those with it. In addition she is now on the FDA’s Patient Engagement Collaborative, a new group helping the FDA ensure the voice of the patient is heard at the highest levels.
David Higgins is a CIRM Board member and a Patient Advocate for Parkinson’s Disease. David has a family history of the disease and in 2011 was diagnosed with Parkinson’s. As a scientist and advocate he has championed research into the disease and worked to raise greater awareness about the needs of people with Parkinson’s.
Also, make sure to “like” our FaceBook page before the event to receive a notification when we’ve gone live for this and future events. If you miss the broadcast, not to worry. We’ll be posting it on our Facebook video page, our website, and YouTube channel shortly afterwards.
We want to answer your most pressing questions, so please email them directly to us beforehand at info@cirm.ca.gov.
And, of course, feel free to share this information with anyone you think might be interested.
Imagine sitting in the doctor’s office and being told the heartbreaking news that your child has been diagnosed with a malignant brain tumor. As one might expect, the doctor states that the most effective treatment option is typically a combination of chemotherapy and radiation. However, the doctor reveals that there are additional risks to take into account that apply to children. Since children’s tiny bodies are still growing and developing, chemotherapy and radiation can cause long-term side effects such as intellectual disabilities. As a parent, it is painful enough to have to watch a child go through chemotherapy and radiation without adding permanent damage into the fold.
Sadly, this scenario is not unique. Medulloblastoma is the most prevalent form of a pediatric brain tumor with more than 350 children diagnosed with cancer each year. There are four distinct subtypes of medulloblastoma, with the deadliest being known as Group 3.
Researchers at Sanford Burnham Prebys Medical Discovery Institute (SBP) are trying to minimize the collateral damage by finding personalized treatments that reduce side effects while remaining effective. Scientists at SBP are working with an inhibitor known as LSD1 that specifically targets Group 3 medulloblastoma in a mouse model. The study, published in Nature Communications, showed that the drug dramatically decreased the size of tumors grown under the mouse’s skin by shrinking the cancer by more than 80 percent. This suggested that it could also be effective against patients’ tumors if it could be delivered to the brain. The LSD1 inhibitor has shown promise in clinical trials, where it has been tested for treating other types of cancer.
According to Robert Wechsler-Reya, Ph.D., senior author of the paper and director of the Tumor Initiation and Maintenance Program at SBP: “Our lab is working to understand the genetic pathways that drive medulloblastoma so we can find better ways to intervene and treat tumors. This study shows that a personalized treatment based upon a patient’s specific tumor type might be within our reach.”
Dr. Wechsler-Reya’s work on medulloblastoma was, in part, funded by the CIRM (LA1-01747) in the form of a Research Leadership Award for $5,226,049.
Glioblastoma, a form of brain cancer, is one of the most dreaded cancer diagnoses. Standard radiation and chemotherapy treatments for glioblastoma almost always prove ineffective because of the cancer’s ability to grow back. With their unlimited potential to self-renew, cancer stem cells within the brain tumor are thought to be responsible for its aggressive reoccurrence. Not surprisingly, researchers looking to develop more effective therapies are focused on trying to better understand the biology of these cancer stem cells in order to exploit their vulnerabilities.
MRI image of high grade glioma brain tumor (white mass on left). Image: Wikipedia
This week, the Dartmouth-Hitchcock Medical Center reports that a research team led by Damian A. Almiron Bonnin has identified a cell signal that the brain cancer stem cells rely on to resist standard treatments and to regrow. They also showed that drugs which interrupt this signal reduced tumor growth in animal studies.
Because if its aggressive growth, the cells within the glioblastoma eventually become starved for oxygen or, in scientific lingo, they become hypoxic. The presence of hypoxia in brain tumors is actually predictive of a poor prognosis in affected patients. A protein called hypoxia-inducible factor (HIF) becomes activated in these low oxygen conditions and helps the cancer stem cells to survive and continue to grow. The research team found that HIF carries out this function by triggering a cascade of cell activity that leads to the secretion of a protein called VEGF out into the microenvironment of the tumor. As secreted VEGF spreads through the tumor, it stimulates new blood vessel growth which is key to the tumor’s survival by nourishing the tumor with oxygen and nutrients.
Adding drugs that block a cell’s ability to release proteins, led to a reduction in glioblastoma tumor growth both in petri dishes and in animal studies. With these results, published in Oncogene, Dr. Almiron Bonnin’s team is performing the necessary preclinical studies that could lead to testing this novel strategy in patients. He summed this effort in a press release:
Damian Almiron Bonnin
“Being able to target the cancer stem cells within these tumors, like we did here, could potentially improve response to current chemotherapies and prevent recurrences, which would translate into an increase in patient survival rates.”
CIRM’s 2017 Annual Report will be going live online very soon. In anticipation of that we are highlighting some of the key elements from the report here on the Stem Cellar.
One of the most exciting new approaches in targeting deadly cancers is chimeric antigen receptor (CAR) T-cell therapy, using the patient’s own immune system cells that have been re-engineered to help them fight back against the tumor.
Today we are profiling City of Hope’s Christine Brown, Ph.D., who is using CAR-T cells in a CIRM-funded Phase 1 clinical trial for an aggressive brain cancer called malignant glioma.
“Brain tumors are the hardest to treat solid tumors. This is a project that CIRM has supported from an early, pre-clinical stage. What was exciting was we finished our first milestone in record time and were able to translate that research out of the lab and into the clinic. That really allowed us to accelerate treatment to glioblastoma patients.
I think there are glimmers of hope that immune based therapies and CAR-T based therapies will revolutionize therapy for patients with brain tumors. We’ve seen evidence that these cells can travel to the central nervous system and eliminate tumors in the brain.
We now have evidence that this approach produces a powerful, therapeutic response in one group of patients. We are looking at why other patients don’t respond as well and the CIRM funding enables us to ask the questions that will, we hope, provide the answers.
Because our clinical trial is a being carried out at the CIRM-supported City of Hope Alpha Stem Cell Clinic this is a great example of how CIRM supports all the different ways of advancing therapy from early stage research through translation and into clinical trials in the CIRM Alpha Clinic network.
There are lots of ways the tumor tries to evade the immune system and we are looking at different approaches to combine this therapy with different approaches to see which combination will be best.
It’s a challenging problem and it’s not going to be solved with one approach. If it were easy we’d have solved it by now. That’s why I love science, it’s one big puzzle about how do we understand this and how do we make this work.
I don’t think we would be where we are at without CIRM’s support, it really gave the funding to bring this to the next level.”
Dr. Brown’s work is also creating interest among investors. She recently partnered with Mustang Bio in a $94.5 million agreement to help advance this therapy.
As we mentioned in last Thursday’s blog, during the month of October we’ll be looking back at what CIRM has done since the agency was created by the people of California back in 2004. To start things off, we’ll be focusing on CIRM-funded clinical trials this week. Supporting clinical trials through our funding and partnership is a critical cornerstone to achieving our mission: to accelerate stem cell treatments to patients with unmet medical needs.
Over the next four days, we will post infographics that summarize CIRM-funded trials focused on therapies for cancer, neurologic disorders, heart and metabolic disease, and blood disorders. Today, we review the nine CIRM-funded clinical trial projects that target cancer. The therapeutic strategies are as varied as the types of cancers the researchers are trying to eradicate. But the common element is developing cutting edge methods to outsmart the cancer cell’s ability to evade standard treatment.
MRI scan of patient with glioblastoma. (wikicommons)
Cancers come in many different forms. Some are treatable if caught early and other aren’t. One of the most deadly types of cancers are glioblastomas – a particularly aggressive form of brain tumor. Patients diagnosed with glioblastoma have an average life expectancy of 12-15 months and there is no cure or effective treatment that extends life.
While a glioblastoma diagnosis has pretty much been a death sentence, now there could be a silver lining to this deadly, fast-paced disease. Last week, scientists from the City of Hope in southern California reported in the New England Journal of Medicine, a new cell-based therapy that melted away brain tumors in a patient with an advanced stage of glioblastoma.
An Immunotherapy Approach to Glioblastoma
The patient is a 50-year-old man named Richard Grady who was participating in an investigational clinical trial run out of the City of Hope’s CIRM Alpha Stem Cell Clinic. A brain scan revealed a brightly lit tumor on the right side of Richard’s brain. Doctors surgically removed the tumor and treated him with radiation in an attempt to staunch further growth. But after six months, the tumors came back with a vengeance, spreading to other parts of his brain, lighting up his MRI scan like a Christmas tree.
With few treatment options and little time left, Richard was enrolled in the City of Hope trial that was testing a cell-based immunotherapy that recognizes and attacks cancer cells. It’s called CAR T-cell therapy – a term that you probably have heard in the news as a promising and cutting-edge treatment for cancer. Scientists extract immune cells, called T-cells, from a patient’s blood and reengineer them in the laboratory to recognize unique surface markers on cancer cells. These specialized CAR T-cells are then put back into the patient to attack and kill off cancer cells.
In Richard’s case, CAR-T cells were first infused into his brain through a tube in an area where a tumor was recently removed. No new tumors grew in that location of his brain, but tumors in other areas continued to grow and spread to his spinal cord. At this point, the scientists decided to place a second tube into a cavity of the brain called the ventricles, which contain a clear liquid called cerebrospinal fluid. Directly infusing into the spinal fluid allowed the cancer fighting cells to travel to different parts of the brain and spinal cord to attack the tumors.
Behnam Badie, senior author on the study and neurosurgery chief at the City of Hope, explained in a news release,
Benham Badie, City of Hope
“By injecting the reengineered CAR-T cells directly into the tumor site and the ventricles, where the spinal fluid is made, the treatment could be delivered throughout the patient’s brain and also to the spinal cord, where this particular patient had a large metastatic tumor.”
Bye Bye Brain Tumors? Almost…
Three infusions of the CAR T-cell treatment shrunk Richard’s tumors noticeably, and a total of ten infusions was enough to melt away Richard’s tumors completely. Amazingly, Richard was able to reduce his medications and go back to work.
CAR T-cell therapy reduces brain tumors when infused into the spinal fluid. (NEJM)
The effects of the immunotherapy lasted for seven-and-a-half months. Unfortunately, his glioblastoma did come back, and he is now undergoing radiation treatment. Instead of being discouraged by these results, we should be encouraged. Patients with advanced cases of glioblastoma like Richard often have only weeks left to live, and the prospect of another seven months of life with family and friends is a gift.
Following these promising results in a single patient, the City of Hope team has now treated a total of nine patients in their clinical trial. Their initial results indicate that the immunotherapy is relatively safe. Further studies will be done to determine whether this therapy will be effective at treating other types of cancers.
CIRM Alpha Clinics Advance Stem Cell Treatments
The findings in this study are particularly exciting to CIRM, not only because they offer a new treatment option for a deadly brain cancer, but also because the clinical trial testing this treatment is housed at one of our own Alpha Clinics. In 2014, CIRM funded three stem cell-focused clinics at the City of Hope, UC San Diego, and a joint clinic between UC Los Angeles and UC Irvine. These clinics are specialized to support high quality trials focused on stem cell treatments for various diseases. The CIRM team will be bringing a new Alpha Clinics concept plan to its governing Board for approval in February.
Geoff Lomax, Senior Officer of Strategic Infrastructure at CIRM who oversees the CIRM Alpha Clinics, commented on the importance of City of Hope’s glioblastoma trial,
“Treating this form of brain cancer is one of the most vexing challenges in medicine. With the support and expertise of the CIRM Alpha Stem Cell Clinic, City of Hope is harnessing the power of patients’ immune cells to treat this deadly disease.”
Neil Littman, CIRM Director of Business Development and Strategic Infrastructure added,
“This study provides important proof-of-concept that CAR-T cells can be used to target hard-to-treat solid tumors and is precisely the type of trial the CIRM Alpha Stem Cell Clinic Network is designed to support.”
For more details on this study, watch the video below from City of Hope:
Malignant brain cancer is a devastating disease and it’s estimated that more than 16,000 patients will die of it this year. One of the most aggressive forms of brain cancer is gliomas, which originate from the support cells in the brain or spine that keep nerve cells happy and functioning. Unfortunately, there is no cure for gliomas and common treatments involving surgery, radiation and chemotherapy are not effective in fully eradicating these tumors.
Brain CT scan of human glioma.
In hopes of finding a cure, scientists have turned to animal models and human cell models derived from tumor biopsies or fetal tissue, to gain understanding of how gliomas form and what makes these type of tumors so deadly and resistant to normal cancer treatments. These models have their limitations, and scientists continue to develop more relevant models in hopes of identifying new potential treatments for brain cancer.
Speaking of which, a CIRM-funded research team from the Salk Institute recently reported a new human stem cell-based model for studying gliomas in Nature Communications. The team figured out how to transform human induced pluripotent stem cells (iPS cells) into glioma tumor-initiating cells (GTICs) that they used to model how gliomas develop and to screen for drugs that specifically target this deadly form of cancer.
Making the Model
One theory for how gliomas form is that neural progenitor cells (brain stem cells) can transform and take on new properties that turn them into glioma tumor-initiating cells or GTICs, which are a subpopulation of cancer stem cells that are really good at staying alive and reproducing themselves into nasty tumors.
The Salk team created a stem cell model for glioma by generating GTICs in a dish from human iPS cells. They genetically manipulated brain progenitor cells (which they called induced neural progenitor cells or iNPCs) derived from human iPS cells to look and behave like GTICs. Building off of previous studies reporting that a majority of human gliomas have genetic mutations in the p53 and Src-family kinase (SFK) genes, they developed different iNPC lines that either turned off expression of p53, a potent tumor suppressor, or that ramped up expression of SFKs, whose abnormal expression are associated with tumor expansion.
The team then compared the transformed iNPC lines to primary GTICs isolated from human glioma tissue. They found that the transformed iNPCs shared many similar characteristics to primary GTICs including the surface markers they expressed, the genes they expressed, and their metabolic profiles.
Their final test of their stem cell model determined whether transformed iNPCs could make gliomas in an animal model. They transplanted normal and transformed iNPC lines into the brains of mice and saw aggressive tumors develop only in mice that received transformed cells. When they dissected the gliomas, they found a mixture of GTICs, more mature brain cells produced from GTICs, and areas of dead cells. This cellular makeup was very similar to that of advanced grade IV primary glioblastomas.
Screening for drugs that target glioma initiating cells
Now comes the applied part of this study. After developing a new and relevant stem cell model for glioma, the team screened their transformed iNPC lines with a panel of 101 FDA-approved anti-cancer drugs to see if any of them were effective at stopping the growth and expansion of GTICs. They identified three compounds that were able to target and kill both transformed iNPCs and primary GTICs in a dish. They also tested these compounds on living brain slices that were injected with GTICs to form tumors and saw that the drugs worked well at reducing tumor size.
The authors concluded that their transformed iNPCs are appropriate for modeling certain features of how GTICs develop into adult gliomas. Their hope is that this model will be useful for developing new targeted therapies for aggressive forms of brain cancer.
“Our results highlight the potential of hiPSCs for studying human tumourigenesis. Similar to conventional disease modeling strategies based on the use of hiPSCs, the establishment of hiPSC cancer models might facilitate the future development of novel therapeutics.”
The Stem Cellar 