Blocking pancreatic cancer stem cells

John Cashman

Cancer stem cells are one of the main reasons why cancers are able to survive surgery, chemotherapy and radiation. They are able to hide from those therapies and, at a future date, emerge and spread the cancer in the body once again.

Jionglia Cheng, PhD.

Jionglia Cheng, PhD., the lead author of a new CIRM-funded study, says that’s one of the reasons why pancreatic cancer has proved so difficult to treat.

“Pancreatic cancer remains a major health problem in the United States and soon will be the second most common cause of mortality due to cancer. A majority of pancreatic cancer patients are often resistant to clinical therapies. Thus, it remains a challenge to develop an efficacious clinically useful pancreatic cancer therapy.”

Dr. Cheng, a researcher with ChemRegen Inc., teamed up with John Cashman at the Human BioMolecular Research Institute and identified a compound, that seems to be effective in blocking the cancer stem cells.

In earlier studies the compound, called PAWI-2, demonstrated effectiveness in blocking breast, prostate and colon cancer. When tested in the laboratory PAWI-2 showed it was able to kill pancreatic cancer stem cells, and also was effective in targeting drug-resistant pancreatic cancer stem cells.

In addition, when PAWI-2 was used with a drug called erlotinib (brand name Tarceva) which is commonly prescribed for pancreatic cancer, the combination proved more effective against the cancer stem cells than erlotinib alone.

In a news release Dr. Cheng said: “In the future, this molecule could be used alone or with other chemotherapy albeit at lower doses, as a new therapeutic drug to combat pancreatic cancer. This may lead to much less toxicity to the patient,”

The study is published in the journal Scientific Reports.

Big time validation for early support

It’s not every day that a company and a concept that you helped support from the very beginning gets snapped up for $4.9 billion. But that’s what is happening with Forty Seven Inc. and their anti-cancer therapies. Gilead, another California company by the way, has announced it is buying Forty Seven Inc. for almost $5 billion.

The deal gives Gilead access to Forty Seven’s lead antibody therapy, magrolimab, which switches off CD47, a kind of “do not eat me” signal that cancer cells use to evade the immune system.

CIRM has supported this program from its very earliest stages, back in 2013, when it was a promising idea in need of funding. Last year we blogged about the progress it has made from a hopeful concept to an exciting therapy.

When Forty Seven Inc. went public in 2018, Dr. Irv Weissman, one of the founders of the company, attributed a lot of their success to CIRM’s support.

Dr. Irv Weissman

“The story of the funding of this work all of the way to its commercialization and the clinical trials reported in the New England Journal of Medicine is simply this: CIRM funding of a competitive grant took a mouse discovery of the CD47 ‘don’t eat me’ signal through all preclinical work to and through a phase 1 IND with the FDA. Our National Institutes of Health (NIH) did not fund any part of the clinical trial or preclinical run up to the trial, so it is fortunate for those patients and those that will follow, if the treatment continues its success in larger trials, that California voters took the state’s right action to fund research not funded by the federal government.”

Dr. Maria Millan, CIRM’s President & CEO, says the deal is a perfect example of CIRM’s value to the field of regenerative medicine and our ability to work with our grantees to make them as successful as possible.

“To say this is incredible would be an understatement! Words cannot describe how excited we are that this novel approach to battling currently untreatable malignancies has the prospect of making it to patients in need and this is a major step. Speaking on behalf of CIRM, we are very honored to have been a partner with Forty Seven Inc. from the very beginning.

CIRM Senior Science Officer, Dr. Ingrid Caras, was part of the team that helped a group of academic scientists take their work out of the lab and into the real world.

“I had the pleasure of working with and helping the Stanford team since CIRM provided the initial funding to translate the idea of developing CD47 blockade as a therapeutic approach. This was a team of superb scientists who we were fortunate to work closely with them to navigate the Regulatory environment and develop a therapeutic product. We were able to provide guidance as well as funding and assist in the ultimate success of this project.”

Forty Seven Inc. is far from the only example of this kind of support and collaboration. We have always seen ourselves as far more than just a funding agency. Money is important, absolutely. But so too is bringing the experience and expertise of our team to help academic scientists take a promising idea and turn it into a successful therapy.

After all that’s what our mission is, doing all we can to accelerate stem cell therapies to patients with unmet medical needs. And after a deal like this, Forty Seven Inc. is definitely accelerating its work.

Rave reviews for new Killer-T Cell study

Anytime you read a news headline that claims a new discovery “may treat all cancer” it’s time to put your skeptic’s hat on. After all, there have been so many over-hyped “discoveries” over the years that later flopped, that it would be natural to question the headline writer. And yet, this time, maybe, this one has some substance behind it.

Andrew Sewell with research fellow Garry Dolton. (Photo Credit: Cardiff University)

Researchers at the University of Cardiff in Wales have discovered a new kind of immune cell, a so-called “killer T-cell”, that appears to be able to target and kill many human cancer cells, such as those found in breast, prostate and lung cancer. At least in the lab.

The immune system is our body’s defense against all sorts of threats, from colds and flu to cancer. But many cancers are able to trick the immune system and evade detection as they spread throughout the body. The researchers found one T-cell receptor (TCR) that appears to be able to identify cancer cells and target them, but leave healthy tissues alone.

In an interview with the BBC, Prof. Andrew Sewell, the lead researcher on the study said: “There’s a chance here to treat every patient. Previously nobody believed this could be possible. It raises the prospect of a ‘one-size-fits-all’ cancer treatment, a single type of T-cell that could be capable of destroying many different types of cancers across the population.”

The study, published in the journal Nature Immunology, suggests the TCR works by using a molecule called MR1 to identify cancerous cells. MR1 is found on every cell in our body but in cancerous cells it appears to give off a different signal, which enables the TCR to identify it as a threat.

When the researchers injected this TCR into mice that had cancer it was able to clear away many of the cells. The researchers admit there is still a long way to go before they know if this approach will work in people, but Sewell says they are encouraged by their early results.

“There are plenty of hurdles to overcome. However, if this testing is successful, then I would hope this new treatment could be in use in patients in a few years’ time.”

CIRM is funding a number of clinical trials that use a similar approach to targeting cancers, taking the patient’s own immune T-cells and, in the lab, “re-educating” to be able to recognize the cancerous cells. Those cells are then returned to the patient where it’s hoped they’ll identify and destroy the cancer. You can read about those here , here, here, here, and here.

Two studies identify a molecule that could be used to block Zika virus and kill cancer cells

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.

Facebook Live: Ask the Stem Cell Team

On December 12th we hosted our latest ‘Facebook Live: Ask the Stem Cell Team’ event. This time around we really did mean team. We had a host of our Science Officers answering questions from friends and supporters of CIRM. We got a lot of questions and didn’t have enough time to address them all. So here’s answers to all the questions.

What are the obstacles to using partial cellular reprogramming to return people’s entire bodies to a youthful state. Paul Hartman.  San Leandro, California

Dr. Kelly Shepard

Dr. Kelly Shepard: Certainly, scientists have observed that various manipulations of cells, including reprogramming, partial reprogramming, de-differentiation and trans-differentiation, can restore or change properties of cells, and in some cases, these changes can reflect a more “youthful” state, such as having longer telomeres, better proliferative capacity, etc. However, some of these same rejuvenating properties, outside of their normal context, could be harmful or deadly, for example if a cell began to grow and divide when or where it shouldn’t, similar to cancer. For this reason, I believe the biggest obstacles to making this approach a reality are twofold: 1)  our current, limited understanding of the nature of partially reprogrammed cells; and 2) our inability to control the fate of those cells that have been partially reprogrammed, especially if they are inside a living organism.  Despite the challenges, I think there will be step wise advances where these types of approaches will be applied, starting with specific tissues. For example, CIRM has recently funded an approach that uses reprogramming to make “rejuvenated” versions of T cells for fighting lung cancer.  There is also a lot of interest in using such approaches to restore the reparative capacity of aged muscle. Perhaps some successes in these more limited areas will be the basis for expanding to a broader use.

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STROKE

What’s going on with Stanford’s stem cell trials for stroke? I remember the first trial went really well In 2016 have not heard anything about since? Elvis Arnold

Dr. Lila Collins

Dr. Lila Collins: Hi Elvis, this is an evolving story.  I believe you are referring to SanBio’s phase 1/2a stroke trial, for which Stanford was a site. This trial looked at the safety and feasibility of SanBio’s donor or allogeneic stem cell product in chronic stroke patients who still had motor deficits from their strokes, even after completing physical therapy when natural recovery has stabilized.  As you note, some of the treated subjects had promising motor recoveries. 

SanBio has since completed a larger, randomized phase 2b trial in stroke, and they have released the high-level results in a press release.  While the trial did not meet its primary endpoint of improving motor deficits in chronic stroke, SanBio conducted a very similar randomized trial in patients with stable motor deficits from chronic traumatic brain injury (TBI).  In this trial, SanBio saw positive results on motor recovery with their product.  In fact, this product is planned to move towards a conditional approval in Japan and has achieved expedited regulatory status in the US, termed RMAT, in TBI which means it could be available more quickly to patients if all goes well.  SanBio plans to continue to investigate their product in stroke, so I would stay tuned as the work unfolds. 

Also, since you mentioned Stanford, I should note that Dr Gary Steinberg, who was a clinical investigator in the SanBio trial you mentioned, will soon be conducting a trial with a different product that he is developing, neural progenitor cells, in chronic stroke.  The therapy looks promising in preclinical models and we are hopeful it will perform well for patients in the clinic.

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I am a stroke survivor will stem cell treatment able to restore my motor skills? Ruperto

Dr. Lila Collins:

Hi Ruperto. Restoring motor loss after stroke is a very active area of research.  I’ll touch upon a few ongoing stem cell trials.  I’d just like to please advise that you watch my colleague’s comments on stem cell clinics (these can be found towards the end of the blog) to be sure that any clinical research in which you participate is as safe as possible and regulated by FDA.

Back to stroke, I mentioned SanBio’s ongoing work to address motor skill loss in chronic stroke earlier.  UK based Reneuron is also conducting a phase 2 trial, using a neural progenitor cell as a candidate therapy to help recover persistent motor disability after stroke (chronic).  Dr Gary Steinberg at Stanford is also planning to conduct a clinical trial of a human embryonic stem cell-derived neuronal progenitor cell in stroke.

There is also promising work being sponsored by Athersys in acute stroke. Athersys published results from their randomized, double blinded placebo controlled Ph2 trial of their Multistem product in patients who had suffered a stroke within 24-48 hours.  After intravenous delivery, the cells improved a composite measure of stroke recovery, including motor recovery.  Rather than acting directly on the brain, Multistem seems to work by traveling to the spleen and reducing the inflammatory response to a stroke that can make the injury worse.

Athersys is currently recruiting a phase 3 trial of its Multistem product in acute stroke (within 1.5 days of the stroke).  The trial has an accelerated FDA designation, called RMAT and a special protocol assessment.  This means that if the trial is conducted as planned and it reaches the results agreed to with the FDA, the therapy could be cleared for marketing.  Results from this trial should be available in about two years. 

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Questions from several hemorrhagic stroke survivors who say most clinical trials are for people with ischemic strokes. Could stem cells help hemorrhagic stroke patients as well?

Dr. Lila Collins:

Regarding hemorrhagic stroke, you are correct the bulk of cell therapies for stroke target ischemic stroke, perhaps because this accounts for the vast bulk of strokes, about 85%.

That said, hemorrhagic strokes are not rare and tend to be more deadly.  These strokes are caused by bleeding into or around the brain which damages neurons.  They can even increase pressure in the skull causing further damage.  Because of this the immediate steps treating these strokes are aimed at addressing the initial bleeding insult and the blood in the brain.

While most therapies in development target ischemic stroke, successful therapies developed to repair neuronal damage or even some day replace lost neurons, could be beneficial after hemorrhagic stroke as well.

We are aware of a clinical trial targeting acute hemorrhagic stroke that is being run by the Mayo clinic in Jacksonville Florida.

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I had an Ischemic stroke in 2014, and my vision was also affected. Can stem cells possibly help with my vision issues. James Russell

Dr. Lila Collins:

Hi James. Vision loss from stroke is complex and the type of loss depends upon where the stroke occurred (in the actual eye, the optic nerve or to the other parts of the brain controlling they eye or interpreting vision).  The results could be:

  1. Visual loss from damage to the retina
  2. You could have a normal eye with damage to the area of the brain that controls the eye’s movement
  3. You could have damage to the part of the brain that interprets vision.

You can see that to address these various issues, we’d need different cell replacement approaches to repair the retina or the parts of the brain that were damaged. 

Replacing lost neurons is an active effort that at the moment is still in the research stages.  As you can imagine, this is complex because the neurons have to make just the right connections to be useful. 

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VISION

Is there any stem cell therapy for optical nerve damage? Deanna Rice

Dr. Ingrid Caras

Dr. Ingrid Caras: There is currently no proven stem cell therapy to treat optical nerve damage, even though there are shady stem cell clinics offering treatments.  However, there are some encouraging early gene therapy studies in mice using a virus called AAV to deliver growth factors that trigger regeneration of the damaged nerve. These studies suggest that it may be possible to restore at least some visual function in people blinded by optic nerve damage from glaucoma

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I read an article about ReNeuron’s retinitis pigmentosa clinical trial update.  In the article, it states: “The company’s treatment is a subretinal injection of human retinal progenitors — cells which have almost fully developed into photoreceptors, the light-sensing retinal cells that make vision possible.” My question is: If they can inject hRPC, why not fully developed photoreceptors? Leonard

Dr. Kelly Shepard: There is evidence from other studies, including from other tissue types such as blood, pancreas, heart and liver, that fully developed (mature) cell types tend not to engraft as well upon transplantation, that is the cells do not establish themselves and survive long term in their new environment. In contrast, it has been observed that cells in a slightly less “mature” state, such as those in the progenitor stage, are much more likely to establish themselves in a tissue, and then differentiate into more mature cell types over time. This question gets at the crux of a key issue for many new therapies, i.e. what is the best cell type to use, and the best timing to use it.

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My question for the “Ask the Stem Cell Team” event is: When will jCyte publish their Phase IIb clinical trial results. Chris Allen

Dr. Ingrid Caras: The results will be available sometime in 2020.

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I understand the hRPC cells are primarily neurotropic (rescue/halt cell death); however, the literature also says hRPC can become new photoreceptors.  My questions are: Approximately what percentage develop into functioning photoreceptors? And what percentage of the injected hRPC are currently surviving? Leonard Furber, an RP Patient

Dr. Kelly Shepard: While we can address these questions in the lab and in animal models, until there is a clinical trial, it is not possible to truly recreate the environment and stresses that the cells will undergo once they are transplanted into a human, into the site where they are expected to survive and function. Thus, the true answer to this question may not be known until after clinical trials are performed and the results can be evaluated. Even then, it is not always possible to monitor the fate of cells after transplantation without removing tissues to analyze (which may not be feasible), or without being able to transplant labeled cells that can be readily traced.

Dr. Ingrid Caras – Although the cells have been shown to be capable of developing into photoreceptors, we don’t know if this actually happens when the cells are injected into a patient’s eye.   The data so far suggest that the cells work predominantly by secreting growth factors that rescue damaged retinal cells or even reverse the damage. So one possible outcome is that the cells slow or prevent further deterioration of vision. But an additional possibility is that damaged retinal cells that are still alive but are not functioning properly may become healthy and functional again which could result in an improvement in vision.

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DIABETES

What advances have been made using stem cells for the treatment of Type 2 Diabetes? Mary Rizzo

Dr. Ross Okamura

Dr. Ross Okamura: Type 2 Diabetes (T2D) is a disease where the body is unable to maintain normal glucose levels due to either resistance to insulin-regulated control of blood sugar or insufficient insulin production from pancreatic beta cells.  The onset of disease has been associated with lifestyle influenced factors including body mass, stress, sleep apnea and physical activity, but it also appears to have a genetic component based upon its higher prevalence in certain populations. 

Type 1 Diabetes (T1D) differs from T2D in that in T1D patients the pancreatic beta cells have been destroyed by the body’s immune system and the requirement for insulin therapy is absolute upon disease onset rather than gradually developing over time as in many T2D cases.  Currently the only curative approach to alleviate the heavy burden of disease management in T1D has been donor pancreas or islet transplantation. However, the supply of donor tissue is small relative to the number of diabetic patients.  Donor islet and pancreas transplants also require immune suppressive drugs to prevent allogenic immune rejection and the use of these drugs carry additional health concerns.  However, for some patients with T1D, especially those who may develop potentially fatal hypoglycemia, immune suppression is worth the risk.

To address the issue of supply, there has been significant activity in stem cell research to produce insulin secreting beta cells from pluripotent stem cells and recent clinical data from Viacyte’s CIRM funded trial indicates that implanted allogeneic human stem cell derived cells in T1D patients can produce circulating c-peptide, a biomarker for insulin.  While the trial is not designed specifically to cure insulin-dependent T2D patients, the ability to produce and successfully engraft stem cell-derived beta cells would be able to help all insulin-dependent diabetic patients.

It’s also worth noting that there is a sound scientific reason to clinically test a patient-derived pluripotent stem cell-based insulin-producing cells in insulin-dependent T2D diabetic patients; the cells in this case could be evaluated for their ability to cure diabetes in the absence of needing to prevent both allogeneic and autoimmune responses.

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SPINAL CORD INJURY

Is there any news on clinical trials for spinal cord injury? Le Ly

Kevin McCormack: The clinical trial CIRM was funding, with Asterias (now part of a bigger company called Lineage Cell Therapeutics, is now completed and the results were quite encouraging. In a news release from November of 2019 Brian Culley, CEO of Lineage Cell Therapeutics, described the results this way.

“We remain extremely excited about the potential for OPC1 (the name of the therapy used) to provide enhanced motor recovery to patients with spinal cord injuries. We are not aware of any other investigative therapy for SCI (spinal cord injury) which has reported as encouraging clinical outcomes as OPC1, particularly with continued improvement beyond 1 year. Overall gains in motor function for the population assessed to date have continued, with Year 2 assessments measuring the same or higher than at Year 1. For example, 5 out of 6 Cohort 2 patients have recovered two or more motor levels on at least one side as of their Year 2 visit whereas 4 of 6 patients in this group had recovered two motor levels as of their Year 1 visit. To put these improvements into perspective, a one motor level gain means the ability to move one’s arm, which contributes to the ability to feed and clothe oneself or lift and transfer oneself from a wheelchair. These are tremendously meaningful improvements to quality of life and independence. Just as importantly, the overall safety of OPC1 has remained excellent and has been maintained 2 years following administration, as measured by MRI’s in patients who have had their Year 2 follow-up visits to date. We look forward to providing further updates on clinical data from SCiStar as patients continue to come in for their scheduled follow up visits.”

Lineage Cell Therapeutics plans to meet with the FDA in 2020 to discuss possible next steps for this therapy.

In the meantime the only other clinical trial I know that is still recruiting is one run by a company called Neuralstem. Here is a link to information about that trial on the www.clinicaltrials.gov website.

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ALS

Now that the Brainstorm ALS trial is finished looking for new patients do you have any idea how it’s going and when can we expect to see results? Angela Harrison Johnson

Dr. Ingrid Caras: The treated patients have to be followed for a period of time to assess how the therapy is working and then the data will need to be analyzed.  So we will not expect to see the results probably for another year or two.

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AUTISM

Are there treatments for autism or fragile x using stem cells? Magda Sedarous

Dr. Kelly Shepard: Autism and disorders on the autism spectrum represent a collection of many different disorders that share some common features, yet have different causes and manifestations, much of which we still do not understand. Knowing the origin of a disorder and how it affects cells and systems is the first step to developing new therapies. CIRM held a workshop on Autism in 2009 to brainstorm potential ways that stem cell research could have an impact. A major recommendation was to exploit stem cells and new technological advances to create cells and tissues, such as neurons, in the lab from autistic individuals that could then be studied in great detail.  CIRM followed this recommendation and funded several early-stage awards to investigate the basis of autism, including Rett Syndrome, Fragile X, Timothy Syndrome, and other spectrum disorders. While these newer investigations have not yet led to therapies that can be tested in humans, this remains an active area of investigation. Outside of CIRM funding, we are aware of more mature studies exploring the effects of umbilical cord blood or other specific stem cell types in treating autism, such as an ongoing clinical trial conducted at Duke University.

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PARKINSON’S DISEASE

What is happening with Parkinson’s research? Hanifa Gaphoor

Dr. Kent Fitzgerald

Dr. Kent Fitzgerald: Parkinson’s disease certainly has a significant amount of ongoing work in the regenerative medicine and stem cell research. 

The nature of cell loss in the brain, specifically the dopaminergic cells responsible for regulating the movement, has long been considered a good candidate for cell replacement therapy.  

This is largely due to the hypothesis that restoring function to these cells would reverse Parkinson’s symptoms. This makes a lot of sense as front line therapy for the disease for many years has been dopamine replacement through L-dopa pills etc.  Unfortunately, over time replacing dopamine through a pill loses its benefit, whereas replacing or fixing the cells themselves should be a more permanent fix. 

Because a specific population of cells in one part of the brain are lost in the disease, multiple labs and clinicians have sought to replace or augment these cells by transplantation of “new” functional cells able to restore function to the area an theoretically restore voluntary motor control to patients with Parkinson’s disease. 

Early clinical research showed some promise, however also yielded mixed results, using fetal tissue transplanted into the brains of Parkinson’s patients.   As it turns out, the cell types required to restore movement and avoid side effects are somewhat nuanced.  The field has moved away from fetal tissue and is currently pursuing the use of multiple stem cell types that are driven to what is believed to be the correct subtype of cell to repopulate the lost cells in the patient. 

One project CIRM sponsored in this area with Jeanne Loring sought to develop a cell replacement therapy using stem cells from the patients themselves that have been reprogrammed into the kinds of cell damaged by Parkinson’s.  This type of approach may ultimately avoid issues with the cells avoiding rejection by the immune system as can be seen with other types of transplants (i.e. liver, kidney, heart etc).

Still, others are using cutting edge gene therapy technology, like the clinical phase project CIRM is sponsoring with Krystof Bankiewicz to investigate the delivery of a gene (GDNF) to the brain that may help to restore the activity of neurons in the Parkinson’s brain that are no longer working as they should. 

The bulk of the work in the field of PD at the present remains centered on replacing or restoring the dopamine producing population of cells in the brain that are affected in disease.   

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HUNTINGTON’S DISEASE

Any plans for Huntington’s? Nikhat Kuchiki

Dr. Lisa Kadyk

Dr. Lisa Kadyk: The good news is that there are now several new therapeutic approaches to Huntington’s Disease that are at various stages of preclinical and clinical development, including some that are CIRM funded.   One CIRM-funded program led by Dr. Leslie Thompson at UC Irvine is developing a cell-based therapeutic that consists of neural stem cells that have been manufactured from embryonic stem cells.   When these cells are injected into the brain of a mouse that has a Huntington’s Disease mutation, the cells engraft and begin to differentiate into new neurons.  Improvements are seen in the behavioral and electrophysiological deficits in these mutant mice, suggesting that similar improvements might be seen in people with the disease.   Currently, CIRM is funding Dr. Thompson and her team to carry out rigorous safety studies in animals using these cells, in preparation for submitting an application to the FDA to test the therapy in human patients in a clinical trial.   

There are other, non-cell-based therapies also being tested in clinical trials now, using  anti-sense oligonucleotides (Ionis, Takeda) to lower the expression of the Huntington protein.  Another HTT-lowering approach is similar – but uses miRNAs to lower HTT levels (UniQure, Voyager)

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TRAUMATIC BRAIN INJURY (TBI)

My 2.5 year old son recently suffered a hypoxic brain injury resulting in motor and speech disabilities. There are several clinical trials underway for TBI in adults. My questions are:

  • Will the results be scalable to pediatric use and how long do you think it would take before it is available to children?
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  • I’m wondering why the current trials have chosen to go the route of intracranial injections as opposed to something slightly less invasive like an intrathecal injection?
  • Is there a time window period in which stem cells should be administered by, after which the administration is deemed not effective?

Dr. Kelly Shepard:  TBI and other injuries of the nervous system are characterized by a lot of inflammation at the time of injury, which is thought to interfere with the healing process- and thus some approaches are intended to be delivered after that inflammation subsides. However, we are aware of approaches that intend to deliver a therapy to a chronic injury, or one that has occurred  previously. Thus, the answer to this question may depend on how the intended therapy is supposed to work. For example, is the idea to grow new neurons, or is it to promote the survival of neurons of other cells that were spared by the injury? Is the therapy intended to address a specific symptom, such as seizures? Is the therapy intended to “fill a gap” left behind after inflammation subsides, which might not restore all function but might ameliorate certain symptoms.? There is still a lot we don’t understand about the brain and the highly sophisticated network of connections that cannot be reversed by only replacing neurons, or only reducing inflammation, etc. However, if trials are well designed, they should yield useful information even if the therapy is not as effective as hoped, and this information will pave the way to newer approaches and our technology and understanding evolves.

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We have had a doctor recommending administering just the growth factors derived from MSC stem cells. Does the science work that way? Is it possible to isolate the growth factors and boost the endogenous growth factors by injecting allogenic growth factors?

Dr. Stephen Lin

Dr. Stephen Lin:  Several groups have published studies on the therapeutic effects in non-human animal models of using nutrient media from MSC cultures that contain secreted factors, or extracellular vesicles from cells called exosomes that carry protein or nucleic acid factors.  Scientifically it is possible to isolate the factors that are responsible for the therapeutic effect, although to date no specific factor or combination of factors have been identified to mimic the effects of the undefined mixtures in the media and exosomes.  At present no regulatory approved clinical therapy has been developed using this approach. 

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PREDATORY STEM CELL CLINICS

What practical measures are being taken to address unethical practitioners whose bad surgeries are giving stem cell advances a bad reputation and are making forward research difficult? Kathy Jean Schultz

Dr. Geoff Lomax

Dr. Geoff Lomax: Terrific question! I have been doing quite a bit research into the history of this issue of unethical practitioners and I found an 1842 reference to “quack medicines.” Clearly this is nothing new. In that day, the author appealed to make society “acquainted with the facts.”

In California, we have taken steps to (1) acquaint patients with the facts about stem cell treatments and (2) advance FDA authorized treatments for unmet medical needs.

  • First, CIRM work with Senator Hernandez in 2017 to write a law the requires provides to disclose to patient that a stem cell therapy has not been approved by the Food and Drug administration.
  • We continue to work with the State Legislature and Medical Board of California to build on policies that require accurate disclosure of the facts to patients.
  • Second, our clinical trial network the — Alpha Stem Cell Clinics – have supported over 100 FDA-authorized clinical trials to advance responsible clinical research for unmet medical needs.

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I’m curious if adipose stem cell being used at clinics at various places in the country is helpful or beneficial? Cheri Hicks

Adipose tissue has been widely used particularly in plastic and reconstructive surgery. Many practitioners suggest adipose cells are beneficial in this context. With regard to regenerative medicine and / or the ability to treat disease and injury, I am not aware of any large randomized clinical trials that demonstrate the safety and efficacy of adipose-derived stem cells used in accordance with FDA guidelines.

I went to a “Luncheon about Stem Cell Injections”. It sounded promising. I went thru with it and got the injections because I was desperate from my knee pain. The price of stem cell injections was $3500 per knee injection. All went well. I have had no complications, but haven’t noticed any real major improvement, and here I am a year later. My questions are:

 1) I wonder on where the typical injection cells are coming from?

  2) I wonder what is the actual cost of the cells?

3) What kind of results are people getting from all these “pop up” clinics or established clinics that are adding this to there list of offerings?

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Dr. Geoff Lomax: You raise a number of questions and point here; they are all very good and it’s is hard to give a comprehensive response to each one, but here is my reaction:

  • There are many practitioners in the field of orthopedics who sincerely believe in the potential of cell-based treatments to treat injury / pain
  • Most of the evidence presented is case reports that individuals have benefited
  • The challenge we face is not know the exact type of injury and cell treatments used.
  • Well controlled clinical trials would really help us understand for what cells (or cell products) and for what injury would be helpful
  • Prices of $3000 to $5000 are not uncommon, and like other forms of private medicine there is often a considerable mark-up in relation to cost of goods.
  • You are correct that there have not been reports of serious injury for knee injections
  • However the effectiveness is not clear while simultaneously millions of people have been aided by knee replacements.

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Do stem cells have benefits for patients going through chemotherapy and radiation therapy? Ruperto

Dr. Kelly Shepard: The idea that a stem cell therapy could help address effects of chemotherapy or radiation is being and has been pursued by several investigators over the years, including some with CIRM support. Towards the earlier stages, people are looking at the ability of different stem cell-derived neural cell preparations to replace or restore function of certain brain cells that are damaged by the effects of chemotherapy or radiation. In a completely different type of approach, a group at City of Hope is exploring whether a bone marrow transplant with specially modified stem cells can provide a protective effect against the chemotherapy that is used to treat a form of brain cancer, glioblastoma. This study is in the final stage of development that, if all goes well, culminates with application to the FDA to allow initiation of a clinical trial to test in people.

Dr. Ingrid Caras: That’s an interesting and valid question.  There is a Phase 1 trial ongoing that is evaluating a novel type of stem/progenitor cell from the umbilical cord of healthy deliveries.  In animal studies, these cells have been shown to reduce the toxic effects of chemotherapy and radiation and to speed up recovery. These cells are now being tested in a First-in-human clinical trial in patients who are undergoing high-dose chemotherapy to treat their disease.

There is a researcher at Stanford, Michelle Monje, who is investigating that the role of damage to stem cells in the cognitive problems that sometimes arise after chemo- and radiation therapy (“chemobrain”).  It appears that damage to stem cells in the brain, especially those responsible for producing oligodendrocytes, contributes to chemobrain.  In CIRM-funded work, Dr. Monje has identified small molecules that may help prevent or ameliorate the symptoms of chemobrain.

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Is it possible to use a technique developed to fight one disease to also fight another? For instance, the bubble baby disease, which has cured (I think) more than 50 children, may also help fight sickle cell anemia?  Don Reed.

Dr. Lisa Kadyk: Hi Don. Yes, the same general technique can often be applied to more than one disease, although it needs to be “customized” for each disease.   In the example you cite, the technique is an “autologous gene-modified bone marrow transplant” – meaning the cells come from the patient themselves.  This technique is relevant for single gene mutations that cause diseases of the blood (hematopoietic) system.  For example, in the case of “bubble baby” diseases, a single mutation can cause failure of immune cell development, leaving the child unable to fight infections, hence the need to have them live in a sterile “bubble”.   To cure that disease, blood stem cells, which normally reside in the bone marrow, are collected from the patient and then a normal version of the defective gene is introduced into the cells, where it is incorporated into the chromosomes.   Then, the corrected stem cells are transplanted back into the patient’s body, where they can repopulate the blood system with cells expressing the normal copy of the gene, thus curing the disease.  

A similar approach could be used to treat sickle cell disease, since it is also caused by a single gene mutation in a gene (beta hemoglobin) that is expressed in blood cells.  The same technique would be used as I described for bubble baby disease but would differ in the gene that is introduced into the patient’s blood stem cells. 

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Is there any concern that CIRM’s lack of support in basic research will hamper the amount of new approaches that can reach clinical stages? Jason

Dr. Kelly Shepard: CIRM always has and continues to believe that basic research is vital to the field of regenerative medicine. Over the past 10 years CIRM has invested $904 million in “discovery stage/basic research”, and about $215 million in training grants that supported graduate students, post docs, clinical fellows, undergraduate, masters and high school students performing basic stem cell research. In the past couple of years, with only a limited amount of funds remaining, CIRM made a decision to invest most of the remaining funds into later stage projects, to support them through the difficult transition from bench to bedside. However, even now, CIRM continues to sponsor some basic research through its Bridges and SPARK Training Grant programs, where undergraduate, masters and even high school students are conducting stem cell research in world class stem cell laboratories, many of which are the same laboratories that were supported through CIRM basic research grants over the past 10 years. While basic stem cell research continues to receive a substantial level of support from the NIH ($1.8 billion in 2018, comprehensively on stem cell projects) and other funders, CIRM believes continued support for basic research, especially in key areas of stem cell research and vital opportunities, will always be important for discovering and developing new treatments.

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What is the future of the use of crispr cas9 in clinical trials in california/globally. Art Venegas

Dr. Kelly Shepard: CRISPR/Cas9 is a powerful gene editing tool. In only a few years, CRISPR/Cas9 technology has taken the field by storm and there are already a few CRISPR/Cas9 based treatments being tested in clinical trials in the US. There are also several new treatments that are at the IND enabling stage of development, which is the final testing stage required by the FDA before a clinical trial can begin. Most of these clinical trials involving CRISPR go through an “ex vivo” approach, taking cells from the patient with a disease causing gene, correcting the gene in the laboratory using CRISPR, and reintroducing the cells carrying the corrected gene back into the patient for treatment.  Sickle cell disease is a prime example of a therapy being developed using this strategy and CIRM funds two projects that are preparing for clinical trials with this approach.  CRISPR is also being used to develop the next generation of cancer T-cell therapies (e.g. CAR-T), where T-cells – a vital part of our immune system – are modified to target and destroy cancer cell populations.  Using CRISPR to edit cells directly in patients “in vivo” (inside the body) is far less common currently but is also being developed.  It is important to note that any FDA sanctioned “in vivo” CRISPR clinical trial in people will only modify organ-specific cells where the benefits cannot be passed on to subsequent generations. There is a ban on funding for what are called germ line cells, where any changes could be passed down to future generations.

CIRM is currently supporting multiple CRISPR/Cas9 gene editing projects in California from the discovery or most basic stage of research, through the later stages before applying to test the technique in people in a clinical trial.

While the field is new – if early safety signals from the pioneering trials are good, we might expect a number of new CRISPR-based approaches to enter clinical testing over the next few years. The first of these will will likely be in the areas of bone marrow transplant to correct certain blood/immune or  metabolic diseases, and cancer immunotherapies, as these types of approaches are the best studied and furthest along in the pipeline.

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Explain the differences between gene therapy and stem cell therapy? Renee Konkol

Dr. Stephen Lin:  Gene therapy is the direct modification of cells in a patient to treat a disease.  Most gene therapies use modified, harmless viruses to deliver the gene into the patient.  Gene therapy has recently seen many success in the clinic, with the first FDA approved therapy for a gene induced form of blindness in 2017 and other approvals for genetic forms of smooth muscle atrophy and amyloidosis. 

Stem cell therapy is the introduction of stem cells into patients to treat a disease, usually with the purpose of replacing damaged or defective cells that contribute to the disease.  Stem cell therapies can be derived from pluripotent cells that have the potential to turn into any cell in the body and are directed towards a specific organ lineage for the therapy.  Stem cell therapies can also be derived from other cells, called progenitors, that have the ability to turn into a limited number of other cells in the body. for example hematopoietic or blood stem cells (HSCs), which are found in bone marrow, can turn into other cells of the blood system including B-cells and T-cells: while mesenchymal stem cells (MSCs), which are usually found in fat tissue, can turn into bone, cartilage, and fat cells.  The source of these cells can be from the patient’s own body (autologous) or from another person (allogeneic).

Gene therapy is often used in combination with cell therapies when cells are taken from the patient and, in the lab, modified genetically to correct the mutation or to insert a correct form of the defective gene, before being returned to patients.  Often referred to as “ex vivo gene therapy” – because the changes are made outside the patient’s body – these therapies include Chimeric Antigen Receptor T (CAR-T) cells for cancer therapy and gene modified HSCs to treat blood disorders such as severe combined immunodeficiency and sickle cell disease. This is an exciting area that has significantly improved and even cured many people already.

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Currently, how can the outcome of CIRM stem cell medicine projects and clinical trials be soundly interpreted when their stem cell-specific doses are not known? James L. Sherley, M.D., Ph.D., Director. Asymmetrex, LLC

Dr. Stephen Lin:  Stem cell therapies that receive approval to conduct clinical trials must submit a package of data to the FDA that includes studies that demonstrate their effectiveness, usually in animal models of the disease that the cell therapy is targeting.  Those studies have data on the dose of the cell therapy that creates the therapeutic effect, which is used to estimate cell doses for the clinical trial.  CIRM funds discovery and translational stage awards to conduct these types of studies to prepare cell therapies for clinical trials.  The clinical trial is also often designed to test multiple doses of the cell therapy to determine the one that has the best therapeutic effect.   Dosing can be very challenging with cell therapies because of issues including survival, engraftment, and immune rejection, but CIRM supports studies designed to provide data to give the best estimate possible.

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Is there any research on using stem cells to increase the length of long bones in people?” For example, injecting stem cells into the growth plates to see if the cells can be used to lengthen limbs. Sajid

Dr. Kelly Shepard: There is quite a lot of ongoing research seeking ways to repair bones with stem cell based approaches, which is not the same but somewhat related. Much of this is geared towards repairing the types of bone injuries that do not heal well naturally on their own (large gaps, dead bone lesions, degenerative bone conditions). Also, a lot of this research involves engineering bone tissues in the lab and introducing the engineered tissue into a bone lesion that need be repaired. What occurs naturally at the growth plate is a complex interaction between many different cell types, much of which we do not fully understand. We do not fully understand how to use the cells that are used to engineer bone tissue in the lab. However, a group at Stanford, with some CIRM support, recently discovered a “skeletal stem cell” that exists naturally at the ends of human bones and at sites of fracture.  These are quite different than MSCs and offer a new path to be explored for repairing and generating bone. 

How early CIRM support helped an anti-cancer therapy overcome obstacles and help patients

Dr. Catriona Jamieson, UC San Diego

When you read about a new drug or therapy being approved to help patients it always seems so simple. Researchers come up with a brilliant idea, test it to make sure it is safe and works, and then get approval from the US Food and Drug Administration (FDA) to sell it to people who need it.

But it’s not always that simple, or straight forward. Sometimes it can take years, with several detours along the way, before the therapy finds its way to patients.

That’s the case with a blood cancer drug called fedratinib (we blogged about it here) and the relentless efforts by U.C. San Diego researcher Dr. Catriona Jamieson to help make it available to patients. CIRM funded the critical early stage research to help show this approach could help save lives. But it took many more years, and several setbacks, before Dr. Jamieson finally succeeded in getting approval from the FDA.

The story behind that therapy, and Dr. Jamieson’s fight, is told in the San Diego Union Tribune. Reporter Brad Fikes has been following the therapy for years and in the story he explains why he found it so fascinating, and why this was a therapy that almost didn’t make it.

CIRM funded research could lead to treatment to prevent recurrence of deadly blood cancer

Chronic myelogenous leukemia

Chronic myelogenous leukemia (CML) is a cancer of the white blood cells. It causes them to increase in number, crowd out other blood cells, leading to anemia, infection or heavy bleeding. Up until the early 2000’s the main weapon against CML was chemotherapy, but the introduction of drugs called tyrosine kinase inhibitors changed that, dramatically improving long term survival rates.

However, these medications are not a cure and do not completely eradicate the leukemia stem cells that can fuel the growth of the cancer, so if people stop taking the medication the cancer can return.

Dr. John Chute: Photo courtesy UCLA

But now Dr. John Chute and a team of researchers at UCLA, in a CIRM-supported study, have found a way to target those leukemia stem cells and possibly eliminate them altogether.

The team knew that mice that had the genetic mutation responsible for around 95 percent of CML cases normally developed the disease and died with a few months. However, mice that had the CML gene but lacked another gene, one that produced a protein called pleiotrophin, had normal white blood cells and lived almost twice as long. Clearly there was something about pleiotrophin that played a key role in the growth of CML.

They tested this by transplanting blood stem cells from mice with the CML gene into healthy mice. The previously healthy mice developed leukemia and died. But when they did the same thing from mice that had the CML gene but lacked the pleiotrophin gene, the mice remained healthy.

So, Chute and his team wanted to know if the same thing happens in human cells. Studying human CML stem cells they found these had not just 100 times more pleiotrophin than ordinary cells, they were also producing their own pleiotrophin.

In a news release Chute, said this was unexpected:

“This provides an example of cancer stem cells that are perpetuating their own disease growth by hijacking a protein that normally supports the growth of the healthy blood system.”

Next Chute and the team developed an antibody that blocked the action of pleiotrophin and when they tested it in human cells the CML stem cells died.

Then they combined this antibody with a drug called imatinib (better known by its brand name, Gleevec) which targets the genetic abnormality that causes most forms of CML. They tested this in mice who had been transplanted with human CML stem cells and the cells died.

“Our results suggest that it may be possible to eradicate CML stem cells by combining this new targeted therapy with a tyrosine kinase inhibitor,” said Chute. “This could lead to a day down the road when people with CML may not need to take a tyrosine kinase inhibitor for the rest of their lives.”

The next step is for the researchers to modify the antibody so that it is better suited for humans and not mice and to see if it is effective not just in cells in the laboratory, but in people.

The study is published in the Journal of Clinical Investigation

Drug used to treat multiple sclerosis may improve glioblastoma outcomes

Dr. Jeremy Rich, UC San Diego

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.

New model unlocks clues to treating deadly childhood cancer

CIRM-funded research at Sanford Burnham Prebys Medical Discovery Institute in San Diego is identifying compounds that could be used to help children battling a deadly brain cancer.

The cancer is choroid plexus carcinoma (CPC), a rare brain tumor that occurs mainly in children. As it grows the tumor can affect nearby parts of the brain resulting in nausea, vomiting and headaches.

Treatment involves surgery to remove the tumor followed by chemotherapy and radiation. However, many of the children are too young to undergo radiation and only around 40 percent are still alive five years after being diagnosed. Even those who do survive often experience life-long consequences such as developmental disabilities.

One obstacle to developing better therapies has been the lack of a good animal model to enhance our understanding of the disease. That’s where this later research, published in the journal Cancer Research, comes in.

The team at Sanford Burnham developed a new mouse model, by knocking out p53, a gene known to suppress tumor formation, and activating a gene called Myc, which is known to cause cancer.  

Robert Wechsler-Reya

In a news release, Robert Wechsler-Reya, the senior author of the paper, says this new model mirrors the way CPC grows and develops in humans.

“This model is a valuable tool that will increase our understanding of the biology of the cancer and allow us to identify and test novel approaches to therapy. This advance brings us one step closer to a future where every child survives—and thrives—after diagnosis with CPC.”

As proof of that the team tested nearly 8,000 compounds against the mouse tumor cells, to see if they could help stop or slow the progression of the disease. They identified three that showed potential of not just stopping the cancer, but of also not harming healthy surrounding cells.

“These compounds are promising, much-needed leads in the quest for an effective CPC treatment,” says Wechsler-Reya. “Our laboratory plans to evaluate these and additional compounds that can effectively treat this cancer.”

Newly developed biosensor can target leukemic stem cells

Dr. Michael Milyavsky (left) and his research student Muhammad Yassin (right). Image courtesy of Tel Aviv University.

Every three minutes, one person in the United States is diagnosed with a blood cancer, which amounts to over 175,000 people every year. Every nine minutes, one person in the United States dies from a blood cancer, which is over 58,000 people every year. These eye opening statistics from the Leukemia & Lymphoma Society demonstrate why almost one in ten cancer deaths in 2018 were blood cancer related.

For those unfamiliar with the term, a blood cancer is any type of cancer that begins in blood forming tissue, such as those found in the bone marrow. One example of a blood cancer is leukemia, which results in the production of abnormal blood cells. Chemotherapy and radiation are used to wipe out these cells, but the blood cancer can sometimes return, something known as a relapse.

What enables the return of a blood cancer such as leukemia ? The answer lies in the properties of cancer stem cells, which have the ability to multiply and proliferate and can resist the effects of certain types of chemotherapy and radiation. Researchers at Tel Aviv University are looking to decrease the rate of relapse in blood cancer by targeting a specific type of cancer stem cell known as a leukemic stem cell, which are often found to be the most malignant.

Dr. Michael Milyavsky and his team at Tel Aviv University have developed a biosensor that is able to isolate, label, and target specific genes found in luekemic stem cells. Their findings were published on January 31, 2019 in Leukemia.

In a press release Dr. Milyavsky said:

“The major reason for the dismal survival rate in blood cancers is the inherent resistance of leukemic stem cells to therapy, but only a minor fraction of leukemic cells have high regenerative potential, and it is this regeneration that results in disease relapse. A lack of tools to specifically isolate leukemic stem cells has precluded the comprehensive study and specific targeting of these stem cells until now.”

In addition to isolating and labeling leukemic stem cells, Dr. Milyavsky and his team were able to demonstrate that the leukemic stem cells labeled by their biosensor were sensitive to an inexpensive cancer drug, highlighting the potential this technology has in creating more patient-specific treatment options.

In the article, Dr. Milyavsky said:

” Using this sensor, we can perform personalized medicine oriented to drug screens by barcoding a patient’s own leukemia cells to find the best combination of drugs that will be able to target both leukemia in bulk as well as leukemia stem cells inside it.”

The researchers are now investigating genes that are active in leukemic stem cells in the hope finding other druggable targets.

CIRM has funded two clinical trials that also use a more targeted approach for cancer treatment. One of these trials uses an antibody to treat chronic lymphocytic leukemia (CLL) and the other trial uses a different antibody to treat acute myeloid leukemia (AML).