Partners in health

From left to right: Heather Dahlenburg, Jan Nolta, Jeannine Logan White, Sheng Yang
From left to right: Heather Dahlenburg, staff research associate; Jan Nolta, director of the Stem Cell Program; Jeannine Logan White, advanced cell therapy project manager; Sheng Yang, graduate student, Bridges Program, Humboldt State University, October 18, 2019. (AJ Cheline/UC Davis)

At CIRM we are modest enough to know that we can’t do everything by ourselves. To succeed we need partners. And in UC Davis we have a terrific partner. The work they do in advancing stem cell research is exciting and really promising. But it’s not just the science that makes them so special. It’s also their compassion and commitment to caring for patients.

What follows is an excerpt from an article by Lisa Howard on the work they do at UC Davis. When you read it you’ll see why we are honored to be a part of this research.

Gene therapy research at UC Davis

UC Davis’ commitment to stem cell and gene therapy research dates back more than a decade.

In 2010, with major support from the California Institute for Regenerative Medicine (CIRM), UC Davis launched the UC Davis Institute for Regenerative Cures, which includes research facilities as well as a Good Manufacturing Practice (GMP) facility.

In 2016, led by Fred Meyers, a professor in the School of Medicine, UC Davis launched the Center for Precision Medicine and Data Sciences, bringing together innovations such as genomics and biomedical data sciences to create individualized treatments for patients.

Last year, the university launched the Gene Therapy Center, part of the IMPACT Center program.

Led by Jan Nolta, a professor of cell biology and human anatomy and the director of the UC Davis Institute for Regenerative Cures, the new center leverages UC Davis’ network of expert researchers, facilities and equipment to establish a center of excellence aimed at developing lifelong cures for diseases.

Nolta began her career at the University of Southern California working with Donald B. Kohn on a cure for bubble baby disease, a condition in which babies are born without an immune system. The blood stem cell gene therapy has cured more than 50 babies to date.

Work at the UC Davis Gene Therapy Center targets disorders that potentially can be treated through gene replacement, editing or augmentation.

“The sectors that make up the core of our center stretch out across campus,” said Nolta. “We work with the MIND Institute a lot. We work with the bioengineering and genetics departments, and with the Cancer Center and the Center for Precision Medicine and Data Sciences.”

A recent UC Davis stem cell study shows a potential breakthrough for healing diabetic foot ulcers with a bioengineered scaffold made up of human mesenchymal stem cells (MSCs). Another recent study revealed that blocking an enzyme linked with inflammation enables stem cells to repair damaged heart tissue. A cell gene therapy study demonstrated restored enzyme activity in Tay-Sachs disease affected cells in humanized mouse models.

Several cell and gene therapies have progressed to the point that ongoing clinical trials are being conducted at UC Davis for diseases, including sickle-cell anemia, retinopathy, muscle injury, dysphasia, advanced cancer, and Duchenne muscular dystrophy, among others.

“Some promising and exciting research right now at the Gene Therapy Center comes from work with hematopoietic stem cells and with viral vector delivery,” said Nolta.

Hematopoietic stem cells give rise to other blood cells. A multi-institutional Phase I clinical trial using hematopoietic stem cells to treat HIV-lymphoma patients is currently underway at UC Davis.

.Joseph Anderson

Joseph Anderson

“We are genetically engineering a patient’s own blood stem cells with genes that block HIV infection,” said Joseph Anderson, an associate professor in the UC Davis Department of Internal Medicine. The clinical trial is a collaboration with Mehrdad Abedi, the lead principal investigator.

“When the patients receive the modified stem cells, any new immune system cell, like T-cell or macrophage, that is derived from one of these stem cells, will contain the HIV-resistant genes and block further infection,” said Anderson.

He explained that an added benefit with the unique therapy is that it contains an additional gene that “tags” the stem cells. “We are able to purify the HIV-resistant cells prior to transplantation, thus enriching for a more protective cell population.

Kyle David Fink

Kyle David Fink

Kyle David Fink, an assistant professor of neurology at UC Davis, is affiliated with the Stem Cell Program and Institute for Regenerative Cures. His lab is focused on leveraging institutional expertise to bring curative therapies to rare, genetically linked neurological disorders.

“We are developing novel therapeutics targeted to the underlying genetic condition for diseases such as CDKL5 deficiency disorder, Angelman, Jordan and Rett syndromes, and Juvenile Huntington’s disease,” said Fink.

The lab is developing therapies to target the underlying genetic condition using DNA-binding domains to modify gene expression in therapeutically relevant ways. They are also creating novel delivery platforms to allow these therapeutics to reach their intended target: the brain.

“The hope is that these highly innovative methods will speed up the progress of bringing therapies to these rare neurodegenerative disease communities,” said Fink.Jasmine Carter, a graduate research assistant at the UC Davis Stem Cell Program.

Jasmine Carter, a graduate research assistant at the UC Davis Stem Cell Program, October 18, 2019. (AJ Cheline/UC Davis)

Developing potential lifetime cures

Among Nolta’s concerns is how expensive gene therapy treatments can be.

“Some of the therapies cost half a million dollars and that’s simply not available to everyone. If you are someone with no insurance or someone on Medicare, which reimburses about 65 percent, it’s harder for you to get these life-saving therapies,” said Nolta.

To help address that for cancer patients at UC Davis, Nolta has set up a team known as the “CAR T Team.”

Chimeric antigen receptor (CAR) T-cell therapy is a type of immunotherapy in which a patient’s own immune cells are reprogrammed to attack a specific protein found in cancer cells.

“We can develop our own homegrown CAR T-cells,” said Nolta. “We can use our own good manufacturing facility to genetically engineer treatments specifically for our UC Davis patients.”

Although safely developing stem cell treatments can be painfully slow for patients and their families hoping for cures, Nolta sees progress every day. She envisions a time when gene therapy treatments are no longer considered experimental and doctors will simply be able to prescribe them to their patients.

“And the beauty of the therapy is that it can work for the lifetime of a patient,” said Nolta.

CIRM Bridges program prepared student for research of a rare disease

Ian Blong, Ph.D., CIRM San Francisco State University Bridges to Stem Cell Research Alumnus

Recently, The New York Times released a powerful article that tells the stories of four different families navigating the challenges of having a family member with a rare disease. One of these stories focused on Matt Wilsey, a tech entrepreneur and investor in California’s Silicon Valley, and his daughter Grace, who was born with an extremely rare genetic disorder named NGLY1 deficiency. This genetic disorder causes developmental delay, intellectual disability, seizures, and other movement issues.

Matt and Kristen Wilsey with their 10-year-old daughter Grace, who has a rare genetic disorder, at the Grace Science headquarters in Menlo Park, Calif.
Image Credit: James Tensuan for The New York Times

Matt decided to put his entrepreneurial and networking skills to good use in order to form Grace Science Foundation, an organization whose focus is to pioneer approaches to scientific discovery in order to develop a cure for NGLY1 deficiency. One researcher that Matt brought on board was Carolyn Bertozzi, Ph.D., a chemist from Stanford University. A graduate student in her laboratory, Ian Blong, Ph.D., decided to study NGLY1 and was able to complete his dissertation while working on this topic at Stanford University.

Ian’s journey towards obtaining his Ph.D. started after being accepted into the San Francisco State University (SFSU) CIRM Bridges to Stem Cell Research Master’s Program. CIRM funding for this program allowed students like Ian to take courses at SFSU while also working in labs at world renown institutions in the Bay Area such as UCSF, Stanford, and UC Berkeley.

Carolyn Bertozzi, Ph.D.
Image Credit: L.A. Cicero

In exploring the various options afforded to him by the CIRM, Ian found Dr. Bertozzi’s lab at UC Berkeley, where he focused on early stage discovery research. His master’s thesis project focused on how to generate rare neuronal and and neural crest cells from human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs). Both of these stem cell types can generate virtually any kind of cell, but iPSCs are unique in that they can be generated from the adult cells (such as skin) of a patient.

Ian decided to continue his studies in Dr. Bertozzi’s lab by continuing his research in a Ph.D. program at UC Berkeley. He credits the SFSU CIRM Bridges Program with giving him the opportunity to work under a prestigious PI and in her lab at UC Berkeley, which allowed him to continue his studies there.

“The CIRM Bridges Program gave me the confidence and resources to pursue my dreams. Being able to have the capability of going to Berkeley and do research with top tier scientists along with the support from CIRM. Without CIRM, I wouldn’t have had the courage to go to those universities to get my foot in the door.”

Eventually, Dr. Bertozzi move her operations to Stanford University and Ian continued his Ph.D. studies there. Stanford provided him the opportunity to focus more on the translational stage, which is an area of research aimed at developing a therapeutic candidate. Going into his Ph.D. work, Ian was able to build upon his previous “discovery stage” knowledge of generating neuronal and neural crest cells from iPSCS and hESCs.

An area of his work at Stanford focused on generating neural crest cells from iPSCs of those with NGLY1 deficiency. The goal was to identify a phenotype, which is an observable characteristic such as physical form. Identifying this would help better understand potential differentiation pathways that underlie NGLY1 deficiency, which could lead to the development a potential treatment for the condition.

Flash forward to present day and Ian is still using the knowledge he learned from his time in the SFSU CIRM Bridges to Stem Cell Research Program. He is currently a scientist at the healthcare company Roche, where his focus is on manufacturing future diagnostics and therapeutics on a much larger scale, a complex and extremely critical process necessary in widely distributing potential stem cell-based treatments.

Ian’s experience and opportunities provided to him is just one of the many examples of how the various CIRM Bridges Programs across California have given students the resources needed to become the next generation of scientists.

It’s all about the patients

Ronnie, born with a fatal immune disorder now leading a normal life thanks to a CIRM-funded stem cell/gene therapy: Photo courtesy of his mum Upasana

Whenever you are designing something new you always have to keep in mind who the end user is. You can make something that works perfectly fine for you, but if it doesn’t work for the end user, the people who are going to work with it day in and day out, you have been wasting your time. And their time too.

At CIRM our end users are the patients. Everything we do is about them. Starting with our mission statement: to accelerate stem cell treatments to patients with unmet medical needs. Everything we do, every decision we make, has to keep the needs of the patient in mind.

So, when we were planning our recent 2020 Grantee Meeting (with our great friends and co-hosts UC Irvine and UC San Diego) one of the things we wanted to make sure didn’t get lost in the mix was the face and the voice of the patients. Often big conferences like this are heavy on science with presentations from some of the leading researchers in the field. And we obviously wanted to make sure we had that element at the Grantee meeting. But we also wanted to make sure that the patient experience was front and center.

And we did just that. But more on that in a minute. First, let’s talk about why the voice of the patient is important.

Some years ago, Dr. David Higgins, a CIRM Board member and patient advocate for Parkinson’s Disease (PD), said that when researchers are talking about finding treatments for PD they often focus on the dyskinesia, the trembling and shaking and muscle problems. However, he said if you actually asked people with PD you’d find they were more concerned with other aspects of the disease, the insomnia, anxiety and depression among other things. The key is you have to ask.

Frances Saldana, a patient advocate for research into Huntington’s disease

So, we asked some of our patient advocates if they would be willing to be part of the Grantee Meeting. All of them, without hesitation, said yes. They included Frances Saldana, a mother who lost three of her children to Huntington’s disease; Kristin MacDonald, who lost her sight to a rare disorder but regained some vision thanks to a stem cell therapy and is hoping the same therapy will help restore some more; Pawash Priyank, whose son Ronnie was born with a fatal immune disorder but who, thanks to a stem cell/gene therapy treatment, is now healthy and leading a normal life.

Because of the pandemic everything was virtual, but it was no less compelling for that. We interviewed each of the patients or patient advocates beforehand and those videos kicked off each session. Hearing, and seeing, the patients and patient advocates tell their stories set the scene for what followed. It meant that the research the scientists talked about took on added significance. We now had faces and names to highlight the importance of the work the scientists were doing. We had human stories. And that gave a sense of urgency to the work the researchers were doing.

But that wasn’t all. After all the video presentations each session ended with a “live” panel discussion. And again, the patients and patient advocates were a key part of that. Because when scientists talk about taking their work into a clinical trial they need to know if the way they are setting up the trial is going to work for the patients they’re hoping to recruit. You can have the best scientists, the most promising therapy, but if you don’t design a clinical trial in a way that makes it easy for patients to be part of it you won’t be able to recruit or retain the people you need to test the therapy.

Patient voices count. Patient stories count.

But more than anything, hearing and seeing the people we are trying to help reminds us why we do this work. It’s so easy to get caught up in the day to day business of our jobs, struggling to get an experiment to work, racing to get a grant application in before the deadline. Sometimes we get so caught up in the minutiae of work we lose sight of why we are doing it. Or who we are doing it for.

At CIRM we have a saying; come to work every day as if lives depend on you, because lives depend on you. Listening to the voices of patients, seeing their faces, hearing their stories, reminds us not to waste a moment. Because lives depend on all of us.

Here’s one of the interviews that was featured at the event. I do apologize in advance for the interviewer, he’s rubbish at his job.

CIRM-funded kidney transplant procedure eyeing faster approval

Kidney transplant surgery.

Medeor Therapeutics, which is running a CIRM-funded clinical trial to help people getting kidney transplants, just got some really good news. The US Food and Drug Administration (FDA) has just granted their product Regenerative Medicine Advanced Therapy (RMAT) designation. That’s a big deal because it means they may be able to apply for faster review and approval and get their therapy to more patients faster.

Here’s why that RMAT designation matters.

Over 650,000 Americans suffer from end-stage kidney disease – a life-threatening condition caused by the loss of kidney function. The best available treatment for these patients is a kidney transplant from a genetically matched living donor. However, patients who receive a transplant must take life-long immunosuppressive drugs to prevent their immune system from rejecting the transplanted organ. Over time, these drugs are toxic and can increase a patient’s risk of infection, heart disease, cancer and diabetes.  Despite these drugs, many patients still lose transplanted organs due to rejection.

To tackle this problem Medeor is developing a stem cell-based therapy called MDR-101. This is being tested in a Phase 3 clinical trial and it’s hoped it will eliminate the need for immunosuppressive drugs in genetically matched kidney transplant patients.

The company takes blood-forming stem cells and immune cells from the organ donor and infuses them into the patient receiving the donor’s kidney. Introducing the donor’s immune cells into the patient creates a condition called “mixed chimerism” where immune cells from the patient and the donor are able to co-exist. In this way, the patient’s immune system is able to adapt to and tolerate the donor’s kidney, potentially eliminating the need for the immunosuppressive drugs that are normally necessary to prevent transplant rejection.

So how does getting RMAT designation help that? Well, the FDA created the RMAT program to help speed up the development and review of regenerative medicine therapies that can treat, modify, reverse, or cure a serious condition. If MDR-101shows it is both safe and effective RMAT could help it get faster approval for wider use.

In a news release Giovanni Ferrara, President and CEO of Medeor, welcomed the news.

“This important designation underscores the tremendous unmet medical need for alternatives to today’s immunosuppressive therapies for transplantation. We have the potential to help people live longer, healthier lives without the need for high dose and chronic immunosuppression and we thank the FDA for this designation that will assist us progressing as efficiently as possible toward a commercially available product.”

This is the seventh CIRM-supported project that has been granted RMAT designation. The others are jCyte, Lineage, Humacyte, St. Jude’s/UCSF X-linked SCID, Poseida, Capricor

Graphite Bio launches and will prepare for clinical trial based on CIRM-funded research

Josh Lehrer, M.D., CEO of Graphite Bio

This week saw the launch of the 45th startup company enabled by CIRM funding of translational research at California academic institutions. Graphite Bio officially launched with the help of $45M in funding led by bay area venture firms Versant Ventures and Samsara BioCapital to spinout a novel CRISPR gene editing platform from Stanford University to treat severe diseases. Graphite Bio’s lead candidate is for sickle cell disease and it harnesses CRISPR gene correction technology to correct the single DNA mutation in sickle cell disease and to restore normal hemoglobin expression in the red blood cells of sickle cell patients (Learn more about CRISPR from a previous blog post linked here).

Matt Porteus, M.D., Ph.D (left) and Maria Grazia Roncarolo, M.D. (right)
Graphite Bio scientific founders

Matt Porteus, M.D., Ph.D and Maria Grazia Roncarolo, M.D., both from Stanford University, are the company’s scientific founders. Dr. Porteus, Dr. Roncarolo, and the Stanford team are currently supported by a CIRM  late stage preclinical grant  to complete the final preclinical studies and to file an Investigational New Drug application with the FDA, which will enable Graphite Bio to commence clinical studies of the CRISPR sickle cell disease gene therapy candidate in sickle cell patients in 2021.

Josh Lehrer, M.D., was appointed CEO of Graphite Bio and elaborated on the company’s gene editing approach in a news release.

“Our flexible, site-specific approach is extremely powerful and could be used to definitively correct the underlying causes of many severe genetic diseases, and also is applicable to broader disease areas. With backing from Versant and Samsara, we look forward to progressing our novel medicines into the clinic for patients with high unmet needs.”

In a press release, Dr. Porteus take a retrospective look on his preclinical research and its progress towards a clinical trial.

“It is gratifying to see our work on new gene editing approaches being translated into novel therapies. I’m very excited to be working with Versant again on a start-up and I look forward to collaborating with Samsara and the Graphite Bio team to bring a new generation of genetic treatments to patients.”

CIRM’s funding of late stage preclinical projects such this one is critical to its funding model, which de-risks the discovery, translational development and clinical proof of concept of innovative stem cell-based treatments until they can attract industry partnerships. You can learn more about CIRM-enabled spinout companies and CIRM’s broader effort to facilitate industry partnering for its portfolio projects on CIRM’s Industry Alliance Program website.

You can contact CIRM’s Director of Business Development at the email below to learn more about the Industry Alliance Program.

Shyam Patel, Ph.D.
Director, Business Development
Email: spatel@cirm.ca.gov

Meet the people who are changing the future

Kristin MacDonald

Every so often you hear a story and your first reaction is “oh, I have to share this with someone, anyone, everyone.” That’s what happened to me the other day.

I was talking with Kristin MacDonald, an amazing woman, a fierce patient advocate and someone who took part in a CIRM-funded clinical trial to treat retinitis pigmentosa (RP). The disease had destroyed Kristin’s vision and she was hoping the therapy, pioneered by jCyte, would help her. Kristin, being a bit of a pioneer herself, was the first person to test the therapy in the U.S.

Anyway, Kristin was doing a Zoom presentation and wanted to look her best so she asked a friend to come over and do her hair and makeup. The woman she asked, was Rosie Barrero, another patient in that RP clinical trial. Not so very long ago Rosie was legally blind. Now, here she was helping do her friend’s hair and makeup. And doing it beautifully too.

That’s when you know the treatment works. At least for Rosie.

There are many other stories to be heard – from patients and patient advocates, from researchers who develop therapies to the doctors who deliver them. – at our CIRM 2020 Grantee Meeting on next Monday September 14th Tuesday & September 15th.

It’s two full days of presentations and discussions on everything from heart disease and cancer, to COVID-19, Alzheimer’s, Parkinson’s and spina bifida. Here’s a link to the Eventbrite page where you can find out more about the event and also register to be part of it.

Like pretty much everything these days it’s a virtual event so you’ll be able to join in from the comfort of your kitchen, living room, even the backyard.

And it’s free!

You can join us for all two days or just one session on one day. The choice is yours. And feel free to tell your friends or anyone else you think might be interested.

We hope to see you there.

Stem Cell All-Stars, All For You

goldstein-larry

Dr. Larry Goldstein, UC San Diego

It’s not often you get a chance to hear some of the brightest minds around talk about their stem cell research and what it could mean for you, me and everyone else. That’s why we’re delighted to be bringing some of the sharpest tools in the stem cell shed together in one – virtual – place for our CIRM 2020 Grantee Meeting.

The event is Monday September 14th and Tuesday September 15th. It’s open to anyone who wants to attend and, of course, it’s all being held online so you can watch from the comfort of your own living room, or garden, or wherever you like. And, of course, it’s free.

BotaDaniela2261

Dr. Daniela Bota, UC Irvine

The list of speakers is a Who’s Who of researchers that CIRM has funded and who also happen to be among the leaders in the field. Not surprising as California is a global center for regenerative medicine. And you will of course be able to post questions for them to answer.

srivastava-deepak

Dr. Deepak Srivastava, Gladstone Institutes

The key speakers include:

Larry Goldstein: the founder and director of the UCSD Stem Cell Program talking about Alzheimer’s research

Irv Weissman: Stanford University talking about anti-cancer therapies

Daniela Bota: UC Irvine talking about COVID-19 research

Deepak Srivastava: Gladsone Institutes, talking about heart stem cells

Other topics include the latest stem cell approaches to COVID-19, spinal cord injury, blindness, Parkinson’s disease, immune disorders, spina bifida and other pediatric disorders.

You can choose one topic or come both days for all the sessions. To see the agenda for each day click here. Just one side note, this is still a work in progress so some of the sessions have not been finalized yet.

And when you are ready to register go to our Eventbrite page. It’s simple, it’s fast and it will guarantee you’ll be able to be part of this event.

We look forward to seeing you there.

Perseverance: from theory to therapy. Our story over the last year – and a half

Some of the stars of our Annual Report

It’s been a long time coming. Eighteen months to be precise. Which is a peculiarly long time for an Annual Report. The world is certainly a very different place today than when we started, and yet our core mission hasn’t changed at all, except to spring into action to make our own contribution to fighting the coronavirus.

This latest CIRM Annual Reportcovers 2019 through June 30, 2020. Why? Well, as you probably know we are running out of money and could be funding our last new awards by the end of this year. So, we wanted to produce as complete a picture of our achievements as we could – keeping in mind that we might not be around to produce a report next year.

Dr. Catriona Jamieson, UC San Diego physician and researcher

It’s a pretty jam-packed report. It covers everything from the 14 new clinical trials we have funded this year, including three specifically focused on COVID-19. It looks at the extraordinary researchers that we fund and the progress they have made, and the billions of additional dollars our funding has helped leverage for California. But at the heart of it, and at the heart of everything we do, are the patients. They’re the reason we are here. They are the reason we do what we do.

Byron Jenkins, former Naval fighter pilot who battled back from his own fight with multiple myeloma

There are stories of people like Byron Jenkins who almost died from multiple myeloma but is now back leading a full, active life with his family thanks to a CIRM-funded therapy with Poseida. There is Jordan Janz, a young man who once depended on taking 56 pills a day to keep his rare disease, cystinosis, under control but is now hoping a stem cell therapy developed by Dr. Stephanie Cherqui and her team at UC San Diego will make that something of the past.

Jordan Janz and Dr. Stephanie Cherqui

These individuals are remarkable on so many levels, not the least because they were willing to be among the first people ever to try these therapies. They are pioneers in every sense of the word.

Sneha Santosh, former CIRM Bridges student and now a researcher with Novo Nordisk

There is a lot of information in the report, charting the work we have done over the last 18 months. But it’s also a celebration of everyone who made it possible, and our way of saying thank you to the people of California who gave us this incredible honor and opportunity to do this work.

We hope you enjoy it.

Stem cell transplant in utero offers potential treatment for congenital diseases

Dr. Tippi Mackenzie, UCSF
Image Credit: UCSF

Each year, around 24,000 women in the US lose a pregnancy. One reason for this unfortunate occurrence are metabolic disorders, one of which is known as Sly syndrome and is caused by a single genetic mutation. In Sly syndrome, the body’s cells lack an enzyme necessary for proper cell function. Many fetuses with this condition die before birth but those that survive are treated with regular injections of the lacking enzyme. Unfortunately, patients can eventually develop an immune response to these injections and it cannot enter the brain after birth.

However, a team of researchers at UCSF are looking at exploring a potential treatment that could be delivered in-utero. In a CIRM supported study, Dr. Tippi Mackenzie and Dr. Quoc-Hung Nguyen transplanted blood-forming stem cells from normal mice into fetal mice carrying the genetic mutation for Sly syndrome. The researchers were most interested to see whether these cells could reach the brain, and whether they would change into cells called microglia, immune cells that originate from blood-forming stem cells. In a normally developing fetus, once matured, microglia produce and store the necessary enzyme, as well as regulate the immune environment of the brain.

Stem cells transplanted in utero (green) engrafted into fetal mouse brain tissue. 
Image credit: Q-H Nguyen/MacKenzie lab.

The researchers found that the stem cells were able to engraft in the brain, liver, kidney, and other organs. Furthermore, these stem cells were able to eventually turn into the appropriate cell type needed to produce the enzyme in each of the organs.

In a press release, Dr. Mackenzie talks about the impact that this potential treatment could have.

“This group of vulnerable patients has been relatively ignored in the fetal surgery world. We know these patients could potentially benefit from a number of medical therapies. So this is our first foray into treating one of those diseases.”

In the same press release, Dr. Nguyen talks about the impact of the results from this study.

“These exciting findings are just the tip of the iceberg. They open up a whole new approach to treating a range of diseases. At the same time, there’s also a lot of work to do to optimize the treatment for humans.”

The next step for Dr. Mackenzie is to apply to the U.S. Food and Drug Administration to launch a clinical trial of enzyme replacement therapy that will ultimately enroll patients with Sly syndrome and related metabolic disorders.

This approach is similar to a CIRM funded trial conducted by Dr. Mackenzie that involves a blood stem cell transplant in utero.

The full results to this study were published in Science Translational Medicine.

Dashed Dreams and New Hope: A Quest to Cure Thymic Deficiency

By Kelly Shepard, PhD., CIRM’s Associate Director, Discovery & Translation

CIRM has previously blogged about advances in treating certain forms of  “bubble baby” disease”, where a person is born with a defect in their blood forming stem cells that results in a deficient immune system, rendering them vulnerable to lethal infections by all manner of bacteria, virus or germ.

If a suitable donor can be found, or if the patient’s own defective cells can be corrected through gene therapy approaches, it is now possible to treat or cure such disorders through a bone marrow transplant. In this procedure, healthy blood stem cells are infused into the patient, taking up residence in his or her bone marrow and dividing to give rise to functioning immune cells such as T cells and B cells.

Unfortunately, there is another type of “bubble baby” disease that cannot be treated by providing healthy blood stem cells, because the defective immune system is caused by a different culprit altogether- a missing or dysfunctional thymus.

Created for the National Cancer Institute, http://www.cancer.gov

T Cells Go to School

What is a thymus?  Most of us give little thought to this leaf-shaped organ, which is large and important in our early childhoods, but becomes small and inconspicuous as we age. This transformation belies the critical role a thymus plays in the development of our adaptive immune systems, which takes place in our youth: to prepare our bodies to fight infections for the rest of our lives.

One might think of the thymus as a “school”, where immature T cells go to “learn” how to recognize and attack foreign antigens (surface markers), such as those found on microorganisms or tissues from other individuals. The thymus also “teaches” our immune system to distinguish “self” from “other” by eliminating any T cells that attack our own tissues. Without this critical function, our immune system could inadvertently turn against us, causing serious autoimmune disorders such as ulcerative colitis and myasthenia gravis.

Many children with a severely deficient or absent thymus, referred to as athymia, have inherited a chromosome that is missing a key stretch of genes on a region called 22q11. Doctors believe perhaps 1/2000-1/4000 babies are born with some type of deletion in this region, which leads to a variable spectrum of disorders called 22q11 syndrome that can affect just about any part of the body, and can even cause learning disabilities and mental illness.

Individuals with one form of 22q11, called DiGeorge Syndrome, are particularly affected in the heart, thymus, and parathyroid glands. In the United States, about 20 infants are born per year with the “complete” and most severe form of DiGeorge Syndrome, who lack a thymus altogether, and have severely depressed numbers of T cells for fighting infections. Without medical intervention, this condition is usually fatal by 24 months of age.

Optimism and Setback                                                                  

Although there are no therapies approved by the Food and Drug Administration (FDA) for pediatric athymia, Dr. Mary Louise Markert at Duke University and Enzyvant, Inc. have been pioneering an experimental approach to treat children with complete DiGeorge syndrome.

In this procedure, discarded thymic tissues are collected from infants undergoing cardiac surgery, where some of the thymus needs to be removed in order for the surgeon to gain access to the heart. These tissues are processed to remove potentially harmful donor T cells and then transplanted into the thigh of an athymic DiGeorge patient.

Results from early clinical trials seemed promising, with more than 70% of patients surviving, including several who are now ten years post-transplant. Based on those results, in June of 2019 Enzyvant applied to the FDA for a Biologics License Application (BLA), which is needed to be able to sell the therapy in the US. Unfortunately, only a few months later, Enzyvant announced that the FDA had declined to approve the BLA due to manufacturing concerns.

While it may be possible to address these issues in time, the need to step back to the drawing board was a devastating blow to the DiGeorge Community, who have waited decades for a promising treatment to emerge on the horizon.

New Opportunities

Despite the setback, there is reason to hope. In early 2019, CIRM granted a “Quest” Award to team of investigators at Stanford University to develop a novel stem cell based approach for treating thymic deficiency. Co-led by Katja Weinacht, a pediatric hematologist/oncologist, and Vittorio Sebastiano, a stem cell expert and developmental biologist, the team’s strategy is to coax induced pluripotent stem cells (iPS) in the laboratory to differentiate into thymic tissue, which could then be transplanted into patients using the route pioneered by Duke and Enzyvant.

Katja Weinacht: Photo courtesy Stanford Children’s Health

The beauty of this new approach is that pluripotent stem cells are essentially immortal in culture, providing an inexhaustible supply of fresh thymic cells for transplant, thereby allowing greater control over the quality and consistency of donor tissues. A second major advantage is the possibility of using pluripotent cells from the patient him/herself as the source, which should be perfectly immune-matched and alleviate the risk of rejection and autoimmunity that comes with use of donated tissues.

Vittorio Sebastiano: Photo courtesy Stanford

Sounds easy, so what are the challenges? As with many regenerative medicine approaches, the key is getting a pluripotent stem cell to differentiate into the right type of cells in the lab, which is a very different environment than what cells experience naturally when they develop in the context of an embryo and womb, where many cells are interacting and providing complex, instructive cues to one another. The precise factors and timing all need to be worked out and in most cases, this is done with an incomplete knowledge of human development.

A second challenge relates to using cells from DiGeorge patients to produce thymic tissue, which are missing several genes on their 22nd chromosome and will likely require sophisticated genetic engineering to restore this ability.

Fortunately, Drs. Weinacht and Sebastiano are up to the challenge, and have already made progress in differentiating human induced pluripotent stem cells (iPS) into thymic lineage intermediates that appear to be expressing the right proteins at the right time. They plan to combine these cells with engineered materials to create a three-dimensional (3D) tissue that more closely resembles an authentic organ, and which can be tested for functionality in athymic mice.

There is more work to be done, but these advances, along with continued technological improvements and renewed efforts from Enzyvant, could forge a path to the clinic and  lead to a brighter future for patients suffering from congenital athymia and other forms of thymic dysfunction.