Antibody effective in cure for rare blood disorders

3D illustration of an antibody binding to a designated target.
Illustration created by Audra Geras.

A variety of diseases can be traced to a simple root cause: problems in the bone marrow. The bone marrow contains specialized stem cells known as hematopoietic stem cells (HSCs) that give rise to different types of blood cells. As mentioned in a previous blog about Sickle Cell Disease (SCD), one problem that can occur is the production of “sickle like” red blood cells. In blood cancers like leukemia, there is an uncontrollable production of abnormal white blood cells. Another condition, known as myelodysplastic syndromes (MDS), are a group of cancers in which immature blood cells in the bone marrow do not mature and therefore do not become healthy blood cells.

For diseases that originate in the bone marrow, one treatment involves introducing healthy HSCs from a donor or gene therapy. However, before this type of treatment can take place, all of the problematic HSCs must be eliminated from the patient’s body. This process, known as pre-treatment, involves a combination of chemotherapy and radiation, which can be extremely toxic and life threatening. There are some patients whose condition has progressed to the point where their bodies are not strong enough to withstand pre-treatment. Additionally, there are long-term side effects that chemotherapy and radiation can have on infant children that are discussed in a previous blog about pediatric brain cancer.

Could there be a targeted, non-toxic approach to eliminating unwanted HSCs that can be used in combination with stem cell therapies? Researchers at Stanford say yes and have very promising results to back up their claim.

Dr. Judith Shizuru and her team at Stanford University have developed an antibody that can eliminate problematic blood forming stem cells safely and efficiently. The antibody is able to identify a protein on HSCs and bind to it. Once it is bound, the protein is unable to function, effectively removing the problematic blood forming stem cells.

Dr. Shizuru is the senior author of a study published online on February 11th, 2019 in Blood that was conducted in mice and focused on MDS. The results were very promising, demonstrating that the antibody successfully depleted human MDS cells and aided transplantation of normal human HSCs in the MDS mouse model.

This proof of concept holds promise for MDS as well as other disease conditions. In a public release from Stanford Medicine, Dr. Shizuru is quoted as saying, “A treatment that specifically targets only blood-forming stem cells would allow us to potentially cure people with diseases as varied as sickle cell disease, thalassemia, autoimmune disorders and other blood disorders…We are very hopeful that this body of research is going to have a positive impact on patients by allowing better depletion of diseased cells and engraftment of healthy cells.”

The research mentioned was partially funded by us at CIRM. Additionally, we recently awarded a $3.7 million dollar grant to use the same antibody in a human clinical trial for the so-called “bubble baby disease”, which is also known as severe combined immunodeficiency (SCID). You can read more about that award on a previous blog post linked here.

Friday Roundup: A better kind of blood stem cell transplant; Encouraging news from spinal cord injury trial; Finding an “elusive” cell that could help diabetics

Cool Instagram image of the week:

Pancreatic Progenitors

Diabetes Research Institute scientists have confirmed that the unique stem cells reside within large ducts of the human pancreas. Two such ducts (green) surrounded by three islets (white) are shown. [Diabetes Research Institute Foundation]

Chemo- and radiation-free blood stem cell transplant showing promise

Bubble baby disease, also known as severe combined immunodeficiency (SCID), is an inherited disorder that leaves newborns without an effective immune system. Currently, the only approved treatment for SCID is a blood stem cell transplant, in which the patient’s defective immune system cells are eliminated by chemotherapy or radiation to clear out space for cells from a healthy, matched donor. Even though the disease can be fatal, physicians loathe to perform a stem cell transplant on bubble baby patients:

Shizuru“Physicians often choose not to give chemotherapy or radiation to young children with SCID because there are lifelong effects: neurological impairment, growth delays, infertility, risk of cancer, etc.,” says Judith Shizuru, MD, PhD, professor of medicine at Stanford University.

To avoid these complications, Dr. Shizuru is currently running a CIRM-funded clinical trial testing a gentler approach to prepare patients for blood stem cell transplants. She presented promising, preliminary results of the trial on Tuesday at the annual meeting of Stanford’s Center for Definitive and Curative Medicine.

Trial participants are receiving a protein antibody called CD117 before their stem cell transplant. Previous studies in animals showed that this antibody binds to the surface of blood stem cells and blocks the action of a factor which is required for stem cell survival. This property of CD117 provides a means to get rid of blood stem cells without radiation or chemotherapy.

Early results in two participants indicate that, 6 and 9 months after receiving the CD117 blood stem cell transplants, the donor cells have successfully established themselves in the patients and begun making immune cells.

Spinal cord injury trial reports more promising results:

AsteriasRegular readers of our blog will already know about our funding for the clinical trial being run by Asterias Biotherapeutics to treat spinal cord injuries. The latest news from the company is very encouraging, in terms of both the safety and effectiveness of the treatment.

Asterias is transplanting stem cells into patients who have suffered recent injuries that have left them paralyzed from the neck down. It’s hoped the treatment will restore connections at the injury site, allowing patients to regain some movement and feeling in their hands and arms.

This week the company announced that of the 25 patients they have treated there have been no serious side effects. In addition:

  • Magnetic Resonance Imaging (MRI) scans show that in more than 90 percent of the patients the cells appear to show signs of engraftment
  • At least 75 percent of those treated have recovered at least one motor level, and almost 20 percent have recovered two levels

In a news release, Michael Mulroy, Asterias’ President and CEO, said:

“The positive safety profile to date, the evidence supporting engraftment of the cells post-implantation, and the improvements we are seeing in upper extremity motor function highlight the promising findings coming from this Phase 1/2a clinical trial, which will guide us as we work to design future studies.”

There you are! Finding the “elusive” human pancreatic progenitor cells – the story behind our cool Instagram image of the week.

Don’t you hate it when you lose something and can’t find it? Well imagine the frustration of scientists who were looking for a group of cells they were sure existed but for decades they couldn’t locate them. Particularly as those cells might help in developing new treatments for diabetes.

Diabetes-Research-Institute_University-of-Miami-Miller-School-of-MedicineWell, rest easy, because scientists at the Diabetes Research Institute at the University of Miami finally found them.

In a study, published in Genetic Engineering and Biotechnology News, the researchers show how they found these progenitor cells in the human pancreas, tucked away in the glands and ducts of the organ.

In type 1 diabetes, the insulin-producing cells in the pancreas are destroyed. Finding these progenitor cells, which have the ability to turn into the kinds of cells that produce insulin, means researchers could develop new ways to regenerate the pancreas’ ability to function normally.

That’s a long way away but this discovery could be an important first step along that path.