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

Stanford scientist uses CRISPR-Cas9 and stem cells to develop potential “bubble baby” therapy

Dr. Matthew Porteus, professor of pediatrics at Stanford University.
Photo courtesy of Stanford Medicine.

Our immune system is an important and essential part of everyday life. It is crucial for fighting off colds and, with the help of vaccinations, gives us immunity to potentially lethal diseases. Unfortunately, for some infants, this innate bodily defense mechanism is not present or is severely lacking in function.

This condition is known as severe combined immunodeficiency (SCID), commonly nicknamed “bubble baby” disease because of the sterile plastic bubble these infants used to be placed in to prevent exposure to bacteria, viruses, and fungi that can cause infection. There are several forms of SCID, one of which involves a single genetic mutation on the X chromosome and is known as SCID-X1

Many infants with SCID-X1 develop chronic diarrhea, a fungal infection called thrush, and skin rashes. Additionally, these infants grow slowly in comparison to other children. Without treatment, many infants with SCID-X1 do not live beyond infancy.

SCID-X1 occurs almost predominantly in males since they only carry one X chromosome, with at least 1 in 50,000 baby boys born with this condition. Since females carry two X chromosomes, one inherited from each parent, they are unlikely to inherit two X chromosomes with the mutation present since it would require the father to have SCID-X1.

What if there was a way to address this condition by correcting the single gene mutation? Dr. Matthew Porteus at Stanford University is leading a study that has developed an approach to treat SCID-X1 that utilizes this concept.

By using CRISPR-Cas9 technology, which we have discussed in detail in a previous blog post, it is possible to delete a problematic gene and insert a corrected gene. Dr. Porteus and his team are using CRISPR-Cas9 to edit blood stem cells, which give rise to immune cells, which are the foundation of the body’s defense mechanism. In a study published in Nature, Dr. Porteus and his team have demonstrated proof of concept of this approach in an animal model.

The Stanford team was able to take blood stem cells from six infants with SCID-X1 and corrected them with CRISPR-Cas9. These corrected stem cells were then introduced into mice modeled to have SCID-X1. It was found that these mice were not only able to make immune cells, but many of the edited stem cells maintained their ability to continuously create new blood cells.

In a press release, Dr. Mara Pavel-Dinu, a member of the research team, said:

“To our knowledge, it’s the first time that human SCID-X1 cells edited with CRISPR-Cas9 have been successfully used to make human immune cells in an animal model.”

CIRM has previously awarded Dr. Porteus with a preclinical development award aimed at developing gene correction therapy for blood stem cells for SCID-X1. In addition to this, CIRM has funded two other projects conducted by Dr. Porteus related to CRISPR-Cas9. One of these projects used CRISPR-Cas 9 to develop a treatment for chronic sinusitis due to cystic fibrosis and the second project used the technology to develop an approach for treating sickle cell disease.

CIRM has also funded four clinical trials related to SCID. Two of these trials are related to SCID-X1, one being conducted at St. Jude Children’s Research Hospital and the other at Stanford University. The third trial is related to a different form of SCID known as ADA-SCID and is being conducted at UCLA in partnership with Orchard Therapeutics. Finally, the last of the four trials is related to an additional form of SCID known as ART-SCID and is being conducted at UCSF.