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

Donor blood stem cells and T cells could help patients wean off immunosuppressive drugs after organ transplant

Dr. Samuel Strober is refining a process that eliminates the need for the many immunosuppresant drugs normally required after a transplant.
Image credit: Stanford Medicine News Center

In 2019, there were over 23,000 kidney transplants in the United States, according to figures from the United Network for Organ Sharing (UNOS). These transplants can be lifesaving, but the donated organ can be perceived as a foreign invader by the patient’s immune system and attacked. In order to protect the organ from attack, transplant recipients are required to take numerous drugs that suppress the immune system, which are referred to as immunosupressive (IS) drugs. Unfortunately, these drugs, while helping protect the organ, can also cause long term problems such as hypertension, diabetes, heart disease, infection, a high concentration of fats in the blood, and cancer.

To address this problem, Dr. Samuel Strober and his team at Stanford University are conducting a CIRM-funded clinical trial that gives patients getting a kidney transplant a mixture of their own blood cells and cells from the kidney donor, a process called mixed chimerism.

Pairing patients and donors for transplants is done via Human Leukocyte Antigen (HLA) matching. HLA are markers on most cells in your body and are used by your immune system to recognize which cells belong to the body. If you are fully HLA matched that means your cells and the donor cells are immunologically compatible, and so less likely to be rejected. If they are HLA haplotypes, it means they are close but not fully matched so rejection is more likely.

In the trial, fifty-one patients with end stage renal failure that had just received a kidney transplant were infused with blood stem cells (cells that can give rise to different kind of blood cells) and T cells (a cell that plays a role in the immune response) obtained from the donor to achieve a mixed chimerism. Of the 51 patients 29 were fully HLA matched, and 22 were HLA haplotype matched.

Standard IS drugs were administered to all the patients after transplantation and the patients were monitored from six to twelve months to ensure there was no organ rejection or graft vs host disease (GVHD), a condition where donated blood stem cells attack the body.

After this period, the patients were taken off the IS drugs and the results of this trial are very promising. Twenty-four of the fully HLA matched patients with a persistent mixed chimerism for at least six months were able to stop taking the IS drugs without evidence of rejection for at least two years. Ten HLA haplotype matched patients with a persistent mixed chimerism for at least twelve months were able to stop taking some of the IS drugs without rejection.

This is encouraging news for patients undergoing any kind of transplant, leading to hope that one day all patients might be able to get a life-saving organ without having to take the IS drugs forever.

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