CIRM-Funded Project Targeting Sickle Cell Disease Gets Green Light for Clinical Trial

Dr. Matthew Porteus

The US Food and Drug Administration (FDA) has granted Investigational New Drug (IND) permission enabling Graphite Bio to test the investigational, potentially revolutionary gene editing therapy GPH101 developed under the supervision of Matthew Porteus, MD, PhD, in a clinical trial for people with sickle cell disease (SCD).

The California Institute for Regenerative Medicine (CIRM) has been supporting this project with a $5.2 million grant, enabling Dr. Porteus and his team at the Institute of Stem Cell Biology and Regenerative Medicine at Stanford University to conduct the preclinical manufacturing and safety studies required by the FDA.

“We congratulate the Graphite Bio team for obtaining the IND, a critical step in bringing the GPH101 gene therapy forward for Sickle Cell Disease,” says Dr. Maria T. Millan, CIRM’s President & CEO. “CIRM is committed to the national Cure Sickle Cell initiative and are delighted that this technology, the product of CIRM funded research conducted by Dr. Porteus at Stanford, is progressing to the next stage of development”

Sickle cell disease is caused by a genetic mutation that turns normally smooth, round red blood cells into rigid, sickle shaped cells. Those cells clump together, clogging up blood vessels, causing intense pain, damaging organs and increasing the risk of strokes and premature death. There are treatments that help control the damage, but the only cure is a bone marrow stem cell transplant, which can only happen if the patient has a stem cell donor (usually a close relative) who has matching bone marrow.  

The investigational therapy GPH101 harnesses the power of CRISPR and natural DNA repair mechanisms to cut out the single mutation in the sickle globin gene and paste in the correct “code.” Correction of this mutation would reverse the defect and result in healthy non-sickling red blood cells.  

CEDAR, a Phase 1/2, multi-center, open-label clinical study is designed to evaluate the safety, preliminary efficacy and pharmacodynamics of GPH101 in adult and adolescent patients with severe SCD.

For patient advocate Nancy Rene, the news is personal: “It’s always exciting to hear about the progress being made in sickle cell research.  If successful it will mean that my grandson, and especially other young adults, can look forward to a life free of pain and organ damage.  They can actually begin to plan their lives, thinking about careers and families. I want to thank Dr. Porteus and all of the scientists who are working so hard for people with sickle cell disease. This is wonderful news.”

CIRM has funded four clinical trials for Sickle Cell Disease using different approaches and has a unique partnership with the National Heart, Lung and Blood Institutes under the NIH “Cure Sickle Cell” initiative.

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.