18 months into the first serious clinical trials of CRISPR gene therapy for sickle cell disease and beta-thalassemia—and all patients are free from symptoms and have not needed blood transfusions.

Sickle cell disease (SCD) can cause a variety of health problems including episodes of severe pain, called vaso-occlusive crises, as well as organ damage and strokes.

Patients with transfusion-dependent thalassemia (TDT) are dependent on blood transfusions from early childhood.

The only available cure for both diseases is a bone marrow transplant from a closely related donor, an option that is not available for the vast majority of patients because of difficulty locating matched donors, the cost, and the risk of complications.

In the studies, the researchers' goal is to functionally cure the blood disorders using CRISPR/Cas9 gene-editing by increasing the production of fetal hemoglobin, which produces normal, healthy red blood cells as opposed to the misshapen cells produced by faulty hemoglobin in the bodies of individuals with the disorders.

The clinical trials involve collecting stem cells from the patients. Researchers edit the stem cells using CRISPR-Cas9 and infuse the gene-modified cells into the patients. Patients remain in the hospital for approximately one month following the infusion.

Prior to receiving their modified cells, the seven patients with beta thalassemia required blood transfusions approximately every three to four weeks and the three patients with SCD suffered episodes of severe pain roughly every other month.

All the individuals with beta thalassemia have been transfusion independent since receiving the treatment, a period ranging between two and 18 months.

Similarly, none of the individuals with SCD have experienced vaso-occlusive crises since CTX001 infusion. All patients showed a substantial and sustained increase in the production of fetal hemoglobin.

15 months on, and the first patient to receive the treatment for SCD, Victoria Gray, has even been on a plane for the first time.

Before receiving CRISPR gene therapy, Gray worried that the altitude change would cause an excruciating pain attack while flying. Now she no longer worries about such things.

She told NPR of her trip to Washington, D.C: "It was one of those things I was waiting to get a chance to do… It was exciting. I had a window. And I got to look out the window and see the clouds and everything."

This December, the New England Journal of Medicine published the first peer-reviewed research paper from the study—it focuses on Gray and the first TDT patient who was treated with an infusion of billions of edited cells into their body.

"There is a great need to find new therapies for beta thalassemia and sickle cell disease," said Haydar Frangoul, MD, Medical Director of Pediatric Hematology and Oncology at Sarah Cannon Research Institute, HCA Healthcare's TriStar Centennial Medical Center. "What we have been able to do through this study is a tremendous achievement. By gene editing the patient's own stem cells we may have the potential to make this therapy an option for many patients facing these blood diseases."

Because of the precise way CRISPR-Cas9 gene editing works, Dr. Frangoul suggested the technique could potentially cure or ameliorate a variety of diseases that have genetic origins.

As WS has reported, researchers are already using CRISPR to try and treat cancer, Parkinson's, heart disease, and HIV, as well.

Source: American Society of Hematology