Only three years ago, the FDA approved the first gene therapies for sickle cell disease (Lyfgenia and Casvegy), historic breakthroughs decades in the making. Yet on World Sickle Cell Awareness Day this year, the reality is that high cost, limited availability, and complex logistics keep these treatments out of reach for most people who need them.  

Yet these breakthroughs offer tremendous hope. For many years, the only treatment option was a matched donor bone marrow transplant. That option is often beyond the reach of most patients because fewer than 20 percent met the strict requirement of an HLA-matched sibling donor. The approach also carries risks such as graft versus host disease.  

Efforts continue to develop other alternative approaches for treatment of sickle cell disease so there are more options available for patients.

 

CIRM’s support for sickle cell research 

Although CIRM did not support the first treatments approved, the agency has invested more than $65 million in developing new or improved approaches to treat sickle cell disease.  

CIRM is currently supporting two clinical trials that are recruiting patients in California, one is a Phase 2 trial the other is Phase 1 trial. Both of these trials are co-funded by CIRM and the National Heart Lung and Blood Institute (NHLBI), a division of the National Institutes of Health (NIH). 

Two current clinical trials 

Both CIRM‑funded trials use the patient’s own bone marrow stem cells. Clinicians collect these cells, treat them with gene therapy outside the body to correct the mutation, and infuse the edited cells back into the patient. The cells then regenerate the blood system with the corrected gene.

In both trials, the gene therapy aims to reduce defective sickling hemoglobin and increase healthy hemoglobin, which should reduce or prevent severe pain crises. The two trials use different approaches to reach this goal.

The Phase 2 trial, led by Dr. David Williams at Boston Children’s Hospital, has treated patients at UCLA Medical Center, Children’s Hospital Los Angeles, UC Davis Medical Center, and UCSF Benioff Children’s Hospital Oakland. This approach increases fetal hemoglobin, a healthy form that does not sickle. The introduced gene therapy reduces expression of the BCL11A gene, allowing fetal hemoglobin to rise.

The Phase 1 trial, led by Dr. Mark Walters at UCSF, uses the gene editing tool CRISPR to directly correct the beta‑globin mutation that causes sickle cell disease. This early‑phase study, enrolling patients at UCSF and UCLA and soon UC Davis, focuses first on safety, with the hope that patients will also benefit from the treatment. 

What is sickle cell disease? 

More than 100,000 people in the United States have sickle cell disease, and about 7 percent live in California. A mutation in the beta‑globin gene causes the disease, making red blood cells stiff and sickle‑shaped. These cells block blood vessels and can trigger severe pain crises, organ damage, and stroke.

Looking Forward 

World Sickle Cell Awareness Day highlights both the urgency and the hope in this field. Despite two approved gene therapies and progress on other potential treatments, too many people still face daily pain and limited options.

California helped drive this era of innovation. CIRM now works to ensure the next era delivers not only scientific breakthroughs but also real-world access. Our goal is to bring safe, lasting, life‑changing treatments to the people who need them most.

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