Scientists Win $3 Million Prize for Breakthrough Research Leading to First CRISPR Sickle Cell Therapy
Key Insights
Dr. Swee Lay Thein and Dr. Stuart H. Orkin received the $3 million Breakthrough Prize in Life Sciences for foundational research that led to Casgevy, the first approved CRISPR gene therapy for sickle cell disease and beta-thalassemia.
Their research identified the BCL11A (search) gene as a key repressor of fetal hemoglobin production and demonstrated that targeting this gene could provide therapeutic benefits for blood disorders affecting 7-8 million people globally.
While Casgevy represents a functional cure for these devastating diseases, accessibility challenges remain due to the treatment's complexity, cost of several million dollars, and year-long process requiring specialized medical facilities.
Dr. Swee Lay Thein of the National Heart, Lung and Blood Institute (NHLBI) and Dr. Stuart H. Orkin of Harvard University have been awarded the prestigious $3 million Breakthrough Prize in Life Sciences for their groundbreaking research that enabled the development of Casgevy, the first approved CRISPR gene therapy for sickle cell disease and beta-thalassemia. The scientists received their awards at a ceremony in Los Angeles on April 18.
"I feel extremely honored, overwhelmed and humbled," Thein told Live Science following the announcement.
Targeting Devastating Blood Disorders
Sickle cell disease affects approximately 7 million to 8 million people globally, predominantly in Africa. The disorder causes red blood cells to take on a characteristic crescent shape due to hemoglobin forming stiff, long fibrils that deform the cells. These sickled cells stick together, triggering blood clots, and burst easily, causing low red-blood-cell counts.
Patients experience excruciating episodes of pain called "crises" when red blood cells block blood vessels, potentially damaging organs including the lungs, liver and spleen. Lung blockages can trigger "acute chest syndrome," which depletes oxygen levels and represents the leading cause of death in sickle cell patients.
Beta-thalassemia affects hemoglobin production differently, with the body either not making or producing insufficient amounts of one portion of the hemoglobin molecule. People with severe forms require lifelong blood transfusions, and Casgevy is approved to treat this severe form of the disease.
Decades of Scientific Investigation
Thein's research journey began in the 1980s when she investigated why some patients with these blood disorders experienced much milder symptoms than others. The foundation for this work traced back to earlier observations by Dr. Janet Watson, a New York-based pediatrician, who demonstrated that infants who later developed sickle cell disease showed no symptoms initially and had red blood cells that did not sickle.
The key insight emerged from understanding that humans produce different types of hemoglobin during development. "Fetal hemoglobin" is produced in the womb, but its production is turned off as babies mature and "adult hemoglobin" takes over.
"I started collecting families — patients — with mild thalassemia, to try to at least unravel the genetics behind it," Thein explained. "It seemed obvious that they have an innate ability, or natural ability, to continue producing fetal hemoglobin."
Her analysis included extensive genetic studies of families with disease history, including one family of Indian origin comprising more than 200 members spanning seven generations across multiple continents.
Breakthrough Discovery of BCL11A
The crucial breakthrough came from studying pairs of identical and fraternal twins who produced either very high or very low levels of fetal hemoglobin. This research enabled Thein and her colleagues to identify gene variants affecting fetal hemoglobin production, focusing on a region of chromosome 11 called BCL11A (search).
Thein's team discovered that BCL11A (search) functions as a repressor, turning off fetal hemoglobin production as babies develop. However, when people carried certain versions of BCL11A, the repressor failed to function properly, allowing continued high-level fetal hemoglobin production throughout life.
"It's a repressor," Thein said, describing the gene's normal function. The logical therapeutic strategy became clear: repressing the repressor could benefit patients with severe sickle cell disease or beta-thalassemia.
Orkin, a pediatric hematologist and oncologist at Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, and Howard Hughes Medical Institute, provided crucial research demonstrating how the repressor mediated the switch to adult hemoglobin and showed that gene editing could target this region.
Development of Casgevy
The biotech company Vertex utilized CRISPR gene-editing technology to target the BCL11A (search) repressor region, leading to Casgevy's development. The therapy involves extracting a patient's bone marrow cells, editing the BCL11A repressor using CRISPR, and reinfusing the gene-edited cells back into the patient. The modified cells then produce red blood cells with high levels of fetal hemoglobin.
Casgevy represents the first "functional cure" for sickle cell disease and has transformed the lives of patients who have received it. However, significant limitations remain regarding accessibility and implementation.
Treatment Challenges and Future Directions
Despite its breakthrough status, Casgevy faces substantial practical challenges. The treatment process can take up to a year, costs several million dollars, and requires harsh chemotherapy to create space in the bone marrow for gene-edited stem cells to establish themselves.
"Physically, it's very grueling for the patient," Thein noted.
Geographic and resource disparities present additional obstacles. Since sickle cell disease and beta-thalassemia predominantly affect populations in Africa, Asia and the Mediterranean, many patients lack access to the specialized resources and facilities required for such complex treatment.
Scientists are now developing "in vivo" approaches that would involve "actually injecting the gene editing machinery into the patient," according to Thein. This strategy would eliminate the need to extract, edit and reinfuse bone marrow cells, potentially making treatment more accessible.
Alternative Therapeutic Approaches
The ongoing need for more accessible treatments remains pressing. Thein has investigated Mitavipat (search), a drug currently approved for treating pyruvate kinase deficiency and beta-thalassemia. The medication appears to work by improving the overall metabolic health of red blood cells.
"Some of the patients on this drug have been on this treatment and with me for six years, and it has really made quite a big difference," Thein said, though further testing is required to approve its use for sickle cell disease.
The ultimate goal remains developing cheaper, more easily delivered treatments including pills, shots or infusions that could reach the millions of patients worldwide who need them.