For decades, many patients cycled through clinics, medications, and transfusions to manage a genetic blood disorder that can trim life expectancy by as much as 20 years. That changed course in 2023 when the FDA authorized Casgevy and Lyfgenia, the first gene therapies for severe sickle cell disease. "That opens up a whole world of individuals potentially being cured of sickle cell disease," said Dr. Edward Donnell Ivy, who is the chief medical officer at the Sickle Cell Disease Association of America.
The results so far are striking: in studies, 88% to 94% of patients reported complete freedom from severe vaso-occlusive pain crises. The promise is real, though actually getting treated remains a heavy lift.
Gene therapy collects a patient's blood-forming stem cells, edits them to boost healthy hemoglobin, then reinfuses those cells. Before that reinfusion, patients undergo conditioning that includes chemotherapy and transfusions, often with hospital stays that run for weeks. Start to finish, the process can extend to a year, and the conditioning step often causes permanent infertility or sterility.
Casgevy is authorized for patients as young as 2, while Lyfgenia is available beginning at age 12. Both target severe disease, including genotypes such as HbSS and HbS beta zero thalassemia. Likely candidates are those who had at least four pain crises or episodes of acute chest syndrome within the previous 24 months. Estimates suggest roughly 25% to 35% of the population with sickle cell disease meets current clinical criteria.
Despite the curative promise, uptake has lagged. Vertex Pharmaceuticals reported that by the end of 2025, 64 patients worldwide had undergone Casgevy infusions, and an additional 147 had finished their first cell collection. According to Genetix Biotherapeutics, 115 U.S. patients had received Lyfgenia since its 2023 approval, and by late 2025 another 216 had initiated cell collection.
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Prices are steep. A single course lists between 2.2 million and 3.1 million dollars, excluding hospitalizations, chemotherapy, and specialized care. To narrow coverage gaps, the Centers for Medicare and Medicaid Services launched the Cell and Gene Therapy Access Model in 2024, where CMS works with states and manufacturers on patient outcomes based pricing intended to lower costs for the therapy and related care.
Thirty two states, the District of Columbia, and Puerto Rico participate. Coverage still differs across jurisdictions. "Depending on the state that someone is in, some of the coverage may be more comprehensive than others," said Dr. Alexis Thompson, an attending hematologist at Children's Hospital of Philadelphia who also speaks on behalf of the American Society of Hematology.
She added, "The patients' priorities are actually a big part of really trying to figure out what the barriers to access are and how we overcome them."
Sickle cell disease affects about 100,000 people in the U.S., and more than 90% are non Hispanic Black or African American, per the CDC. The biology is punishing: rigid, crescent shaped red blood cells can block blood flow and limit oxygen delivery, driving complications from anemia and chronic fatigue to clots, infections, organ damage, stroke, and episodes of severe pain.
Progress took time. "In the past six or seven years, there's been an explosion" of new therapies, said Dr. Andrew Campbell of Children's National, but "from 1910 until about 2015, there was very little progress in disease modifying treatments for sickle cell disease." Funding lagged too. From 2008 to 2018, NIH support averaged 812 dollars per patient for sickle cell disease versus 2,807 dollars for cystic fibrosis, which affects about 40,000 people in the U.S. Hydroxyurea, approved in 1998, became a mainstay by roughly halving pain crises and reducing hospitalizations and transfusions.
Transplants offered a potential cure for some, but donor matches were a bottleneck. As Ivy noted, gene therapy changes that calculus because patients can serve as their own donor.
For portfolios, the setup is clear: a sizable eligible pool, premium pricing, and early throughput constrained by complex logistics and uneven coverage. If the 2024 CMS model gains traction and more specialized centers expand capacity, utilization could climb, and so could revenue for the companies behind these therapies.
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