Stem Cells Out, Stem Cells In
Last year, Yusuf went to Cohen Children’s Medical Center to donate stem cells, which were sent to a laboratory where they were genetically engineered to add copies of the beta-globin gene. Then, in January 2024, the modified stem cells were infused back into Yusuf after he underwent chemotherapy to make room for them in his bone marrow.
In April, a bald-headed Yusuf played with toy dinosaurs while his mother and clinicians met the media at a hospital press conference about his so-far-successful treatment. Early reports about the efficacy of the treatment suggest it may be the proverbial “game changer” for many of the estimated 100,000-plus people in the world who are diagnosed with transfusion-dependent beta thalassemia each year.
Over a median follow-up of 29.5 months, 20 of 22 patients treated with beti-cel no longer needed transfusions, according to a 2022 open-label phase 3 study published in the New England Journal of Medicine. Only one adverse event — thrombocytopenia in one patient — was considered both serious and related to the treatment, the industry-funded trial reported.
Costly Treatment Seems to Be Cost-Effective
As of 2022, gene therapy for transfusion-dependent beta thalassemia was listed as $2.8 million per treatment making it the most expensive single-treatment therapy ever approved in the United States. The price is “extraordinary,” said Dr. Thompson. “For some families, it gives them pause when they first hear about it.”
The hospital makes the case to insurers that covering the treatment is cost-effective in the long run, considering the high cost of traditional treatment, she said. “We’ve been very successful in getting coverage.”
In addition, the independent Institute for Clinical and Economic Review reported in 2022 that the treatment will be cost-effective at the “anticipated price of $2.1 million with an 80% payback option for patients who do not achieve and maintain transfusion independence over a 5-year period.”
Moving Forward, Clinicians Want to Reduce Complications
What’s next for transfusion-dependent beta thalassemia treatment? Earlier this year, the FDA approved a second gene therapy treatment called exagamglogene autotemcel (exa-cel, Casgevy). “We’re just beginning to evaluate individuals for the product, and we intend to make it available for families as well,” Dr. Thompson said.
In the bigger picture, she said gene therapy still has room for improvement. The need for chemotherapy is one target. According to her, it causes most of the complications related to gene therapy.
“Chemotherapy is a part of all gene therapies today because one has to make space in the bone marrow in order to have modified stem cells to come back to settle in and grow,” she said.
One strategy is to reduce the number of stem cells that are required for the therapy to work. “That would essentially eliminate the need for chemotherapy,” she said. “We’re not there yet.”
Another goal is to reduce the small risk of complications from gene therapy itself, she said. “Overall, though, this doesn’t detract us at all from being very excited about how well children are doing with the current approach. We’re very enthusiastic and very confident in recommending it to families.”