Jan 17, 2024 - Health

FDA expands use of newly approved CRISPR therapy

Axios illustration about CRISPR

Illustration: Rebecca Zisser/Axios

A therapy based on CRISPR gene-editing technology that the Food and Drug Administration approved in December for sickle cell disease can be used for a second inherited blood disorder, the agency said on Tuesday.

Why it matters: The approval expands applications for multimillion-dollar therapies that edit genes directly in a patient's body. But it could present additional cost challenges for employers, public health programs and other payers.

Driving the news: The FDA gave the go-ahead for Vertex Pharmaceuticals and CRISPR Therapeutics' one-time treatment Casgevy to be used for beta thalassemia in patients 12 years and older who need regular blood transfusions.

  • It will compete with a gene therapy with a different mechanism, Bluebird Bio's Zynteglo, which the FDA approved in 2022.
  • Casgevy costs $2.2 million and works by rewriting a patient's stem cells to produce high levels of fetal hemoglobin, which reduces or eliminates the need for transfusions.

Zoom in: Transfusion-dependent beta thalassemia, or TDT, is a life-threatening genetic disease that can cause fatigue, shortness of breath, enlarged organs and delayed puberty. The median age of death is 37 years.

  • Stem cell transplants are another treatment option, but they are only available to a limited number of patients because of the lack of available donors. Vertex said the lifetime cost of managing the condition can be between $5 million and $5.7 million.
  • About 1,000 more patients are eligible for Casgevy after Tuesday's decision on the expanded use. Vertex is initially partnering with nine medical centers with specialized experience in stem cell transplantation.

The intrigue: The FDA extended the approval well ahead of a March 30 deadline for making the decision.

  • "It is exciting to now secure approval for TDT well ahead of the [Prescription Drug User Fee Act] date," said Reshma Kewalramani, Vertex's CEO. "TDT patients deserve new, potentially curative treatment options, and we look forward to bringing Casgevy to eligible patients who are waiting."

Yes, but: One concern surrounding CRISPR is whether the therapy could inadvertently target the wrong genetic sequence and increase the risk of a patient developing cancer.

Go deeper: New sickle cell gene therapies pose cost and access questions

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