Lyfgenia from Bluebird Bio and Casgevy, developed through a partnership between Vertex Pharmaceuticals and CRISPR Therapeutics, each received approval from the Food and Drug Administration (FDA) Friday.
Both treatments involve taking a patient’s owns stem cells and altering them to produce red blood cells that don’t become sickle shaped. Sickle-shaped red blood cells clump together, clog blood vessels and die early, leading to pain and other complications.
After undergoing a round of chemotherapy to kill off the faulty cells, the edited stem cells are transplanted back into the patient.
Up until now, there has only been one viable curative treatment for SCD, a bone marrow transplant. But this option was available to very few people as the best donor — usually a fully related sibling — only has a 1-in-4 chance of being a match.
Now the roughly 100,000 people in the U.S. suffering from the disease, most of whom are Black, have a chance at living without SCD symptoms. However, the cost may prove to be prohibitive.
Vertex has listed the wholesale price of Casgevy as $2.2 million while Bluebird said in a statement that Lyfgenia’s wholesale price will be $3.1 million.
Those who ultimately access these new treatments will need to be aware of some risks.
A concern that has long followed CRISPR is off-target editing, or unintended genetic alterations. While off-target editing may cause changes that have no discernible effect, regulators and doctors have said the risk of an altered stem cell becoming cancerous is present.
Off-target editing was not observed in Vertex’s trials. Two cases of fatal acute myeloid leukemia were observed among clinical trial participants who received Lyfgenia. According to Bluebird, the treatment these patients received was from an earlier version created through a “different manufacturing process and transplant procedure.”
Still, the FDA has attached a black box warning onto Lyfgenia, with officials saying this was done for the sake of transparency and so patients know the risk.
