Bluebird Bio, Third Rock & Genzyme’s Gene Therapy Bet, Shows Promise for Blood Disorder
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to efficiently deliver their genetic payload inside cells, Bluebird has sought a way around this by delivering the genes into cells when they aren’t even in the body.
Here’s how this is supposed to work. Patients with beta-thalassemia can potentially be cured of their condition by getting a bone marrow transplant, in which the adult blood-forming stem cells from a sibling donor are injected into the patient, Leschly says. Only about 15 to 20 percent of patients are eligible to get this kind of therapy. Bluebird’s therapy is designed to sidestep the problem of finding a genetic match. It extracts the patient’s own adult blood-forming stem cells, and exposes them in the laboratory to the gene therapy, which essentially programs the cells to start producing hemoglobin on their own. Then the blood cells get re-infused into the patient, hopefully with new ability to produce the essential protein.
That’s what the scientists saw happen. Researchers tagged the gene so that when they took blood samples from the patient, they could see that the treated cells were producing more hemoglobin after getting the experimental treatment. The scientists also saw a connection between that improvement in the blood, and the clinical improvement that enabled the patient to stop getting transfusions.
If Bluebird can repeat this kind of finding in more of the patients it enrolls, without any severe side effects popping up later, it could be an important step ahead for gene therapy. But it’s still way too early to really talk about a “breakthrough.”
“What we need to do as a company is continue to enroll more patients, and get this on an aggressive clinical/regulatory path,” Leschly says. “It sounds simple, but to execute on this is not straightforward.” But despite the necessary caveats, Leschly, who left his post as a partner at Third Rock to become Bluebird’s CEO this month, speaks with a voice filled with optimism: “I wouldn’t be here if I wasn’t pretty passionate about it,” he says.