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So Far, So Good in Bluebird’s First Glimpse of Sickle Cell Data

Xconomy Boston — 

Sickle cell is a rare disease; a blood disorder with no effective treatments affecting around 300,000 new patients across the globe every year. While those numbers seem small compared to millions of folks with cardiovascular problems or cancer, they’re monstrous in the context of gene therapy—when, potentially, a single shot could not only wipe out the disease, but command an astronomical price tag.

That’s why a single patient with sickle cell, being treated with a gene therapy from Bluebird Bio (NASDAQ: BLUE), is front and center this morning.

Cambridge, MA-based Bluebird has just submitted an abstract for the upcoming European Hematology Association’s annual meeting in June. That abstract includes some information about that sickle cell patient, as well as some updates from two of the beta-thalassemia patients dosed with Bluebird’s gene therapy, LentiGlobin.

It’s important to note that these data aren’t current; they’re the results Bluebird had as of a Feb. 26 cutoff, or about 4.5 months after treatment in the case of the sickle cell patient. Bluebird will have the latest data at EHA next month. But what the numbers show is that after 4.5 months, that patient is producing more “marked” beta-globin than before—that is, hemoglobin that is the result of Bluebird’s gene therapy—and importantly, anti-sickling hemoglobin, which might alter the course of the disease.

Specifically, 31.6 percent of the hemoglobin the patient is producing is anti-sickling. That’s significant, because Bluebird says, based on historical data, patients who have greater than 30 percent of anti-sickling hemoglobin have the potential to be rid of the severe complications of sickle cell disease.

To this point, that’s been the case with this single sickle cell patient—he hasn’t, as of yet, needed hospitalization for any sickle cell-related complications. The patient was enrolled needing chronic blood transfusions, started being weaned off those transfusions after 37 days, and got his last one 88 days after treatment.

Additionally, Bluebird noted that two beta-thalassemia patients have been on therapy for 14 months and 11 months, respectively, without needing a blood transfusion—a hallmark of the disease. (Just a few days ago, Bluebird said the main goal of its pivotal trials for beta-thalassemia is to halt the need for blood transfusions for one year.) There have been no significant gene therapy-related side effects so far in any of these patients.

Shares of Bluebird climbed about 15 percent in pre-market trading on Thursday.

Sickle cell occurs when a defective gene causes the bone marrow to produce abnormal, flatter, crescent or “sickle” shaped red blood cells. These cells don’t move freely through the bloodstream like normal red blood cells; they’re stiff and liable to get stuck and block blood flow, causing chronic pain that can last for weeks or months at a time, anemia, and damage to organs. Normal blood cells are pliable and transport oxygen from the lungs to the rest of the body.

Sickle cell patients often have to get blood transfusions to boost their levels of normal hemoglobin, the protein in healthy red blood cells that carries oxygen. A drug called hydroxyurea, which helps the body make fetal hemoglobin (the type newborns have), is also approved for the condition.

Still, the only thing available that can cure sickle cell, rather than just manage the symptoms, is a bone marrow transplant, a risky procedure that many patients can’t qualify for. As in the case of beta-thalassemia, Bluebird’s LentiGlobin is supposed to essentially mimic the effects of a bone transplant and restart the production of normal hemoglobin.

The company takes stem cells harvested from a patient’s bone marrow. Then it uses HIV viruses that have been genetically modified to be harmless to insert a healthy version of the beta-globin gene into them. Those cells are then grown in a culture, and infused back into the patient in a one-time procedure. The cells then head to the bone marrow and divide, giving rise to more cells with the correct gene—and eventually (in theory) normal levels of hemoglobin.

Bluebird has soared from an IPO price of $17 to almost ten times that number, $165 a share, off of data in four patients with beta-thalassemia showing it’s been able to rid them—at least so far—of the need for transfusions. Those data have put Bluebird as close as anyone to owning the first FDA-approved gene therapy; and also heightened the anticipation for what LentiGlobin can do for sickle cell patients. After all, about 40,000 people every year are born with the serious form of beta-thalassemia, a fraction of the number with sickle cell (some 20 million to 25 million people currently live with sickle cell, according to Bluebird).