Beta thalassemia patients endure a lifetime of blood transfusions that can cause iron overload and life-threatening organ damage, but a new gene therapy developed by bluebird bio (BLUE -8.70%) may be about to change that. On Thursday, bluebird bio unveiled intriguing interim results from trials evaluating its beta thalassemia therapy, LentiGlobin, and so far, those results suggest that LentiGlobin could significantly reduce the need for blood transfusions.

If the data still is positive when these trials finish, bluebird bio plans to file for European Union approval of LentiGlobin by the end of 2018, and that could mean bluebird bio's about to make the leap from clinical-stage to commercial-stage biotech.

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What is beta thalassemia?

Worldwide, roughly 60,000 children are born with beta thalassemia every year, including 1,500 per year in the United States. It's an inherited genetic disorder that prevents patients from adequately producing beta globin, which is necessary for making the oxygen-carrying protein, hemoglobin. Without hemoglobin, most red blood cells die, so to survive, beta thalassemia patients must regularly receive transfusions of red blood cells.

These transfusions are necessary, but they expose patients to life-threatening risks. Over time, red blood cell transfusions can cause iron overload because the human body can't remove iron as quickly as the transfusions add it.

A buildup in iron stores is complicated further by the fact that beta thalassemia patients tend to absorb more iron in the intestines than healthy people. Because excess iron is toxic to cells, iron overload can cause serious and irreversible organ damage, including cirrhosis, diabetes, heart disease, and hypogonadism that results in an increased risk of mortality.

Solving the problem?

LentiGlobin inserts a functional human beta-globin gene into a patient's own hematopoietic stem cells. The process is done outside of the body, or ex vivo, and then the modified cells are infused back into the patient's bloodstream, a process known as autologous stem cell transplantation.

While more data is needed to demonstrate LentiGlobin's effectiveness, bluebird bio's latest results are intriguing. Specifically, 12 of 13 patients who can produce some hemoglobin (non-beta 0/beta 0 genotypes), but were transfusion dependent, didn't need a transfusion for a median 27 months following a single infusion of LentiGlobin. Nine patients with the more severe form of beta thalassemia (beta 0/beta 0 genotypes) also benefited with transfusions being stopped in three patients, and overall median transfusion volume decrease of 73%.

These findings are important because it suggests that LentiGlobin significantly reduces the number of transfusions necessary and the volume of red blood cells transfused. These are two benefits that could substantially lower the risk of iron overload. 

Pathway to market

The interim data is from bluebird bio's Northstar and HGB 205 studies. That's important to know because EU regulators have said they'll consider a conditional approval of LentiGlobin based on the final results from those two trials.

According to management, the Northstar study now is complete and the HGB 205 study is ongoing, but it's expected to wrap up soon. If the final look at data from these trials is positive, then bluebird bio expects to file for an EU green light by the end of 2018.

In the U.S., patients will have to wait a bit longer for beta thalassemia's approval. After discussing a path to market with the Food and Drug Administration, bluebird bio has decided to wait until it also has data from its HGB-207 and HGB-212 trials in hand to file for an OK. According to, HGB-207's estimated completion date is January 2020; for HGB-212, it's April 2021.

Overall, LentiGlobin is one of three gene therapies that's approaching the finish line at bluebird bio. The company's also closing in on fling for approval of a multiple myeloma therapy bb2121 and Lenti-D, a therapy for a rare genetic disorder called cerebral ALD (CALD). If everything goes according to management's plan, these therapies all will be filed by the end of 2019 and potentially, all three could be generating revenue for the company in 2020. Clearly, this is an exciting time for patients, the company, and its investors.