A big weekend for bluebird bio (BLUE), the company reported on Saturday that the first two patients taking LentiGlobin, its product candidate for the treatment of beta-thalassemia major, had rapid and sustained responses to the gene therapy. Beta-thalassemia is a genetic blood disorder that reduces the production of hemoglobin, the protein in red blood cells that carries oxygen to cells throughout the body. Patients are typically dependent on lifelong blood transfusions due to chronic anemia.
In the small study (bluebird expects a total of 7 patients at completion), bluebird reported at the congress of the European Hematology Association (EHA) that patients one and two at 6.5 months and 3.5 months post-transplant, respectively, remain completely blood-transfusion independent. Subject 1 had a total hemoglobin of 10.1 g/dL, and at 2 months Subject 2 had a total hemoglobin of 11.6 g/dL.
In trading on Monday morning, investors have driven BLUE up 65% to top a one billon dollar valuation. The market is rewarding BLUE for what appears to be the first efficacious gene therapy to emerge from the sector.
The results are still early and, of course, in a small population, but are made more encouraging by comparison to an earlier version of LentiBlogin, the lentiviral HPV569, on which just one of four patients treated became transfusion-independent. bluebird reported Vector Copy Numbers (quantification of the cells benefitting from the new gene) for Subjects 1 and 2 on LentiBlogin of 1.5 and 2.1, respectively, significantly higher than the VCN 0.6 and 0.3 for Subjects 3 and 4 on HPV569.
