CAMBRIDGE, Mass. (TheStreet) -- Bluebird Bio's (BLUE) gene therapy, administered once to a patient with sickle cell anemia, is increasing the number of normally functioning red blood cells and is just barely at the level believed necessary to have a curative effect on the inherited blood disease.
After four and a half months of follow-up, the sickle cell patient's blood contained 24% "marked" beta globin, a measure of normally functioning hemoglobin, Bluebird announced Thursday. This healthy marked hemoglobin, the oxygen-carrying molecule in red blood cells, is produced by the working gene inserted into patients via Bluebird's gene therapy. Overall, the patient's total anti-sickling hemoglobin was 31.6%, and he has not been re-hospitalized for a sickle-cell related event since being treated with the gene therapy.
Bluebird believes its gene therapy, known as Lentiglobin, can begin to reduce or eliminate the serious and life-threatening events associated with sickle cell disease when "marked" plus other anti-sickling hemoglobin reaches at least 30%.
Three months after the sickle cell patient was infused with Lentiglobin, his blood contained 9.6% marked hemoglobin, Bluebird said. This suggests the performance of Lentiglobin is improving over time, although perhaps more slowly than what the company showed previously in patients with beta thalassemia, a blood disease similar to sickle cell.
The Bluebird Lentiglobin data released Thursday come from an analysis conducted in February. More current data will be presented at the European Hematology Association meeting in June.
In a statement, Bluebird's Chief Medical Officer David Davidson described the new sickle cell data plus an update from beta thalassemia patients also treated with Lentiglobin as "very encouraging" and a validation of the company's gene therapy approach to curing inherited diseases.