The field of gene therapy is making significant strides towards the day when a one-time treatment ― inserting a healthy gene into patients ― could cure a host of inherited, often fatal diseases. But it’s been a rocky road. And new clinical data presented this morning by Bluebird Bio make clear that success is far from guaranteed. Bluebird is testing a gene therapy for two inherited blood disorders ― and the data managed both to impress and to leave important questions unanswered.
On the impressive side: A patient with the inherited blood disease beta-thalassemia, which causes severe anemia, was able to stop regular blood transfusions one month after treatment and achieved a normal level of hemoglobin in six months, according to interim data from an ongoing phase 3 clinical trial. The positive outcome for this patient suggests, but does not yet prove, that manufacturing changes made by Bluebird last year to improve the efficacy of its investigational therapy, Lentiglobin, are having the desired effect.