Bluebird shares dented after gene therapy patient experiences a setback

bluebird's David Davidson

Shares of bluebird bio ($BLUE) took a hit midday Monday after the closely watched biotech noted that one of the patients in a pioneering gene therapy study for beta-thalassemia required two blood transfusions after demonstrating symptoms of anemia following 7 years of being transfusion-free.

This particular case centered on patient 1003 from the LG001 study, which used the original lentiviral vector used to insert a corrective gene into patients. As bluebird went to some pains to point out, the gene therapy pioneer has since developed a new (and hopefully significantly improved) vector, to do the delivery work.

Shares of bluebird nevertheless dropped 15% on the news Monday, another indication that this field is always close to a catalyst, as stocks rev up and slide down in quick reaction to the news of the day.

Gene therapy developers have been enjoying a solid run recently based on the success of Spark Therapeutics' ($ONCE) Phase III trial, which builds on a foundation of data on positive responses. But despite the evidence that gene therapies have provided lasting benefits that have been tracked over years, concerns still linger over whether bluebird and its rivals can deliver lifelong cures. Any evidence that the effect may be limited will likely figure heavily into how these therapies will ultimately be priced, as payers look to hedge patients' gambles on a cure.

Bluebird's chief medical officer is looking to the near future, as the biotech preps for new updates at ASH.

"The data from the LG001 study were invaluable to our efforts over the last five years to optimize our gene therapy approach with improvements to the potency, robustness and manufacturing for the next-generation lentiviral vector, BB305," said bluebird CMO David Davidson in a statement. "LentiGlobin BB305 drug product is being evaluated in three ongoing clinical trials for the treatment of patients with beta-thalassemia major and severe sickle cell disease, and three abstracts related to these ongoing clinical trials have been accepted for presentation at this year's American Society of Hematology's Annual Meeting in December."

- here's the release