First doubts about Spark Therapeutics’ gene therapy, company loses $1bn in capitalization

Philadelphia-based Spark Therapeutics yesterday lost over one billion dollars in capitalization after announcing the results of a small-scale Phase I/II clinical trial  conducted with the investigational SPK-8011 gene therapy on 12 patients with hemophilia A. The data showed that the therapy had been efficacious in reducing bleeding in 10 patients.   The therapy hadn’t shown efficacy in 2 patients, and had caused such a serious immune response that one of them had been hospitalized and treated with methylprednisolone. By contrast, Biomarin, direct competitor of Spark Therapeutics’ in the research for a gene therapy for hemophilia, has benefited from the trial’s results, indeed its shares (Nasdaq) have risen by 6.4%. Spark has announced it plans to start an important Phase III clinical trial before the end of the year.

(Source: Spark Therapeutics)