Spark announces hemophilia A data, proposes $300M follow-on

Spark Therapeutics Inc. (NASDAQ:ONCE) jumped $13.13 (20%) to $79.72 on Wednesday after reporting preliminary Phase I/II data showing that a single IV dose of its gene therapy candidate SPK-8011 stabilized Factor VIII activity levels at 14% and 11% of normal in two patients with hemophilia A at weeks 12 and 23, respectively. SPK-8011 is an adeno-associated virus (AAV) vector that delivers the Factor VIII gene.

After market hours on Wednesday, the company also proposed to raise $300 million in a follow-on underwritten by JPMorgan, Goldman Sachs and Cowen...