Roche to buy gene-therapy developer

Spark Therapeutics Inc., founded by researchers from Children’s Hospital of Philadelphia, has agreed to be sold to Switzerland-based Roche Holding AG for $4.3 billion, the gene-therapy developer said Monday.

The hospital’s foundation will collect about $430 million of that total for its Spark shares — a big return for the hospital’s $33 million investment since 2013. Venture capitalists and investment funds that backed the company early will also profit.

“This is a resounding affirmation of the vibrancy of the genetic engineering field,” and for Spark co-founder Katherine High, a “terrific” pioneer, said Richard Vague, founder of Philadelphia-based Gabriel Investments and a donor and investor in biotech research.

Roche is also taking over about $500 million in Spark debt, for a total deal value of about $4.8 billion. The sale price is the biggest payout for a gene-therapy company since doctors at research hospitals including Children’s Hospital and the University of Pennsylvania began genetherapy trials in the 1990s, in hopes of giving people the power to fight lethal diseases using their own improved cells.

Spark said it will continue operating in Philadelphia as an independent company within Roche, a $57 billion yearly sales multinational that sells treatments for diseases from acne to cancer.