ZURICH (Reuters) - Roche Holding has extended until May 2 its $4.3 billion (£3.3 billion) offer for U.S. gene therapy specialist Spark Therapeutics, the Swiss drugmaker said after getting only 29.4 percent of Spark's shares in a tender originally due to end on Wednesday.
Roche needs to get at least a majority of outstanding Spark stock for the offer to go through.
"All terms and conditions of the offer shall remain unchanged during the extended period," Roche said in a statement on the $114.50 per share offer it announced in February.
Spark shares closed at $114.01 on Tuesday.
Roche offered more than twice the Philadelphia-based company's closing price on Feb. 22 for a portfolio that includes a blindness treatment that has U.S. and European approval and other projects for haemophilia and neurodegenerative disorders like Huntington's disease.
The offer comes as rivals, including Novartis, also move aggressively into gene therapy, where treatments for rare, inherited diseases command some of the highest prices in medicine. Spark's blindness therapy Luxturna is priced at $850,000 per patient.
(Reporting by Michael Shields, Editing by John Revill)
