GENEVA (AP) — Swiss pharmaceuticals giant Novartis says it has agreed to buy the U.S.-based gene therapy company AveXis Inc. for $8.7 billion, part of its goal to become a leader in the treatment of neurodegenerative diseases.

The two companies say their respective boards have voted unanimously to approve the deal, to be paid for through cash and short-term borrowing.

The tender offer for $218 per share announced Monday marks a whopping 88 percent premium from AveXis' closing price in Nasdaq trading on Friday.

Basel, Switzerland-based Novartis called the deal set to close in mid-2018 a "financially attractive acquisition with multi-billion dollar peak sales potential" even if it isn't expected to add to core operating income until 2020.