April 30 (Reuters) - Swiss drugmaker Novartis has agreed to buy Regulus Therapeutics for up to $1.7 billion to gain access to its experimental kidney disease drug, the California-based drug developer said on Wednesday.

Shares of Regulus surged nearly 130% to $7.74 in morning trading.

Under terms of the deal, Novartis would pay Regulus upfront $7 per share in cash, or about $800 million, which represents a premium of about 108% to the stock's last closing price.

Regulus is also eligible to receive an additional $7 per share contingent upon certain regulatory milestones for the kidney disease drug, farabursen.

The deal is expected to be completed in the second half of this year.