Adds details on rival treatments and Novartis' pipeline in paragraphs 4-8

April 30 (Reuters) - Novartis NOVN.S has agreed to buy Regulus Therapeutics RGLS.O for up to $1.7 billion, giving the Swiss drugmaker access to an experimental drug to treat a life-threatening kidney disease.

Under the deal terms, Novartis will pay $7 per share in cash upfront, or about $800 million, and another $7 per share to Regulus shareholders if the lead drug candidate, farabursen, gets regulatory approval, the California-based biotech said on Wednesday.

The offer represents a premium of about 108% to the stock's last closing price. Shares of Regulus more than doubled to $8.09 in early trading.

Farabursen is being tested in an early-stage study to treat autosomal dominant polycystic kidney disease, which causes fluid-filled cysts in the organ.

The condition affects about 500,000 people in the U.S. and has limited treatment options. Otsuka Pharmaceutical's 4578.T drug, tolvaptan, is approved in the U.S. for patients with the condition, while PYC Therapeutics PYC.AX is developing a rival treatment.

Farabursen adds to Novartis' existing pipeline of kidney disease drugs, including those acquired through its $3.5 billion buyout of Chinook Therapeutics in 2023.

Novartis has recently received U.S. regulatory approvals for its drugs Fabhalta and Vanrafia for the treatment of different types of kidney disorders.

The deal with Regulus — expected to close in the second half of this year — will also give Novartis access to the U.S. company's platform that can help develop drugs targeting a type of genetic material called microRNAs.

The transaction comes at a time when policy and regulatory changes for the healthcare sector in the United States have been stalling large lifescience deals in what was initially expected to be a stellar year for mergers and acquisitions.

Novartis had said on Tuesday it expects adjusted earnings to grow by "a low double-digit" percentage in 2025.

(Reporting by Mariam Sunny and Bhanvi Satija in Bengaluru; Editing by Shilpi Majumdar)

((Mariam.ESunny@thomsonreuters.com))