AstraZeneca has bought rights to an experimental antisense therapy from Ionis Pharmaceuticals, in a deal that could be worth more than $300 million.

The move, which builds on an existing strategic partnership between the firms, was triggered by the drug’s advance into development, Ionis said.

IONIS-AZ6-2.5-LRx/AZD2693 is designed to inhibit an undisclosed target to treat patients with nonalcoholic steatohepatitis (NASH), a progressive form of non-alcoholic fatty liver disease.

AZ will pay a $30 million license fee to Ionis, and takes over responsibility for further development and commercialization of the drug.

Ionis could also receive up to $300 million in additional development and regulatory milestone payments, as well as tiered royalties up to the low teens from sales of the drug, if it makes it to market.

"This is the third drug to enter development under our strategic collaboration with AstraZeneca to discover drugs to treat cardiovascular, renal and metabolic diseases,” noted Brett Monia, chief operating officer, senior vice president of antisense drug discovery and translational medicine at Ionis Pharmaceuticals.

“AstraZeneca has played a strategic role in advancing this program forward by providing both preclinical and development expertise in NASH that has contributed to the rapid advance of this drug into development. We look forward to AstraZeneca moving this program swiftly into clinical testing and ultimately to the market."