AstraZeneca has agreed to grant exclusive rights for its Zurampic gout treatment in the US to partner Ironwood Pharmaceuticals. Zurampic was approved by the US Food and Drug Administration (FDA) in December 2015, in combination with a xanthine oxidase inhibitor (XOI) for treating hyperuricemia – excess levels of uric acid in the blood –associated with uncontrolled gout.

Under the terms of the deal, Ironwood will also gain exclusive US rights to the fixed-dose combination program of Zurampic and XOI allopurinol, which AstraZeneca plans to submit for regulatory review in the second half of 2016.

Ironwood will pay the British-Swedish drugmaker related and other milestone payments of up to $265 million and tiered single-digit royalties on product sales. AstraZeneca will manufacture and supply Zurampic, provide certain support and services and perform the FDA-post approval commitment on Ironwood’s behalf.

The licensing agreement is expected to close in the second quarter of 2016, subject to US antitrust approval. The development of AstraZeneca’s gout portfolio is led by its wholly owned subsidiary, Ardea Biosciences. The company will retain rights to the rest of Ardea’s portfolio, including RDEA3170, a potent selective uric acid reabsorption inhibitor which is ready for Phase IIb trials. Ironwood will have certain rights to potentially access RDEA3170 for gout indications in the US.

Luke Miels, executive vice president of AstraZeneca’s global product and portfolio strategy, said the agreement with Ironwood, with which it already has a number of commercial partnerships, will allow the company to concentrate its resources on its main therapy areas. Ironwood’s chief commercial officer, Tom McCourt, commented: “With focused investment into the gout franchise over time, we believe we can maximize cash flows and accelerate our efforts to build a top-performing commercial biotechnology company.”

Gout is a progressive and debilitating form of inflammatory arthritis. In the US, around two million patients on urate lowering therapy are said to be inadequately controlled, as XOI treatment alone is not sufficient to control the condition.