– Arrowhead to receive $40 million upfront payment

– Horizon to receive a worldwide exclusive license for an investigational short interfering RNA (siRNA) therapeutic targeting xanthine dehydrogenase (XDH)

PASADENA, CA, USA & DUBLIN, Ireland I June 21, 2021 I Arrowhead Pharmaceuticals Inc. (NASDAQ: ARWR) and Horizon Therapeutics plc (NASDAQ: HZNP) today announced a global collaboration and license agreement for ARO-XDH, a previously undisclosed discovery-stage investigational RNA interference (RNAi) therapeutic being developed by Arrowhead as a potential treatment for people with uncontrolled gout.

Gout is a serious and painful form of arthritis that is caused by excess uric acid in the blood. In the United States, there are more than nine million gout patients and approximately a third of those patients are treated with oral urate-lowering therapies. However, a meaningful portion of treated patients do not respond sufficiently to treatment and therefore continue to experience painful and debilitating gout symptoms. XDH represents a clinically validated target that is the primary source of serum uric acid (sUA). High levels of sUA, if left untreated or undertreated, can potentially lead to serious long-term or even permanent damage to the bones, joints and organs.

Under the terms of the agreement, Arrowhead will conduct all activities through preclinical stages of development of the siRNA therapeutic. Horizon will receive a worldwide exclusive license to the therapeutic and will be wholly responsible for clinical development and commercialization. Arrowhead will receive $40 million as an upfront payment from Horizon and is eligible to receive up to $660 million in potential development, regulatory and commercial milestones, and is further eligible to receive royalties in the low- to mid-teens range on net product sales.

“We believe Horizon’s expertise in the clinical development and commercialization of therapies for gout makes them an ideal partner. We look forward to working closely with Horizon as we advance this potential new therapy for patients in need,” said Christopher Anzalone, Ph.D., Arrowhead’s president and CEO. “This collaboration with Horizon also represents further expansion of our rapidly growing pipeline of investigational RNAi therapeutics that utilize Arrowhead’s proprietary Targeted RNAi Molecule (TRiMTM) platform.”

“As a commercial and clinical leader in gout, we understand the disease and its impact, and that there is still a tremendous unmet treatment need,” said Tim Walbert, chairman, president and CEO, Horizon. “The collaboration with Arrowhead adds an additional program to our research and development focus to discover and develop new, innovative medicines that continue to improve gout treatment across the continuum of care.”

About Arrowhead Pharmaceuticals

Arrowhead Pharmaceuticals develops medicines that treat intractable diseases by silencing the genes that cause them. Using a broad portfolio of RNA chemistries and efficient modes of delivery, Arrowhead therapies trigger the RNA interference mechanism to induce rapid, deep, and durable knockdown of target genes. RNA interference, or RNAi, is a mechanism present in living cells that inhibits the expression of a specific gene, thereby affecting the production of a specific protein. Arrowhead’s RNAi-based therapeutics leverage this natural pathway of gene silencing.

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About Horizon

Horizon is focused on the discovery, development and commercialization of medicines that address critical needs for people impacted by rare, autoimmune and severe inflammatory diseases. Our pipeline is purposeful: we apply scientific expertise and courage to bring clinically meaningful therapies to patients. We believe science and compassion must work together to transform lives. For more information on how we go to incredible lengths to impact lives, please visit www.horizontherapeutics.com and follow us on Twitter, LinkedIn, Instagram and Facebook.

SOURCE: Horizon Therapeutics