Ultragenyx Pharmaceutical said today it will partner with Arcturus Therapeutics to discover and develop messenger RNA (mRNA) therapeutics for rare disease targets, through a collaboration and licensing agreement that could generate $1.56 billion for Arcturus.

During the initial phase of the collaboration, Arcturus will design and optimize mRNA therapeutics for two selected rare disease targets, using its unlocked nucleomonomer agent (UNA) Oligomer™ chemistry and LUNAR™ nanoparticle delivery platform.

Arcturus' platform is designed to be applied toward all RNA therapeutics—including small interfering RNA, messenger RNA, antisense RNA, microRNA, and gene-editing therapeutics. The company’s UNA technology can target any gene in the human genome, as well as viral genes, and other species for therapeutic purposes.

Ultragenyx has the option to add up to eight additional rare disease targets.

Under the collaboration, Ultragenyx will also oversee the development and commercialization of all products developed with Arcturus, which was founded in 2013 and is based in San Diego.

In return, Ultragenyx agreed to pay Arcturus $10 million upfront, and up to $156 million for each target in payments tied to preclinical, clinical, regulatory, and sales milestones.

Arcturus will also be reimbursed by Ultragenyx for all research expenses, as well as “mid-single to low double-digit” royalties on commercial sales in the mid-single to low double digits.

“This collaboration with Arcturus will help us address a wider range of rare diseases than is possible with currently available approaches,” Ultragenyx CEO Emil D. Kakkis, M.D., Ph.D., said in a statement. “The joint program combines Arcturus' technology platform, which we believe solves some of the key issues associated with mRNA therapeutics, with Ultragenyx's expertise in rare disease drug development.”

Based in Novato, CA, Ultragenyx focuses on developing rare disease treatments. The company’s pipeline is led by two Phase III candidates— aceneuramic acid extended release for GNE myopathy, licensed from Nobelpharma, AAI Pharma, and the HIBM Research Group; and rhGUS for mucopolysaccharidosis 7, licensed from Saint Louis University.

The collaboration is Arcturus’ second announced in four months. In June, the company partnered with Johnson & Johnson’s Janssen Pharmaceuticals to discover, develop and commercialize RNA-based drug products for undisclosed diseases. Arcturus started out as a tenant of Janssen Labs (now JLABS) in San Diego.

The value of that partnership, facilitated by J&J Innovation, was not disclosed—though Arcturus announced terms similar to the deal with Ultragenyx: An upfront payment, R&D support, and pr-clinical, development and sales milestone payments, as well as royalty payments on any future licensed product sales.