-Collaboration combines Solid’s differentiated microdystrophin construct and Ultragenyx’s HeLa PCL manufacturing platform for use with AAV8 and variants-

-Solid receives $40 million upfront via equity investment at a premium; up to $255 million in milestones plus royalty payments-

-Solid retains exclusive rights to all other uses of its microdystrophins, including its existing SGT-001 program-

NOVATO, CA and CAMBRIDGE, MA, USA I October 23, 2020 I Ultragenyx Pharmaceutical Inc. (Nasdaq: RARE), a biopharmaceutical company focused on the development and commercialization of novel products for serious rare and ultra-rare diseases, and Solid Biosciences Inc. (Nasdaq: SLDB), a life sciences company focused on advancing meaningful therapies for Duchenne muscular dystrophy (Duchenne), today announced a strategic collaboration and license agreement to focus on the development and commercialization of new gene therapies for Duchenne. The parties will collaborate to develop products that combine Solid’s differentiated microdystrophin construct, Ultragenyx’s HeLa producer cell line (PCL) manufacturing platform, and AAV8 variants. The collaboration also brings together Solid’s expertise in muscle biology and Ultragenyx’s expertise in bringing novel therapies to patients with rare diseases.

Under the terms of the collaboration, Solid granted Ultragenyx an exclusive license for any pharmaceutical product that expresses Solid’s proprietary microdystrophin construct from AAV8 and variants thereof in clade E for use in the treatment of Duchenne and other diseases resulting from lack of functional dystrophin, including Becker muscular dystrophy. Ultragenyx has made a $40 million investment in Solid and has agreed to pay up to $255 million in cumulative milestone payments per product upon achievement of specified milestone events, and tiered royalties on worldwide net sales at low double digit to mid-teens percentages. Upon achievement of proof-of-concept, Solid has the right to opt-in to co-fund collaboration programs in return for participation in a profit share or increased royalty payments.

“We believe that Solid’s microdystrophin is best-in-class with its unique neuronal nitric oxide synthase binding domain,” said Emil D. Kakkis, MD, PhD, Chief Executive Officer and President of Ultragenyx. “By using an AAV8 variant validated in prior human and other studies combined with our scalable, efficient HeLa producer cell line platform, we believe we can leverage our mutual strengths to develop a high-quality AAV-based treatment alternative for Duchenne.”

“Ultragenyx has a demonstrated track record of success in developing and commercializing innovative therapies for rare diseases,” said Ilan Ganot, Co-Founder, President and Chief Executive Officer at Solid Biosciences. “We believe it is the partner of choice for exploring new gene therapy opportunities for patients with Duchenne.”

Solid’s proprietary microdystrophin construct has exhibited functional benefit in preclinical models. In preclinical studies, animals expressing a microdystrophin capable of restoring neuronal nitric oxide synthase (nNOS) resisted fatigue better than those expressing a microdystrophin that does not. Patients dosed with Solid’s proprietary microdystrophin construct at the 2E14 vg/kg dose in Solid’s ongoing IGNITE DMD clinical trial have also preliminarily demonstrated nNOS activity and function, further validating these preclinical results. Solid expects to dose the next patient in the IGNITE DMD clinical trial, using SGT-001 produced using its improved HSV manufacturing process, in the first quarter of 2021.

Ultragenyx intends to use its AAV-based HeLa PCL platform including HeLa 3.0 improvements for the development of product candidates. The platform enables large 2,000 liter commercial-scale AAV-based gene therapy product manufacturing. The PCL platform yields high-quality product from a highly reproducible, highly scalable, and less expensive process – a distinct vantage in higher dose indications like Duchenne. The capsid planned is an AAV8 variant with a favorable immunological profile that has been used successfully in the large scale 2,000 liter production process.

About Ultragenyx

Ultragenyx is a biopharmaceutical company committed to bringing novel products to patients for the treatment of serious rare and ultra-rare genetic diseases. The company has built a diverse portfolio of approved therapies and product candidates aimed at addressing diseases with high unmet medical need and clear biology for treatment, for which there are typically no approved therapies treating the underlying disease.

The company is led by a management team experienced in the development and commercialization of rare disease therapeutics. Ultragenyx’s strategy is predicated upon time- and cost-efficient drug development, with the goal of delivering safe and effective therapies to patients with the utmost urgency and ensuring majority access to its therapies for patients who can benefit.

Ultragenyx currently has three AAV gene therapies in clinical development, including DTX201 that uses an AAV8 variant in the HeLa PCL platform and that is partnered with Bayer, who has released positive Phase 1/2 data in Hemophilia A. The company’s other clinical AAV8 gene therapies, DTX301 and DTX401, are in Phase 1/2 studies for ornithine transcarbamylase (OTC) deficiency and glycogen storage disease type Ia (GSDIa), respectively. An investigational new drug (IND) application is expected by the end of 2020 for a fourth AAV gene therapy for Wilson disease, which will also use the HeLa PCL AAV manufacturing platform.

For more information on Ultragenyx, please visit the company’s website at www.ultragenyx.com.

About Solid Biosciences

Solid Biosciences is a life sciences company focused on advancing transformative treatments to improve the lives of patients living with Duchenne. Disease-focused and founded by a family directly impacted by Duchenne, our mandate is simple yet comprehensive – work to address the disease at its core by correcting the underlying mutation that causes Duchenne with our lead gene therapy candidate, SGT-001.

Solid’s SGT-001 is a novel adeno-associated viral (AAV) vector-mediated gene transfer therapy designed to address the underlying genetic cause of Duchenne. Duchenne is caused by mutations in the dystrophin gene that result in the absence or near absence of dystrophin protein. SGT-001 is a systemically administered candidate that delivers a synthetic dystrophin gene, called microdystrophin, to the body. This microdystrophin encodes for a functional protein surrogate that is expressed in muscles and stabilizes essential associated proteins, including nNOS. Data from Solid’s preclinical program suggests that SGT-001 has the potential to slow or stop the progression of Duchenne, regardless of genetic mutation or disease stage.

SGT-001 is based on pioneering research in dystrophin biology by Dr. Jeffrey Chamberlain of the University of Washington and Dr. Dongsheng Duan of the University of Missouri. SGT-001 has been granted Rare Pediatric Disease Designation, or RPDD, and Fast Track Designation in the United States and Orphan Drug Designations in both the United States and European Union.

For more information, please visit www.solidbio.com.

SOURCE: Solid Biosciences