Prosensa, the Dutch biopharmaceutical company focusing on RNA-modulating therapeutics for rare diseases with high unmet needs, announced today that it has raised EURO 23 million in new equity financing.

The financing was led by new investor New Enterprise Associates (NEA) and was supported by existing Prosensa investors, Abingworth, Life Sciences Partners, Gimv, Idinvest Partners and MedSciences Capital. David Mott, General Partner of NEA, will join Prosensa's Supervisory Board. The fundraising will enable Prosensa to advance its portfolio of RNA-modulating therapeutics for the treatment of rare diseases, including Duchenne muscular dystrophy (DMD), Myotonic Dystrophy (DM1) and Huntington's disease (HD).

Hans Schikan, CEO of Prosensa, commented: "Over the past few years, we have made substantial progress in our research and development pipeline. Our lead drug candidate for Duchenne muscular dystrophy is in Phase III clinical trials in partnership with GlaxoSmithKline. We have advanced the development of five additional compounds in DMD and have announced preclinical testing for a compound for DM1. This financing will help us to further strengthen our position in rare diseases and will allow us to deliver on our promise of accelerated development of treatments for patients in need."

"We are excited by the opportunity to invest in Prosensa, one of the most promising emerging European biopharmaceutical companies," said David Mott, General Partner of New Enterprise Associates. "Prosensa has world-class science, management and co-investors, and most importantly is developing therapies for rare genetic diseases which may offer tremendous benefits to patients. Their progress to date, particularly with the Phase III Duchenne muscular dystrophy program, is very encouraging." Mr. Mott added, "While NEA is one of the largest venture firms in the world, with more than $11 billion in capital under management, Prosensa is our first biopharma investment in Europe and signals our openness to selectively consider investing in truly exceptional innovation in Europe as well as in our traditional geographies in the U.S., China and India."

Daan Ellens, Chairman of Prosensa's Supervisory Board commented: "Prosensa welcomes NEA to its investor base and David Mott to its Supervisory Board. David's impressive track record, and his prior experience at MedImmune and AstraZeneca, will be a valuable extension in the Supervisory Board's expertise, thereby helping Prosensa reach its next milestones."

Prosensa has the most advanced portfolio of drug candidates for DMD in the industry, with two compounds in clinical trials in partnership with GSK (PRO051/GSK2402968 and PRO044) and four additional compounds in preclinical development, as well as preclinical compounds for DM1 and HD. Prosensa's DMD compounds are based on its proprietary exon-skipping technology that uses antisense oligonucleotides to restore expression of a functional dystrophin protein and to provide potential treatment for patients affected by this progressively debilitating neuromuscular disease.

About DMD

Duchenne muscular dystrophy (DMD) is a severely debilitating childhood neuromuscular disease that affects 1 in 3,500 live male births. This rare disease is caused by mutations in the dystrophin gene, resulting in the absence or defect of the dystrophin protein. As a result, patients suffer from progressive loss of muscle strength, often rendering them wheelchair-bound before the age of 12. Respiratory and cardiac muscle can also be affected by the disease and most patients die in early adulthood due to respiratory and cardiac failure.

About exon skipping

The dystrophin gene is the largest gene in the body, consisting of 79 exons. Exons are small sequences of genetic code which, via an intermediate step involving RNA, lead to the assembly of sections of protein. In DMD, when certain exons are mutated/deleted, the RNA cannot read past the fault. This prevents the remainder of the exons from being read, resulting in a non-functional dystrophin protein and the severe symptoms of DMD. RNA-based therapeutics, specifically antisense oligonucleotides inducing exon skipping, are currently in development for DMD. These antisense oligonucleotides skip an exon next to a defective exon and thereby correct the reading frame, enabling the production of a novel, functional dystrophin protein.

About Prosensa

Prosensa is an innovative Dutch biopharmaceutical company focused on the discovery, development and commercialization of RNA-modulating therapeutics correcting gene expression in diseases with significant unmet need, in particular neuromuscular disorders. Prosensa's current focus is on developing treatments for Duchenne muscular dystrophy (DMD), Myotonic Dystrophy and Huntington's disease. In 2009 Prosensa entered into a strategic alliance for part of its DMD exon skipping program with GlaxoSmithKline. Prosensa's lead compound (GSK2402968/ PRO051), being developed by GSK, entered Phase III clinical trials in January 2011. Prosensa is a privately held biopharmaceutical company, backed by a consortium of Abingworth, Gimv, Idinvest Partners, Life Sciences Partners, MedSciences Capital and New Enterprise Associates. For more information, please visit www.prosensa.com.

About NEA

New Enterprise Associates, Inc. (NEA) is a leading venture capital firm focused on helping entrepreneurs build transformational businesses across multiple stages, sectors and geographies. With approximately $11 billion in committed capital, NEA invests in information technology, healthcare and energy technology companies at all stages in a company's lifecycle, from seed stage through IPO. The firm's long track record includes more than 170 portfolio company IPOs and more than 290 acquisitions. In the U.S., NEA has offices in the Washington, D.C. metropolitan area; Menlo Park, California; and New York City. In addition, New Enterprise Associates (India) Pvt. Ltd. has offices in Bangalore and Mumbai, India and New Enterprise Associates (Beijing), Ltd. has offices in Beijing and Shanghai, China. For additional information, please visit www.nea.com.