BioMarin Pharmaceutical said today it plans to acquire Prosensa Holding for up to $840 million, in a deal that adds the Duchenne muscular dystrophy (DMD) candidate Drisapersen and potential follow-on products to the buyer’s pipeline of rare-disease products.

Part of the deal’s value hinges on BioMarin’s ability to secure U.S. and European approvals for Drisapersen, whose failure in a Phase III study in 2013 led GlaxoSmithKline to terminate their collaboration and return to Prosensa its rights to the DMD treatment.

Drisapersen is currently under a rolling review of its NDA, and has the FDA’s Orphan, Fast Track and Breakthrough Therapy designations. BioMarin stands to gain an $80 million milestone payment if the company can win FDA approval of Drisapersen no later than May 15, 2016—and another $80 million milestone payment if it wins European approval by Feb. 15, 2017.

“We will leverage our experience at developing rare disease therapies to achieve regulatory approvals and bring Drisapersen to market as quickly as possible,” BioMarin CEO Jean-Jacques Bienaimé said in a statement.

If BioMarin succeeds in advancing Drisapersen to early regulatory approvals, he added, “we believe this transaction would be accretive to operating and GAAP profitability in 2017.”

BioMarin also agreed to buy all outstanding shares of Prosensa at $17.75 per share—$680 million, to be paid upfront. The buyer also agreed to purchase, within five days, a $50 million convertible note that will automatically convert into 4,395,914 share of Prosensa stock if the deal fails to close for any reason.

BioMarin pledged it would maintain operations at Prosensa's headquarters, based in Leiden, The Netherlands, and integrate Prosensa personnel from that office.

In addition to Drisapersen, BioMarin acquired Prosensa’s pipeline of products based on Drisapersen’s RNA-modulating technology platform, but indicated for various genotypes of Duchenne muscular dystrophy as well as other rare genetic disorders.

According to its website, Prosensa’s pipeline consists of Drisapersen and six other experimental drugs designed to fight DMD. Three of those six are in Phase I/II:

  • PRO044—induces exon 44 skipping in the dystrophin gene and is intended for approximately 6% of DMD patients, including those with deletions of exon 43, exon 45, exons 38-43, exons 40-43, exons 42-43, and exons 45-54.


  • PRO045—induces exon 45 skipping in the dystrophin gene and is intended for approximately 8% of all DMD patients, including patients with deletions of exon 44, exon 46, exons 46-47, exons 46-48, exons 46-49, and exons 46-51


  • PRO053—induces exon 53 skipping in the dystrophin gene and is intended for more than 6% of all DMD patients, including patients with deletions of exon 52, exons 47-52, exons 48-52, exons 49-52 and exons 50-52.

The other three DMD compounds are in preclinical phases: PRO052 (which induces exon 52 skipping and affects 4% of DMD patients); PRO055 (induces exon 55 skipping and affects 2% of DMD patients); and PROSPECT, which applies multiple exon skipping, to specifically target rarer mutations in the dystrophin gene—initially in the exon 10-30 region.

Prosensa’s pipeline also includes two other preclinical candidates, PRO135 against myotonic dystrophy; and PRO289 against Huntington’s disease.

BioMarin said it will conduct a tender offer for all of the issued and outstanding Prosensa ordinary shares, which it expects will close in the first quarter of 2015. The offer will be subject to consulting with Prosensa’s workers council in the Netherlands, and customary closing conditions that include the tender of at least 80% of the issued and outstanding Prosensa ordinary shares and the receipt of regulatory clearance.

Following completion of the offer, BioMarin said, the Supervisory Board of Prosensa will consist of five individuals designated by BioMarin, and two individuals who currently serve on the board, who will act as independent directors. The two independent directors will, in accordance with Dutch practice, act as independent supervisory directors to protect the interest of any minority shareholders until BioMarin acquires full ownership of Prosensa's outstanding shares and/or its business.

Headquartered in San Rafael, CA, BioMarin markets five drugs for rare diseases. They include VIMIZIM™ (elosulfase alfa) for Morquio A Syndrome (MPS IVA); Kuvan® (sapropterin dihydrochloride) Tablets for Phenylketonuria (PKU); Naglazyme® (galsulfase) for the lysosmal storage disorder mucopolysaccharidosis (MPS) VI; Aldurazyme® (laronidase) for MPS I; and Firdapse (amifampridine), a treatment approved in Europe for the autoimmune disease Lambert-Eaton Myasthenic Syndrome (LEMS).

BioMarin's pipeline includes three Phase III compounds—BMN 165 for PKU; BMN 673 for genetically defined cancers; and BMN 701 for Pompe disease. Another compound BMN 111, is in Phase II study for achondroplasia.

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