PTC Therapeutics to Acquire Censa for $10 Million in Cash, $41 Million in Stock and More


PTC Therapeutics is acquiring Censa Pharmaceuticals in a cash and stock deal. PTC, based in South Plainfield, New Jersey, focuses on rare diseases. Censa, based in Wellesley, Massachusetts, is developing CNSA-001 for phenylketonuria and other metabolic diseases.

Under the terms of the deal, PTC is paying Censa $10 million in cash and up to 850,000 shares of PTC common stock, which as of Tuesday, May 5, was trading at $48 per share, totaling about $41 million. In addition, there are development and regulatory milestones for the two most advanced programs that can reach $217.5 million. There is also receipt of a priority review voucher and $30 million to be paid in either cash or PTC common stock after completing the enrollment of a Phase III clinical trial for CNSA-001, $109 million in development and regulatory milestones for each extra indication for CNSA-001, net sales milestones up to about $160 million and a contingent value payment of a percentage of annual net sales in the single to low double digits.

“Results from a Phase II clinical trial of CNSA-001 demonstrated significant and clinically relevant reductions in phenylalanine levels compared to current first-line treatment,” said Stuart W. Peltz, PTC’s chief executive officer. “We believe that CNSA-001 has the potential to address the majority of PKU patients whose condition is not adequately managed by current treatments. We look forward to initiating a Phase III study in PKU so that patients diagnosed with this devastating condition can have a new oral treatment option as soon as possible.”

Phenylketonuria (PKU) is an inborn metabolic disorder that results in decreased metabolism of the amino acid phenylalanine. If untreated, it can cause intellectual disability, seizures, behavioral issues, and mental disorders. It is caused by a mutation in the gene that codes for the enzyme needed to metabolize phenylalanine. Patients with PKU must eat a diet that limits phenylalanine, found mostly in protein.

There are two drugs, both commercialized by BioMarin Pharmaceutical, approved for PKU. Sapropterin hydrochloride (Kuvan), an oral formulation, was approved in 2007 with a diet low in phenylalanine. In a Phase II trial, Censa’s drug was superior to Kuvan.

BioMarin’s Palynziq (pegvaliase-pqpz) was approved in 2018 by the U.S. Food and Drug Administration (FDA). It is an injectable enzyme therapy approved for adults with PKU whose blood phenylalanine concentrations remain high on current treatment. BioMarin planned to begin clinical testing of a gene therapy for the disease this year, but the COVID-19 pandemic has delayed the launch, although the company indicates it hopes to begin in the second half of 2020.

CNSA-001 is an oral formulation of synthetic sepiapterin, a precursor to intracellular tetrahydrobiopterin. Intracellular tetrahydrobiopterin is a critical enzymatic cofactor involved in the metabolism and synthesis of various metabolic products.

PTC’s pipeline includes early research in gene therapy, nonsense mutation, splicing and oncology. The therapies are focused on Huntington’s disease, Angelman syndrome, relapsed/refractory acute leukemias, ovarian cancer and others. The company markets Emflaza, a treatment for Duchenne muscular dystrophy (DMD) in the U.S., and markets another DMD drug, Translarna, in Europe. It also markets Tegsedi for polyneuropathy of hereditary transthyretin-mediated amyloidosis in Latin America.

PTC, with Roche, is awaiting an approval by the FDA this year for risdiplam for spinal muscular atrophy (SMA).

“I am proud of the team at Censa and its achievements to date demonstrating the potential role of CNSA-001 in treating diseases of the BH4 pathway,” said Jonathan Reis, president and chief executive officer of Censa. “It is the right time to have an excellent fully integrated, patient-focused biotechnology organization like PTC Therapeutics take over the late-stage development of CNSA-001 so that this promising compound becomes available to patients in the near future.”

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