SOUTH PLAINFIELD, N.J. /PRNewswire/ -- PTC Therapeutics, Inc. (NASDAQ: PTCT) today announced that it has entered into an agreement to acquire Censa Pharmaceuticals, Inc., a biopharmaceutical company focused on the development of CNSA-001 (sepiapterin), a clinical-stage investigational therapy for orphan metabolic diseases, including phenylketonuria (PKU) and other diseases associated with defects in the tetrahydrobiopterin (BH4) biochemical pathways diagnosed at birth. The transaction was approved by the Boards of both companies.

"Results from a Phase 2 clinical trial of CNSA-001 demonstrated significant and clinically relevant reductions in phenylanaline levels compared to current first-line treatment," said Stuart W. Peltz, Ph.D., Chief Executive Officer, PTC Therapeutics, Inc. "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 3 study in PKU so that patients diagnosed with this devastating condition can have a new oral treatment option as soon as possible."

CNSA-001 has been pursued as a possible treatment for orphan metabolic diseases associated with defects in the tetrahydrobiopterin biochemical pathways. CNSA-001 is an oral formulation of synthetic sepiapterin, a precursor to intracellular tetrahydrobiopterin, which is a critical enzymatic cofactor involved in the metabolism and synthesis of numerous metabolic products. The Phase 2 trial evaluating CNSA-001 for PKU met its primary and secondary endpoints in December 2019¹, and the program is Phase 3 ready.

"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 M.D., M.B.A., President and Chief Executive Officer of Censa Pharmaceuticals, Inc. "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." 

The transaction is expected to close in the second quarter, pending successful fulfillment of closing conditions. PTC is not obligated to give full time employment to any Censa personnel or acquire any additional facilities in connection with the closing.

Transaction Details
Under the terms of the merger agreement, PTC will pay an upfront consideration of approximately $10 million in cash and up to 850,000 shares of PTC common stock. In addition to the upfront payments, potential future consideration includes $217.5 million in development and regulatory milestones for the two most advanced programs and receipt of a priority review voucher, including $30 million to be paid in either cash or PTC common stock at our option for completing the enrollment of a Phase 3 clinical trial for CNSA-001 for PKU, $109 million in development and regulatory milestones for each additional indication of CNSA-001, net sales milestones up to an aggregate amount of $160 million and a contingent value payment of a percentage of annual net sales ranging from single to low double digits.

About Phenylketonuria (PKU)
Phenylketonuria (PKU) is an inborn error of metabolism caused predominantly by mutations in the phenylalanine hydroxylase (PAH) gene and resulting in toxic buildup of the amino acid phenylalanine (Phe) in the brain. Gene mutations of PAH result in inefficient Phe metabolism leading to hyperphenylalaninemia. There are at least 1,000 unique mutations in the PAH gene, resulting in phenotypic variation in the amount of enzyme produced and/or enzyme activity. With the near universal adoption of newborn screening for high plasma phenylalanine PKU is typically diagnosed at birth. PKU has been described in all ethnic groups, and its incidence worldwide varies widely, but is estimated that there are 16,500 patients in the U.S. If left untreated, severe and irreversible disability can occur to include permanent intellectual disability, seizures, delayed development, behavioral problems, and possibly psychiatric disorders. It has been shown that administration of tetrahydrobiopterin improves the function of PAH resulting in reduction in phenylalanine plasma concentration. CNSA-001 has the potential to address the metabolic and neurological signs and symptoms of a broad range of PKU patients.

About Censa Pharmaceuticals 
Censa Pharmaceuticals, Inc. is developing CNSA-001, an oral therapy for phenylketonuria (PKU) patients across all ages and disease severities. Censa's CNSA-001 has demonstrated a strong safety profile and clinical benefit in a Phase 2 study that included a comparison to currently available therapy. CNSA-001 is also being studied in other diseases associated with defects in the tetrahydrobiopterin biochemical pathways. Arkin Bio-Ventures is Censa Pharmaceutical's main institutional investor.

For More Information:
Investors:
Alex Kane
+1 (908) 912-9643
akane@ptcbio.com