SOUTH PLAINFIELD, N.J.—PTC Therapeutics, Inc. has announced an agreement to acquire Censa Pharmaceuticals, Inc., a biopharmaceutical company focused on the development of CNSA-001 (sepiapterin). The transaction was approved by the boards of both companies.
CNSA001 is a clinical-stage investigational therapy for orphan metabolic diseases, including phenylketonuria (PKU), and for other metabolic diseases associated with defects in the tetrahydrobiopterin (BH4) 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 2019, and the program is ready for Phase 3.
“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 of PTC Therapeutics. “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.”
PKU is an inborn error of metabolism predominantly caused by mutations in the phenylalanine hydroxylase (PAH) gene, resulting in toxic buildup of the amino acid phenylalanine (Phe) in the brain. Gene mutations of PAH result in inefficient Phe metabolism, which leads 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. If left untreated, severe and irreversible disability can occur — including 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.
“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. 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,” added Jonathan Reis M.D., M.B.A., president and chief executive officer of Censa Pharmaceuticals.
Under the terms of the agreement, PTC will pay an upfront consideration of approximately $10 million in cash and up to 850,000 shares of PTC common stock. 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 for completing enrollment in 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.
The transaction is expected to close in the second quarter of 2020, pending successful fulfillment of closing conditions. PTC has not been obligated to give full time employment to any Censa personnel or to acquire any additional facilities in connection with the closing.