PTC Therapeutics to Acquire Censa Pharma for Mid-Stage Rare Disease Drug

Xconomy New York — 

PTC Therapeutics has reached an agreement to acquire Censa Pharmaceuticals and its lead asset, an experimental metabolic disorder therapy that is now being prepared for a pivotal study.

The deal, announced after the market close Wednesday, will bring South Plainfield, NJ-based PTC (NASDAQ: PTCT) another compound for its pipeline of rare disease drugs.

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Wellesley, MA-based Censa in December reported that its drug, an oral formulation of synthetic sepiapterin, or CNSA-001, met the main goal of a Phase 2 study evaluating the drug as a potential treatment for signs and symptoms associated with phenylketonuria (PKU), a genetic condition in which the body is unable to break down phenylalanine, an amino acid commonly found in many foods. Censa’s drug performed better in the trial than the only approved oral PKU treatment and a placebo, the company says.

Now the potential PKU treatment is ready for Phase 3 testing, and PTC is counting on it to succeed there, too.

Under the terms of the cash-and-stock deal, PTC agreed to pay for the acquisition with about $10 million up front and up to 850,000 shares of its common stock. The company’s stock price closed Tuesday at about $48 per share, putting the value of that portion of the payment at nearly $41 million.

The deal also includes $217.5 million more tied to development and regulatory milestones for Censa’s two most advanced programs plus a priority review voucher, which allows for expedited FDA review.

PKU, which without treatment can lead to severe intellectual disability, is typically diagnosed at birth through newborn screenings. People with the condition control its symptoms via a strict diet.

Two drugs, both developed by San Rafael, CA-based BioMarin Pharmaceutical (NASDAQ: BMRN), are approved to treat patients with the rare disease. Sapropterin hydrochloride (Kuvan), an oral treatment, was OK’d in 2007 to be used in conjunction with a diet low in phenylalanine; the treatment is intended to prompt phenylalanine’s metabolism. The Cesna drug performed better than this drug in its Phase 2 trial.

In 2018, a BioMarin injectable enzyme therapy, pegvaliase-pqpz (Palynziq), was approved by the FDA as a treatment for adults with PKU whose blood phenylalanine concentrations remain abnormally high on current treatment.

This year BioMarin plans to enter the clinic with a third potential PKU treatment: a gene therapy designed to normalize blood concentration levels of phenylalanine. The company says it is possible a single dose of treatment could restore natural phenylalanine metabolism. But disruptions related to COVID-19 have pushed back the start of a planned Phase 1/2 trial from the first quarter to the second half of 2020, according to the company’s first-quarter report.

In a statement, PTC Therapeutics CEO Stu Peltz said: “We believe that CNSA-001 has the potential to address the majority of PKU patients whose condition is not adequately managed by current treatments.”

The drug is a precursor to intracellular tetrahydrobiopterin (BH4), which plays a key role in metabolism. The Censa drug is also being evaluated in the clinic as a treatment for primary BH4 deficiency, a rare disorder caused by a deficiency in one of the pathways responsible for the production of BH4. It is also in a Phase 1 trial for an undisclosed indication.

Censa’s main institutional backing was from Israel’s Arkin Bio-Ventures. Its acquisition by PTC is anticipated to close in this quarter.