Retrophin and Censa Enter Agreement for Development of Potential PKU Treatment

This morning, it was announced that Retrophin, Inc. and Censa Pharmaceuticals are partnering to continue development and evaluate CNSA-001 for the treatment of phenylketonuria (PKU).

Under the terms of the agreement, Retrophin will pay Censa $10-million up front and will provide additional funding for the development of the drug. Censa will lead the development program, which will be conducted under the oversight of a joint steering committee.

CNSA-001, an orally bioavailable proprietary form of sepiapterin, serves as a natural precursor of tetrahydrobiopterin (BH4) that is converted by an endogenous enzymatic pathway to BH4.

PKU is a genetic disorder in which patients lack the ability to metabolize Phe, an amino acid. An untreated accumulation of Phe can result in cognitive issues and intellectual disability, among other serious health-related issues. Preclinical research has implied that CNSA-001 has the potential to provide improved bioavailability, plasma stability and tissue exposure, resulting in higher intracellular BH4 levels and subsequent greater Phe reduction when compared to the current standard-of-care in PKU.

At present, there are an estimated 16,500 people living with the disorder in the U.S., as per the National PKU Alliance. Approximately 45,000 to 50,000 patients have PKU worldwide.

“This transaction represents a significant opportunity to further strengthen our product pipeline and expands Retrophin’s strategy of delivering life-changing therapies to individuals living with rare diseases who have limited treatment options,” said Stephen Aselage, chief executive officer of Retrophin in a press release. “Importantly, the data generated by the program to date suggest that CNSA-001 has both the potential to offer a meaningful improvement in care for PKU patients, and the ability to move rapidly through the clinic upon positive proof of concept data.”

As part of the agreement, Retrophin will pay certain milestone payments and obtain the exclusive option to acquire Censa upon conclusion of a specified option period, pending clinical proof of concept of CNSA-001 in PKU.

“We believe Retrophin’s specialized capabilities and focus on developing and delivering therapies for rare diseases are highly differentiated and well-suited to this important program,” said Jonathan Reis, M.D., president and chief executive officer of Censa. “The pre-clinical data supporting this program are very encouraging, and suggest that treatment with CNSA-001 may lead to higher intracellular BH4 levels and improved phenylalanine reduction, which may offer a significant benefit for the large subset of PKU patients who do not achieve an optimal response with the current standard of care. We look forward to working with Retrophin to advance CNSA-001 through clinical proof of concept as expeditiously as possible.”

CNSA-001 is currently being evaluated in a single ascending dose study and a Phase 2 proof-of-concept study in PKU, which is anticipated to launch in mid-2018.

For more from within the rare disease community, follow Rare Disease Report on Facebook and Twitter.