Retrophin announced the completion of its previously announced acquisition of Orphan Technologies Limited, a privately held, clinical-stage biopharmaceutical company focused on the development of product candidate OT-58 for the treatment of classical homocystinuria (HCU). OT-58 is a novel investigational human enzyme replacement therapy being evaluated in Phase 1/2 development for the treatment of classical HCU, a rare metabolic disorder characterized by elevated levels of plasma homocysteine that can lead to life-threatening thrombotic events such as stroke and heart attacks, ophthalmologic and skeletal complications, as well as developmental delay.

“We are excited to begin working with the HCU community to develop a deeper understanding of how we can continue to integrate their perspectives into the development of OT-58, and help address their unmet needs,” said Eric Dube, Ph.D., chief executive officer of Retrophin. “We look forward to building upon the promising potential of OT-58 with the goal of developing and ultimately delivering the first disease modifying therapy for people living with HCU.”

Under the terms of the agreement, Retrophin made an upfront payment of $90 million in cash at closing of the transaction. Orphan Technologies shareholders will remain eligible to receive up to $427 million in additional cash payments contingent upon the achievement of key milestones in the development and commercialization of OT-58. Retrophin will also pay a tiered mid-single digit royalty on future net sales of OT-58 in the US and Europe, and potentially make a milestone payment in the event a rare pediatric disease priority review voucher is granted.

Classical homocystinuria (HCU) is a rare genetic metabolic disorder caused by a deficiency in the enzyme cystathionine beta synthase (CBS). CBS is a pivotal enzyme that is essential for the management of methionine and cysteine in the body. Classical HCU leads to toxic levels of homocysteine that can result in life-threatening thrombotic events such as stroke and heart attacks, ophthalmologic and skeletal complications, as well as developmental delay. Current treatment options are limited to protein-restricted diet and supplemental use of vitamin B6 and betaine.