BioMarin Pharmaceutical Inc. announced that the first subject has initiated treatment in a phase 3b study (PKU-016) to evaluate the effects of Kuvan (sapropterin dihydrochloride) on neuropsychiatric symptoms in subjects with phenylketonuria (PKU). BioMarin expects to report results in the first half of 2012.

"We hope that this trial will provide quantitative data regarding the neuropsychiatric effects of Kuvan for PKU patients, and if successful, will continue to build its value proposition and to drive the continued expansion of the market," said Jean-Jacques Bienaime, chief executive officer of BioMarin. "Although we have heard anecdotal accounts from patients and physicians regarding Kuvan's impact beyond blood Phe level reduction, BioMarin has never formally evaluated these endpoints in a company trial due to the extremely short development time for Kuvan. We are excited to have this important study underway, and if the results are positive, we plan to file for a label amendment. We also look forward to upcoming data from several investigator-sponsored studies on the neurocognitive effects of Kuvan at the SSIEM meeting in Istanbul in late August."

The phase 3b study is a double-blind, placebo-controlled, randomized 28-week study (2-week screening period, 13-week randomized treatment period, 13-week open-label treatment period) to evaluate the safety and therapeutic effects of sapropterin dihydrochloride on neuropsychiatric symptoms in subjects with PKU. The study will enrol approximately 200 subjects ages twelve and above at approximately 40 sites in the US and Canada.

The primary efficacy variable for symptoms of attention deficit hyperactivity disorder (ADHD) will be evaluated using the Attention-Deficit Hyperactivity Disorder Rating Scale (ASRS) in subjects twelve to 17 years of age and the Adult ADHD Self-Report Scale (ASRS) in subjects ages 18 and above. The Clinical Global Impression of Improvement (CGI-I) scale will be assessed to determine improvement in global impression of behaviour, symptoms and functioning relative to treatment as the primary efficacy endpoint for global function.

BioMarin develops and commercializes innovative biopharmaceuticals for serious diseases and medical conditions. The company's product portfolio comprises four approved products and multiple clinical and pre-clinical product candidates.