BioMarin drug fails to show inattention, mood benefit in study

By Natalie Grover (Reuters) - BioMarin Pharmaceutical Inc's drug met a study's main goal of reducing a toxic buildup of an amino acid in the blood of patients with a genetic disorder, but did not show enough benefit in related inattention and mood complications. BioMarin's shares fell as much as 6 percent in early trading on Monday after the company released preliminary data from the late-stage study, which is testing the drug against a placebo in patients of phenylalanine hydroxylase (PAH) deficiency. Patients with PAH deficiency are unable to break down the amino acid phenylalanine, found in most protein-containing foods. When phenylalanine levels are not adequately controlled through a restricted diet, complications including severe intellectual disability, seizures, behavioral problems and psychiatric symptoms occur. The injectable drug, pegvaliase, reduced phenylalanine levels by about 62 percent compared with a placebo, but did not improve inattention or mood scores even though it showed a trend towards neurocognitive improvement. Wall Street will probably view the data as "murky and uncertain" from a regulatory perspective, given that the drug didn't hit secondary endpoints and neurocognition data was "exploratory", RBC Capital analyst Michael Yee wrote in a note. PAH deficiency is diagnosed in about 50,000 patients in the developed world. BioMarin said it expected to submit a marketing application for the drug later this year, subject to further discussions with the U.S. Food and Drug Administration. Raymond James analysts said significant reduction of phenylalanine levels in blood could still warrant an accelerated approval for the drug. The drug has the potential to bring in a billion dollars in revenue, they wrote in a preview note. Last year, German chemicals and drugs company Merck KGaA returned the rights to pegvaliase and Kuvan, another drug for the disorder, to BioMarin. Kuvan, jointly developed by BioMarin and Merck, is approved in 51 countries for use in combination with a phenylalanine-restricted diet. Kuvan does not carry a label that includes neurocogitive benefit. BioMarin said pegvaliase was the first drug to show the ability to improve phenylalanine levels in a study in patients who did not follow a restricted diet. An approval for pegvaliase without the neurocognition label will probably slow down the adoption of the drug initially after launch, but it is unlikely to impact the long-term potential of the drug, BioMarin executives told analysts on a conference call. Shares of the San Rafael, California-based company were down 3 percent at $78.45. (Reporting by Natalie Grover in Bengaluru; Editing by Kirti Pandey)