US approves Kyowa Hakko Kirin's Nourianz for Parkinson's disease "off" episodes

Kyowa Hakko Kirin announced Wednesday that the FDA has cleared Nourianz (istradefylline) for use as an adjunctive treatment to levodopa/carbidopa in adults with Parkinson's disease experiencing "off" episodes. According to the company, the decision makes Nourianz the first adenosine A2A receptor antagonist for use in Parkinson's disease in the country. 

Tom Stratford, president of the company's US business, said the "FDA approval of Nourianz...provides US patients with a novel non-dopaminergic once-a-day oral treatment option to be used in conjunction with levodopa/carbidopa for Parkinson's disease."

The clearance was backed by results from four randomised, 12-week studies comparing Nourianz to placebo in a total of 1143 patients with Parkinson's disease taking a stable dose of levodopa/carbidopa, with or without other Parkinson's disease medications. In all four studies, patients in the Nourianz group experienced a significant decrease from baseline in daily "off" time, compared with placebo. In 2011, the company announced Phase III results from a study in Japan showing that Nourianz, also known as KW-6002, had significantly reduced "off" time versus placebo and was well tolerated at both tested doses.

Jeffrey Humphrey, chief medical officer at Kyowa Hakko Kirin, noted that in clinical studies, the drug was also "associated with an...increase in 'on' time without troublesome dyskinesia."

The company received a "not approvable" letter for the drug in 2008 in which the FDA "expressed concern if the efficacy findings support clinical utility of [the treatment]." An updated filing was resubmitted by Kyowa Hakko Kirin and accepted by the FDA earlier this year.

The therapy is indicated in Japan for the improvement of the "wearing-off" phenomenon in patients with Parkinson's disease on levodopa-containing medications, and has been marketed under the name Nouriast since 2013.

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