Decades in the making, Kyowa Hakko Kirin finally wins FDA approval for add-on Parkinson's therapy
More than two decades after Kyowa Hakko Kirin kicked off the clinical evaluation of its Parkinson’s disease drug, the Japanese pharma group has finally secured FDA approval.
The drug, istradefylline, targets the adenosine A2A receptor, which is located in the basal ganglia — understood to play a key role in controlling voluntary movement. It was approved by the FDA as an add-on treatment to levodopa/carbidopa on Tuesday. The drug was cleared for use in Japan back in 2013.
The drug, branded as Nourianz, was sanctioned to treat Parkinson’s patients on the basis of four 12-week placebo-controlled clinical studies that included a total of 1,143 participants. In each trial, patients given Nourianz experienced a statistically significant decrease from baseline in daily ‘off’ time compared to those on a placebo, the FDA said.
However, its path to the finish line with the FDA was not smooth sailing — Kyowa Hakko Kirin had originally applied for approval more than a decade prior and was handed a rejection by the agency in 2008. But the Japanese group elected to plow ahead with its development program, although data was not always pristine. For example, in late 2016, a 12-week Phase III trial tested two doses of the drug against a placebo, showing a trend towards efficacy in Parkinson’s patients — but the results were not statistically significant.
The class of drugs Nourianz belongs to has a turbulent past. In 2013, late-stage data on Merck’s adenosine A2A receptor agonist, preladenant, suggested the drug was no better than a placebo — which caused the US drugmaker to walk away from the molecule. Acorda spent $363 million to swallow Biotie, and its adenosine A2A receptor antagonist — tozadenant — in 2016, but decided to shelve its development the year after, in response to unsavory safety data that blighted a late-stage trial. Late last year, however, Acorda finally scored approval for its inhaled levodopa therapy, Inbrija.
The first line of therapeutic defense for Parkinson’s disease patients is typically levodopa/carbidopa. However, the effectiveness of oral levodopa is limited by its short half-life — it remains in plasma for only up to four hours following a single dose, requiring patients to take multiple doses daily to fight ‘off’ periods of decline in motor and non-motor function. Excessive/intermittent oral doses of levodopa often lead to involuntary movements, or dyskinesia, in some patients.
Nearly one million Americans will be living with Parkinson’s by 2020 — more than the combined number of people diagnosed with multiple sclerosis, muscular dystrophy and Lou Gehrig’s disease, estimates the non-profit Parkinson’s Foundation.
Social image: Kyowa Hakko Kirin