While the EMA’s recent recommended rejection of Kyowa Kirin’s Parkinson’s disease (PD) drug Nouryant (istradefylline) may have come as a surprise, key opinion leaders interviewed by leading data and analytics company GlobalData had mixed views on the drug’s efficacy and safety as an add-on therapy. Kyowa Kirin needs to capitalize on Nouryant’s sales in the US and Japan, which GlobalData believes should not be impacted by CHMP’s rejection, as wel as quickly address motor fluctuations effectively within its PD pipeline in order to have a better chance at a European release.

Sarah Elsayed, Neurology Analyst at GlobalData, comments: “Nouryant’s recommended rejection came as a shock to the PD community because the drug has been approved in the US and Japan for many years. However, while some of the experts GlobalData asked about the drug noted that they had seen faster effects in reducing off-episodes compared to other therapeutic classes, others still had concerns regarding the drug’s unclear mechanism of action and neuropsychiatric side effects.”

The EMA’s decision was based on the CHMP’s opinion that the drug showed a lack of consistency in the efficacy data presented as four out of eight trials failed to show any significant reduction in motor fluctuations experienced in patients with PD, including two negative trials conducted on European populations. On the other hand, the FDA’s approval in 2019 was based on the positive results of four safety and efficacy trials that included a total of 1,143 patients.

Elsayed adds: “CHMP’s opinion all but halts Nouryant’s launch plan in Europe—a setback for the once-promising, first-in-class drug. Effective treatment of motor fluctuations remains to be one of the key unmet needs in the PD market. Although levodopa is a highly effective drug, the emergence of motor fluctuations with its prolonged use is a major challenge for physicians and patients. Therefore, the market for new products aimed at controlling motor fluctuations holds great commercial potential.

“GlobalData expects that the recent setback of the CHMP’s rejection is not likely to have a negative impact on Nouryant’s current uptake in the US and Japan, despite the fact that it is has delayed the drug’s expansion in Europe.”

*GlobalData forecasts that Nouryant would generate its peak sales of $200m in 2023 in the US and Japan just before being hit by the erosion of cheaper generics starting 2024. As such, Nouryant is expected to only generate $57m in those two markets by 2029.

*Data taken from GlobalData’s report: Parkinson’s Disease – Global Drug Forecast and Market Analysis to 2029.