Objective: Istradefylline is FDA approved for use in patients with PD treated with carbidopa-levodopa to reduce off time. GUH Movement Disorder Group has observed that PD patients who have levodopa resistant tremor have significant improvement in their tremor control when istradefylline is added. The objective of this study is to treat levodopa resistant tremor with istradefylline in our clinical patient population.

Background: Istradefylline is an adenosine receptor antagonist indicated as adjunctive treatment to levodopa/carbidopa in adult patients with Parkinson’s disease (PD) experiencing “off” episodes. Approved by the FDA in August 2019, the drug has been shown through clinical trials to be effective in reducing the off time in patients who have been on existing therapy with levodopa and carbidopa.  Post hoc analysis of pooled data from 6 randomized, placebo-controlled phase 2b/3 pivotal studies, in which patients on baseline anti-PD medication received istradefylline (20 or 40 mg/day) or placebo for 12 or 16 weeks showed that patients with TD subtype at baseline had a significant reduction in MDS-UPDRS II/III TD total score vs placebo (-1.13) for istradefylline 20 mg/day (-3.72; difference -2.60, 95% CL [-4.57, -0.62]) and istradefylline 40 mg/day (-2.96; difference -1.83, 95% CL [3.55, 0.11]).

Method: In this 6-month open label, single arm, exploratory pilot study, 25 patients with Parkinson’s disease will be started on 40 mg istradefylline daily as adjunctive therapy to carbidopa/levodopa for management of motor symptoms. Motor symptoms are evaluated prior to starting istradefylline and after 8 weeks of therapy by measuring change in amplitude of tremor from baseline to 8 weeks (56 days +/- 4 days) by assessing MDS – UPDRS Total and MDS-UPDRS III, a tremor quantifying software, eye-tracking technology and through the GDS, EQ5D, NMSS and MoCA assessments. Enrolled patients are required to be on a stable regimen of their concomitant medications for at least 30 days prior to baseline visit. Participants must also have a MOCA score of 22 or greater, and the absence of a diagnosis of dementia.

Results: N/A

Conclusion: This study will further our understanding of the effects of istradefylline in Parkinson’s patients with TD subtype who are experiencing tremor that is not adequately controlled on the current therapy.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/istradefylline-effect-on-parkinsons-disease-tremor-motor-symptoms-and-non-motor-symptoms/