What Emerging Drug Therapies Are in the Clinical Trial Pipeline for Parkinson Disease?

Overall, there are 145 registered and ongoing clinical trials for therapies targeting Parkinson disease (PD), of which 28 are currently in phase 3, according to review findings published in the Journal of Parkinson Disease.

In the second half of the last century, researchers highlight that the majority of pharmacological treatments approved for clinical use only provide symptomatic relief as opposed to slowing or reversing the progression of PD. In examining the current evolution of potential pharmacological interventions within PD, they note that a number of similar treatments to those already approved are being assessed in current clinical trials.

While additionally accounting for these therapies tailored toward symptomatic issues, the researchers sought to create greater awareness toward disease modifying therapies (DMT) in the current state of clinical trials within PD. They conducted a review and breakdown analysis of clinical trials for drug therapies in PD that were active as of January 21, 2020.

Of the 145 registered and ongoing clinical trials for therapies targeting PD, 37 (26%) were phase 1, 14 (10%) were phase 1/2, 61 (42%) were phase 2, 5 (3%) were phase 2/3, and 28 (19%) were phase 3.

Based on review findings, 57 (39%) of these trials were considered to be DMT trials and 88 (61%) were symptomatic treatment (ST) trials. Focusing on notable phase 3 DMT trials, STEADY-PD (evaluating isradipine) and SURE-PD (testing inosine) were referenced. Phase 1 and 2 DMT studies that provided encouraging results included the Herantis CDNF trial and the Denali-sponsored evaluation of their LRRK2 inhibitor, DNL-201, both of which focused on novel targets and achieved their primary endpoints, noted the researchers.

“We are also still awaiting the results of some studies that recently completed, such as the phase 2 trial assessing the DMT potential of the iron chelator, deferiprone,” the authors noted.

Assessing the ST studies, about 65% were focused on motor symptoms, including overall movement (45 trials), levodopa-induced dyskinesia (6 trials), gait and balance (4 trials), and tremor (3 trials). Only 1 of these ST studies focused on both motor and nonmotor symptoms.

The remaining ST studies focused on nonmotor symptoms, such as pain (3 trials), PD dementia (2 trials), PD psychosis (2 trials) and 1 trial each for anxiety, constipation, depression, fatigue, hallucinations, neuropsychiatric symptoms, PD mild cognitive impairment, sialorrhea, sleepiness, and urinary symptom.

In looking at the pipeline of PD therapies under consideration, the researchers were encouraged at the wide range of options across multiple phases of clinical development. However, they note that it remains challenging to bring DMTs to clinical use in PD.

“Improvements in the clinical trial process may accelerate the assessment of ST and DMTs, and we look forward with hope to further therapies becoming available for people with PD,” they concluded.

Reference

McFarthing K, Buff S, Rafaloff G, et al. Parkinson disease drug therapies in the clinical trial pipeline: 2020. J Parkinsons Dis. Published online July 28, 2020. doi:10.3233/JPD-202128