Objective: To evaluate enrollment rates and challenges in clinical trials of disease-modifying therapies (DMTs) for early-stage Parkinson’s disease (PD), comparing treatment-naïve patients with those permitted prior symptomatic treatment.

Background: DMTs aim to slow or halt PD progression. Enrolling early-stage patients, particularly treatment-naïve, is critical but challenging. Understanding these challenges is essential for improving trial design and recruitment.

Method: We conducted a systematic review of Phase 2 and 3 trials of DMTs in early-stage PD registered between 2016-2023 (Citeline). Trials with >5 sites were categorized based on whether they allowed previously treated or required treatment-naïve patients. We analyzed enrollment rates, time to full enrollment, and reported challenges.

Results: Ten eligible trials were identified. Key findings include:

• Trials allowing prior symptomatic treatment (6/10) achieved full enrollment 28 months faster than treatment-naïve trials (16 vs. 44 months)

• Treatment-naïve trials (4/10) had lower enrollment rates (0.16 vs. 0.25 patients/site/month) but higher average enrollment (407 vs. 308 patients)

• Patient enrollment ranges: 372-506 (treatment-naïve) vs. 140-586 (prior treatment allowed)

• Common challenges for treatment-naïve trials: early-stage patient identification, placebo concerns, stringent criteria, limited patient pool

• Trials allowing prior treatment had broader inclusion criteria, contributing to faster enrollment

• Treatment-naïve trials employed more intensive screening, potentially slowing recruitment but ensuring homogeneous population.

Conclusion: Enrolling treatment-naïve patients in early-stage PD DMT trials presents significant challenges. To improve enrollment, researchers should consider:

1) Partnering with PD registries and advocacy groups for targeted outreach

2) Enhancing patient education on DMT benefits and early intervention importance

3) Implementing adaptive designs to reduce placebo exposure and increase appeal

4) Leveraging technology for efficient screening

5) Collaborating with movement disorder clinics to identify newly diagnosed patients

6) Offering practical support (e.g., transportation, flexible scheduling) to reduce participation barriers

These strategies address recruitment challenges, potentially accelerating enrollment in early-stage PD DMT trials.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/enrollment-challenges-and-strategies-in-early-stage-parkinsons-disease-clinical-trials-comparing-treatment-naive-and-previously-treated-patient-populations/