Trial Participation in Neurodegenerative Diseases: Barriers and Facilitators: A Systematic Review and Meta-Analysis.

BACKGROUND AND OBJECTIVES: Clinical trials in neurodegenerative diseases often encounter selective enrollment and under-representation of certain patient populations. This delays drug development and substantially limits the generalizability of clinical trial results. To inform recruitment and retention strategies, and to better understand the generalizability of clinical trial populations, we investigated which factors drive participation. METHODS: We reviewed the literature systematically to identify barriers to and facilitators of trial participation in 4 major neurodegenerative disease areas: Alzheimer disease, Parkinson disease, amyotrophic lateral sclerosis, and Huntington disease. Inclusion criteria included original research articles published in a peer-reviewed journal and evaluating barriers to and/or facilitators of participation in a clinical trial with a drug therapy (either symptomatic or disease-modifying). The Critical Appraisal Skills Program checklist for qualitative studies was used to assess and ensure the quality of the studies. Qualitative thematic analyses were employed to identify key enablers of trial participation. Subsequently, we pooled quantitative data of each enabler using meta-analytical models. RESULTS: Overall, we identified 36 studies, enrolling a cumulative sample size of 5,269 patients, caregivers, and health care professionals. In total, the thematic analysis resulted in 31 unique enablers of trial participation; the key factors were patient-related (own health benefit and altruism), study-related (treatment and study burden), and health care professional-related (information availability and patient-physician relationship). When meta-analyzed across studies, responders reported that the reason to participate was mainly driven by (1) the relationship with clinical staff (70% of the respondents; 95% CI 53%-83%), (2) the availability of study information (67%, 95% CI 38%-87%), and (3) the use or absence of a placebo or sham-control arm (53% 95% CI 32%-72%). There was, however, significant heterogeneity between studies (all p < 0.001). DISCUSSION: We have provided a comprehensive list of reasons why patients participate in clinical trials for neurodegenerative diseases. These results may help to increase participation rates, better inform patients, and facilitate patient-centric approaches, thereby potentially reducing selection mechanisms and improving generalizability of trial results.

A randomized, double-blind, placebo-controlled phase 2 study to assess safety, tolerability, and efficacy of RT001 in patients with amyotrophic lateral sclerosis.

BACKGROUND AND PURPOSE: RT001 is a deuterated synthetic homologue of linoleic acid, which makes membrane polyunsaturated fatty acids resistant to lipid peroxidation, a process involved in motor neuron degeneration in amyotrophic lateral sclerosis (ALS). METHODS: We conducted a randomized, multicenter, placebo-controlled clinical trial. Patients with ALS were randomly allocated to receive either RT001 or placebo for 24 weeks. After the double-blind period, all patients received RT001 during an open-label phase for 24 weeks. The primary outcome measures were safety and tolerability. Key efficacy outcomes included the ALS Functional Rating Scale (ALSFRS-R), percent predicted slow vital capacity, and plasma neurofilament light chain concentration. RESULTS: In total, 43 patients (RT001 = 21; placebo = 22) were randomized. RT001 was well tolerated; one patient required dose reduction due to adverse events (AEs). Numerically, there were more AEs in the RT001 group compared to the placebo group (71% versus 55%, p = 0.35), with gastrointestinal symptoms being the most common (43% in RT001, 27% in placebo, p = 0.35). Two patients in the RT001 group experienced a serious AE, though unrelated to treatment. The least-squares mean difference in ALSFRS-R total score at week 24 of treatment was 1.90 (95% confidence interval = -1.39 to 5.19) in favor of RT001 (p = 0.25). The directions of other efficacy outcomes favored RT001 compared to placebo, although no inferential statistics were performed. CONCLUSIONS: Initial data indicate that RT001 is safe and well tolerated. Given the exploratory nature of the study, a larger clinical trial is required to evaluate its efficacy.