Feasibility of Simon 2-Stage Futility Trials in Early Parkinson Disease: Analysis of the PRECEPT and DATATOP Trial Datasets.

Abstract

Background and objectives: Disease-modifying treatments (DMTs) are a major unmet need in Parkinson disease (PD). To date, trials investigating DMT candidates in PD most often used a randomized controlled trial (RCT) design. Unfortunately, RCTs to date have not led to a breakthrough, in part because of the large sample sizes and length of follow-up required. In the interest of testing DMT candidates in a more efficient manner, it may be worthwhile to perform futility trials, which are smaller clinical trials that have originally been developed as phase 2 trials in oncology and more recently been used in progressive multiple sclerosis. In this investigation, we used original, patient-level data from DATATOP and PRECEPT, 2 large RCTs in early PD, to explore the feasibility of using the Simon 2-Stage futility trial design in early PD.

Methods: This is a post hoc analysis of original, patient-level data from the DATATOP and PRECEPT RCTs in early PD. In our analyses, we use descriptive statistics, survival analysis, and binary logistic regression to explore thresholds of change in the Unified Parkinson Disease Rating Scale (UPDRS) motor score as the primary outcome measure, length of follow-up, inclusion and exclusion criteria, and projected sample sizes for Simon 2-Stage futility trials in early PD. We also performed bootstrapping experiments to illustrate the ability of trials using the Simon 2-Stage futility design to identify selegiline as nonfutile and tocopherol as futile.

Results: PRECEPT included 806 participants (mean age 59.7 years, SD 10.3, 64.4% male), and DATATOP included 800 participants (mean age 61.1 years, SD 9.5, 64.4% male). Our analyses suggest that futility trials using the Simon 2-Stage methodology are feasible in PD. We propose a 5-point worsening on the UPDRS motor score as the primary outcome measure and a length of follow-up of 12 months. Trial simulations based on these data suggest the required sample size for such clinical trials to be lower than 200 participants.

Discussion: Based on our analysis of DATATOP and PRECEPT, phase 2 clinical trials using the Simon 2-Stage methodology are feasible in PD and may offer an opportunity to expedite the discovery of promising treatments in early PD.