Here, we describe the results of PASADENA Part 2 at Week 104 and Part 3 Week 52 open-label extension (OLE).

Prasinezumab is a humanised monoclonal antibody designed to target aggregated alpha-synuclein and slow disease progression in Parkinson’s disease (PD). PASADENA (NCT03100149) is multicentre, randomised, double-blind, placebo-controlled study evaluating the efficacy of prasinezumab in participants with early-stage PD.

Participants with early-stage PD (diagnosis ≤2 years of age at screening; Hoehn & Yahr Stages I–II) were randomised to receive intravenous prasinezumab every 4 weeks (1500 mg or 4500 mg) for approximately three years (early-start group), or placebo for 52 weeks followed by prasinezumab (1500 mg or 4500 mg) for approximately two years (delayed-start group). All 316 PASADENA participants were considered in the analysis, with participants included regardless of change in symptomatic therapy. Motor progression and motor complications were defined, respectively, as a ≥5-point increase on the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part III and reaching a score ≥1 point on MDS-UPDRS Part IV, and were analysed using Cox proportional hazards models.

Baseline characteristics were balanced between individuals in the early- and delayed-start groups. At the end of Part 2, fewer participants in the early-start group showed motor progression (80.1%) or developed motor complications (45.0%) compared with the delayed-start group (89.5% and 55.2%) (hazard ratio: 0.77 [80% confidence interval (CI) 0.65–0.91] and 0.74 [80% CI 0.60–0.92]). One-year results from Part 3 will be further described.

The PASADENA Part 3 OLE is currently ongoing, and we aim to describe the long-term safety and efficacy on a yearly basis.