An Extension Study to Evaluate the Long-Term Efficacy, Safety and Tolerability of Minzasolmin (UCB0599) in Study Participants With Parkinson's Disease

Change From Baseline in Dopamine Transporter Imaging, Measured by Single Photon Emission Computed Tomography (DaT-SPECT), Whole Striatum Specific Binding Ratio up to PD0055 EOT or ET (Corresponding to a Visit Between PD0055 Month 6 and Month 18 Inclusive)

Timeframe: From Baseline (PD0053 Screening Visit) up to PD0055 end of treatment (EOT) or early termination (ET) (corresponding to a visit between PD0055 Month 6 and Month 18 inclusive), up to 36 months post PD0053 Screening

Change from PD0053 Baseline (screening) in mean striatum specific binding ratio (SBR) was assessed by DaT-SPECT using 123I-Ioflupane. Whole striatum was calculated as average of SBR data values for the four following "small" regions: left caudate, right caudate, left putamen, and right putamen. SBR was calculated for each region with the occipital cortex as a reference region. SBR = Average Small region minus Average Occipital region divided by Average Occipital region. Lower SBR indicated worse disease. Data were summarized by mapped visits: a DaT-SPECT within 2 months of PD0055 Screening was mapped to PD0053 Month 18; assessments after Month 23 from PD0053 Baseline were grouped as a single PD0055 EOT/ET visit.

Cumulative Levodopa Equivalent Daily Dose (LEDD) at PD0055 Month 18

Timeframe: From Baseline (PD0053 Screening Visit) to PD0055 Month 18, up to 36 months post PD0053 Screening

The Cumulative Levodopa Equivalent Daily Dose (LEDD) was calculated for each participant at each visit, based on the dose level and frequency indicated on the concomitant medication form and at the end of study. This was the sum of all the LEDDs taken up to that visit. Any changes in medication (type, dose, or dosing regimen) were accounted for when calculating cumulative doses.

Percentage of Participants With Treatment-emergent Adverse Events (TEAEs)

Timeframe: From PD0055 Baseline (Day 0) to the Safety Follow-up Visit (PD0055 Month 31)

An adverse event (AE) was any untoward medical occurrence in a patient or clinical study participant, temporally associated with the use of study medication, whether or not considered related to the study medication. A TEAE was defined as any AE with a start date on or after the first dose of treatment or any unresolved event already present before administration of treatment that worsens in intensity following exposure to the treatment in PD0055. The percentage of participants data was rounded to one decimal place.

Percentage of Participants With Serious TEAEs

Timeframe: From PD0055 Baseline (Day 0) to the Safety Follow-up Visit (PD0055 Month 31)

A SAE was defined as any untoward medical occurrence that, at any dose results in death, is life-threatening, requires inpatient hospitalisation or prolongation of existing hospitalisation, results in persistent disability or incapacity, is a congenital anomaly or birth defect, and other important medical events which are based on medical or scientific judgement may jeopardise the participant's life, or may require medical or surgical intervention to prevent any of the above. The percentage of participants data was rounded to one decimal place.

Percentage of Participants With TEAEs Leading to Withdrawal From the Study

Timeframe: From PD0055 Baseline (Day 0) to the Safety Follow-up Visit (PD0055 Month 31)

Percentage of participants with TEAEs leading to withdrawal from the study are presented. A TEAE was defined as any AE with a start date on or after the first dose of treatment or any unresolved event already present before administration of treatment that worsens in intensity following exposure to the treatment in PD0055. The percentage of participants data was rounded to one decimal place.