A 52-Week, Open-label, Single-arm Study to Evaluate the Safety and Tolerability of 24-hour Daily Exposure of Continuous Subcutaneous Infusion of ABBV-951 in Subjects With Parkinson's Disease

Number of Participants With Adverse Events of Special Interest

Time Frame: From first dose of study drug until 30 days following last dose of study drug (up to 480 days)

Treatment emergent adverse events of special interest are defined as any adverse event of infusion site infections, infusion site reactions, hallucinations/psychosis, falls and associated injuries, polyneuropathy (peripheral neuropathy), weight loss, or somnolence from the first dose of study drug until 30 days following last dose of study drug.

Hemoglobin (Hematology): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

White Blood Cell (WBC) Count (Hematology): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Number of Participants With Adverse Events

Time Frame: From first dose of study drug until 30 days following last dose of study drug (up to 480 days)

An adverse event (AE) is defined as any untoward medical occurrence in a patient or clinical investigation participant administered a pharmaceutical product which does not necessarily have a causal relationship with this treatment. The investigator assesses the relationship of each event to the use of study drug. A serious adverse event (SAE) is an event that results in death, is life-threatening, requires or prolongs hospitalization, results in a congenital anomaly, persistent or significant disability/incapacity or is an important medical event that, based on medical judgment, may jeopardize the participant and may require medical or surgical intervention to prevent any of the outcomes listed above. Treatment-emergent adverse events/treatment-emergent serious adverse events (TEAEs/TESAEs) are defined as any event that began or worsened in severity on or after the first dose of study drug.

Hematocrit (Hematology): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Number of Participants With Numeric Grade Equal to or Higher Than 5 and With Letter Grade Equal to or Higher Than D on the Infusion Site Evaluation Scale

Time Frame: Day 1, Day 2, Week 1, Week 2, Week 3, Week 4, Week 6, Week 13, Week 26, Week 39, and Week 52

Skin tolerability was assessed using the Infusion Site Evaluation Scale, a 2-part numeric (0-7) and letter (A-G) grade scale, where a notable skin reaction is defined as a reaction with a numeric grade of 6 or 7 or a letter grade of D, E, F, or G. Any observation of infusion site reaction with irritation criteria \> 2 or \> C was recorded as an adverse event (AE).

Red Blood Cell (RBC) Count (Hematology): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Mean Corpuscular Hemoglobin (Hematology): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Blood Urea Nitrogen (BUN) (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Serum Alanine Aminotransferase (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Inorganic Phosphorus (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Total Cholesterol (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Albumin (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Monocytes (Hematology): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Mean Corpuscular Volume Concentration (MCHC) (Hematology): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Prothrombin Time (PT) (Hematology): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Creatinine (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Vitamin B6 (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Electrocardiogram (ECG) Aggregate PR Interval: Change From Baseline to End of Study

Time Frame: Baseline, Day 1 (postdose), Weeks 6 and 52

12-lead electrocardiograms (ECGs) were recorded at study visits after the participant had been supine for at least 5 minutes. Participants were instructed to remain stationary (no talking, laughing, deep breathing, sleeping, or swallowing) for approximately 10 seconds during the ECG recording. When an ECG was recorded at a time near that of a blood collection, the ECG was obtained prior to the blood collection. ECGs on Day 1 were recorded after initiation of the continuous subcutaneous infusion (CSCI) of ABBV-951 prior to the end of the study visit.

Electrocardiogram (ECG) Aggregate QRS Duration: Change From Baseline to End of Study

Time Frame: Baseline, Day 1 (postdose), Weeks 6 and 52

12-lead electrocardiograms (ECGs) were recorded at study visits after the participant had been supine for at least 5 minutes. Participants were instructed to remain stationary (no talking, laughing, deep breathing, sleeping, or swallowing) for approximately 10 seconds during the ECG recording. When an ECG was recorded at a time near that of a blood collection, the ECG was obtained prior to the blood collection. ECGs on Day 1 were recorded after initiation of the continuous subcutaneous infusion (CSCI) of ABBV-951 prior to the end of the study visit.

Neutrophils (Hematology): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Activated Partial Thromboplastin Time (Hematology): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Serum Aspartate Aminotransferase (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Gamma-glutamyl Transferase (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Sodium (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Uric Acid (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Sodium Bicarbonate/CO2 (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Creatinine Clearance (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Vitamin B12 (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Lymphocytes (Hematology): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Absolute Platelet Count (Hematology): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Serum Lactate Dehydrogenase (LDH) (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Alkaline Phosphatase (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Creatine Phosphokinase (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Total Bilirubin (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Potassium (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Calcium (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Glucose (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Magnesium (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Homocysteine (Clinical Chemistry): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

pH (Urinalysis): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Specific Gravity (Urinalysis): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 6, 26, 39, and 52

Samples for clinical laboratory tests were collected at study visits, and a certified central laboratory was used to process the samples and provide results.

Orthostatic Systolic Blood Pressure (Vital Signs): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 1, 6, 26, and 52 (orthostatic and standing); Baseline, Weeks 2, 4, 13, and 39 (supine)

Orthostatic blood pressure was measured after the participant had been supine (lying down with their face up) for at least 5 minutes and then, after the participant had been standing for 2 minutes. When vital sign measurements were scheduled at the same time as a blood collection, vital sign measurements were obtained prior to blood collection.

Orthostatic Diastolic Blood Pressure (Vital Signs): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 1, 6, 26, and 52 (orthostatic and standing); Baseline, Weeks 2, 4, 13, and 39 (supine)

Orthostatic blood pressure was measured after the participant had been supine (lying down with their face up) for at least 5 minutes and then, after the participant had been standing for 2 minutes. When vital sign measurements were scheduled at the same time as a blood collection, vital sign measurements were obtained prior to blood collection.

Electrocardiogram (ECG) Aggregate QTcF Interval: Change From Baseline to End of Study

Time Frame: Baseline, Day 1 (postdose), Weeks 6 and 52

12-lead electrocardiograms (ECGs) were recorded at study visits after the participant had been supine for at least 5 minutes. Participants were instructed to remain stationary (no talking, laughing, deep breathing, sleeping, or swallowing) for approximately 10 seconds during the ECG recording. When an ECG was recorded at a time near that of a blood collection, the ECG was obtained prior to the blood collection. ECGs on Day 1 were recorded after initiation of the continuous subcutaneous infusion (CSCI) of ABBV-951 prior to the end of the study visit.

Orthostatic Pulse Rate (Vital Signs): Change From Baseline to End of Study

Time Frame: Baseline, Weeks 1, 6, 26, and 52 (orthostatic and standing); Baseline, Weeks 2, 4, 13, and 39 (supine)

Orthostatic pulse rate was measured after the participant had been supine (lying down with their face up) for at least 5 minutes and then, after the participant had been standing for 2 minutes. When vital sign measurements were scheduled at the same time as a blood collection, vital sign measurements were obtained prior to blood collection.

Electrocardiogram (ECG) Mean Heart Rate: Change From Baseline to End of Study

Time Frame: Baseline, Day 1 (postdose), Weeks 6 and 52

12-lead electrocardiograms (ECGs) were recorded at study visits after the participant had been supine for at least 5 minutes. Participants were instructed to remain stationary (no talking, laughing, deep breathing, sleeping, or swallowing) for approximately 10 seconds during the ECG recording. When an ECG was recorded at a time near that of a blood collection, the ECG was obtained prior to the blood collection. ECGs on Day 1 were recorded after initiation of the continuous subcutaneous infusion (CSCI) of ABBV-951 prior to the end of the study visit.

Electrocardiogram (ECG) Aggregate QT Interval: Change From Baseline to End of Study

Time Frame: Baseline, Day 1 (postdose), Weeks 6 and 52

12-lead electrocardiograms (ECGs) were recorded at study visits after the participant had been supine for at least 5 minutes. Participants were instructed to remain stationary (no talking, laughing, deep breathing, sleeping, or swallowing) for approximately 10 seconds during the ECG recording. When an ECG was recorded at a time near that of a blood collection, the ECG was obtained prior to the blood collection. ECGs on Day 1 were recorded after initiation of the continuous subcutaneous infusion (CSCI) of ABBV-951 prior to the end of the study visit.

Electrocardiogram (ECG) Aggregate QTcB Interval: Change From Baseline to End of Study

Time Frame: Baseline, Day 1 (postdose), Weeks 6 and 52

12-lead electrocardiograms (ECGs) were recorded at study visits after the participant had been supine for at least 5 minutes. Participants were instructed to remain stationary (no talking, laughing, deep breathing, sleeping, or swallowing) for approximately 10 seconds during the ECG recording. When an ECG was recorded at a time near that of a blood collection, the ECG was obtained prior to the blood collection. ECGs on Day 1 were recorded after initiation of the continuous subcutaneous infusion (CSCI) of ABBV-951 prior to the end of the study visit.

Electrocardiogram (ECG) Aggregate RR Interval: Change From Baseline to End of Study

Time Frame: Baseline, Day 1 (postdose), Weeks 6 and 52

12-lead electrocardiograms (ECGs) were recorded at study visits after the participant had been supine for at least 5 minutes. Participants were instructed to remain stationary (no talking, laughing, deep breathing, sleeping, or swallowing) for approximately 10 seconds during the ECG recording. When an ECG was recorded at a time near that of a blood collection, the ECG was obtained prior to the blood collection. ECGs on Day 1 were recorded after initiation of the continuous subcutaneous infusion (CSCI) of ABBV-951 prior to the end of the study visit.