A Prospective Exploratory Study of the Safety and Preliminary Efficacy of the α-Syn H21 Monoclonal Antibody in Patients With Multiple System Atrophy

Multiple system atrophy (MSA) is a progressive neurodegenerative disorder characterized by autonomic dysfunction, parkinsonism, and cerebellar ataxia. Abnormal aggregation of alpha-synuclein is believed to play an important role in disease progression. The α-Syn H21 monoclonal antibody is designed to selectively bind pathological alpha-synuclein aggregates and may reduce their spread and related neuroinflammation.

This single-center, prospective, exploratory study will evaluate the safety, tolerability, and preliminary efficacy of the α-Syn H21 monoclonal antibody in patients with MSA. Participants will receive intravenous infusions of H21 every 4 weeks for 3 doses and will be followed for 12 weeks. Clinical symptoms, laboratory tests, imaging findings, and adverse events will be assessed to determine whether H21 may provide clinical benefit and support future larger studies.

Study Overview

• Status: Not yet recruiting
• Conditions: Multiple System Atrophy
• Intervention / Treatment: Biological: α-Syn H21 Monoclonal Antibody

• Study Type: Interventional
• Enrollment (Estimated): 3
• Phase: Phase 1

Contacts and Locations

• Study Contact: Name: Jun Liu, MD, PhD; Phone Number: 021-86-64370045; Email: jly0520@hotmail.com
• Study Contact Backup: Name: Yan SHEN, MD, PhD; Phone Number: +86-021-64370045; Email: shenyanzmins@sina.com

Study Locations

• China
  • Shanghai Municipality
    • Shanghai, Shanghai Municipality, China, 200025
      • Department of Neurology and Institute of Neurology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, Shanghai 200025
      • Contact: Jun LIU, MD, PhD; Phone Number: 86-021-64370045; Email: jly0520@hotmail.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Age 45 to 75 years, male or female
• Diagnosis of Multiple System Atrophy meeting current clinical diagnostic criteria for probable or possible MSA
• Disease duration of 2 years or less from onset of motor or autonomic symptoms
• Clinically stable disease without significant fluctuation or acute worsening within 4 weeks before enrollment
• Able to comply with study procedures and follow-up assessments
• Mini-Mental State Examination (MMSE) score not consistent with significant dementia
• Willing and able to provide written informed consent

Exclusion Criteria:

• History or presence of other neurological disorders that may interfere with study assessments, including Parkinson's disease, progressive supranuclear palsy, corticobasal degeneration, or stroke
• Severe cognitive impairment or psychiatric disorder, including clinically significant depression or anxiety
• Severe cardiac, hepatic, renal, or other major systemic disease
• History of severe hypersensitivity to monoclonal antibody therapies Pregnant or breastfeeding women
• Women or men unwilling to use effective contraception during the study
• Participation in another clinical trial or receipt of investigational treatment within 3 months before enrollment
• Any other condition that, in the investigator's judgment, would make participation inappropriate

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: H21 Treatment	Biological: α-Syn H21 Monoclonal Antibody; The α-Syn H21 monoclonal antibody is a humanized monoclonal antibody designed to selectively bind pathological alpha-synuclein aggregates. Participants will receive the study drug by intravenous infusion once every 4 weeks for a total of 3 doses during the 12-week study period.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence of treatment-emergent adverse events	Incidence, severity, and relationship of adverse events (AEs) and serious adverse events (SAEs) to study treatment.	From first dose through Week 12
Change from Baseline in Unified Multiple System Atrophy Rating Scale (UMSARS) Total Score (Parts I-IV)	Change from baseline in the total score and subscale scores of the Unified Multiple System Atrophy Rating Scale (UMSARS Parts I-IV). The UMSARS is a clinician-administered scale used to assess disease severity in patients with multiple system atrophy. Total scores are derived from Parts I-IV, with higher scores indicating greater disease severity and worse clinical status. The total score ranges from 0 to 249, with higher scores indicating more severe impairment.	Baseline, Week 4, Week 8, and Week 12
Change from baseline in DAT-PET/MRI measures of striatal dopamine transporter uptake and brain structural changes	Change from baseline in DAT-PET/MRI imaging parameters, including brain metabolic and structural changes.	Baseline and Week 12

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from Baseline in Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Total Score	Change from baseline in the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS Parts I-IV) total and subscale scores. The MDS-UPDRS is a clinician-administered scale used to assess the severity and progression of Parkinsonian symptoms. The total score ranges from 0 to 260, with higher scores indicating greater disease severity and worse motor and non-motor impairment.	Baseline, Week 4, Week 8, and Week 12
Change in Patient Global Impression of Improvement (PGI-I) Score	The Patient Global Impression of Improvement (PGI-I) is a patient-reported measure assessing overall perceived improvement following treatment. Scores range from 1 (very much improved) to 7 (very much worse), with lower scores indicating better perceived improvement.	Baseline, Week 4, Week 8, and Week 12
Change from Baseline in Mini-Mental State Examination (MMSE) Score	Change from baseline in the Mini-Mental State Examination (MMSE) score. The MMSE is a widely used clinician-administered screening tool for global cognitive function, assessing domains including orientation, attention, memory, language, and visuospatial abilities. Scores range from 0 to 30, with higher scores indicating better cognitive function and lower scores indicating greater cognitive impairment.	Baseline, Week 4, Week 8, and Week 12
Change from Baseline in Hamilton Depression Rating Scale (HAMD) Score	Change from baseline in the Hamilton Depression Rating Scale (HAMD) score. The HAMD is a clinician-administered scale used to assess the severity of depressive symptoms. Scores range from 0 to 52 (17-item version), with higher scores indicating more severe depressive symptoms and lower scores indicating less severe depression.	Baseline, Week 4, Week 8, and Week 12
Change from Baseline in Hamilton Anxiety Rating Scale (HAMA) Score	Change from baseline in the Hamilton Anxiety Rating Scale (HAMA) score. The HAMA is a clinician-administered scale used to assess the severity of anxiety symptoms. Scores range from 0 to 56, with higher scores indicating more severe anxiety symptoms and lower scores indicating less severe anxiety.	Baseline, Week 4, Week 8, and Week 12
Change from Baseline in Parkinson's Disease Sleep Scale-2 (PDSS-2) Score	Change from baseline in the Parkinson's Disease Sleep Scale-2 (PDSS-2) score. The PDSS-2 is a patient-reported scale used to assess the severity of nocturnal disturbances and sleep-related symptoms in patients with Parkinson's disease. Scores range from 0 to 60, with higher scores indicating more severe sleep disturbances and poorer sleep quality.	Baseline, Week 4, Week 8, and Week 12
Change from Baseline in Parkinson's Disease Questionnaire-39 (PDQ-39) Score	Change from baseline in the Parkinson's Disease Questionnaire-39 (PDQ-39) score. The PDQ-39 is a patient-reported questionnaire used to assess health-related quality of life in patients with Parkinson's disease across eight domains, including mobility, activities of daily living, emotional well-being, and social support. Scores range from 0 to 156, with higher scores indicating poorer health-related quality of life and greater disease impact.	Baseline, Week 4, Week 8, and Week 12
Number of Participants With Clinically Significant Abnormal Laboratory Values	The number of participants with clinically significant abnormal laboratory values following H21 administration, including abnormalities in hematology, urinalysis, liver function, and renal function tests, as assessed by the investigator.	Baseline, Week 4, Week 8, and Week 12
Change from baseline in electrocardiogram parameters including heart rhythm, PR interval, QRS duration, and QTc interval	Standard 12-lead electrocardiograms will be performed at scheduled visits to assess changes from baseline in cardiac conduction and rhythm parameters, including heart rhythm, PR interval, QRS duration, and corrected QT (QTc) interval, following H21 administration.	Baseline, Week 4, Week 8, and Week 12
Change in Blood Pressure After Infusion	Change in blood pressure measured before each H21 infusion and at 10 minutes and 30 minutes after infusion to evaluate short-term hemodynamic changes associated with study drug administration.	Pre-dose and 10 minutes and 30 minutes after each infusion through Week 12
Change in Heart Rate After Infusion	Change in heart rate measured before each H21 infusion and at 10 minutes and 30 minutes after infusion to evaluate short-term cardiac responses associated with study drug administration.	Pre-dose and 10 minutes and 30 minutes after each infusion through Week 12
Change in Respiratory Rate After Infusion	Change in respiratory rate measured before each H21 infusion and at 10 minutes and 30 minutes after infusion to evaluate short-term respiratory changes associated with study drug administration.	Pre-dose and 10 minutes and 30 minutes after each infusion through Week 12
Serum Concentration of H21	Serum concentrations of H21 will be measured at prespecified time points following administration to characterize the concentration-time profile of H21.	During treatment through Week 12
Maximum Observed Serum Concentration (Cmax) of H21	The maximum observed serum concentration (Cmax) of H21 following administration.	During treatment through Week 12
Time to Maximum Observed Serum Concentration (Tmax) of H21	The time to reach the maximum observed serum concentration (Tmax) of H21 following administration.	During treatment through Week 12
Area Under the Serum Concentration-Time Curve (AUC) of H21	The area under the serum concentration-time curve (AUC) of H21 following administration.	During treatment through Week 12
Terminal Elimination Half-life (t1/2) of H21	The terminal elimination half-life (t1/2) of H21 following administration.	During treatment through Week 12

Collaborators and Investigators

• Sponsor: Ruijin Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): September 15, 2026
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): December 31, 2026

Study Registration Dates

• First Submitted: May 12, 2026
• First Submitted That Met QC Criteria: August 17, 2026
• First Posted (Actual): August 19, 2026

Study Record Updates

• Last Update Posted (Actual): August 19, 2026
• Last Update Submitted That Met QC Criteria: August 17, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Synucleinopathies; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Neurodegenerative Diseases; Movement Disorders; Basal Ganglia Diseases; Primary Dysautonomias; Autonomic Nervous System Diseases; Multiple System Atrophy
• Other Study ID Numbers: H21-MSA

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No