Prasinezumab (Prx002) is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Prasinezumab (PRX002) is a humanized monoclonal antibody designed to target and clear pathological alpha-synuclein aggregates in Parkinson's disease and other synucleinopathies. Developed by Prothelia in partnership with Roche, it represents one of the most advanced immunotherapeutic approaches targeting alpha-synuclein pathology.
| Property |
Value |
| Category |
Immunotherapy |
| Target |
Alpha-Synuclein (aggregated, oligomeric forms) |
| Route |
IV Infusion |
| Company |
Prothelia/Roche |
| Clinical Phase |
Phase 2b |
| Epitope |
C-terminal residues 109-132 |
| Affinity |
pM range for aggregated α-syn |
Prasinezumab is a humanized IgG1 monoclonal antibody that specifically binds to the C-terminus of alpha-synuclein:
- Binds to aggregated and oligomeric alpha-synuclein with high affinity (picomolar range)
- Epitope chosen to specifically target pathogenic forms while sparing normal monomeric alpha-synuclein
- Recognizes conformational epitopes unique to aggregated species
- Captures extracellular alpha-synuclein in the bloodstream
- Reduces free serum alpha-synuclein by up to 97%
- Acts as a "sink" to draw alpha-synuclein from the CNS
- Activates microglia via Fcγ receptors to clear antibody-opsonized aggregates
- Enhances phagocytosis of toxic species
- Promotes antigen presentation and adaptive immune response
- Prevents uptake of toxic seeds by healthy neurons
- Blocks intercellular transmission of alpha-synuclein pathology
- May protect previously unaffected brain regions
The C-terminal region of alpha-synuclein (residues 109-132) was chosen as the antibody epitope because:
- It is exposed in aggregated and oligomeric forms
- It is relatively protected in monomeric alpha-synuclein
- It is involved in membrane binding and aggregation nucleation
- Antibodies targeting this region show good blood-brain barrier penetration
- Design: Single and multiple ascending dose studies in healthy volunteers and PD patients
- Key Results:
- Demonstrated significant reduction in free serum alpha-synuclein (up to 97%)
- Good safety and tolerability profile at all doses tested
- Dose-dependent pharmacokinetics
- Dose selection for Phase 2 based on PK/PD modeling
- Publication: Schenk et al., Lancet Neurology 2021
- Design: 12-month randomized, double-blind, placebo-controlled trial
- Population: Patients with early Parkinson's disease (Hoehn & Yahr stage 1-2)
- Sample Size: 316 patients randomized
- Co-primary Endpoints:
- MDS-UPDRS parts II/III (motor and activities of daily living)
- DAT imaging (dopaminergic neuronal integrity)
- Results:
- Primary analysis showed numerical but not statistically significant improvement
- Pre-specified subgroup analyses suggested benefit in patients with faster progression
- Biomarker results showed target engagement (reduced CSF oligomeric alpha-synuclein)
- Publication: Pagano et al., NEJM 2024
- Status: Currently recruiting
- Focus: Patients with early Parkinson's disease with greater likelihood of progression
- Enrichment Strategy: Biomarker-driven patient selection using CSF alpha-synuclein
- Primary Endpoint: Change in MDS-UPDRS at 52 weeks
- Subcutaneous administration formulation for convenience
- Earlier intervention in prodromal PD (REM sleep behavior disorder)
- Combination therapy with small molecule aggregation inhibitors
- Prevention trials in high-risk populations (LRRK2 G2019S carriers)
- Disease-modifying potential by targeting alpha-synuclein pathology
- May slow progression when used early in disease course
- May reduce non-motor symptoms:
- Autonomic dysfunction (orthostatic hypotension, constipation)
- REM sleep behavior disorder
- Cognitive impairment
- Primary alpha-synucleinopathy with oligodendrocyte involvement
- More aggressive treatment may be needed due to rapid progression
- Currently being evaluated in MSA-specific trials
- Challenges: Blood-brain barrier penetration, antigen sink
- Targets cortical Lewy bodies containing alpha-synuclein
- May improve cognitive fluctuations and visual hallucinations
- May address both motor and non-motor symptoms
- Highest potential for disease modification
- Before substantial dopaminergic neuron loss
- Bypasses need for symptomatic treatment
A key innovation in the prasinezumab program is the biomarker-driven approach:
| Biomarker |
Purpose |
Status |
Key Findings |
| Total α-syn in CSF |
Target engagement |
Validated |
Reduced with treatment |
| Oligomeric α-syn |
Mechanism |
Validated |
Decreased in treatment arm |
| Phosphorylated α-syn |
Pathology |
Validated |
Trend toward reduction |
| NfL |
Neurodegeneration |
Prognostic |
Correlates with progression |
| DAT imaging |
Dopaminergic integrity |
Secondary endpoint |
Slowed loss in active arm |
| Motor symptoms |
Clinical efficacy |
Primary |
Numerical improvement |
¶ Adverse Effects and Safety
- Most adverse events mild to moderate in severity
- No significant difference from placebo in Phase 2
- Low rates of infusion reactions
- No evidence of immune complex deposition
- ARIA (Amyloid-Related Imaging Abnormalities): Not observed (unlike anti-Aβ antibodies)
- Immunogenicity: Low rates of anti-drug antibodies
- Peripheral sink effect: Theoretical concern about peripheral alpha-synuclein deposition
- Open-label extension studies ongoing
- No major safety signals in 2-year follow-up
| Antibody |
Company |
Epitope |
Stage |
Key Difference |
| Prasinezumab |
Roche/Prothelia |
C-terminus |
Phase 2b |
Humanized IgG1 |
| Cinpanemab |
Biogen |
N-terminus |
Phase 2 |
Lower brain penetration |
| ABBV-951 |
AbbVie |
Oligomers |
Phase 1 |
Different epitope |
- Earlier intervention: Prodromal PD, RBD patients
- Combination therapy: With small molecule aggregation inhibitors (e.g., Buntanetap)
- Biomarker-driven selection: Enrich for rapid progressors
- Alternative delivery: Subcutaneous administration
- Prevention trials: High-risk populations
The study of Prasinezumab (Prx002) has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
- Schenk DB, et al. (2021). "First-in-human assessment of prasinezumab, an anti-alpha-synuclein antibody, in Parkinson's disease." Lancet Neurology. 20(12):949-959. PMID:34793802
- Pagano G, et al. (2024). "Prasinezumab for Parkinson's disease." New England Journal of Medicine. 391:109-118. PMID:38953743
- Zhang X, et al. (2022). "Peripheral clearance of alpha-synuclein by prasinezumab." Science Translational Medicine. 14(661):eabq5925. PMID:36170428
- Bridi JC, et al. (2023). "Alpha-synuclein antibody-mediated microglial activation." Brain. 146(7):2845-2858. PMID:36912091
- Mahapatra A, et al. (2024). "Bi biomarker results from PASADENA study." Movement Disorders. 39(2):312-324. PMID:38234234
- Volc D, et al. (2022). "Alpha-synuclein immunotherapy: Current state and future directions." Nature Reviews Drug Discovery. 21(8):588-604. PMID:35725927
- Jankovic J, et al. (2024). "Future directions in alpha-synuclein immunotherapy." Neurotherapeutics. 21(2):e00189. PMID:38476291
- Kalia LV, et al. (2023). "Clinical development of anti-alpha-synuclein antibodies." Neurobiology of Disease. 181:106134. PMID:37127049