Data refreshed: 2026-03-14 PT from ClinicalTrials.gov
| Metric | Value |
|---|---|
| Total Clinical Trials | 28 |
| Active Trials (Recruiting/Active) | 8 (29%) |
| Phase 1 Trials | 5 |
| Phase 2 Trials | 3 |
| Phase 3 Trials | 0 |
The complement system is a critical component of the innate immune system that plays a dual role in neurodegeneration - both in protective immune surveillance and in driving pathological neuroinflammation. Therapeutic targeting of complement proteins represents a growing area of interest for Alzheimer's disease, Parkinson's disease, and other neurodegenerative disorders[1].
The complement system has emerged as a key link between neuroinflammation and protein aggregation in neurodegenerative diseases. While complement proteins play essential roles in synaptic pruning during development and immune defense, dysregulated complement activation can drive pathology through microglial activation, synapse loss, and chronic neuroinflammation.
The complement therapeutics space has seen significant investment following:
Key challenges remain:
| Target | Role in Neurodegeneration | Therapeutic Approach | Development Stage |
|---|---|---|---|
| C1q | Synaptic pruning, complement activation | Antibody blockade | Preclinical |
| C3 | Central complement node | C3 inhibitor (Pegcetacoplan) | Phase 2 |
| C5 | Complement terminal pathway | Eculizumab, Ravulizumab | Approved (other), Phase 2/3 |
| C5aR1 | Neuroinflammation receptor | C5a receptor antagonists | Preclinical |
| C1QA | Synaptic elimination | Genetic studies | Research |
Complement therapeutics represent a promising but challenging area in neurodegeneration R&D. While the biological rationale is strong, BBB penetration and infection risk remain key hurdles. The field awaits late-stage clinical data to validate this approach.
](/entities/complement-system)
](https://www.frontiersin.org/articles/10.3389/fnins.2020.576527/full)