Linked Clinical Trials (LCT) is the flagship international clinical trials program of Cure Parkinson's, a UK-based charity dedicated to finding a cure for Parkinson's disease. Founded in 2009, LCT represents a unique approach to drug repurposing, bringing together leading Parkinson's researchers, pharmaceutical companies, and people with Parkinson's to rapidly advance promising disease-modifying therapies through clinical trials 1.
The program has reviewed over 200 compounds and has been instrumental in advancing more than 30 repurposed drugs into clinical trials for Parkinson's disease, making it one of the most productive drug repurposing initiatives in the Parkinson's field 2.
Drug repurposing—also called drug repositioning or indication expansion—offers significant advantages over traditional de novo drug development 3. This approach leverages compounds that have already been approved for other conditions or have demonstrated safety in human trials, dramatically reducing development timelines and costs. For neurodegenerative diseases like Parkinson's, where the pipeline of disease-modifying therapies remains limited, repurposing provides a critical pathway to bring new treatments to patients faster 4.
The LCT program specifically focuses on identifying compounds that target the underlying pathological mechanisms of Parkinson's disease rather than merely managing symptoms 5. These mechanisms include:
The Linked Clinical Trials program was established in 2009 by Cure Parkinson's (then known as The Cure Parkinson's Trust) with the vision of accelerating the development of disease-modifying treatments for Parkinson's disease. The founding principle was that many existing drugs, originally developed for other conditions, might have therapeutic potential in Parkinson's disease that could be rapidly tested in clinical trials.
| Year | Milestone |
|---|---|
| 2009 | LCT program founded by Cure Parkinson's |
| 2012 | First compounds advanced to clinical trials |
| 2017 | Exenatide Phase II trial shows positive results |
| 2018 | Ambroxol trial initiated for GBA-PD |
| 2020 | Multiple Phase III trials in progress |
During its first decade, the LCT program expanded significantly:
The 2020s have seen the program mature with several compounds advancing through late-stage clinical trials:
The LCT is governed by an international committee of leading Parkinson's researchers who evaluate compounds based on rigorous scientific criteria 11. The committee includes:
| Role | Focus Area |
|---|---|
| Neurologists | Clinical trial design, patient selection |
| Basic Scientists | Preclinical evidence evaluation |
| Biostatisticians | Trial design and endpoint selection |
| Pharmaceutical Experts | Drug development and regulatory pathways |
| Patient Representatives | Patient-centric trial design |
The committee evaluates compounds using a weighted scoring system:
| Evaluation Criterion | Weight | Description |
|---|---|---|
| Scientific Rationale | High | Mechanistic basis for efficacy in PD |
| Preclinical Evidence | High | Animal model data, mechanism-of-action studies |
| Safety Profile | High | Prior clinical experience, known adverse effects |
| Feasibility | Medium | Regulatory pathway, manufacturing requirements |
| Patient Accessibility | Medium | Trial site availability, eligible patient population |
The committee meets annually to review new compounds and assess progress of those in development. This systematic approach ensures that resources are focused on the most promising candidates while maintaining flexibility to respond to new scientific discoveries 12.
Mechanistic Relevance: Targets pathological pathways in PD
Preclinical Evidence: Strong animal model data demonstrating:
Clinical Safety: Known safety profile from existing use in:
| Drug | Original Indication | PD Target | Trial Phase | Key Findings |
|---|---|---|---|---|
| Exenatide | Diabetes | GLP-1R | Phase III | Motor score improvements in Phase II 13 |
| Ambroxol | Mucolytic | GBA | Phase II | Increased GBA enzyme activity in CSF 14 |
| Inosine | Gout | Urate elevation | Phase III | Elevated serum urate associated with slower progression 15 |
| Nilotinib | Leukemia | Autophagy | Phase II | Increased CSF biomarkers of autophagy 16 |
| Simvastatin | High cholesterol | Neuroprotection | Phase II | Anti-inflammatory effects 17 |
| Metformin | Diabetes | AMPK | Phase II | Metabolic modulation 18 |
Exenatide, a glucagon-like peptide-1 (GLP-1) receptor agonist originally developed for type 2 diabetes, represents one of the LCT program's most significant achievements. The drug's journey from diabetes therapy to Parkinson's disease treatment exemplifies the power of drug repurposing 19.
GLP-1 receptors are expressed in the brain, particularly in regions affected by Parkinson's disease pathology. Activation of these receptors leads to:
The Phase 2 trial showed that patients receiving exenatide alongside their standard Parkinson's medication demonstrated significantly better motor function scores compared to those receiving standard treatment alone. Notably, these benefits persisted even after the drug was discontinued, suggesting potential disease-modifying effects.
Ambroxol represents a targeted approach for a specific genetic subgroup of Parkinson's disease. The drug is a beta-glucocerebrosidase (GCase) chaperone that can increase enzyme activity, which is particularly relevant for patients with GBA gene mutations 21.
Mutations in the GBA gene are the most common genetic risk factor for Parkinson's disease, increasing risk 5-6 fold in heterozygous carriers. These mutations lead to reduced GCase activity, which impairs lysosomal function and contributes to alpha-synuclein aggregation.
The Inosine program targets the neuroprotective properties of serum urate, a natural antioxidant. Higher urate levels have been associated with slower Parkinson's disease progression in observational studies 23.
The Inosine SPRING trial was one of the largest single intervention trials in Parkinson's disease history:
Results demonstrated that inosine supplementation safely elevated serum urate levels, with associated changes in CSF oxidative stress markers. A Phase 3 trial (NOPARK) is now evaluating whether these biochemical effects translate to clinical benefits 24.
Nilotinib, a tyrosine kinase inhibitor originally developed for chronic myeloid leukemia, showed promise in Parkinson's disease through its ability to activate autophagy—the cellular process responsible for clearing misfolded proteins including alpha-synuclein 25.
Nilotinib inhibits several kinases that negatively regulate autophagy, including:
By activating autophagy, nilotinib may help clear pathogenic alpha-synuclein aggregates and protect dopaminergic neurons.
Beyond the flagship programs, the LCT pipeline includes numerous other compounds at various stages of development:
| Compound | Target | Development Stage |
|---|---|---|
| Simvastatin | HMG-CoA reductase, inflammation | Phase II |
| Metformin | AMPK, metabolism | Phase II |
| Sargramostim | GM-CSF, immunomodulation | Phase I |
| AZD3241 | Myeloperoxidase inhibition | Phase I |
| Pegylated uricase | Urate degradation | Preclinical |
Exenatide Phase II Trial (2017)
Ambroxol for GBA-PD (2020)
Inosine SPRING Trial (2022)
Nilotinib Phase II Results (2021)
| Metric | Value | Context |
|---|---|---|
| Compounds Reviewed | 200+ | Since program inception |
| Trials Initiated | 30+ | All phases of clinical development |
| Countries Involved | 15+ | International collaboration |
| Patients Enrolled | 5,000+ | Across all LCT-sponsored trials |
| Phase III Trials | 3 | Exenatide, Inosine, Ambroxol |
| Fast Track Designations | 2 | FDA-granted |
The LCT program has established a global network of clinical trial sites spanning:
This international infrastructure enables rapid patient recruitment and ensures diverse representation in clinical trials.
A distinguishing feature of the LCT program is its integration of patient perspectives throughout the drug development process. People with Parkinson's disease are involved in:
The program maintains close relationships with organizations including Parkinson's UK, the Michael J. Fox Foundation, and the Parkinson's Foundation.
The LCT program continues to evaluate new compounds targeting emerging mechanisms:
Alpha-synuclein propagation inhibitors: Drugs that prevent the spread of pathological alpha-synuclein between neurons 27
Microglial activation modulators: Targeting the neuroinflammatory component of PD pathology
Mitochondrial quality control: Enhancing mitophagy and mitochondrial biogenesis
Synaptic function protectors: Preserving dopamine neuron connectivity
Cellular stress response enhancers: Activating endogenous neuroprotective pathways
The program is moving toward a precision medicine model that matches specific therapies to patient subgroups based on:
The LCT program continues to expand partnerships with: