Linked Clinical Trials Program

Introduction

<div class="infobox infobox-institution">
{| class="infobox-table"
| colspan="2" class="infobox-header" | Linked Clinical Trials (LCT) Program
|-
| Established | 2009
|-
| Lead Organization | Cure Parkinson's
|-
| Type | International Clinical Trials Consortium
|-
| Focus | Accelerating disease-modifying therapies for Parkinson's disease
|-
| Drugs Advanced | 30+ compounds into clinical trials
|-
| Compounds Reviewed | 200+
|-
| Countries | 15+
|}
</div>

Overview

Introduction

<div class="infobox infobox-institution">
{| class="infobox-table"
| colspan="2" class="infobox-header" | Linked Clinical Trials (LCT) Program
|-
| Established | 2009
|-
| Lead Organization | Cure Parkinson's
|-
| Type | International Clinical Trials Consortium
|-
| Focus | Accelerating disease-modifying therapies for Parkinson's disease
|-
| Drugs Advanced | 30+ compounds into clinical trials
|-
| Compounds Reviewed | 200+
|-
| Countries | 15+
|}
</div>

Overview

Linked Clinical Trials (LCT) is the flagship international clinical trials program of [Cure Parkinson's](/institutions/cure-parkinsons), 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](https://www.linkedclinicaltrials.org).

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](https://www.cureparkinsons.org.uk).

The Drug Repurposing Approach

Drug repurposing—also called drug repositioning or indication expansion—offers significant advantages over traditional de novo drug development [3](https://pubmed.ncbi.nlm.nih.gov/30661063/). 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](https://pubmed.ncbi.nlm.nih.gov/31129945/).

The LCT program specifically focuses on identifying compounds that target the underlying pathological mechanisms of Parkinson's disease rather than merely managing symptoms [5](https://pubmed.ncbi.nlm.nih.gov/31129950/). These mechanisms include:

• [Alpha-synuclein](/proteins/alpha-synuclein) aggregation and propagation
• Mitochondrial dysfunction and energy metabolism deficits
• Neuroinflammation and glial activation
• Lysosomal dysfunction and autophagy impairment
• Neurotrophic factor signaling deficiencies
• Oxidative stress and cellular stress responses

History and Foundation

Establishment and Evolution

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.

Key Milestones

| 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 |

Growth and Expansion (2010-2019)

During its first decade, the LCT program expanded significantly:

• 2012: First major drug—exenatide—entered clinical testing [6](https://pubmed.ncbi.nlm.nih.gov/30047582/)
• 2014: Program reached 20 compounds advanced to clinical trials
• 2016: International expansion to include centers across Europe, North America, and Australia
• 2018: Launch of the Inosine SPRING Trial, the largest urate elevation trial in PD history [7](https://pubmed.ncbi.nlm.nih.gov/37457789/)
• 2019: Program surpassed 30 compounds in clinical development

Recent Advances (2020-Present)

The 2020s have seen the program mature with several compounds advancing through late-stage clinical trials:

• 2020: Ambroxol Phase 2 trial for [GBA](/genes/gba)-associated Parkinson's disease [8](https://pubmed.ncbi.nlm.nih.gov/35604659/)
• 2021: Nilotinib Phase 2 results published, showing potential for autophagy activation [9](https://pubmed.ncbi.nlm.nih.gov/34554209/)
• 2022: Exenatide Phase 3 trial initiation
• 2023: Inosine Phase 3 trial results demonstrated safety and tolerability [10](https://pubmed.ncbi.nlm.nih.gov/37457789/)

Program Structure

International Committee

The LCT is governed by an international committee of leading Parkinson's researchers who evaluate compounds based on rigorous scientific criteria [11](https://pubmed.ncbi.nlm.nih.gov/32246844/). 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 |

Evaluation Criteria

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 |

Drug Pipeline Management

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](https://pubmed.ncbi.nlm.nih.gov/32246851/).

Selection Criteria

• [Alpha-synuclein](/proteins/alpha-synuclein) aggregation and spread
• Mitochondrial dysfunction and energy metabolism
• Neuroinflammation and glial activation
• Lysosomal dysfunction and autophagy
• Neurotrophic factor signaling
• Metal ion homeostasis

• Neuroprotective or disease-modifying effects
• Target engagement in relevant tissue
• Pharmacokinetic properties suitable for CNS delivery

• Other therapeutic indications
• Healthy volunteer studies
• Exploratory clinical trials

Pipeline Drugs in Detail

Currently in Clinical Trials

| Drug | Original Indication | PD Target | Trial Phase | Key Findings |
|------|---------------------|-----------|-------------|--------------|
| Exenatide | Diabetes | GLP-1R | Phase III | Motor score improvements in Phase II [13](https://pubmed.ncbi.nlm.nih.gov/28436599/) |
| Ambroxol | Mucolytic | GBA | Phase II | Increased GBA enzyme activity in CSF [14](https://pubmed.ncbi.nlm.nih.gov/34089001/) |
| Inosine | Gout | Urate elevation | Phase III | Elevated serum urate associated with slower progression [15](https://pubmed.ncbi.nlm.nih.gov/35444312/) |
| Nilotinib | Leukemia | Autophagy | Phase II | Increased CSF biomarkers of autophagy [16](https://pubmed.ncbi.nlm.nih.gov/35168912/) |
| Simvastatin | High cholesterol | Neuroprotection | Phase II | Anti-inflammatory effects [17](https://pubmed.ncbi.nlm.nih.gov/35093456/) |
| Metformin | Diabetes | AMPK | Phase II | Metabolic modulation [18](https://pubmed.ncbi.nlm.nih.gov/34198908/) |

Exenatide: The Flagship Program

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](https://pubmed.ncbi.nlm.nih.gov/32941461/).

Mechanism of Action

GLP-1 receptors are expressed in the brain, particularly in regions affected by Parkinson's disease pathology. Activation of these receptors leads to:

Clinical Development

• 2013: First-in-PD study demonstrates safety and preliminary efficacy
• 2017: Phase II randomized controlled trial shows significant improvement in motor scores [20](https://pubmed.ncbi.nlm.nih.gov/28436599/)
• 2020: FDA grants Fast Track designation
• 2022: Phase 3 trial initiation

Ambroxol for GBA-Associated Parkinson's Disease

Ambroxol represents a targeted approach for a specific genetic subgroup of Parkinson's disease. The drug is a [beta-glucocerebrosidase](/proteins/gba-protein) (GCase) chaperone that can increase enzyme activity, which is particularly relevant for patients with [GBA](/genes/gba) gene mutations [21](https://pubmed.ncbi.nlm.nih.gov/35604659/).

Genetic Context

Mutations in the [GBA](/genes/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](/proteins/alpha-synuclein) aggregation.

Clinical Results

• 2019: Open-label study shows increased GCase activity in CSF
• 2021: Phase 2 trial demonstrates safety and target engagement [22](https://pubmed.ncbi.nlm.nih.gov/34089001/)
• 2022: Expansion to multi-center Phase 2b trial
• Current: Planning for Phase 3 trial in GBA-PD population

Inosine and Urate Elevation

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](https://pubmed.ncbi.nlm.nih.gov/35444312/).

The SPRING Trial

The Inosine SPRING trial was one of the largest single intervention trials in Parkinson's disease history:

• Design: Randomized, double-blind, placebo-controlled
• Participants: Over 300 patients with early Parkinson's disease
• Primary endpoint: Safety and tolerability of urate elevation
• Secondary endpoints: Biomarker changes, clinical progression measures

Nilotinib: Autophagy Activation

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](/proteins/alpha-synuclein) [25](https://pubmed.ncbi.nlm.nih.gov/34554209/).

Mechanism

Nilotinib inhibits several kinases that negatively regulate autophagy, including:

• c-Abl (BCR-ABL)
• DDR1 (Discoidin Domain Receptor 1)
• SRC family kinases

Clinical Development

• 2016: First-in-PD study demonstrates safety and CSF biomarker changes
• 2021: Phase 2 trial results published [26](https://pubmed.ncbi.nlm.nih.gov/35168912/)
• Current: Ongoing studies to optimize dosing and identify responsive patient populations

Additional Pipeline Compounds

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 |

Impact and Achievements

Key Achievements Timeline

• First positive Phase II trial of a GLP-1 agonist in PD
• Showed significant improvement in motor scores
• Paved way for Phase III trial

• First targeted therapy for [GBA](/genes/gba)-associated PD
• Demonstrated increased GBA enzyme activity in CSF

• Largest urate elevation trial in PD
• Established safety of target engagement approach

• Demonstrated autophagy activation in humans
• Validated new mechanism-based approach

Impact Metrics

| 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 |

Global Collaboration Network

The LCT program has established a global network of clinical trial sites spanning:

• Europe: United Kingdom, Germany, France, Spain, Netherlands, Belgium, Denmark, Sweden
• North America: United States, Canada
• Asia-Pacific: Australia, Japan

Patient Involvement and Advocacy

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](/institutions/parkinsons-foundation), the [Michael J. Fox Foundation](/institutions/michael-j-fox-foundation), and the [Parkinson's Foundation](/institutions/parkinsons-foundation).

Future Directions

Emerging Targets

The LCT program continues to evaluate new compounds targeting emerging mechanisms:

Precision Medicine Approach

The program is moving toward a precision medicine model that matches specific therapies to patient subgroups based on:

• Genetic markers: [GBA](/genes/gba), [LRRK2](/genes/lrrk2), [SNCA](/genes/snca) mutations
• Biomarker profiles: CSF, blood, and imaging biomarkers
• Clinical phenotypes: Motor subtype, cognitive status, non-motor symptoms

Strategic Partnerships

The LCT program continues to expand partnerships with:

• Pharmaceutical companies for drug supply and development expertise
• Academic institutions for preclinical research and clinical capabilities
• Regulatory agencies for accelerated approval pathways
• Patient organizations for advocacy and outreach

See Also

• [Cure Parkinson's](/institutions/cure-parkinsons)](/institutions)
• [Exenatide for Parkinson's Disease](/therapeutics/exenatide-parkinsons-disease)](/therapeutics)
• [Ambroxol for Parkinson's Disease](/therapeutics/ambroxol-parkinsons)](/therapeutics)
• [Drug Repurposing for Neurodegenerative Diseases](/therapeutics/drug-repurposing-neurodegeneration)](/therapeutics)
• [GLP-1 Receptor Agonists in Parkinson's Disease](/therapeutics/glp1-parkinsons)](/therapeutics)
• [GBA-Associated Parkinson's Disease](/diseases/parkinsons-disease-gba)](/proteins/parkin)
• [Michael J. Fox Foundation](/institutions/michael-j-fox-foundation)](/institutions)
• [Parkinson's Foundation](/institutions/parkinsons-foundation)

References