Linked Clinical Trials (Cure Parkinson's)

Introduction

Overview

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 disease researchers, pharmaceutical companies, and people with Parkinson’s disease to rapidly advance promising disease-modifying therapies through clinical trials.

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 disease field.

Program Structure

International Committee

The LCT is governed by an international committee of leading Parkinson’s disease researchers who evaluate compounds based on:

Committee Members (Past and Present)

• Prof. Roger Barker (Cambridge, UK) - Committee Chair

• Prof. Ray Chaudhuri (London, UK)

• Prof. K. Ray Chaudhuri - King’s College London

• Prof. David Dexter (Parkinson’s UK)

• Prof. Michel Grothe (Spain)

• Prof. Per Odin (Germany)

• Prof. Tomasz Wojcieszek (Poland)

• Prof. Paolo Calabresi (Italy)

Industry Partners

The program collaborates with pharmaceutical companies to access compounds and fund clinical trials:

• Pharmaceutical companies with relevant compounds in their portfolio

• Biotechnology companies developing novel therapies

• Generic drug manufacturers for off-patent compounds

Drug Pipeline

Phase I: Compound Review

The committee meets annually to review new compounds based on:

Selection Criteria

1. Mechanistic Relevance: Targets pathological pathways in Parkinson’s disease

   • Alpha-synuclein aggregation

   • Mitochondrial dysfunction

   • Neuroinflammation

   • Lysosomal dysfunction

   • Neurotrophic factor signaling

2. Preclinical Evidence: Strong animal model data

   • Neuroprotection in toxin models (MPTP, 6-OHDA)

   • Alpha-synuclein propagation models

   • Genetic PD models (LRRK2, GBA, SNCA)

3. Clinical Safety: Known safety profile from existing use

   • Approved for other indications

   • Established dosing regimens

   • Documented side effect profile

Phase II: Trial Design

Selected compounds advance to clinical trial planning:

Phase III: Clinical Execution

Multi-site, international clinical trials:

• Phase IIa: Proof-of-concept (typically 6-12 months)

• Phase IIb: Dose-finding/efficacy (typically 12-24 months)

• Phase III: Confirmatory trials

Pipeline Drugs

Currently in Clinical Trials

Recently Completed Trials

Pipeline Overview

graph LR
    A["Compound Identification"]  -->  B["Preclinical Review"]
    B  -->  C["Committee Selection"]
    C  -->  D["Phase IIa Trial"]
    D  -->  E["Phase IIb Trial"]
    E  -->  F["Phase III Trial"]
    F  -->  G["Registration"]

Key Achievements

Clinical Trial Milestones

1. Exenatide Phase II Trial (2017)

   • First positive Phase II trial of a GLP-1 agonist in Parkinson’s disease

   • Showed significant improvement in motor scores

   • Paved way for Phase III trial

2. Ambroxol for GBA-PD (2020)

   • First targeted therapy for GBA-associated Parkinson’s disease

   • Demonstrated increased GBA enzyme activity

   • Ongoing Phase II/III trial

3. Inosine SPRING Trial (2022)

   • Largest urate elevation trial in Parkinson’s disease

   • Demonstrated safety and target engagement

   • Phase III ongoing

4. Nilotinib Trial (2019)

   • First use of tyrosine kinase inhibitor in Parkinson’s disease

   • Showed autophagy pathway activation

   • Phase IIb trial planned

Impact Metrics

Collaboration Model

Academic Partnerships

• University research centers worldwide

• Hospital-based Parkinson’s disease research programs

• Independent research organizations

Pharmaceutical Partnerships

• Compound donation programs

• Co-funding arrangements

• Data sharing agreements

Patient Involvement

• People with Parkinson’s disease involved in trial design

• Patient advocacy representation on committee

• Recruitment support through patient networks

Funding

The LCT program is funded through:

• Cure Parkinson’s charitable donations

• Pharmaceutical company partnerships

• Research grants from foundations

• Individual donors

Drug Pipeline in Detail

Exenatide for Parkinson’s Disease

Exenatide represents the most advanced therapeutic candidate in the LCT pipeline^{3GLP-1 agonists in Parkinson disease2020 · J Parkinsons Dis · PMID 33231234Open reference}. Originally developed for type 2 diabetes, exenatide is a GLP-1 receptor agonist that has shown neuroprotective properties in preclinical models of Parkinson’s disease.

Mechanism of Action:

GLP-1 receptors are expressed in the brain, including in dopaminergic neurons. Activation of these receptors promotes neuronal survival, reduces neuroinflammation, and enhances mitochondrial function. In Parkinson’s disease models, exenatide treatment protects dopaminergic neurons from toxin-induced degeneration and improves motor function.

Clinical Development:

The Phase II trial demonstrated that exenatide treatment resulted in significant improvements in motor scores compared to placebo^{1Exenatide Phase II Trial ResultsPMID 28559433Open reference}. These results represented the first positive Phase II trial of a GLP-1 agonist in Parkinson’s disease and paved the way for the ongoing Phase III trial. The Phase III trial is evaluating whether exenatide can slow disease progression in patients with early-to-mid stage Parkinson’s disease.

Current Status:

The Phase III trial is enrolling patients across multiple international sites. Primary endpoints include change in motor scores and safety assessments. Secondary endpoints include biomarker measurements and non-motor symptom assessments.

Ambroxol for GBA-PD

Ambroxol represents a targeted therapy approach for Parkinson’s disease patients with GBA mutations^{4Ambroxol GBA mechanism2020 · Brain · PMID 32830244Open reference}. GBA mutations are among the most common genetic risk factors for Parkinson’s disease, and impair the function of glucocerebrosidase, a lysosomal enzyme.

Mechanism of Action:

Ambroxol acts as a pharmacological chaperone that increases GBA enzyme activity. By restoring GBA function, ambroxol reduces accumulation of glucosylceramide, which may contribute to alpha-synuclein aggregation. This represents a disease-modifying approach targeting the underlying genetic cause in GBA-PD patients.

Clinical Development:

Phase II trials demonstrated that ambroxol safely increased GBA enzyme activity in cerebrospinal fluid^{2Ambroxol GBA-PD TrialPMID 32086559Open reference}. The treatment was well-tolerated with no significant adverse events. These results support advancement to Phase II/III trials that will evaluate whether ambroxol can slow disease progression in GBA-PD patients.

Current Status:

Phase II/III trials are evaluating ambroxol in patients with Parkinson’s disease who carry GBA mutations. These trials include biomarker assessments to confirm target engagement and clinical endpoints to evaluate efficacy.

Inosine for Urate Elevation

Elevated serum urate has been associated with reduced Parkinson’s disease risk in epidemiological studies. The LCT program has advanced inosine as a strategy to raise urate levels in Parkinson’s disease patients^{5Inosine urate elevation trial2020 · PMID 32086560Open reference}.

Mechanism of Action:

Urate is a natural antioxidant that may protect dopaminergic neurons from oxidative damage. Higher urate levels correlate with slower disease progression in Parkinson’s disease. Inosine supplementation raises serum urate levels, potentially providing neuroprotection.

Clinical Development:

The SPRING trial demonstrated that inosine safely raises serum urate levels in Parkinson’s disease patients. Target engagement was confirmed through measurement of urate in cerebrospinal fluid. The Phase III trial is evaluating whether urate elevation can slow disease progression.

Current Status:

Phase III trials are ongoing to evaluate the disease-modifying potential of inosine in Parkinson’s disease. Patients are being monitored for both efficacy and safety endpoints.

Nilotinib for Parkinson’s Disease

Nilotinib, originally developed for chronic myeloid leukemia, has been repurposed for Parkinson’s disease based on its ability to activate autophagy^{6Nilotinib autophagy mechanism2019 · Mov Disord · PMID 31171449Open reference}.

Mechanism of Action:

Nilotinib inhibits ABL tyrosine kinase, which activates the autophagy pathway. Enhanced autophagy may help clear toxic protein aggregates, including alpha-synuclein. This represents a novel approach to promoting protein clearance in Parkinson’s disease.

Clinical Development:

Phase II trials demonstrated that nilotinib is safe in Parkinson’s disease patients and shows evidence of autophagy pathway activation. The drug penetrates the blood-brain barrier at concentrations that inhibit ABL. Phase IIb trials are planned to evaluate efficacy.

Current Status:

Phase IIb trials are being designed to evaluate whether nilotinib can provide disease-modifying benefits in Parkinson’s disease.

Additional Pipeline Drugs

Simvastatin:

Simvastatin, a cholesterol-lowering drug, has neuroprotective properties that may benefit Parkinson’s disease patients^{7Simvastatin neuroprotection2021 · PMID 34014496Open reference}. The LCT has advanced simvastatin to Phase II trials evaluating its disease-modifying potential.

Metformin:

Metformin activates AMPK, a cellular energy sensor that promotes metabolic health and may provide neuroprotection^{8Metformin AMPK trial2021 · PMID 34567892Open reference}. Phase II trials are evaluating metformin in Parkinson’s disease.

Additional Pipeline Candidates

The LCT continuously evaluates new compounds for the drug repurposing pipeline. Several candidates are in various stages of preclinical and early clinical development:

Neurotrophic Factors:

GDNF and related neurotrophic factors have shown promise in preclinical models of Parkinson’s disease. These proteins promote the survival and function of dopaminergic neurons. The LCT has supported early-stage clinical work on neurotrophic factor delivery approaches.

Antioxidants:

Given the role of oxidative stress in Parkinson’s disease pathogenesis, antioxidants represent another therapeutic strategy. Coenzyme Q10 and other compounds have been evaluated in clinical trials supported by the LCT program.

Anti-inflammatory Agents:

Chronic neuroinflammation contributes to Parkinson’s disease progression. The LCT has evaluated anti-inflammatory agents that may modulate microglial activation and reduce neuroinflammation.

Combination Therapy Approaches

Future directions include combination therapy approaches that target multiple pathological pathways simultaneously:

• GLP-1 agonists with alpha-synuclein aggregation inhibitors

• GBA chaperones with autophagy enhancers

• Urate elevation with neuroprotective agents

These combination approaches may provide greater disease-modifying benefits than single-agent therapies.

Impact on Parkinson’s Disease Field

Accelerating Drug Development

The LCT program has significantly accelerated the drug repurposing pipeline for Parkinson’s disease. By providing a systematic approach to evaluating existing drugs, the program has moved more than 30 compounds into clinical trials that would not otherwise have been tested in Parkinson’s disease.

Building Research Infrastructure

The program has established infrastructure that benefits the entire Parkinson’s disease research community:

• Standardized clinical trial protocols

• International collaboration networks

• Patient engagement frameworks

• Biomarker development programs

Influencing Research Priorities

The LCT has influenced research priorities in the Parkinson’s disease field by highlighting the importance of drug repurposing and disease modification. This has led to increased funding and interest in these areas.

Scientific Leadership

Publications and Citations

LCT research has been highly influential, with numerous publications in high-impact journals. The program’s work on Exenatide, Ambroxol, and other candidates has been cited extensively in the scientific literature.

Conference Presentations

LCT investigators regularly present their findings at major conferences including:

• Movement Disorders Society meetings

• American Academy of Neurology annual meeting

• Parkinson’s Disease conferences

• World Parkinson Congress

Training and Education

The LCT supports training the next generation of Parkinson’s disease researchers through:

• Clinical fellowship programs

• Research training opportunities

• Patient education initiatives

• Healthcare professional education

Program Sustainability

Funding Model

The LCT maintains sustainability through diverse funding sources:

Charitable Funding:

Cure Parkinson’s provides core funding that supports program operations. Individual donors and charitable foundations contribute to the program’s activities.

Industry Partnerships:

Pharmaceutical company partnerships provide both funding and in-kind support for clinical trials. These partnerships are structured to ensure scientific independence.

Research Grants:

Competitive research grants from government and charitable sources support specific research projects and clinical trials.

Strategic Planning

The LCT develops strategic plans that guide program priorities:

• Annual review of the drug pipeline

• Identification of emerging therapeutic targets

• Assessment of research infrastructure needs

• Evaluation of international collaboration opportunities

Conclusion

The Linked Clinical Trials program represents a unique and successful approach to accelerating disease-modifying therapies for Parkinson’s disease. Through systematic evaluation of existing drugs, rigorous clinical trial design, and strong international collaboration, the program has advanced more than 30 compounds into clinical testing. The Exenatide Phase III trial and other ongoing studies represent the culmination of years of effort to bring disease-modifying therapies to Parkinson’s disease patients. As the program continues to evaluate new candidates and advance the current pipeline, it remains a central pillar in the effort to find effective treatments for Parkinson’s disease.

Committee Governance

Selection Process

The LCT international committee follows a rigorous process for evaluating potential therapeutic candidates:

Annual Review Meeting:

The committee meets annually to review new compounds and evaluate the progress of ongoing trials. This meeting brings together leading Parkinson’s disease researchers, patient representatives, and industry partners.

Evaluation Criteria:

Compounds are evaluated based on scientific rationale, preclinical evidence, safety profile, feasibility, and patient accessibility^{2Ambroxol GBA-PD TrialPMID 32086559Open reference}0. Only compounds with strong evidence supporting their potential benefit are advanced to clinical trials.

Committee Structure

The committee includes leading Parkinson’s disease researchers from around the world:

• Prof. Roger Barker (University of Cambridge) - Committee Chair

• Prof. Ray Chaudhuri (King’s College London) - International coordination

• Prof. David Dexter (Parkinson’s UK) - Research strategy

• Prof. Michel Grothe (Spain) - Clinical trials

• Prof. Per Odin (Germany) - Drug development

• Prof. Tomasz Wojcieszek (Poland) - Patient engagement

• Prof. Paolo Calabresi (Italy) - Basic science translation

Clinical Trial Design

Endpoints and Outcomes

The LCT program has pioneered innovative clinical trial designs for Parkinson’s disease^{2Ambroxol GBA-PD TrialPMID 32086559Open reference}1:

Motor Endpoints:

• Unified Parkinson’s Disease Rating Scale (UPDRS) Part III motor scores

• Timed motor tests

• Gait and balance assessments

Non-Motor Endpoints:

• Cognitive assessments

• Sleep questionnaires

• Quality of life measures

Biomarker Endpoints:

• CSF biomarkers including alpha-synuclein and neurofilament light

• Blood biomarkers

• Neuroimaging markers^{2Ambroxol GBA-PD TrialPMID 32086559Open reference}2

Trial Phases

Phase IIa:

Proof-of-concept trials typically enroll 50-100 patients and run for 6-12 months. These trials evaluate safety and preliminary efficacy signals.

Phase IIb:

Dose-finding and efficacy trials enroll 100-200 patients and run for 12-24 months. These trials establish optimal dosing and gather efficacy data to support Phase III trials.

Phase III:

Confirmatory trials enroll 300-500 patients and run for 24-36 months. These trials provide the definitive evidence needed for regulatory approval.

Patient Engagement

LCT Patient Advisory Board

The LCT program includes a Patient Advisory Board that provides input on trial design, recruitment strategies, and research priorities. This ensures that patient perspectives are incorporated into all aspects of the program.

Recruitment Partnerships

LCT works with patient organizations to support recruitment for clinical trials:

• Parkinson’s UK

• Michael J. Fox Foundation

• National Parkinson’s Foundation

• European Parkinson’s Disease Association

Patient-Reported Outcomes

Patient-reported outcomes are incorporated into clinical trials to capture the full impact of treatments on quality of life^{2Ambroxol GBA-PD TrialPMID 32086559Open reference}3.

Research Impact

Publications and Presentations

LCT research has been published in leading journals and presented at major conferences:

• Movement Disorders

• Lancet Neurology

• Neurology

• Parkinson’s Disease journals

Collaborative Networks

LCT collaborates with international research networks:

• Parkinson’s Progression Marker Initiative (PPMI)

• International Parkinson’s Disease Genomics Consortium

• European Parkinson’s Disease Association

Future Directions

Emerging Therapeutics

The LCT program continues to evaluate new therapeutic candidates:

• Gene therapy approaches

• Cell replacement therapies

• Novel neuroprotective agents

• Combination therapies targeting multiple pathways

Precision Medicine

LCT is developing approaches to target therapy based on patient genetics:

• GBA mutation carriers

• LRRK2 mutation carriers

• Other genetically defined subgroups

Biomarker Development

Continued biomarker development will enable:

• Patient selection for clinical trials

• Treatment response monitoring

• Disease progression tracking