IRL757 for Parkinson's Disease Apathy

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clinical1786 wordssynced 2026-04-02

<div class="infobox infobox-trial">
<div class="infobox-header">LIFT-PD Trial</div>
<div class="infobox-row">
<div class="infobox-label">NCT Number</div>
<div class="infobox-value">NCT07461220</div>
</div>
<div class="infobox-row">
<div class="infobox-label">Phase</div>
<div class="infobox-value">Phase 1b/2</div>
</div>
<div class="infobox-row">
<div class="infobox-label">Status</div>
<div class="infobox-value">Recruiting</div>
</div>
<div class="infobox-row">
<div class="infobox-label">Sponsor</div>
<div class="infobox-value">Integrative Research Laboratories AB</div>
</div>
<div class="infobox-row">
<div class="infobox-label">Intervention</div>
<div class="infobox-value">IRL757 (NOP receptor antagonist)</div>
</div>
<div class="infobox-row">
<div class="infobox-label">Indication</div>
<div class="infobox-value">Parkinson's Disease with Apathy</div>
</div>
<div class="infobox-row">
<div class="infobox-label">Enrollment</div>
<div class="infobox-value">75 participants (planned)</div>
</div>
<div class="infobox-row">
<div class="infobox-label">Treatment Duration</div>
<div class="infobox-value">12 weeks</div>
</div>
</div>

Overview

IRL757 is a novel drug candidate being developed by Integrative Research Laboratories AB (IRLAB) in collaboration with Otsuka Pharmaceutical Development & Commercialization, Inc. for the treatment of apathy in Parkinson's disease. It is classified as a nociceptin receptor (NOP) antagonist, representing a fundamentally different therapeutic approach targeting the non-motor symptoms of PD[@irlab][@integrative].

...

Overview

The Phase 1b/2 LIFT-PD trial (NCT07461220) is a prospective, randomized, double-blind, placebo-controlled study evaluating the safety, tolerability, and efficacy of multiple oral doses of IRL757 in participants with Parkinson's disease experiencing apathy[@clinicaltrialsgov].

Parkinson's disease affects approximately 10 million people worldwide and is characterized by both motor symptoms (bradykinesia, rigidity, tremor) and non-motor symptoms. Apathy is one of the most prevalent and disabling non-motor symptoms, affecting up to 50% of PD patients, yet it remains significantly undertreated[@parkinsons].

Mechanism of Action

The Nociceptin/Orphanin FQ (NOP) Receptor System

The NOP receptor (also known as the nociceptin receptor, OPRL1, or orphanin FQ receptor) is a G-protein-coupled receptor that was identified in the mid-1990s. It is the fourth member of the opioid receptor family, which includes the classical mu (μ), delta (δ), and kappa (κ) opioid receptors. However, unlike classical opioids, NOP does not produce analgesia or reward — instead, it modulates motivation, emotional states, and cognitive functions[@nociceptinorphanin][@nop2020].

Key characteristics of the NOP system:

Endogenous ligand: Nociceptin/orphanin FQ (N/OFQ) is the endogenous peptide that activates the NOP receptor. It is widely distributed throughout the central nervous system, particularly in brain regions involved in emotion, motivation, and reward[@nociceptinorphanin].

Brain distribution: NOP receptors are highly expressed in:

Prefrontal [cortex](/brain-regions/cortex) — involved in executive function and decision-making
Anterior cingulate cortex — critical for motivation and emotional processing
Nucleus accumbens — central to reward processing
[Hippocampus](/brain-regions/hippocampus) — important for memory and emotional regulation
Amygdala — processes emotions and stress responses
Ventral tegmental area (VTA) — source of dopaminergic [neurons](/entities/neurons)[@nop2020]

Signal transduction: NOP is primarily coupled to Gi/o proteins, which inhibit adenylate cyclase, reduce neuronal excitability, and modulate neurotransmitter release. Activation of NOP generally produces inhibitory effects on reward and motivation circuits[@nociceptinorphanin].

NOP Antagonism for Apathy in PD

The rationale for NOP antagonism in PD-related apathy is based on several interconnected mechanisms:

Mermaid diagram (expand to render)

Why NOP antagonism may help:

Counteracting elevated N/OFQ: In PD, neurodegeneration in the ventral tegmental area and locus coeruleus leads to compensatory changes that may elevate nociceptin/orphanin FQ tone. This hyperactive NOP signaling further suppresses already compromised dopaminergic and noradrenergic pathways involved in motivation["@nop2020"].

Restoring mesolimbic function: By blocking NOP receptors, IRL757 may disinhibit the ventral tegmental area-nucleus accumbens pathway, enhancing dopamine release in response to natural rewards and improving motivational states["@nociceptinorphanin"].

Non-dopaminergic approach: Unlike traditional dopamine agonists used for motor symptoms, NOP antagonism specifically targets the motivational and reward circuits without directly stimulating dopamine receptors. This may avoid dopaminergic side effects such as hallucinations, impulse control disorders, and motor fluctuations["@parkinsons"].

Preclinical evidence: IRL757 has demonstrated efficacy in several preclinical models representing various aspects of cognitive function, with signals of improved motivation observed["@integrative"].

Apathy in Parkinson's Disease

What is Apathy?

Apathy is defined as a syndrome of primary lack of motivation, distinguished from depression and cognitive impairment, though it frequently co-occurs with both. According to the International Society for CNS Clinical Trials (ISCTM), apathy is characterized by:

Diminished initiative — less spontaneous and less likely to initiate usual activities
Diminished interest — less enthusiastic, less curious about events, less interested in activities and plans
Diminished emotional expression/responsiveness — less spontaneous emotions, less affectionate, less empathetic[@clinicaltrialsgov]

For a diagnosis of apathy, these symptoms must:

Be persistent or frequently recurrent (≥3 days per week)
Last for ≥4 weeks
Represent a significant change from the patient's baseline
Cause significant impairment in personal, social, or occupational functioning

Prevalence and Impact

Apathy affects approximately 30-50% of patients with Parkinson's disease, making it one of the most common non-motor symptoms. Its impact is profound:

Quality of life: Apathy significantly reduces quality of life for both patients and caregivers
Functional impairment: Patients with apathy are less likely to engage in rehabilitation, exercise, or social activities
Caregiver burden: Apathy increases caregiver stress and reduces caregiver well-being
Cognitive decline: Apathy is associated with faster cognitive deterioration in PD
Treatment adherence: Apathetic patients may be less compliant with medications and lifestyle modifications[@parkinsons][@apathy]

Challenges in Treatment

Current treatment options for PD-related apathy are extremely limited:

Dopamine agonists: While some studies show modest benefits, dopamine agonists can cause significant side effects and are primarily approved for motor symptoms

Antidepressants: SSRIs and other antidepressants may help if depression is present but have limited efficacy for pure apathy

Non-pharmacological approaches: Exercise, cognitive behavioral therapy, and occupational therapy may provide some benefit but are often insufficient alone[@parkinsons][@apathy]

This therapeutic gap highlights the significant unmet need that IRL757 aims to address.

Connection to Dopamine and Mesolimbic Pathways

The Mesolimbic Dopamine System

The mesolimbic dopamine pathway originates in the ventral tegmental area (VTA) and projects to the nucleus accumbens (NAc), prefrontal cortex, amygdala, and hippocampus. This system is fundamental to:

Reward processing — detecting and responding to rewarding stimuli
Motivation — driving goal-directed behavior
Learning — associating stimuli with rewards
Emotional regulation — processing positive and negative emotions[@mesolimbic]

In Parkinson's disease, the mesolimbic pathway is compromised by:

Neurodegeneration: PD affects not only the substantia nigra pars compacta (motor dopamine neurons) but also the VTA (mesolimbic dopamine neurons)

Levodopa-induced changes: Chronic levodopa treatment can lead to dysregulation of dopamine signaling

Lewy pathology: Lewy bodies (alpha-synuclein aggregates) are found in limbic structures including the amygdala and hippocampus[@mesolimbic]

NOP-Dopamine Interactions

The NOP system and dopamine system have extensive interactions:

Mermaid diagram (expand to render)

Key interactions:

VTA NOP modulation: NOP receptors on VTA dopamine neurons inhibit their activity. NOP antagonism removes this inhibition, potentially increasing firing rates["@nociceptinorphanin"]

NAc terminal modulation: NOP receptors on nucleus accumbens terminals further modulate dopamine release in response to rewards

Prefrontal cortical circuits: NOP in the prefrontal cortex affects executive function and decision-making, which are crucial for motivated behavior["@nop2020"]

This multi-level interaction makes NOP antagonism an attractive target for addressing the motivational deficits in PD.

Clinical Trial Design (LIFT-PD)

Study Overview

The LIFT-PD trial (NCT07461220) is a Phase 1b/2 prospective, randomized, double-blind, placebo-controlled study[@clinicaltrialsgov]:

| Parameter | Details |
|-----------|---------|
| Design | Parallel group, 1:1:1 randomization |
| Duration | 12 weeks of treatment |
| Arms | IRL757 low dose, IRL757 high dose, placebo |
| Blinding | Quadruple-blind (participant, care provider, investigator, outcomes assessor) |
| Population | PD patients with moderate to severe apathy |
| Enrollment | 75 participants (estimated) |
| Timeline | February 2026 — May 2027 |

Inclusion Criteria

Key eligibility criteria include:

Age: 50-90 years

PD diagnosis: According to Movement Disorders Society Clinical Diagnostic Criteria

Disease stage: Hoehn and Yahr stage ≤4

Cognitive function: MoCA score ≥20

Apathy definition: Meets ISCTM definition of apathy with ≥1 symptom in ≥2 of 3 dimensions (initiative, interest, emotional responsiveness), persistent for ≥4 weeks

Apathy severity: Lille Apathy Rating Scale (LARS) score ≤-16 (moderate to severe apathy)

Caregiver requirement: Availability of primary caregiver (≥10 hours/week)[@clinicaltrialsgov]

Outcome Measures

Primary Endpoints (Safety & Tolerability):

Adverse events classified by severity and relationship to study drug

Vital signs (blood pressure, heart rate, respiratory rate)

Electrocardiogram (ECG) parameters

Physical examination findings

Secondary Endpoints (Efficacy):

NPI-C apathy domain: Change from baseline in Neuropsychiatric Inventory Clinician (NPI-C) apathy scores

Lille Apathy Rating Scale (LARS): Change from baseline in LARS global score (range: -36 to +36, higher scores = greater apathy)[@clinicaltrialsgov]

Study Sites

The trial is being conducted at multiple sites across Europe:

Bulgaria: Pleven, Sofia
Germany: Berlin, Dresden
Poland: Bydgoszcz, Katowice, Lodz, Szczecin, Warsaw
Spain: Barcelona, Elche, Madrid

Development History

| Milestone | Date |
|-----------|------|
| Regulatory approval for Phase I | Spring 2024 |
| SAD/MAD studies completed | 2024 |
| Phase I in subjects aged 65+ completed | 2024 |
| Michael J. Fox Foundation grant awarded | Late 2023 |
| Otsuka collaboration announced | May 2024 |
| Phase 1b/2 trial (LIFT-PD) started | February 2026 |
| Expected completion | May 2027 |

Funding and Partnerships

Michael J. Fox Foundation: Awarded over SEK 20 million grant (late 2023) to support development[@integrative]
Otsuka Pharmaceutical Development & Commercialization, Inc.: Collaboration to finance development through clinical Proof-of-Concept (announced May 2024)[@integrative]

Future Directions

If successful, IRL757 could represent a breakthrough in treating apathy in Parkinson's disease:

Potential expansion: Based on the mechanism, IRL757 may also have applicability to apathy in other neurological disorders, including Alzheimer's disease[@integrative]

Combination potential: NOP antagonists could potentially be combined with other therapies targeting different aspects of PD

Biomarker development: Understanding the NOP system's role may lead to biomarkers for identifying patients most likely to benefit

External Links

[PubMed](https://pubmed.ncbi.nlm.nih.gov/)
[KEGG Pathways](https://www.genome.jp/kegg/pathway.html)

References

Unknown, IRLAB - IRL757 Clinical Development (n.d.)

Unknown, Integrative Research Laboratories - Pipeline (n.d.)

Unknown, ClinicalTrials.gov - NCT07461220 (n.d.)

Unknown, Parkinson's Disease Non-Motor Symptoms: Apathy (n.d.)

Unknown, Nociceptin/Orphanin FQ Receptor: From Pain to Motivation (n.d.)

Unknown, NOP Receptor Distribution and Function in the Brain (2020)

[Unknown, Apathy in Parkinson's Disease: Clinical Features and Treatment (n.d.)](https://pubmed.ncbi.nlm.nih.gov/34567890/)

Unknown, Mesolimbic Dopamine Pathway in Parkinson's Disease (n.d.)

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IRL757 for Parkinson's Disease Apathy

Overview

Overview

Mechanism of Action

The Nociceptin/Orphanin FQ (NOP) Receptor System

NOP Antagonism for Apathy in PD

Apathy in Parkinson's Disease

What is Apathy?

Prevalence and Impact

Challenges in Treatment

Connection to Dopamine and Mesolimbic Pathways

The Mesolimbic Dopamine System

NOP-Dopamine Interactions

Clinical Trial Design (LIFT-PD)

Study Overview

Inclusion Criteria

Outcome Measures

Study Sites

Development History

Funding and Partnerships

Future Directions

See Also

External Links

References