ClinicalTrials.gov record NCT06891703

[18F]ACI-15916 PET in α-synucleinopathies

Record copied from ClinicalTrials.gov: Oct 10, 2026AI summaries generated: Sep 7, 2026

Phase 1 Study to Evaluate [18F]ACI-15916 as a Potential PET Radioligand for Imaging α-synuclein Deposits in the Brain of Patients With Suspected α-synuclein Pathology Compared With Healthy Volunteers

StatusRecruitingThe study is currently enrolling participants. Only the study team can say whether a particular person can join.
Study typeInterventionalA study in which researchers assign participants to one or more interventions, such as a drug, procedure, device, behavioural programme or other approach, to measure their effects.
PhaseEarly phase 1A very early study, usually in a small number of people, to learn how the body handles a treatment. It is not designed to show whether the treatment works.
Healthy volunteersAcceptedPeople who do not have the condition being studied who are allowed to take part. Some studies include both people with the condition and healthy volunteers; others may enrol only healthy volunteers.
Age20 years old and older
SexAll
LocationSweden
AI summaryWhat this study is about, in plain languageShow ▾Hide ▴

AI-written from the registry record, not the study's own wording. May contain errors or omissions. Check the registry text on this page and the original record ↗ before acting on it.

This first-in-human interventional study gives an intravenous microdose of the PET radioligand [18F]ACI-15916 to healthy volunteers and people with suspected α-synucleinopathies (PD, MSA, or DLB). It measures safety and tolerability, brain uptake on PET imaging, reproducibility for some participants (test-retest), and whole-body radiation dose in a small subgroup. Visits include screening, a PET scan with blood sampling (and optional spinal fluid), and a follow-up safety phone call.

What it is studying. The study is testing whether [18F]ACI-15916 is safe to give and whether the tracer can be measured in the brain with PET to detect α-synuclein deposits. It also assesses how reliably the tracer's brain signal can be measured on repeat scans and estimates the radiation dose to the body. The trial evaluates methods to quantify tracer uptake and compares uptake between people with suspected α-synuclein pathology and healthy volunteers.

What the researchers hope to learn. Scientific goals: to qualify [18F]ACI-15916 as a PET radioligand for imaging α-synuclein deposits, to assess safety and tolerability, to measure brain uptake and evaluate simplified quantification methods, to determine test-retest variability, and to estimate whole-body radiation dosimetry.

What this study is about

The study's own summary, as published on ClinicalTrials.gov. Underlined terms have a short explanation.

The goal of this clinical trial is to test whether we can reliably and safely measure the accumulation of pathological protein α-synuclein [involved in some diseases such as Parkinson's disease, Lewy body dementia and Multiple System Atrophy (MSA), collectively named α-synucleinopathies] using a new positron emission tomography (PET) tracer called [18F]ACI-15916. Both healthy people and people with (suspected) α-synuclein pathology will participate to this trial. The main questions it aims to answer are:

  • whether [18F]ACI-15916 is safe and well tolerated when injected into participants
  • whether [18F]ACI-15916 reliably detects α-synuclein in the brain using PET technique.
  • whether there are differences in the amount of this protein between people with diseases related to α-synuclein accumulation in the brain and people without these diseases.

Participants will:

  • Visit the clinic to consent to their participation and to ensure they are eligible [physical and neurological examinations, questionnaires, blood and urine tests, ECG and in some cases a MRI and a PET scan with a licensed tracer ([18F]FE-PE2I) to confirm or not the disease].
  • Visit the clinic to receive the tracer [18F]ACI-15916 intravenously and be scanned in a PET scanner, during which blood will be collected (and optionally spinal fluid).
  • Receive a phone call from the clinic 1 week after the PET scan to report any symptoms and side-effects that they may be having.

Some of the participants may be asked to come again to the clinic for a second PET scan with [18F]ACI-15916, allowing the researchers to determine if the measurements with the first PET scan are stable and reproducible. Some of the participants will participate in a specific part of the study to evaluate the distribution of the PET ligand in the whole body, with a similar visit schedule.

Interventions being studied

Being studied in this trial does not mean the treatment or procedure is approved or available for this condition.

Other
  • [18F]ACI-15916

Eligibility

The criteria exactly as listed on ClinicalTrials.gov. Only the study team can say whether they apply to you.

Inclusion criteria

  • for all Participants:
  • Subject is able to provide written informed consent, which must be obtained before any assessment is performed.
  • Subjects must be able to understand and be willing to comply with study procedures, restrictions, and requirements.
  • Body mass index is > 18 and < 31 kg/m2 and Bodyweight ≥ 50 kg and ≤ 100 kg.
  • Female participants must not be of childbearing potential or agree to use highly effective methods of contraception.
  • For subjects receiving arterial cannulation, an adequate circulation to the hand for safe placement of arterial line (as determined by Allen's test).
  • Additional Inclusion Criteria for Healthy Volunteers:
  • Males and females aged ≥ 20 at the time of signing the informed consent.
  • Normal MRI and DAT PET or SPECT (except for Part 4 participants), as judged by the investigator.
  • The subject is, in the opinion of the investigator, generally healthy based on the assessment of medical history, physical examination, vital signs, ECG, and the results of the hematology, clinical chemistry, urinalysis, serology, and other laboratory tests.
  • No family history of α-synucleinopathy, including PD, or other early-onset neurological disease associated with dementia.
  • No personal history of clinically significant neurologic and/or psychiatric disorders.
  • Have a Montreal Cognitive Assessment (MoCA) score ≥ 26
  • No cognitive impairment as judged by the PI or delegated physician.
  • Additional Inclusion Criteria for Participants with α-synucleinopathies:
  • Males and females aged ≥ 40 at the time of signing the informed consent.
  • Subjects diagnosed with any of the following:
  • Idiopathic PD based on MDS criteria
  • PD with genetic risk factor (except some mutations as mentioned in

Exclusion criteria

  • )
  • Dementia with Lewy bodies (DLB)
  • Diagnosis of possible or probable Multiple System Atrophy (MSA)
  • Evidence of dopamine transporter deficit on DAT PET or SPECT imaging performed either as part of Screening or previously acquired (if not older than 6 months) and of good quality as judged by the investigator.
  • Medications taken for symptomatic treatment of α-synucleinopathy must be maintained on a stable dosage regimen for at least 30 days before the Screening Visit.
  • Exclusion Criteria for all Participants:
  • Female subjects pregnant, lactating or breastfeeding.
  • Presence of psychiatric symptoms that may interfere with the objectives of the study, as judged by the investigator.
  • Clinically significant concomitant disease or condition within 6 months prior to screening, that could interfere with the conduct of the study, or that would, in the opinion of the investigator, pose an unacceptable risk to the participant, or compromise the scientific quality of the study.
  • History of brain surgery or any neurosurgical procedures. Subject has received treatment with a drug, antibody or vaccine targeting α-synuclein.
  • Known or suspected drug, alcohol or other abuse, or positive urine drug screen which may interfere with the study objective, as judged by the investigator.
  • History of severe allergy/hypersensitivity or ongoing allergy/hypersensitivity as judged by the investigator.
  • Subject is involved in the planning and/or conduct of the study (i.e. part of the study team)
  • History of clinically significant cardio-or cerebrovascular, pulmonary, renal, hepatic, neurological, mental or gastrointestinal disorder or any other major disorder that may interfere with the objectives of the study, as judged by the investigator.
  • History of and/or screening brain MRI scan (except for Part 4 subjects) indicative of, clinically significant abnormality including but not limited to prior haemorrhage or infarct or >3 lacunar infarcts, except changes consistent with α-synucleinopathies for PD, MSA, DLB patients.
  • Subjects being treated with any anticoagulants or antiplatelet drugs, except aspirin at doses of 100 mg daily or lower within 2 weeks of the planned arterial cannula placement (if performed) for either the baseline or retest imaging.
  • Screening supine blood pressure > 150 mm Hg (systolic) or > 90 mm Hg (diastolic), following at least 5 minutes of supine rest. If blood pressure (BP) is > 150 mm Hg (systolic) or > 90 mm Hg (diastolic), the BP should be repeated two more times and the average of the three BP values should be used to determine the subject's eligibility.
  • Electrocardiographic (ECG) abnormalities of clinical significance as judged by the investigator. Screening supine 12-lead ECG demonstrating QTc > 450 msec at Screening.
  • Any contraindications to obtaining a brain MRI (except for Part 4 subjects), DaT-SPECT (except for Part 4 subjects) or PET (e.g., claustrophobia unresponsive to reassurance or low dose of an anxiolytic agent, metal implants not compatible with MRI or known hypersensitivity to the active substance or to any of the excipients) and ability to tolerate lying in the scanner for up to ~180 minutes.
  • Previous exposure to radiation for medical, scientific or other reasons which could have a high negative impact on the research subject, as judged by the investigator.
  • Treatment with any other investigational therapy within 5 drug elimination half-lives or 30 days (whichever is longer) prior to inclusion in the study.
  • Additional Exclusion Criteria for Healthy Volunteers:
  • Current use of CNS active drugs, including antidepressant or neuroleptic medications is not permitted, anti-inflammatory drugs or sleep medications may be allowed at the discretion of the investigator.
  • History of neurological disease/condition that may interfere with the objectives of the study, as judged by the investigator.
  • Additional Exclusion Criteria for Participants with α-synucleinopathy:
  • Medical history indicating a Parkinsonian syndrome other than idiopathic PD, including but not limited to, progressive supranuclear palsy, drug-induced parkinsonism, essential tremor, vascular parkinsonism, primary dystonia or corticobasal syndrome (CBS).
  • Known carriers of certain familial PD gene mutations (PRKN, PINK1, DJ1, LRRK2), based on previous source documentation.

Study description and what participation involves

The study's detailed description, as published on ClinicalTrials.gov.

Show the detailed description from the registry

This is an open-label, first in human (FiH) positron emission tomography (PET) microdose study in patients with suspected α-synuclein pathology and healthy volunteers (HVs) using [18F]ACI-15916 as a novel radioligand. This study will be dedicated to qualification of the ligand [18F]ACI-15916 to measure α-synuclein pathology using PET investigations, including estimation of effective dose and test-retest reliability. The study consists of four parts in which a total of up to 46 participants may be included:

  • Part 1: Up to 5 HVs and up to 5 patients with Parkinson's Disease (PD) will be included.
  • Part 2: Up to 30 additional subjects including: HV cases (maximum 10) and patients with α-synucleinopathies such as PD, Multiple System Atrophy (MSA) and Dementia with Lewy Bodies (DLB).
  • Part 3: Up to 10 participants from Part 1 and/or Part 2 will have a second PET measurement within one month after their initial PET measurement to evaluate test-retest variability and reproducibility.
  • Part 4. Up to 6 HVs (3 female and 3 male) will undergo a whole-body PET-CT examination to estimate the effective dose after one administration of [18F]ACI-15916.

The four study parts can overlap. The study consists of a screening period of up to 60 days to assess participants' eligibility, a PET scan with [18F]ACI-15916 along with arterial blood sampling, and a safety phone call following the scanning visit. For participants in Part 3, a second PET scan with [18F]ACI-15916 will be performed up to one month after the first scan to evaluate test-retest variability and reproducibility, followed by a new safety phone call. For subjects in Part 4 (dosimetry), no arterial blood sampling will be performed. The total study duration will be up to 10 weeks for Part 1, 2 and 4 participants and up to 14 weeks for Part 3 participants.

AI summaryWhat participation may involve, in plain languageShow ▾Hide ▴

AI-written from the registry record, not the study's own wording. May contain errors or omissions. Check the registry text on this page and the original record ↗ before acting on it.

After giving informed consent, participants undergo a screening visit (medical and neurological exams, questionnaires, blood and urine tests, ECG; MRI and DAT PET/SPECT may be done if needed). On the scan visit they receive an intravenous injection of [18F]ACI-15916 and have a PET brain scan (arterial blood sampling is done for most participants; spinal fluid collection is optional). Some people may be invited back for a second PET within one month to test reproducibility; a small group of healthy volunteers will have a whole-body PET-CT (no arterial sampling) to measure radiation dose. A safety phone call about side effects is made about 1 week after the PET scan; total study time is up to about 10 weeks (or up to 14 weeks if a retest PET is done).

How the study is structured. Open-label, non-randomized early phase 1 PET study with parallel groups (people with suspected α-synucleinopathies and healthy volunteers). Up to four overlapping parts include initial safety/imaging, an expanded imaging group, a test-retest subgroup (second PET within one month), and a small whole-body dosimetry subgroup. Participants undergo screening tests, a single intravenous administration of [18F]ACI-15916 followed by PET scanning (with arterial blood sampling for most participants), and a safety phone call; some participants may have a second PET or a whole-body PET-CT.

Questions you could ask

These questions are suggestions for a conversation with the study team or your own clinician, not advice.

  • This is an early-phase study, mainly about safety and dose. What is already known about this treatment?
  • The listed sites are in Sweden. Is any of them reachable for me, and does the study help with travel?
  • Which of the eligibility criteria would need to be checked with tests before I could join?

More on multiple system atrophy

Important dates

Study start
Mar 20, 2025
Primary completion
March 2026 (estimated)
Study completion
March 2026 (estimated)
Target enrollment
46 participants (estimated)
Last updated on registry
Nov 19, 2025
Data verified
Oct 10, 2026

Sponsor and research team

The lead sponsor funds and oversees the trial. A pharmaceutical or biotech company sponsor typically means the study is testing that company's drug or device; a hospital, university, or government agency usually indicates investigator-initiated or publicly funded research.

Lead sponsor
AC Immune SA
Collaborators
  • Karolinska Institutet

Central study contact

If you're interested in participating, the central contact can answer general questions about the study — including eligibility requirements and how to find a recruiting site near you. Actual eligibility is determined by the site's medical team.

Participating sites (1)

Terms used on this page · explanations by MedicalUpdates.ai

positron emission tomography
A scan in which a small amount of a radioactive tracer is injected so that activity in tissues can be seen. Often combined with a CT or MRI scan.
ECG
A recording of the heart's electrical activity. QTc is one measurement from it; some drugs are avoided if it is prolonged.
MRI
A scan that uses magnets and radio waves, not X-rays, to make detailed pictures of the inside of the body. Some implants and metal objects mean a person cannot have one.
written informed consent
The process of explaining a study, including its risks and what participation involves, so that a person can decide freely whether to take part. Consent is usually documented in writing, and a participant can choose to leave the study later.
childbearing potential
Studies often ask participants who could become pregnant, or could father a child, to use contraception during the study and for a period afterwards, because the effect of the treatment on a pregnancy is unknown.
Inclusion Criteria
The conditions a person must meet to be considered for the study, for example a confirmed diagnosis, an age range or a test result.
Screening Visit
The checks done before enrolment to see whether a person qualifies, such as tests, scans or a review of medical history.
Exclusion Criteria
The conditions that rule a person out even if they meet the inclusion criteria, for example other illnesses, certain medicines or pregnancy.
baseline
Measurements taken at the start of the study, before any study treatment, so that later results can be compared with them.
contraindications
A reason a particular test or treatment should not be used for a person, for example a metal implant that rules out an MRI scan.
investigational
A treatment that is being tested and has not been approved for this use. It may be approved for a different condition. Being studied does not mean it works or is available outside the study.
half-lives
The time it takes for the amount of a drug in the body to fall by half. 'Five half-lives' is often used as the point at which a previous drug has essentially left the body.
open-label
No masking is used, so the assigned intervention is not deliberately hidden from participants or study staff.
first in human
The first study in which a treatment is given to people. Safety is the main question and the number of participants is usually small.
CT
An X-ray scan that builds detailed cross-section images of the body. 'High-resolution' CT (HRCT) is used to look closely at the lungs.

The study record on this page is reproduced from ClinicalTrials.gov, a database of the U.S. National Library of Medicine, where it was submitted by the study sponsor. MedicalUpdates.ai does not own this content, is not affiliated with or endorsed by ClinicalTrials.gov, NIH, or the U.S. Government, and does not verify the record. Plain-language notes, the glossary and the questions above are added by this site; text in the boxes marked "AI summary" was written by an AI model and may contain errors. Registry records change over time. Check the original record for the current version and discuss eligibility or participation with a qualified healthcare professional.

← Back to clinical trials