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Trial · Interventional

RecruitingPhase 3Registry data

A Study of NNZ-2591 in Pediatric Participants With Phelan-McDermid Syndrome

NCTNCT07281079 (opens ClinicalTrials.gov in a new tab)Other idNEU-2591-PMS-301
Open at ClinicalTrials.govAsk about this trial

Overview

Status
Recruiting
Phase
Phase 3
Enrollment
160 participants (estimated)
Sponsor
Neuren Pharmaceuticals Limited · Industry
Design
Randomized · Quadruple masking
Countries
2 countries

United States, Canada

Start
12 Nov 2025
Primary completion
31 Oct 2027 (estimated)
Completion
15 Nov 2027 (estimated)
First posted
15 Dec 2025
Last update posted
28 Sept 2026
Conditions
Phelan-McDermid Syndrome

Timeline

1 trial · 1 ongoing

  • Completed
  • Ongoing
  • Not yet recruiting
  • Stopped
  • Estimated dates (est.)
  • Results posted
2025202620272028
  1. Ph 3

    A Study of NNZ-2591 in Pediatric Participants With Phelan-McDermid Syndrome

    NCT07281079

    12 Nov 2025 to est. 15 Nov 2027

Registry summary

Text and fields below are the sponsor's entries at ClinicalTrials.gov, shown as posted.

This Phase 3, randomized, double-blind, parallel-group (2-arm), placebo-controlled, multicenter study will evaluate the efficacy and safety of NNZ-2591 compared to placebo in pediatric participants with Phelan- McDermid Syndrome.

Interventions

  • NNZ-2591Drug
  • PlaceboDrug

Arms2

  • Experimental

    NNZ-2591 Arm

    The total duration of this study for each participant will be up to approximately 17 to 19 weeks. Participants will be randomized in a 1:1 ratio to receive orally administered NNZ-2591 during the 13-week Treatment Period.

  • Placebo comparator

    Placebo Arm

    The total duration of this study for each participant will be up to approximately 17 to 19 weeks. Participants will be randomized in a 1:1 ratio to receive orally administered placebo matching NNZ-2591 during the 13-week Treatment Period.

Primary outcomes2

Outcomes the sponsor listed as primary.

  1. Efficacy of NNZ-2591 compared with placebo as measured by the Phelan-McDermid Syndrome Assessment of Change (PMSA-C) overall score.

    Time frame · Week 13

    Registry description

    Efficacy of NNZ-2591 compared with placebo as measured by the Phelan-McDermid Syndrome Assessment of Change (PMSA-C) overall score. The PMSA-C scores range from 1 to 7 with 1 indicating very much improved and 7 indicating very much worse.

  2. Efficacy of NNZ-2591 compared with placebo as measured by the change from baseline in the Vineland Adaptive Behavior Scales-3, Interview version (Vineland-3) receptive communication subdomain raw score.

    Time frame · Week 13

    Registry description

    Efficacy of NNZ-2591 compared with placebo as measured by the change from baseline in the Vineland Adaptive Behavior Scales-3, Interview version (Vineland-3) receptive communication subdomain raw score. A higher raw score for the receptive communication subdomain indicates better adaptive behavior.

Secondary outcomes(6)

  1. Efficacy of NNZ-2591 compared with placebo as measured by the Caregiver Impression of Change (CIC) overall score.

    Time frame · Week 13

    Registry description

    Efficacy of NNZ-2591 compared with placebo as measured by the Caregiver Impression of Change (CIC) overall score. The CIC scores range from 1 to 7 with 1 indicating very much improved and 7 indicating very much worse.

  2. Efficacy of NNZ-2591 compared with placebo as measured by the Phelan-McDermid Syndrome Assessment of Change (PMSA-C) domain scores.

    Time frame · Week 13

    Registry description

    Efficacy of NNZ-2591 compared with placebo as measured by the Phelan-McDermid Syndrome Assessment of Change (PMSA-C) domain scores. The PMSA-C domain scores range from 1 to 7 with 1 indicating very much improved and 7 indicating very much worse.

  3. Efficacy of NNZ-2591 compared with placebo as measured by the Caregiver Impression of Change (CIC) domain scores.

    Time frame · Week 13

    Registry description

    Efficacy of NNZ-2591 compared with placebo as measured by the Caregiver Impression of Change (CIC) domain scores. The CIC scores range from 1 to 7 with 1 indicating very much improved and 7 indicating very much worse.

  4. Efficacy of NNZ-2591 compared with placebo as measured by the change from baseline in Phelan-McDermid Syndrome Assessment of Severity (PMSA-S) domain scores.

    Time frame · Week 13

    Registry description

    Efficacy of NNZ-2591 compared with placebo as measured by the change from baseline in Phelan-McDermid Syndrome Assessment of Severity (PMSA-S) domain scores. The PMSA-S scores range from 1 to 7 with 1 indicating typical for age, not at all impaired and 7 among the most severely impaired.

  5. Efficacy of NNZ-2591 compared with placebo as measured by the change from baseline in PMSA-S overall score.

    Time frame · Week 13

    Registry description

    Efficacy of NNZ-2591 compared with placebo as measured by the change from baseline in PMSA-S overall score. The PMSA-S scores range from 1 to 7 with 1 indicating typical for age, not at all impaired and 7 among the most severely impaired.

  6. Efficacy of NNZ-2591 compared with placebo as measured by the change from baseline in PMS Clinician Domain Specific Rating Scale (PMS-DSRS) scores.

    Time frame · Week 13

    Registry description

    Efficacy of NNZ-2591 compared with placebo as measured by the change from baseline in PMS Clinician Domain Specific Rating Scale (PMS-DSRS) scores. The PMS-DSRS scores range from 0 to 4 with 0 indicating Symptom Not Present and 4 indicating Very Severe.

Posted results

Values are shown as posted at ClinicalTrials.gov, with their units. PepBank has not converted, pooled or compared them.

No results are posted for this trial.

A trial that is still running, or that stopped early, may post results later.

Registry data comes from ClinicalTrials.gov. Study results come from studies, not from the registry. How PepBank works

Studies0

Studies that cite this trial.

No study cites this trial.

Eligibility

Who could join, as posted.

Sex
All
Age
from 3 Years up to 12 Years
Healthy volunteers
Not accepted
Inclusion and exclusion criteria, as posted
Inclusion Criteria: 1. Male or female pediatric participants with Phelan-McDermid syndrome ages 3 to 12 years (inclusive) at the time of signing the informed consent. 2. Clinical diagnosis of Phelan-McDermid syndrome with a documented disease-causing genetic abnormality of SHANK3. 3. Body weight ≥ 10 kg at Screening. 4. Participants with a PMSA-S overall score ≥ 3 at the Screening and Baseline visits. 5. Not actively undergoing regression or loss of skills. Exclusion Criteria: 1. Use of exclusionary medication or unstable treatment regimens of acceptable concomitant medications as required by the protocol. 2. Current treatment with more than 3 allowable psychotropic medications. 3. Participants with seizures must be controlled on no more than 2 anticonvulsant medications (not counting rescue medications). 4. Psychotropic medications or any other medication used for a chronic illness (not including antibiotics, pain relievers, anti-diarrheals, and laxatives) with doses and dosing regimen that have not been stable for at least 4 weeks before Screening. If the treatment was discontinued, the discontinuation must have occurred no fewer than 2 weeks before the start of Screening. 5. Any intercurrent seizures in the past 6 months and /or more than 1 seizure in the past 12 months. •A single febrile seizure in the 6 months prior to screening is allowable if no rescue medication was required. 6. Abnormal liver function laboratory results during the Screening period, as defined by the protocol 7. Abnormal QT interval on Screening ECG as defined by the protocol.

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