A Double-Blind, Randomized, Multicenter, Trial Evaluating the Efficacy and Safety of PRAX-628 in Adults with Focal Seizures (POWER 1)

Overview

Sponsor-declared trial summary

Key facts

Sponsor

Praxis Precision Medicines Inc.

Participant type

Patients

Age range

18-64 years, 65+ years

Gender

Male and Female

Therapeutic area

Diseases [C] - Nervous System Diseases [C10]

Trial duration

26 Nov 2024 → 14 May 2026

Decision date (initial)

2025-04-17

Transition trial

No

Low-intervention

No

Rare-disease indication

No

Vulnerable population

No

Trial design

CTIS Part I — objectives, methods, condition coding

Main objective

Scope: Efficacy, Pharmacodynamic, Pharmacokinetic, Safety, Others

To evaluate the efficacy of PRAX-628 compared to placebo on focal seizure frequency in adults
currently taking 1 to 3 ASMs

Secondary objectives 3

1. To evaluate the efficacy of PRAX-628 compared to placebo on focal seizure frequency in adults currently taking 1 to 3 ASMs
2. To assess the safety and tolerability of PRAX-628 in adults with focal seizures
3. To assess trends over time in efficacy of PRAX-628 on focal seizure frequency

Conditions and MedDRA coding

Focal Epilepsy

Eligibility criteria

Principal inclusion / exclusion criteria as submitted by sponsor

Inclusion criteria 8

1. Participant and care giver, if applicable, is willing to sign an informed consent document in accordance with International Council for Harmonization (ICH)/Good Clinical Practice (GCP) guidelines, indicating that they understand the purpose of the clinical trial; understands, and can perform, complete, and comply with all the procedures and assessments that are required during the clinical trial, including the seizure diary and use of appropriate contraception (as defined in Section 5.4.2), and is willing to participate in the clinical trial.
2. Aged ≥18 to ≤75 years of age at the time of consent.
3. A diagnosis of focal onset epilepsy according to the International League Against Epilepsy (ILAE) Classification of Epilepsy (2017).
4. Prior to randomization, past evidence by computed tomography (CT) or magnetic resonance imaging (MRI) that has ruled out a progressive cause of epilepsy in the judgement of the investigator and/or in consultation with the medical monitor.
5. Participant must attest to be taking stable doses of 1 or up to 3 acceptable ASMs (none listed as a prohibited concomitant medication in Table 10) for at least 4 weeks prior to screening (SC1).
6. At least XXXX countable focal onset seizures during the Screening/Observation Period and no less than XXXXX prior to Visit 1. Countable focal seizures are defined as: (1) focal aware seizures with clear observable signs by the patient or caregiver, (2) focal seizures with impaired awareness, or (3) focal to bilateral tonic-clonic seizures.
7. Seizure diary completion must occur on ≥80% days in the Screening/Observation Period.
8. The participant may not be seizure-free for a single period of more than XXXX consecutive days during the XXXX-week Screening/Observation Period. The seizure distribution throughout this period will be evaluated to avoid including patients with only clustering seizures.eizure distribution throughout this period will be evaluated to avoid including patients with only clustering seizures.

Exclusion criteria 18

1. Participant has had any of the following within the 12-month period preceding trial entry: − evidence of experiencing pseudo or psychogenic seizures, − cluster seizures where the individual seizures cannot be counted, − an episode of convulsive status epilepticus requiring hospitalization and intubation.
2. Seizures secondary to illicit drug or alcohol use, ongoing infection, neoplasia, demyelinating disease or central nervous system disease deemed progressive, metabolic illness, or progressive degenerative disease, progressive structural lesion or encephalopathy.
3. Planned epilepsy surgery during the course of the clinical trial.
4. History of any of the following: a. neurosurgery for seizures <1 year prior to enrollment b. radiosurgery <2 years prior to enrollment c. neurostimulator placed <1 year prior to Screening d. neurostimulator placed >1 year prior to Screening but settings have not been stable for at least 2 months prior to Screening.
5. Active suicidal plan/intent in the past 6 months, or a history of suicide attempt in the last 2 years, or more than 1 lifetime suicide attempt, as confirmed by Columbia-Suicide Severity Rating Scale (C-SSRS).
6. Has any significant ongoing disease, disorder, psychiatric, medical, or surgical condition, laboratory abnormalities, alcohol or drug abuse or dependence, or environmental factor at Screening that in the judgement of the investigator in consultation with the medical monitor and/or sponsor designee, might jeopardize the participant’s safety or interfere with the absorption, distribution, metabolism or excretion of PRAX-628; or impact the clinical trial objectives; or interfere with participation in the clinical trial.
7. History of malignancy, myeloproliferative or lymphoproliferative disorders within the past 5 years are excluded. Exceptions:1) Participants with completely excised non-melanoma skin cancer (such as basal cell carcinoma or squamous cell carcinoma) or cervical carcinoma in situ are permitted at any time 2) Participants with a history of indolent or early-stage malignancies that are unlikely to progress or other malignancies deemed cured by adequate treatment are also permitted at any time 3) low grade prostate cancer with Gleason score ≤2.
8. History or presence of uncontrolled cardiac diseases including conduction and structural abnormalities (eg, family history of sudden death, long QT syndrome, familial short QT syndrome, Brugada syndrome, or sustained ventricular arrythmia) which may place patients at increased risk determined by the investigator.
9. Has any of the following: persistently abnormal test results at Screening: a serum total bilirubin value >1.5×upper limit of normal (ULN); a serum alanine aminotransferase (ALT) or aspartate aminotransferase (AST) value >3×ULN. As an exception, participants that present with elevated bilirubin in the absence of elevations in ALT or AST that fits the pattern of Gilbert’s syndrome may be enrolled after discussion with the medical monitor and/or sponsor designee if their conjugated bilirubin is below the ULN.
10. Has a positive test result or a known history of a positive test result for human immunodeficiency virus (HIV). Evidence of active hepatitis B or hepatitis C infection, as determined by relevant screening assessments.
11. Is pregnant or is breastfeeding at the time of Screening or has a positive serum pregnancy test at Screening or is planning to become pregnant during the clinical trial or within 14 days of the last study drug dose.
12. Has received any other experimental or investigational drug, device or other therapy within 30 days or 5 half-lives (whichever is longer) prior to Screening, or any prior use of gene therapy.
13. Use of vigabatrin in the last 5 years without stable visual fields tested twice over the 12 months after the last dose of vigabatrin.
14. Use of felbamate: If used as a concomitant ASM, patients must be on felbamate for at least 2 years, with a stable dose for 2 months prior to Screening. If a participant received felbamate in the past, it must have been discontinued at least 2 months prior to Screening.
15. Participant is receiving a prohibited medication as per the prohibited concomitant medications section (Section 6.4.1).
16. Significant allergic reaction to an ASM(s), including dermatological (eg, Stevens-Johnson syndrome), hematological, or organ toxicity reactions.
17. If on a ketogenic or other diet for management of seizures, must have started the diet at least 3 months prior to Screening with stable parameters for at least 1 month prior to Screening, with the intention to remain on a stable diet throughout the trial; diets are not counted as an ASM.
18. Previously documented EEG which shows any pattern not consistent with focal etiology of seizures. (A new EEG is not required, if not available).

Endpoints

Primary and secondary outcome measures (English text)

Primary endpoints 1

1. Median percent change in monthly (28 days) focal seizure frequency from the Screening/Observation Period to the Treatment Period for PRAX-628 compared to placebo.

Secondary endpoints 5

1. Proportion of participants experiencing a ≥50% reduction in monthly (28 days) focal seizure frequency from the Screening/Observation Period to the Treatment Period (Responder Rate) for PRAX-628 compared to placebo.
2. Number of days post-randomization to reach the same number of monthly focal seizures as the Screening/Observation Period through the end of the Treatment Period • Impact of PRAX-628 compared to placebo on PGI-S and CGI-S
3. Incidence and severity of TEAEs, including discontinuation of study drug due to TEAEs • Changes in vital sign measurements • Changes in clinical laboratory results • Changes in ECG parameters • Changes in suicidality, as assessed by C-SSRS
4. Percent change in monthly focal seizure frequency from the Screening/Observation Period to the Treatment Period for PRAX-628 compared with placebo.
5. Proportion of participants experiencing seizure freedom, 100% reduction in monthly (28 days) focal seizure frequency from the Screening/Observation Period to the Treatment Period for PRAX-628 compared with placebo.

Investigational products

Investigational medicinal products (IMPs), comparators, placebo, auxiliary

Test 1

Placebo 1

Sponsors and contacts

Sponsor organisations, regulatory contacts, third parties

Praxis Precision Medicines Inc.

Sponsor organisation

Praxis Precision Medicines Inc.

Address

99 High Street Floor 30th

City

Boston

Postcode

02110-2345

Country

United States

Scientific contact point

Organisation

Praxis Precision Medicines Inc.

Contact name

William C. Motel

Public contact point

Organisation

Praxis Precision Medicines Inc.

Contact name

William C. Motel

Third parties 10

Locations

3 EU/EEA countries · 32 investigational sites

By country

Investigational sites

Country notifications

Trial-start, recruitment-start, end and early-termination notifications submitted per Member State

Results and documents

Annex IV summary of results, Annex V layperson summary, and all documents registered in CTIS for this trial

Documents 49 files

Public protocol annexes, IB summaries, regulatory submissions and post-authorisation documents registered in CTIS.

Application history

12 submissions — initial application plus substantial / non-substantial modifications