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Mitochondrial DiseasesPhase 2Falcon-OLENCT07514338

Open Label Extension to Assess Long Term Safety and Efficacy of KL1333 in Patients With Primary Mitochondrial Disease

A Phase 2 study testing Napazimone in people with Mitochondrial Diseases, run by Pharming Technologies B.V. at 23 sites in 9 countries.

Recruiting

Looking for participants now. Contact the study team or a site below to ask about taking part.

Sites and contacts
Official record
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Trial summary

The purpose of this study is to investigate if the study medicine, KL1333, is safe, well-tolerated and effective long-term in improving the symptoms of fatigue and impacts on daily living and functional capacity (physical abilities) in people with PMD. Read more about this study

Who is it for?
Ages 18 years and older
Conditions the study is for
Mitochondrial Diseases
What is being tested?
Napazimone
Type of treatment
Pill or oral medicine
Could I receive a placebo?
No, everyone receives an active treatment
How many people
140 participants
Where
23 sitesin 9 countries
Study dates
12 Jun 2026to 31 Mar 2029
Phase
Phase 2
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Completed the FALCON study (age 18 years or older), and in the opinion of the investigator and sponsor has been compliant with the study requirements
  • Willingness and ability to attend study appointments within the specified time windows
  • Willingness and ability to complete electronic patient-reported outcomes
  • Concomitant medications likely to remain stable throughout participation in the study where clinically possible
  • Willingness to suspend treatment with idebenone during the study

Who cannot join

  • The subject is, in the investigator's opinion, unlikely to comply with the protocol, e.g., due to cognitive impairment, or is unsuitable for any reason.
  • Any medical, psychiatric, laboratory or other condition that may negatively affect the benefit-risk considerations of study participation or interfere with the interpretation of study results and, in the judgment of the investigator and/or the medical monitor, would make the subject inappropriate for entry into this study.
  • Subjects not enrolling directly at the FALCON study completion visit (FALCON Week 48) or the safety follow-up visit (FALCON Week 53) study will be required to fulfill the additional exclusion criteria below during the screening visit:
  • General fatigue or muscle weakness due to causes other than mitochondrial disease, in the opinion of the investigator.

Trial locations and contacts

23 sites in 9 countries. Contact the study team or a site near you to ask about taking part.

Audrey Simon, Sr. CPM contact

+31 71 524 7448

a.simon@pharming.com

23 sites in 9 countries

France7 sites, 7 recruiting
  • Centre Hospitalier Universitaire d'Angers

    Angers, 49933

    Marco Spinazzi, MD

    Marco Spinazzi

    Recruiting
  • Centre Hospitalier Universitaire (CHU) de Bordeaux - Groupe Hospitalier Pellegrin

    Bordeaux

    Aurelien Trimouille, MD

    Aurelien Trimouille, MD

    Recruiting
  • Hopital Roger Salengro, CHRU de Lille

    Lille

    Celine Tard

    Celine Tard, MD

    Recruiting
  • Centre Hospitalier Universitaire de Nantes

    Nantes, 44093

    Yann Pereon, MD

    Yann Pereon

    Recruiting
  • Centre Hospitalier Universitaire de Nice, Hopital Pasteur 2

    Nice

    Sabrina Sacconi, MD

    Sabrina Sacconi, MD

    Recruiting
  • CHU de NICE - Hôpital Archet 2

    Nice

    Véronique Paquis-Flucklinger, MD

    Recruiting
  • Hopitaux Universitaires de Strasbourg

    Strasbourg, 67091

    Aleksandra Nadaj-Pakleza

    Aleksandra Nadaj-Pakleza

    Recruiting

Other trials in France

Belgium6 sites, 6 recruiting
  • Hospital Erasme

    Brussels, 1070

    Gauthier Remiche

    Recruiting
  • Hopital Universitaire de Bruxelles (H.U.B)/ Academisch Ziekenhuis Brussel

    Brussels

    Gauthier Remiche, MD

    Christiane Kitoko

    Recruiting
  • University Hospital

    Ghent, 9000

    Hemelsoet, PI

    Recruiting
  • Universitair Ziekenhuis Gent

    Ghent

    Fien Demeulemeester

    Dimitri Hemelsoet, MD

    Recruiting
  • University Hospital

    Leuven, 3000

    Claeys

    Recruiting
  • Universitair Ziekenhuis Leuven Gasthuisberg Campus

    Leuven

    Kristl Claeys, MD

    Kristl Claeys, MD

    Recruiting

Other trials in Belgium

Italy3 sites, 3 recruiting
  • Azienda Ospedaliera Universitaria Gaetano Martino Messina

    Messina, 98125

    Olimpia Musumeci, MD Professor

    Selene Drago

    Recruiting
  • Fondazione IRCCS Istituto Neurologico Carlo Besta

    Milan, 20133

    Costanza Lamperti, MD

    Valeria Nicoletta

    Recruiting
  • Azienda Ospedaliero Universitaria Pisana

    Pisa, 56126

    Michelangelo Mancuso, MD

    Riani Pierangela

    Recruiting

Other trials in Italy

Spain2 sites, 2 recruiting
  • Hospital General Universitario de Catalunya

    Barcelona

    Susana Andrade Olivié

    Josep Gamez Carbonell, MD

    Recruiting
  • Hospital Universitario 12 de Octubre

    Madrid

    Montserrat Morales, MD

    Montserrat Morales, MD

    Recruiting

Other trials in Spain

United States1 site, 1 recruiting
  • Akron Children's Hospital

    Akron, Ohio, 44308

    Bruce Cohen

    Recruiting

Other trials in United States

Czechia1 site, 1 recruiting
  • Charles University and General University Hospital

    Prague, 128 08

    Hana Krejcova, MD

    Hana Krejcova

    Recruiting

Other trials in Czechia

Denmark1 site, 1 recruiting
  • Copenhagen Neuromuscular Center, Rigshospitalet

    Copenhagen

    Nicolai Rasmus Preisler, MD

    Nicolai Preisler, MD

    Recruiting

Other trials in Denmark

Germany1 site, 1 recruiting
  • Universitaetsklinikum Halle

    Halle, 6120

    Alexander Mensch, MD

    Recruiting

Other trials in Germany

Netherlands1 site, 1 recruiting
  • Radboud University Medical Center

    Nijmegen, 6525

    Christiaan Saris, MD

    Recruiting

Other trials in Netherlands

About this study

Official title: An Open-label, Single-arm Extension Study to Evaluate the Long-term Safety, Tolerability, and Efficacy of KL1333 (Napazimone) in Patients With Primary Mitochondrial Disease

The purpose of this study is to investigate if the study medicine, KL1333, is safe, well-tolerated and effective long-term in improving the symptoms of fatigue and impacts on daily living and functional capacity (physical abilities) in people with PMD.

Read the detailed description

This is a 12-month open-label extension (OLE) study to evaluate the safety, tolerability, and efficacy of KL1333 in subjects previously treated with KL1333 or placebo in Study KL1333-2020-104A (hereafter referred to as FALCON).

Subjects can be enrolled in this extension study either directly at the FALCON study completion visit (FALCON Week 48) or the safety follow-up visit (FALCON Week 53) or later in time. Subjects who previously received KL1333 in FALCON will receive retreatment whereas subjects previously treated with placebo will be treatment naïve to KL1333.

The study consists of a screening visit (if the subject rolls over directly from the FALCON study completion visit [FALCON Week 48] or the safety follow up visit [FALCON Week 53], the screening visit is coincident with the visit), a 48-week treatment course with KL1333 up to 100 mg/day, a completion visit (end of treatment; EoT) and approximately 5 weeks of follow up, including the end of study (EoS) visit. The treatment period may extend beyond 48 weeks until the study drug is commercially or otherwise available, in which case the EoT visit will occur later than Week 48. Periodic safety monitoring visits (phone visits every 4 weeks after Week 48 and clinic visits every 24 weeks after Week 48) will continue for subjects who receive KL1333 in the optional extended treatment period until the study drug is commercially or otherwise available.

Being tested
Napazimone
Medical subject headings
Mitochondrial Diseases

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • NapazimoneDrug

    Also called KL1333

    Product: KL1333 (international nonproprietary name: napazimone) Dose: Each subject will be up-titrated to his/her maximum well tolerated dose. The starting dose will be 25 mg KL1333 twice daily (BID; total daily dose of 50 mg). If KL1333 is considered to be well tolerated after 4 weeks of treatment, the dose will be increased to 50 mg KL1333 BID (total daily dose of 100 mg). The dose may be lowered from 50 mg BID to 25 mg BID at the investigator's discretion throughout the study in case of tolerability issues.

    Frequency: Twice daily Route: Oral

Study groups in NCT07514338
Study groupRoleWhat they receive
Open label extensionExperimentalSubjects will receive medication twice a day for 48 weeks minimum
Receives: Drug: Napazimone

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Adverse events

    Number of adverse events will be monitored throughout the study for all subjects

    Measured: Through study at least for 48 weeks

  2. Physical examination

    The following parameters and body systems will be examined and any abnormalities described: height and weight; general appearance; skin; head, ears, eyes, nose, and throat; lungs; heart; lower extremity examination; abdomen; neurologic and lymph nodes. Any clinically significant changes from baseline should be recorded as AEs.

    Measured: At Baseline Week 0, Week 4, Week 24 and Week 48

  3. Vital signs

    Body temperature, systolic and diastolic cuff blood pressure, pulse rate and pulse oximetry will be measured and any clinically significant changes from baseline should be recorded as AEs.

    Measured: At Baseline Week 0, Week 4, Week 24 and Week 48

  4. Electrocardiogram

    Changes from baseline of ECG parameters will be evaluated.

    Measured: At Baseline Week 0, Week 4, Week 24 and Week 48

  5. Safety laboratory - blood chemistry

    Monitoring of the clinically significant laboratory results for sodium, potassium, chloride, bicarbonate/carbon dioxide;, blood urea nitrogen, serum creatinine, glucose, albumin, total protein, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, total bilirubin, direct bilirubin, indirect bilirubin, calcium, gamma-glutamyl transferase, creatine kinase

    Measured: At Baseline Week 0, Week 4, Week 24 and Week 48

  6. Safety laboratory - urinalysis

    Monitoring of the clinically significant laboratory results for specific gravity, pH, semi-quantitative "dipstick" evaluation of glucose, protein, bilirubin, ketones, leukocytes, blood microscopy and/or culture to be performed if clinically indicated or if urinalysis results positive.

    Measured: At Baseline Week 0, Week 4, Week 24 and Week 48

  7. Safety laboratory - hematology

    Monitoring of the clinically significant laboratory results for Hemoglobin, hematocrit, white blood cell with differentials (monocytes, eosinophils, basophils, neutrophils, lymphocytes) as an absolute value, red blood cell count, platelet count, C-reactive protein

    Measured: At Baseline Week 0, Week 4, Week 24 and Week 48

  8. Occurence of metabolic decompensation and lactic acidosis or image-verified stroke-like episodes consequent to GI AE and AESIs

    These events will be monitored throughout the study.

    Measured: Through study at least for 48 weeks

  9. Columbia Suicide Severity Rating Scale (C-SSRS)

    C-SSRS assesses suicidal ideation and behavior risk through a series of questions to assess for suicidal ideation and behavior, the severity and immediacy of the risk, and the level of support the subject may need. C-SSRS Severity of Ideation scores of 4 or 5 are considered SAEs.

    Measured: At Baseline Week 0

Secondary outcomes (8)
  1. Patient-reported mitochondrial fatigue

    Patient-Reported Outcomes Measurement Information System® Fatigue PMD short form. The PROMIS® Fatigue PMD short form consists of 9 items. Each item has numerical rating scale (NRS) response options consisting of never (1), rarely (2), sometimes (3), often (4), and always (5).

    Measured: Through study at least for 48 weeks

  2. Functional outcome

    30 seconds sit-to-stand test

    Measured: At Baseline Week 0, Week 4, Week 24 and Week 48

  3. Patient-reported lower extremity function

    Neuro-QOL Lower Extremity Function (Mobility) - short form. It is a reliable and validated brief 8-item survey of one's ability to carry out various activities involving the lower limb/trunk region and increasing degrees of bodily movement. Each item has numeric rating scale (NRS) response options consisting of Without any difficulty (5), With a little difficulty (4), With some difficulty (3), With much difficulty (2), and unable to do (1).

    Measured: At Baseline Week 0, Week 4, Week 12, Week 24, Week 36 and Week 48

  4. Other patient-reported outcome - Patient Global Impression (multiple)

    The Patient Global Impression of Severity is rated on a 4-point NRS, assessed on a scale ranging from 1 (none) to 4 (severe) for severity. The Patient Global Impression of Change is rated on a 5-point numeric rating scale (NRS), with the change from baseline assessed on a scale ranging from 2 (much better) to -2 (much worse), with 0 indicating no change from baseline.

    Measured: At Baseline Week 0, Week 4, Week 12, Week 24, Week 36 and Week 48

  5. Other patient-reported outcomes - 5-level EuroQol-5 Dimension

    The EQ-5D-5L includes items addressing mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. The scale yields a single score on a 0 to 100 scale.

    Measured: At Baseline Week 0, Week 4, Week 12, Week 24, Week 36 and Week 48

  6. Global impression of severity of PMD disease expression

    Clinician Global Impression of PMD - severity and change

    Measured: At Baseline Week 0, Week 24 and Week 48

  7. Assessments of mitochondrial disease progression

    Newcastle Mitochondrial Disease Adult Scale, Subscales I-III

    Measured: At Baseline Week 0, Week 24 and Week 48

  8. Mitochondrial diabetes, subgroup analysis

    Glycated hemoglobin (HbA1c, in subjects with diabetes)

    Measured: At Baseline Week 0, Week 24 and Week 48

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted7 Apr 2026
  2. Study start12 Jun 2026
  3. Primary completion31 Mar 2029 (estimated)
  4. Study completion31 Mar 2029 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 2
Primary purpose
Treatment
Allocation
Not applicable
Intervention model
Single group
Model description
Open-label Extension
Masking
None (open label)
Enrolment
140 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07514338
Sponsor's protocol ID
KL1333 2025-104B
Other IDs
2025-524367-20-00, 2025
Acronym
Falcon-OLE
Status last verified
Jul 2026
First submitted
24 Feb 2026
Last updated
16 Sep 2026
Results posted
No
Data monitoring committee
No
FDA-regulated drug
Yes
FDA-regulated device
No

Questions about this trial

What is this clinical trial studying?

A Phase 2 study testing Napazimone in people with Mitochondrial Diseases, run by Pharming Technologies B.V. at 23 sites in 9 countries.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 5 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: looking for participants now, as of the sponsor's last update on 16 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 23 sites in France, Belgium, Italy, Spain, United States and 4 more countries. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Contact Audrey Simon, Sr. CPM (+31 71 524 7448, a.simon@pharming.com), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Adverse events (time frame: Through study at least for 48 weeks). The study lists 9 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 16 Sep 2026.

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