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Taking people in United StatesPhase 2

Long-term study of KL1333 in adults with primary mitochondrial disease

Tests KL1333 over a long time in adults with primary mitochondrial disease.

Key facts

Who runs it
Pharming Technologies B.V.
Where
Akron, United StatesSee the siteAlso in 8 other countries, 25 sites
Registry title
Open Label Extension to Assess Long Term Safety and Efficacy of KL1333 in Patients With Primary Mitochondrial Disease
Status
Recruiting
Phase
Phase 2
People taking part
140 people, planned
Started
12 Jun 2026
Expected to end
31 Mar 2029
Type of study
Interventional
Treatments tested
  • Napazimone
Record updated
16 September 2026

Who can take part

Age
18 years and older
Sex
Women and men
Healthy volunteers
Cannot take part

The registry criteria, word for word

Show all 8 criteriaShow less

Who can take part

  • 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 take part

  • 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
  • General fatigue or muscle weakness due to causes other than mitochondrial disease, in the opinion of the investigator
  • 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:

Where in United States

Also in 8 other countries, 25 sites

  • Akron Children's HospitalAkron, United StatesContact: Bruce Cohen (principal investigator)Taking people

About the trial

What the trial wants to find out

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.

The group in the trial

  • Open label extensionTreatment being tested

    Subjects will receive medication twice a day for 48 weeks minimum

    Treatment: Napazimone

Questions to ask the study team

  1. How often do I need to come in, and for how long each time?
  2. Are travel costs paid?
  3. Can I keep my own doctor?
  4. What happens if I want to stop?

Contact the study team: see the registry record → Contacts and Locations

Print a page for my doctor

Data and sources

Registry record
Listed on ClinicalTrials.gov and on the EU's official list of trials (CTIS).
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
Plain-language title
Long-term study of KL1333 in adults with primary mitochondrial diseaseGenerated from the registry record. The registry title is the official one.
Record updated
16 September 2026