What is KL1333 studying for primary mitochondrial disease?

KL1333 is being studied to see if it can improve fatigue and physical function in adults with primary mitochondrial disease. Researchers are comparing KL1333 with a placebo to understand its effects on symptoms and daily activities. The study is sponsored by Pharming Technologies B.V.

Who may be eligible for this primary mitochondrial disease clinical trial?

Adults aged 18 years or older diagnosed with primary mitochondrial disease caused by specific gene mutations may be eligible. Participants must have moderate mitochondrial fatigue, be able to perform physical tests, and be willing to follow study requirements. Please review eligibility criteria for more details.

Is there any cost to participate in this primary mitochondrial disease clinical trial?

Study-related care, including the study drug or placebo and all trial visits, is provided at no cost. Personal travel expenses to and from study visits may vary and are not guaranteed to be covered.

Actively Recruiting

Phase 2

Age: 18Years +

All Genders

ID05650229

Study Evaluating KL1333 to Reduce Fatigue and Improve Physical Function in Adults with Primary Mitochondrial Disease

Led by Pharming Technologies B.V. · Updated on 2026-06-26

180

Participants Needed

Research Sites

4 weeks

Total Duration

AI-Summary

What this Trial Is About

Researchers are evaluating KL1333 in adults with primary mitochondrial disease PMD to assess its effects on fatigue symptoms, daily living impacts, and physical strength and endurance. This Phase 2 study compares KL1333 with a placebo over 48 weeks, focusing on how the medication may influence selected disease aspects and evaluating its safety and tolerability. Participants take either KL1333 or a matching placebo tablet twice daily during the 48-week treatment period. The study is divided into three parts an 8 to 12-week screening and baseline phase, the 48-week treatment phase, and a 5-week safety follow-up. Participants are randomly assigned to receive KL1333 or placebo, with a higher chance of receiving KL1333, and neither they nor the study team know which treatment is given. Throughout the study, participants will undergo assessments including patient-reported fatigue measures and the 30-second sit-to-stand test at the start and end of treatment. Additional evaluations cover quality of life, activity interference, global impressions of severity and change, and neurological function. Safety is monitored through physical examinations, ECGs, laboratory tests, and adherence to treatment and study procedures. Total participation lasts approximately 61 to 65 weeks.

CONDITIONS

Brief Title

Efficacy of KL1333 in Adult Patients With Primary Mitochondrial Disease

Who Can Participate

Age: 18Years +

All Genders

Eligibility Criteria

You may qualify if you...

Age 18 years or older
Confirmed primary mitochondrial disease diagnosis caused by known pathogenic gene mutation or mitochondrial genome deletion
Diagnosis includes multisystemic disease expressions such as MELAS-MIDD, KSS-CPEO, or other mtDNA-related diseases
History of mitochondrial fatigue for at least 3 months prior to screening
Moderate or higher fatigue level with PROMIS® Fatigue PMD Short Form raw score ≥ 27 at screening and baseline
Presence of mitochondrial myopathy defined by specific muscle weakness or exercise tolerance scores
Ability to perform at least 2 repetitions and not exceed 17 (males) or 16 (females) repetitions in 30-second sit-to-stand test at screening
Clinically stable apart from mitochondrial disease symptoms at screening and baseline
Willing and able to attend study visits and complete electronic patient-reported outcomes
Willing to maintain a stable diet during screening and study periods
Stable dose of mitochondrial vitamins or supplements for at least 3 months prior and intends to remain stable
Willingness to suspend idebenone treatment during the study
Female participants not pregnant and either not of childbearing potential or agreeing to use effective contraception
Male participants with female partners of childbearing potential agree to use condoms and contraception
Female participants agree not to breastfeed and not donate ova during study and follow-up
Male participants agree not to donate sperm during study and follow-up

You will not qualify if you...

Primary mitochondrial disease with predominant neurodegenerative types such as Leigh syndrome, LHON, or NARP
Nuclear DNA mutations causing mitochondrial disease or uncertain genetic variants below pathogenic levels
Fatigue or muscle weakness caused by other conditions than mitochondrial disease
Significant cardiovascular disease or clinically significant abnormal ECG including prolonged QTcF
Recent unstable neurological disease, stroke-like episodes, frequent seizures, status epilepticus, or frequent migraines
History of inflammatory bowel disease, gastric erosions, peptic ulcers, or recent symptomatic gastroesophageal reflux
Clinical laboratory abnormalities posing safety risks including low kidney function, elevated bilirubin or liver enzymes
Severe ataxia, neuropathy, balance problems, or other conditions interfering with physical tests
Untreated or undertreated sleep apnea
Use of idebenone within 14 days prior to first dose
History of unstable or severe pulmonary, immunological, oncological, hepatic, renal disease or other serious illnesses
Medications interfering with safety, tolerability, efficacy, or study assessments
Unlikely to comply with protocol or unsuitable due to cognitive impairment or other reasons
Immediate family member residing at the same address participating in the study
Positive pregnancy test at screening or baseline
Use of other investigational drugs within 30 days or plans to use during the study
Hypersensitivity to study drug or placebo ingredients

Research Team

Communication Manager

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Study Evaluating KL1333 to Reduce Fatigue and Improve Physical Function in Adults with Primary Mitochondrial Disease

On this page

AI-Summary

What this Trial Is About

Brief Title

Who Can Participate

Eligibility Criteria

Research Team

Not the Right Trial for You?

On this page

Who Can Participate

Eligibility Criteria