for people ages 18-75 (full criteria)
at La Jolla, California and other locations
study started
completion around



PRIZM is a Phase 2b randomized, double-blind, placebo-controlled, 3-treatment, 2-period, crossover study evaluating the efficacy and safety of oral zagociguat 15 and 30 mg vs. placebo when administered daily for 12 weeks in participants with genetically and phenotypically defined MELAS.

Official Title

Phase 2b Randomized, Double-blind, Placebo-controlled Crossover Study Evaluating the Efficacy and Safety of Zagociguat in Participants With MELAS (PRIZM)


The goal of this clinical trial is to learn about the effectiveness of zagociguat in patients with MELAS. The main questions it aims to answer are:

  • Does zagociguat improve fatigue in patients with MELAS?
  • Does zagociguat improve cognitive performance in patients with MELAS?
  • What is the safety and tolerability profile of zagociguat?

The PRIZM study is evaluating 2 dose levels of zagociguat in a crossover design consisting of two 12-week treatment periods separated by a 4-week washout. Patients will be screened and if eligible, randomly assigned to either receive placebo in period 1 followed by active drug in period 2. Study medication is a once daily oral tablet and will be provided at the clinic and/or shipped to the patient's home. Clinic visits will occur at screening and Week 1 and Week 12 of each crossover period. Visits at Week 4 and Week 8 of both crossover periods will either be in clinic or optionally at the patient's home. Study assessments will be conducted weekly on a phone app and a separate tablet and additional assessments will be conducted during visits. Patients who complete the study will be eligible for an open label extension study.


Mitochondrial Encephalopathy, Lactic Acidosis and Stroke-Like Episodes (MELAS Syndrome), MELAS, MELAS Syndrome, Brain Diseases, Acidosis, Lactic Acidosis, zagociguat 15mg, zagociguat 30mg


You can join if…

Open to people ages 18-75

  1. Signed consent form.
  2. 18 to 75 years of age.
  3. Diagnosed with MELAS based on the presence of each of the following criteria:
    1. A documented pathogenic variant in a mitochondrial DNA (mtDNA) gene.
    2. History of one or more stroke-like episodes (SLEs) with magnetic resonance imaging (MRI) findings consistent with stroke-like lesions.
  4. Scores below normal average on composite memory score from One Back and One Card Learning tests.
  5. Reports fatigue due to MELAS.
  6. Can complete at least 1 sit-to-stand in the 30-second test interval.
  7. Complete all at-home weekly activities during the Screening Period.
  8. Other criteria per the protocol.

You CAN'T join if...

  1. Severe visual impairment that precludes ability to complete cognitive performance tests independently.

    Note: a caregiver can provide support throughout the study.

  2. Systolic blood pressure (BP) 90 mmHg or diastolic BP 60 mmHg.
  3. Orthostatic hypotension when measured after standing from a semi-recumbent/supine position.
  4. Active cancer significant enough to confound the results of this study.

    6. Recent history (within last 6 months) of platelet dysfunction, hemophilia, von Willebrand disease, coagulation disorder, other bleeding diathesis condition(s), or significant, nontraumatic bleeding episodes. 7. History of spontaneous fracture(s) that in the investigator's opinion represents a safety risk for trial participation. 8. Current use of prohibited medication (reviewed by investigator). 9. Any medical or other condition that the investigator think would preclude study participation. 10. Other exclusion criteria per protocol.


  • UC San Diego - Altman Clinical and Translational Research Institute
    La Jolla California 92037 United States
  • Children's Hospital of Colorado
    Aurora Colorado 80045 United States


not yet accepting patients
Start Date
Completion Date
Tisento Therapeutics
Phase 2
Study Type
Expecting 36 study participants
Last Updated