The GEMZ Study in CDKL5 Deficiency Disorder (CDD)
Find out more about the GEMZ research study for CDD.
The GEMZ Study is being conducted to learn more about patients with CDKLS deficiency disorder (CDD) and to find out if the study medication fenfluramine hydrochloride can reduce the seizures in patients who have a confirmed mutation in the cyclin-dependent kinase-like 5 (CDKL5) gene which is thought to be causing their disease.
This study is open to patients between the ages of 2 and 35 who have been diagnosed with CDD using both a genetic test (which can determine if there is a mutation or mistake in the CDKL5 gene) and through a clinical diagnosis by a doctor. Some patients who have been diagnosed with CDD have also been diagnosed as having Lennox-Gastaut Syndrome (LGS) in the past because both disorders have some things in common including a lot of seizure activity. These patients are also eligible for this study.
The GEMZ Study is part of the FAiRE (Fenfluramine hydrochloride Assessment in Rare Epilepsy) program of clinical studies that are evaluating whether an investigational drug called fenfluramine hydrochloride, when taken in addition to current anti-epileptic treatments, can improve seizure control in children and young adults with CDD or also other rare epilepsies.
For more information and resources about CDD, you can visit the International Foundation for CDKL5 Research (IFCR) website.
Learn more about the study from one of the study investigators and a representative from The International Foundation for CDKL5 Research in the video below.
For more information and resources about CDD, you can visit the International Foundation for CDKL5 Research (IFCR) website.
There are several criteria to meet to join the GEMZ Study. In order to participate in the GEMZ Study, patients must:
- Be between 2 and 35 years of age
- Have a confirmed mutation in the CDKL5 gene which is thought to be causing their disease
- Have a diagnosis of CDD with epilepsy first starting in the first year of life
- Have motor and developmental delays
- Have uncontrolled seizures despite previous or current use of 2 or more antiepileptic treatments
- Currently be receiving at least 1 anti seizure treatment
- Currently not be receiving more than 4 antiseizure medications (excluding rescue medications)
- Have 4 or more motor seizures per week
There are additional criteria to enroll in the study—the study team will assess these and discuss them with you.
At the study center, the study staff will discuss the study in detail with you and tell you more about taking part.
Find A Study Center
Choosing to participate in a clinical study is an important decision. Talk with your doctor and family member or friends about deciding to join a study. To learn more, you can contact the study research staff at active study sites.
The interactive map shows the cities where the study is conducted. Please click on the + sign (bottom left) to zoom in on an area, then click the pin to view the city name. Click the tabs below the map to view participating countries and cities.
Global Study Locations
The study starts with a visit to a participating physician’s office, where the doctor and staff will fully explain the clinical trial and answer any questions you may have. If your loved one meets all the study criteria, and you agree to have them participate, you will be given an electronic diary to record all seizures for the next 4 weeks. At the end of that time, you will return to the study physician’s office and they will review the diary and collect some additional information.
If your loved one is still eligible to join the study, they will be randomized by chance (like the flip of a coin) to receive either the investigational drug (fenfluramine hydrochloride) or placebo (a substance that looks like the investigational drug but has no medicinally active ingredients). Neither you nor the study team will know which you receive.
For the next 14 weeks of part 1, the participant will take either study medication or placebo, and you will continue to record all their seizures in the electronic diary. During that time, you will make 4 visits to the physician’s office.
After the last visit in part 1, all study participants will have a two-week period where they transition to taking fenfluramine hydrochloride for another year. There will be 8 visits at various times during part 2 of the study. All participants in this part of the study will receive fenfluramine hydrochloride (no placebo).
Following the last dose of study medication, there will be two more follow-up visits. The first is two weeks after the last dose, and the second is 6 months after the last dose.
What happens at study visits will vary, but may include certain tests, procedures, and questionnaires.
Assessments may include:
- Blood and urine samples, incl. genetic samples
- Physical exams
- Vital signs (blood pressure, pulse rate, breathing rate, body temperature)
- Questions about medical history and medications taken
- Echocardiograms and ECGs (heart function tests)
- Questionnaires
- Side effects review
- Study drug administration
- Neurological exams
Clinical studies (also known as clinical trials) are a type of medical research.
During these studies, scientists research different diseases and conditions as well as potential treatments that could help people with those diseases or conditions. Research studies allow scientists to see if and how new treatments work in study participants. Without participants, modern medicine would not exist!
By joining a study, participants have the opportunity to potentially help others with CDD in the future. However, it’s important to note that while your loved one may experience a beneficial effect on the disease, there’s also a possibility that the condition may not improve.
For more information and resources about CDD, you can visit the International Foundation for CDKL5 Research (IFCR) website.
Frequently Asked Questions
There are several criteria to meet to join the GEMZ Study. In order to participate in the GEMZ Study, patients must
- Be between 2 and 35 years of age
- Have a confirmed mutation in the CDKL5 gene which is thought to be causing their disease
- Have a diagnosis of CDD with epilepsy first starting in the first year of life
- Have motor and developmental delays
- Have uncontrolled seizures despite previous or current use of 2 or more antiepileptic treatments
- Currently be receiving at least 1 antiseizure treatment
- Currently not be receiving more than 4 antiseizure medications (excluding rescue medications)
- Have 4 or more motor seizures per week
- Have not previously been treated with Fintepla® (fenfluramine hydrochloride)
There are additional criteria to enroll in the study—the study team will assess these and discuss themwith you. Patients diagnosed with CDD who have also been diagnosed as having LGS in the past can also join the study, provided they meet all the study criteria.
If your loved one qualifies for the study and you choose to take part, you will be asked to complete up to 18 study visits for over two years. About 80 study participants will take part at approximately 70 study sites across the globe.
The GEMZ Study consists of two parts:
- Part 1: (approx. 5 months) There is an equal chance of participants being assigned to receive fenfluramine hydrochloride or placebo (this looks exactly like fenfluramine hydrochloride but contains no medicinally active ingredient). Part 1 will have a Baseline Period (4 weeks) to assess suitability for the study, a Titration Period (2 weeks) where the study medication is adjusted to the right dose, and a Maintenance Period (12 weeks) where the study medication or placebo is given. Before going into part 2, a 2-week titration period will follow.
- Part 2: (up to approx. 20 months) All participants will receive fenfluramine hydrochloride during this 54-week Open-Label Extension period, which will be followed by a 6 month safety follow-up period.
What happens at study visits will vary, but may include certain tests, procedures, and questionnaires.
The safety of all study participants will be carefully monitored throughout the entire study using a variety of assessments that may include:
- Blood and urine samples, incl. genetic samples
- Physical examinations
- Nervous system assessments
- Vital signs (blood pressure, pulse rate, breathing rate, body temperature)
- Questions about medical history and medications taken
- Echocardiograms and ECGs (painless heart function tests)
- Questionnaires about cognition, behavior and quality of life
- Diary review of the electronic diary (recording of seizures, use of rescue medication, and dosing of study medicine)
- Side effects review
- Study drug administration
- Neurological exams
The medication used in this study is called fenfluramine hydrochloride. It is already approved in some countries to treat certain types of epilepsy in certain age groups, including other rare forms of epilepsy like Dravet syndrome and Lennox-Gastaut syndrome.
The exact way that fenfluramine hydrochloride works in the brain of patients with CDD associated seizures is not fully understood. Based on previous studies, it is believed that the active ingredient in fenfluramine hydrochloride works in two ways. First, it increases the amount of a naturally occurring substance called serotonin in the brain, which helps in the regulation of emotions, sleep, anxiety, and other body functions. Second, it affects specific structures of nerve cells (called Sigma-1 receptors), which are thought to play a role in seizure activity in patients with CDD.
Fenfluramine hydrochloride (or the placebo in part 1 of the study) is taken orally (by mouth) as liquid solution twice a day with or without food.
Study participants can continue taking their normal background antiseizure medication(s) during the entire study.
Once participants have been stable on fenfluramine hydrochloride for at least 4 months (with good seizure control) following the beginning of part 2 of the study, the study doctor is allowed to change one or more of the antiseizure medications (or other therapy) as appropriate.
It is completely up to you to decide if you want to take part in a clinical study. Whether or not you decide to participate in this study will not affect your current or future relationships with your doctors or negatively affect benefits to which you are entitled.
Travel reimbursement will be provided, and you will have a contact at study site. Your study doctor will be able to give you more information on this.
This study is sponsored by Zogenix (a member of the UCB Group of Companies), a global biopharma company focusing on neurology and immunology disorders, including rare epilepsies. Zogenix has worked with CDD patient organizations and caregivers of CDD patients to better understand their evolving needs and continues to engage with CDD and other epilepsy organizations that support patients and their families.
In order to analyze the results of the study, Zogenix will have to wait until all participants in all countries have finished the study. For a lot of studies, this can take up to several years, depending on the duration of the study.
Zogenix will make the results of the study available in the applicable public study registry databases such as clinicaltrials.gov or the EU Clinical Trials Register. You can ask your study doctor about the availability of the study results after you have left the study. Results for the GEMZ study are not expected to be available before the fourth quarter of 2026, but could also become available later than that.
For more information and resources about CDD, you can visit the International Foundation for CDKL5 Research (IFCR) website.
