Ganaxolone Receives Rare Pediatric Disease Designation for CDD

Scott Braunstein, MD

Marinus pharmaceuticals announced that the FDA has granted a rare pediatric disease (RPD) designation to ganaxolone for the treatment of CDKL5 deficiency disorder (CDD), a rare refractory form of pediatric epilepsy.¹

“This designation for ganaxolone for CDD underscores the significant unmet medical need for children and young adults with this serious and rare genetic disease, which causes early-onset, difficult-to-control seizures and severe neuro-developmental impairment,” Scott Braunstein, MD, chief executive officer of Marinus, said in a statement.

Braunstein went on to say that the timing of the RPD aligns with the company’s data readout from the phase 3 Marigold study (NCT03572933), which is expected to be released sometime this quarter. The global, double-blind, placebo-controlled study is currently evaluating the use of oral ganaxolone in children and young adults with CDD and just recently finished enrollment of 101 patients between the ages of 2 and 21 back in February.²

Ganaxolone is a synthetic neurosteroid that acts as a positive allosteric modulator of synaptic and extrasynaptic GABAA receptors. It exhibits anti-seizure, anti-depressant and anti-anxiety effects and is noted to be generally safe and well-tolerated in studies.

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Patients enrolled in Marigold underwent a baseline period before being randomized to receive either ganaxolone (up to 1800 mg per day) or placebo for 17 weeks in addition to their existing anti-seizure treatment. All patients that met certain eligibility requirements following the treatment period will have the option to receive ganaxolone in the open-label phase of the study.

Investigators are using the percent reduction in seizures as the primary end point of the study and observe other secondary outcome measures, such as non-seizure-related end points, to capture certain changes in behavioral and sleep disturbances that were seen as improvements in previous clinical studies with ganaxolone. Joe Hulihan, MD, chief medical officer, Marinus, said in a statement following completion of enrollment that getting “100 patients in our registrational, pivotal Phase 3 trial evaluating ganaxolone in children with CDD is a significant milestone for both Marinus and the CDD community.”

For those who were unable to participate in the phase 3 study, Marinus has begun preparations for an Expanded Access Program (EAP) to offer ganaxolone to patients with CDD if the topline data proves to be successful. The current program for RPD designation will expire after September 30, 2020 unless Congress renews the program. However, ganaxolone may still receive a voucher if the drug is submitted and approved by the September 30, 2022, deadline.

Marinus presented positive results from its phase 2 trial of ganaxolone in October 2019 at the Neurocritical Care Society’s 17^th Annual Meeting. The findings showed that no patients with status epilepticus progressed to intravenous (IV) anesthetics within 24 hours of treatment initiation.^3,4

Furthermore, results from the study showed that treatment with ganaxolone not only prevented progression to third line IV anesthetics, but also reduced median time to status cessation to 5 minutes. Status-free at 24 hours from infusion initiation was shown in 16 of the 17 patients, and 3 patients in the 500 mg group escalated to additional IV antiepileptic drugs (AEDs) or IV anesthetics due to status relapse during the follow-up period.

CDD was designated a new, unique disease code by the World Health Organization (WHO) and was added to the International Classification of Diseases (ICD) in January 2020. The latest diagnostic code was added to help facilitate clinical research and care, as well as improve billing and reimbursement related to health insurance.⁵

REFERENCES

1. Marinus Pharmaceuticals receives rare pediatric disease designation from FDA for ganaxolone for the treatment of CDKL5 Deficiency Disorder (CDD) [news release]. Radnor, PA. Marinus Pharmaceuticals. Published July 30, 2020. Accessed August 6, 2020. https://marinuspharma.com/investors/news/news-2020/408-marinus-pharmaceuticals-receives-rare-pediatric-disease-designation-from-fda-for-ganaxolone-for-the-treatment-of-cdkl5-deficiency-disorder-cdd

2. Marinus Pharmaceuticals completes targeted enrollment in pivotal phase 3 study for CDKL5 Deficiency Disorder [news release]. Radnor, PA. Marinus Pharmaceuticals. Published February 25, 2020. Accessed August 6, 2020. https://www.marinuspharma.com/investors/news/news-2020/346-Marinus_Pharmaceuticals_Completes_Targeted_Enrollment_in_Pivotal_Phase_3_Study_for_CDKL5_Deficiency_Disorder

3. Vaitkevicius H, Husain AM, Swisher CB, et al. Phase 2 open-label study of intravenous ganaxolone for the treatment of refractory status epilepticus. Presented at: Neurocritical Care Society 17^th Annual Meeting. October 15-18, 2019; Vancouver, British Columbia. Oral Abstract 4. Marinus Pharmaceuticals Announces Positive Top-Line Results With Ganaxolone in Phase 2 Refractory Status Epilepticus Trial [news release]. Radnor, PA. Marinus Pharmaceuticals. Published September 26, 2019. Accessed August 6, 2020. www.globenewswire.com/news-release/2019/09/26/1921176/0/en/Marinus-Pharmaceuticals-Announces-Positive-Top-Line-Results-With-Ganaxolone-in-Phase-2-Refractory-Status-Epilepticus-Trial.html

5. Rare disease CDKL5 deficiency disorder granted WHO disease classification [news release]. London, UK. LouLou Foundation. Published January 27, 2020. Accessed August 6, 2020. www.businesswire.com/news/home/20200127005604/en