8-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(D)

OF THE SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of earliest event reported): December 7, 2020

Marinus Pharmaceuticals, Inc.

(Exact name of registrant as specified in its charter)

Delaware	001-36576	20-0198082
(State or other jurisdiction of incorporation)	(Commission File Number)	(IRS Employer Identification No.)

5 Radnor Corporate Center, Suite 500 100 Matsonford Rd Radnor, PA	19087
(Address of principal executive offices)	(Zip Code)

Registrant’s telephone number, including area code: (484) 801-4670

__________________________________________________________________

(Former name or former address, if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

¨ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Common Stock, par value $0.001	MRNS	Nasdaq Global Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company  ¨

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ¨

Item 8.01 Other Events.

On December 7, 2020, Marinus Pharmaceuticals, Inc. (the “Company”) issued a press release announcing additional ganaxolone data to be presented during its virtual scientific exhibit at the American Epilepsy Society Annual Meeting on December 7, 2020, as well as other corporate updates. A copy of the press release is filed herewith as Exhibit 99.1 and is incorporated by reference herein.

On December 7, 2020, the Company posted an updated corporate presentation on its website at www.marinuspharma.com. A copy of the presentation is filed herewith as Exhibit 99.2 and is incorporated by reference herein.

Item 9.01. Financial Statements and Exhibits.

(d)            Exhibits

Exhibit No.	Description
99.1	Press Release, dated December 7, 2020
99.2	Corporate Presentation, dated December 7, 2020
104	The cover page from this Current Report on Form 8-K, formatted in Inline XBRL

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	MARINUS PHARMACEUTICALS, INC.
Date: December 7, 2020	/s/ Edward Smith
	Edward Smith
	Vice President, Chief Financial Officer, and Treasurer

EX-99.1

Exhibit 99.1

Marinus Pharmaceuticals Provides Additional Ganaxolone Data During Scientific Exhibit at AES2020 Virtual Annual Meeting and Provides Corporate Update

· Top-line data from the Marigold Study in CDKL5 deficiency disorder (CDD) presented as late breaking results during AES scientific sessions; An analysis of data from the Marigold Study shows a consistent efficacy signal across multiple subgroups, including a 36.7% estimated difference in major motor seizure frequency relative to placebo in U.S. patients (n=41)

· Preliminary analysis of the Marigold Study open label extension provides supportive data on the durability of ganaxolone efficacy data, including a 52.7% median major motor seizure frequency reduction in patients who have completed approximately one year of therapy

· Higher average ganaxolone plasma concentrations correlated with improved seizure frequency reductions in CDD patients. Findings support three times a day dosing as utilized in the Marigold Study and studies in other chronic epilepsy indications, as well as future oral formulation development designed to improve ganaxolone exposure levels

· Two case studies on pediatric super-refractory status epilepticus (SRSE) are the first published abstracts on the use of IV ganaxolone in treating SRSE

· Marinus also announces an expanded access program (EAP) for U.S. patients with CDD, making ganaxolone available to patients under a treatment IND

RADNOR, Pa., December 07, 2020— Marinus Pharmaceuticals, Inc. (Nasdaq: MRNS), a pharmaceutical company dedicated to the development of innovative therapeutics to treat rare seizure disorders, today announced it will host a virtual Scientific Exhibit at the American Epilepsy Society (AES) Annual Meeting (AES2020) from 8:00 AM to 11:00 AM Eastern Time today. At the Scientific Exhibit, Marinus will have 10 posters highlighting the company’s clinical development programs in treating CDKL5 deficiency disorder (CDD) and refractory status epilepticus (RSE).

“We are excited to share the important insights and data we have compiled for this year’s AES meeting, with four scientific posters, two of which were accepted as late breaking results – one in CDD and another in RSE. We will also highlight key data from the Marigold Study during our Scientific Exhibit, with analyses on patient subsets, preliminary durability of effect in the open label portion of the trial, and on the PK/PD profile of ganaxolone,” said Scott Braunstein, M.D., Chief Executive Officer of Marinus Pharmaceuticals. “We also look forward to discussing these data further at our AES Virtual Investor Event later today.”

Highlights from new analyses in the Phase 3 Marigold Study of ganaxolone in CDD presented during the Scientific Exhibit include the following:

“Effect of Ganaxolone on Seizure Frequency Across Subpopulations of Patients with CDKL5 Deficiency Disorder: Subgroup Analyses of the Marigold Study,” by E. M. Pestana-Knight, et al.

An analysis of data from the Marigold Study showed patients on ganaxolone consistently demonstrated numerical improvements in the change in major motor seizure frequency relative to placebo across the following subgroups: age, gender, baseline seizure frequency, number of concomitant antiepileptic drugs, geography and baseline allopregnanolone sulfate levels. These findings support ganaxolone’s effect across the broad CDD population studied. Data collected in patients enrolled in the United States (n=41) showed a stronger effect with a 36.7% estimated difference in major motor seizure frequency relative to placebo.

“Pharmacokinetic-Pharmacodynamic Analysis in Ganaxolone-Treated Patients with CDKL5 Deficiency Disorder: Results From the Marigold Study,” by J. Hulihan, et al.

Higher plasma ganaxolone concentrations were correlated with greater reductions in major motor seizure frequency. However, no differences in the rates of relevant adverse events were noted across ganaxolone plasma concentration groups. These findings highlight the importance of achieving adequate plasma ganaxolone concentrations and suggest that three times a day (TID) dosing has the potential to increase trough ganaxolone levels and may provide improved seizure control. In addition, this analysis supports efforts to develop new oral ganaxolone formulations that aim to improve pharmacokinetic properties to better achieve target ganaxolone exposure levels.

“Extended Duration Safety and Efficacy of Ganaxolone for the Treatment of CDKL5 Deficiency Disorder: Preliminary Open-Label Extension Analysis (Marigold Study),” by N. Specchio, et al.

Preliminary data from patients in the open-label extension phase of the Marigold Study as of September 2020 were summarized. Patients on ganaxolone in the double-blind phase continued to experience a maintained improvement in major motor seizure frequency through eight months in the open-label extension, representing approximately 12 months in total on ganaxolone. This group of patients treated with ganaxolone for 12 months (n=17) experienced a median 52.7% reduction in major motor seizure frequency relative to baseline.

Patients on placebo in the double-blind phase showed improvements in major motor seizure frequency when transitioning to open label ganaxolone. These preliminary findings suggest that ganaxolone has the potential to provide clinically meaningful, durable seizure improvements in patients with CDD.

The following posters were presented during the AES Scientific Sessions:

· “Ganaxolone Significantly Reduces Major Motor Seizures Associated with CDKL5 Deficiency Disorder: A Randomized, Double-blind, Placebo-Controlled Phase 3 Study (Marigold Study)”; E. M. Pestana-Knight, et al.

· “IV Ganaxolone in Pediatric Super-Refractory Status Epilepticus: A Single Patient Case Study”; R. Singh, et al.

· “Treatment of Super Refractory Status Epilepticus Using Intravenous Ganaxolone in a Patient with Lennox-Gastaut Syndrome and Angelman Syndrome”; M. G. Chez, J. Hulihan, and M. Gasior

· “Status Epilepticus: Inpatient Burden of Illness and Association with Disease Severity”; E. L. Guterman, et al.

For full list of posters presented, please visit the Marinus Website Poster Page

Corporate Update:

Status Epilepticus

Marinus is currently recruiting patients in RSE in its Phase 3 RAISE clinical trial. In addition, the company is planning a clinical trial of ganaxolone in Established Status Epilepticus (ESE) in patients presenting to emergency rooms, with a projected trial initiation in 2H 2021. Marinus also intends to continue making ganaxolone available to clinicians who request the drug for treatment of super refractory status epilepticus on a case-by-case basis under emergency IND treatment.

Expanded access program (EAP) in CDD makes ganaxolone broadly available to patients

During AES2020, Marinus announced the launch of an expanded access program (EAP) that will allow the company to offer ganaxolone to U.S. patients with CDD, including children at least two years of age, who were unable to participate in the company’s Phase 3 Marigold Study. This will provide patients with CDD access to ganaxolone under a treatment IND.

CDD Regulatory Plans

Marinus is preparing to meet with the FDA in Q1 2021 in connection with its planned mid-2021 NDA submission for CDD, with a 1H 2021 pre-marketing authorization application (MAA) meeting with the European Medicines Agency (EMA).

Investor Meeting Today

Marinus to Host Virtual Investor Event at AES today from 12:00 PM – 2:00 PM Eastern Time.

To register in advance and listen to the live webinar please click on http://wsw.com/webcast/cc/mrns.

About Ganaxolone

Ganaxolone, a positive allosteric modulator of GABA_A receptors, is being developed in intravenous and oral formulations intended to maximize therapeutic reach to adult and pediatric patient populations in both acute and chronic care settings. Unlike benzodiazepines, ganaxolone exhibits antiseizure, antidepressant and anti-anxiety activity via its effects on synaptic and extrasynaptic GABA_A receptors. More than 1,600 study participants, both adults and children, have received ganaxolone at therapeutically relevant dose levels and treatment regimens for up to four years.

About Marinus Pharmaceuticals

Marinus Pharmaceuticals, Inc. is a pharmaceutical company dedicated to the development of innovative therapeutics to treat rare seizure disorders. Ganaxolone is a positive allosteric modulator of GABA_A receptors that acts on a well-characterized target in the brain known to have anti-seizure, anti-depressant and anti-anxiety effects. Ganaxolone is being developed in IV and oral dose formulations intended to maximize therapeutic reach to adult and pediatric patient populations in both acute and chronic care settings. Marinus recently completed the first ever Phase 3 pivotal trial in children with CDKL5 deficiency disorder and is conducting a Phase 2 trial in tuberous sclerosis complex, as well as a Phase 2 biomarker-driven proof-of-concept trial in PCDH19-related epilepsy. The company is initiating a Phase 3 trial in status epilepticus. For more information visit www.marinuspharma.com.

Forward-Looking Statements

To the extent that statements contained in this press release are not descriptions of historical facts regarding Marinus, they are forward-looking statements reflecting the current beliefs and expectations of management made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Words such as “may”, “will”, “expect”, “anticipate”, “estimate”, “intend”, “believe”, and similar expressions (as well as other words or expressions referencing future events, conditions or circumstances) are intended to identify forward-looking statements. Examples of forward-looking statements contained in this press release include, among others, statements regarding: our plans to initiate a clinical trial of ganaxolone in ESE in the second half of 2021; our expectations to meet with the FDA regarding our NDA for ganaxolone for the treatment of CDD in the first quarter of 2021; our expectation to submit an NDA for ganaxolone for the treatment of CDD in mid-2021; our expectation to have a pre-MAA meeting with the EMA in the first half of 2021; our clinical development plans for ganaxolone; and for the safety and efficacy of ganaxolone. Forward-looking statements in this release involve substantial risks and uncertainties that could cause our clinical development programs, future results, performance or achievements to differ significantly from those expressed or implied by the forward-looking statements. Such risks and uncertainties include, among others, uncertainties and delays relating to the design, enrollment, completion, and results of clinical trials; unanticipated costs and expenses; clinical trial results may not support further development in a specified indication or at all; actions or advice of the U.S. Food and Drug Administration may affect the design, initiation, timing, continuation and/or progress of clinical trials or result in the need for additional clinical trials; our ability to obtain and maintain regulatory approval for our product candidate; delays, interruptions or failures in the manufacture and supply of our product candidate; our ability to raise additional capital; the effect of the COVID-19 pandemic on our business, the medical community and the global economy; and the availability or potential availability of alternative products or treatments for conditions targeted by us that could affect the availability or commercial potential of our product candidate. Marinus undertakes no obligation to update or revise any forward-looking statements. For a further description of the risks and uncertainties that could cause actual results to differ from those expressed in these forward-looking statements, as well as risks relating to the business of the Company in general, see filings Marinus has made with the Securities and Exchange Commission.

CONTACT:

Sasha Damouni Ellis
Vice President, Investor Relations & Corporate Communications
Marinus Pharmaceuticals, Inc.
484-253-6792
sdamouni@marinuspharma.com

EX-99.2

Exhibit 99.2

 NASDAQ: MRNS@MarinusPharma Corporate Overview 2020

Safe Harbor Statement To the extent that statements contained in this presentation are not descriptions of historical facts regarding Marinus, they are forward-looking statements reflecting the current beliefs and expectations of management made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Words such as “may”, “will”, “expect”, “anticipate”, “estimate”, “intend”, “believe”, and similar expressions (as well as other words or expressions referencing future events, conditions or circumstances) are intended to identify forward-looking statements. Examples of forward-looking statements contained in this presentation include, among others, statements regarding our clinical development plans for ganaxolone; expected dosing in our clinical trials; the clinical development schedule and milestones; our expected timing to begin and complete enrollment in our clinical trials; the expected trial design, target patient population and endpoints for our clinical trials; interpretation of scientific basis for ganaxolone use; timing for availability and release of data, including the expected release of topline data from our Phase 3 trial in status epilepticus (SE) in 1H 2022; from our proof of concept study in PCDH19 in the first half of 2021, and from our Phase 2 tuberous sclerosis complex (TSC) trial in mid 2021; the potential safety and efficacy and therapeutical potential of ganaxolone; timing and expectation regarding submissions of regulatory applications, including our expectation to submit an NDA for ganaxolone in CDD in mid-2021 and an MAA by the end of Q3 2021; expectations regarding commercial launch of ganaxolone in CDD in 1H 2022; expectations regarding our agreement with BARDA; expectations regarding the potential market opportunities for our product candidates, including oral ganaxolone; potential commercial alliances; and our expectations regarding the effect of the COVID-19 pandemic on our business and clinical development plans. Forward-looking statements in this presentation involve substantial risks and uncertainties that could cause our clinical development programs, future results, performance or achievements to differ significantly from those expressed or implied by the forward-looking statements. Such risks and uncertainties include, among others, uncertainties and delays relating to the design, enrollment, completion, and results of clinical trials; interpretation of results of clinical trials; unanticipated costs and expenses; early clinical trials may not be indicative of the results in later clinical trials; clinical trial results may not support regulatory approval or further development in a specified indication or at all; actions or advice of the FDA or other regulatory agencies may affect the design, initiation, timing, continuation and/or progress of clinical trials or result in the need for additional clinical trials; our ability to obtain and maintain regulatory approval for our product candidate; our ability to obtain and maintain patent protection for our product candidates; delays, interruptions or failures in the manufacture and supply of our product candidate; our ability to raise additional capital; the effect of the COVID-19 pandemic on our business, the medical community and the global economy; and the availability or potential availability of alternative products or treatments for conditions targeted by us that could affect the availability or commercial potential of our product candidate. Marinus undertakes no obligation to update or revise any forward-looking statements. For a further description of the risks and uncertainties that could cause actual results to differ from those expressed in these forward-looking statements, as well as risks relating to the business of the Company in general, see filings Marinus has made with the Securities and Exchange Commission. You may access these documents for free by visiting EDGAR on the SEC web site at www.sec.gov.

Ganaxolone (GNX) Targets Synaptic & Extrasynaptic GABAA Receptors Ganaxolone a positive allosteric GABAA receptor modulator with a well-defined MOA designed to treat patients suffering from epilepsy and neuropsychiatric disorders. GNX is designed to modulate both synaptic and extrasynaptic GABAA receptors to calm over-excited neurons GNX is a synthetic analog of allopregnanolone Clinical development focused on status epilepticus and rare genetic epilepsies that have few or no treatment options Multiple dose formulations IV and oral – to meet the needs of adult and pediatric patients in acute and chronic care settings Extensive safety record in more than 1,600 patients both pediatric and adult, at therapeutically relevant dose levels for up to two years

Corporate Strategy Evaluation of IV and Oral Opportunities Building Upon Status Epilepticus (SE) Maximizing Value for Orphan Epilepsies Leveraging GNX Molecule Expand clinical opportunities from refractory status epilepticus (RSE) to broader SE market Initiate commercial plan Create a global development strategy Develop pharmacoeconomic value proposition Complete BARDA activities Continue CDKL5 deficiency disorder (CDD) and tuberous sclerosis complex (TSC) clinical development Consider expansion opportunities based on scientific rationale Further develop commercial roadmap, including scientific and clinical differentiation Explore opportunities to improve bioavailability and PK Prioritize clinical trials based on unmet need, improved product profile New therapeutic indications driven by scientific rationale

Ganaxolone Development Pipeline

 Status Epilepticus Indication

Status Epilepticus (SE): Definition and Epidemiology Background Continuous seizures lasting >5 min SE is the second most common neurologic emergency in the U.S. 1 Heterogenous patient population with various etiologies, including glioblastoma, vascular disease, encephalitis, drug or alcohol withdrawal or overdose Pre-existing epilepsy in less than half of SE cases Prolonged seizure activity can result in permanent neuronal damage and contribute to high morbidity and mortality SE becomes more treatment refractory as it progresses 1. Anaethesia and Intensive Care Medicine, February 02, 2018 , Update on the management of status epilepticus ©2020 Marinus Pharmaceuticals. All Rights ReservedI7

Goals of a New Therapy for the Treatment of SE Established Status Epilepticus (ESE) Refractory Status Epilepticus (RSE) Medically induced Coma Super Refractory Status Epilepticus (SRSE) 1st line2nd line 3rd line Benzodiazepine Administered IV AED’s (antiepileptic drugs) IV GNX IV Anesthetics ©2020 Marinus Pharmaceuticals. All Rights ReservedI8

Pharmacokinetics/Pharmacodynamics Well Suited for Acute SE Treatment Experimental PK – plasma and brain1 Human PD – EEG changes2 Ganaxolone targets the extrasynaptic receptor, is associated with high brain concentrations, and delivers a rapid onset of action Brain and plasma concentration after ganaxolone 3 mg/kg IM in mice Human PK2 Following 20 mg ganaxolone bolus (over 2 minutes): Cmax 1,240 ng/mL Tmax 0.08 hrs EEG bispectral index in healthy volunteers following IV ganaxolone Zolkowska D, Wu CY, Rogawski MA. Intramuscular allopregnanolone and ganaxolone in a mouse model of treatment-resistant status epilepticus. Epilepsia. 2018 Oct;59:220-7. Data on file, Marinus Pharmaceuticals, inc. ©2020 Marinus Pharmaceuticals. All Rights ReservedI9

Phase 2 SE Trial Design Evaluate IV ganaxolone in refractory SE patients SE Patients Diagnosis of convulsive or non-convulsive SE Failed at least one 2nd line IV AED but had not progressed to 3rd line IV anesthetics Screening Treatment Period Loading DoseMaintenanceTaper Post-treatment Follow-up 24 hourWeeks 2, 3, 4 Bolus plus continuous infusion 2-4 day infusion18-hour taper CohortDose of GNX/dayN Low500mg/day5 Medium650mg/day4 High713mg/day8 Goals of a new treatment Rapid cessation Maintenance of seizure control Prevent progression to IV anesthetics Limitations of current treatments 1st line Benzodiazepines ineffective in 45%-50%; limited by cardiovascular and respiratory side effects 2nd line Ineffective in over 50% of established SE; further decreased response in refractory SE 3rd line IV Anesthetics: high morbidity, mortality ~35%; increased duration of hospitalization and costs of care Endpoints Primary: Percent of patients who did not require escalation of treatment with IV anesthetic within the first 24 hours after ganaxolone initiation Secondary: Additional efficacy, safety and tolerability

Patient Demographics of Phase 2 Trial 17 patients enrolled 8 males, 9 females Mean age: 57 years old (range: 23-88) History of Epilepsy 7 (41%) yes, 10 (59%) no Types of SE 5 (29%) CSE, 11 (65%) NCSE, 1 (6%) CSE→NCSE Mean # of failed first-and-second line IV AEDs (including benzodiazepines) Mean # of failed 2nd-line IV AEDs 2.1 (range: 1-4), all failed LEV or LAC 14/17 patients failed two or more 2nd-line 7 vascular 4 tumor Etiologies 2.9 (range: 2-5) AEDs All prior AEDs were administered within recommended dosing guidelines 2 autoimmune 2 drug overdose 2 unknown

Phase 2 Trial Results Demonstrated Rapid Onset And Durability of Effect Cohort No escalation to IV anesthetics within 24 hours from infusion initiation (Primary Endpoint) Status-free through 24 hours from infusion initiation (investigator determination) No escalation to additional IV AEDs or IV anesthetics for status relapse at any time through 24 hours after ganaxolone discontinuation No SE Relapse at anytime during the wk follow up period High (713 mg/day) (n=8) 100% (8 of 8) 88% (7 of 8) 100% (8 of 8) 100% (6 of 6) (1ET, 1 died) Medium (650 mg/day) (n=4) 100% (4 of 4) 100% (4 of 4) 75% (3 of 4) 67% (2 of 3) (1 ET) Low (500 mg/day) (n=5) 100% (5 of 5) 100% (5 of 5) 60% (3 of 5) 50% (1 of 2) (1 died) SE Cessation Occurred Rapidly in All Dose Groups (median = 5 minutes) Data presented at AES 2019 AEDs – antiepileptic drugs ©2020 Marinus Pharmaceuticals. All Rights ReservedI12

PK/PD Relationship and Rationale for Target Dose Modeled PK Curves for All Dose Groups Seizure Burden Reduction Occurred Rapidly in All Dose Groups High Dose Achieves Target Range ≥ 500 ng/mL for ~8 hoursOnly High Dose Provided Sustained Reduction (>80%) Throughout Entire Analysis Window Data presented at AES 2019 PK: Pharmacokinetics / PD: Pharmadynamic ©2020 Marinus Pharmaceuticals. All Rights ReservedI13

IV Ganaxolone Safety Summary 10 SAEs in 6 patients (also included in AEs) 50 AEs in 16 patients 2 related in 2 patients 2 severe sedation 8 non-related in 4 patients 1 Death due to withdrawal of life support 1 Respiratory depression 1 Bowel perforation (fatal) 1 Sepsis (fatal) 1 Fall 1 Loss of consciousness 1 Pneumothorax 1 Multiple fracture Intubation: 13 related in 7 patients 6 mild (2 hypotension, 2 somnolence, 1 urinary retention, 1 hypercarbia) 5 moderate (4 somnolence; 1 hypercarbia) 2 severe (2 sedation) 37 not-related in 12 patients 20 mild 8 moderate (2 pain; 2 pneumonia, 2 dysphagia, 1 delirium, 1 hypertension) 9 severe (respiratory depression, death due to withdrawal of support, sepsis, embolic stroke, perforated bowel, fall, loss of consciousness, multiple fractures, pneumothorax) 9 patients were not intubated upon enrollment. Of these, 6 remained intubation-free during the entire ganaxolone treatment period Data presented at AES 2019 AE: adverse event / SAE: serious adverse event ©2020 Marinus Pharmaceuticals. All Rights ReservedI14

Overview of U.S. Phase 3 RSE RAISE Trial Design Trial design•Randomized, placebo-controlled (adjunctive to standard-of-care) clinical trial Target patient population•Status epilepticus patients (n=124) who have failed benzodiazepines and ≥ 2 IV AEDs Dosing 36-hour infusion followed by a 12-hour taper (48-hour treatment) Phase 2 dose paradigm and extends ganaxolone plasma exposure ≥ 500 ng/mL for 12 hours Co-primary endpoints Proportion of participants with SE cessation within 30 minutes of study drug initiation without medications for the acute treatment of SE Proportion of participants with no progression to IV anesthesia for 36 hours following study drug initiation Secondary endpoints No progression to IV anesthesia for 24 hours off study drug (i.e., 72 hours) Time to SE cessation Healthcare utilization metrics (eg, length of stay, # of days in the ICU) Functional outcomes Safety measures ©2020 Marinus Pharmaceuticals. All Rights ReservedI15

RSE Phase 3 RAISE Clinical Planning Treatment PeriodFollow-up Period Initiation Status Site identification through initiation underway Drug and placebo supply ready for shipment to sites Daily S CHours 0 -24 Day 2 Hours 24-36 Hours 36-48 Daily hours Weeks 1,2,3 & 4 Currently recruiting patients R EBolus Edose N Continuous Infusion Infusion Taper Phase 3 Target Plasma Concentration IContinuous Infusion N G Taper Treatment is planned to be 2 days (including a 12-hour taper). Dose Initiation (Time 0) Trial Overview 1:1 randomized, double-blind, placebo-controlled trial Failure of a benzodiazepine and 2 second-line IV AEDs 3-minute bolus, 36-hour infusion, 12-hour taper Approx. 125 randomized patients 80-100 sites ©2020 Marinus Pharmaceuticals. All Rights ReservedI16

RAISE Trial Sites Standard of Care Progression to IV Anesthesia Surveyed PI’s at selected RAISE Trial sites to learn more about their standard of care natural history progression to IV anesthesia following the failure of one versus more than one 2nd-line IV AEDs 100 %of Patients Progressing to 3rd-line IV anesthetics 60 40 20 Patients with non-convulsive status epilepticus (NCSE) 0 1 2 nd median + 95% CI Of those that escalate to 3rd-line IV anesthesia, they do so in ~2.5 hours median following failure of the second 2nd-line IV AED Clear unmet medical need in patients that fail two or more 2nd line IV AEDs Guides site selection and approximates placebo response for escalation to IV anesthesia co-primary # of failed 2 -line IV AEDs ©2020 Marinus Pharmaceuticals. All Rights ReservedI17

BARDA Contract – Refractory Status Epilepticus Key Contract Parameters BARDA to contribute $21 million in base contract to support the Phase 3 RAISE clinical trial in RSE and preclinical studies of ganaxolone in nerve agent exposure animal models. BARDA may contribute up to an additional $30 million in support of manufacturing, supply chain, clinical, regulatory and toxicology activities based on favorable clinical and pre-clinical outcomes. Total contract value = $84 million; $51 million BARDA / $33 million Marinus - if all options are undertaken. On successful development, BARDA and Marinus may negotiate for a supply of ganaxolone for a potential response to nerve gas exposure threats. ©2020 Marinus Pharmaceuticals. All Rights ReservedI18

 Commercial Opportunity

Quantifying the Significant Clinical and Economic Burden of RSE The Phase 3 trial of ganaxolone in refractory SE aims to demonstrate rapid onset of action capable of preventing escalation to IV anesthetics. Treatment with IV anesthetics has been reported to lead to increased length of hospital admission and risk of infections, new disability, and death.1-3 $$There’s a potential pharmacoeconomic opportunity to quantify cost of care and characterize clinical outcomes based on treatment progression to IV anesthetics. Understanding the spectrum of clinical and economic burden based on disease severity will help support treatment value Sutter R et al. 2014 Neurology Hawkes MA et al. 2019 Crit. Care Med. 3Marchi NA et al. 2015 Crit. Care Med. ©2020 Marinus Pharmaceuticals. All Rights ReservedI20

RSE is a Neurological Emergency With Significant Unmet Need in a Severely Impaired and Costly Patient Population Utilization and Cost Outcomes Metric Cohort 1 (≤ 1 IV AED) Cohort 2 (> 1 IV AED) Cohort 3 (≥ 1 IV anesthetic) All Unique RSE patient encounter, N (%) 14,694 (33.4) 10,140 (23.1) 19,154 (43.5) 43,988 (100) Hospital length of stay (LOS) (days) Mean* 4.7 7.2 12.0 8.4 Median* 3 4 8 5 ICU LOS (for ICU patients only) Mean* 2.7 3.1 6.6 5.4 Median* 2 2 4 3 Total hospital cost* ($USD) Mean* $11,532 $18,328 $41,858 $26,304 Median* $6,812 $10,592 $24,105 $13,201 Marinus estimates that effective therapeutics that prevent progression to SRSE (i.e., treatment with IV anesthetics) may reduce mortality rates by ~70% and $30,000 in hospital cost *Indicates p<0.05 across all pairwise comparisons Ŧindicates p<0.05 C1 or C2 vs. C3 Manuscript in preparation ©2020 Marinus Pharmaceuticals. All Rights ReservedI21

Potential Launch Into the Hospital Setting Designed to be Driven by Data, Customer Collaboration & Protocolization of Ganaxolone in RSE Critical Success Factors for RSE Launch Clinical and Economic Evidence Society Guideline & Account Access Experienced Hospital Sales • Ph3 data to support clinical adoption and Protocol Inclusion• Early engagement with Pharmacy to best frame Force budget model • Clear clinical benefit eg, SE cessation, IV escalation • Economic advantage – LOS, ICU duration Compelling Clinical and HEOR Data • Partner with KOLs and societies to update RSE treatment guidelines • Collaborative approach to protocol augmentation with health systems and local hospitals Clinical Adoption value proposition • Determine formulary process and requirements • Reimbursement, logistics and operational processes ite, Pharmacy, & Admin Engagement • Navigate and influence hospital decision makers • Educate and generate customer usage data • Collaborate with physicians to protocolize usage Pull-Through LOS – Longer length of stay HEOR – Health economics and outcomes research ©2020 Marinus Pharmaceuticals. All Rights ReservedI22

Additional Commercial Opportunities Along SE Continuum Potential to leverage existing hospital sales force to address > 3x patient population in ESE & SRSE ESETT DeLorenzo RJ Pellock JM Towne AR Boggs JG. Epidemiology of status epilepticus. J Clin Neurophysiol. 1995; 12: 316-325 ©2020 Marinus Pharmaceuticals. All Rights ReservedI23 Rossetti and Lowenstein. Management of refractory status epilepticus in adults Lancet Neurol. 2011 Oct; 10(10): 922–930

Potential Expansion of Ganaxolone into Established Status Epilepticus (ESE) Emergency RoomICU Tertiary Center ICU Unique Environment: -No EEG -Risk of rapid escalation of care -Convulsive patients: new dosing paradigm – bolus and short infusion time (2-24 hours)

 Established Status Epilepticus – Use of Ganaxolone in Emergency Room Pilot: N = 4-5 per cohort Failed benzodiazepine Open bolusIV ganaxolone infusion Standard of care IV AED Blinded: N = 40 per arm Failed benzodiazepine 1:1 bolus Placebo bolus IV ganaxolone: Placebo Standard of care IV AED Screening Randomization Double-blind treatment (2-24h) <30 min 2-24h • Not enough time for consent -Exception from Informed Consent (EFIC) -Community consent activities • First patient expected to be enrolled in 1H of 2022 ©2020 Marinus Pharmaceuticals. All Rights Reserved I25

 Genetic Epilepsy Franchise

 CDKL5 Deficiency Disorder

CDKL5 Deficiency Disorder (CDD) Cause Mutation of the cyclin-dependent kinase-like 5 (CDKL5) gene, located on the X chromosome Symptoms Early-onset, treatment refractory seizures, & severe neuro-developmental delay Most can’t walk, talk or care for themselves Suffer from scoliosis, visual impairment, gastrointestinal difficulties & sleeping disorders Prevalence ~12,500 children US and EU5, predominantly affects females Genetic testing available Orphan Drug designation TreatmentsNo disease-specific treatments are approved Rationale Potential GABAA dysfunction, promising data in Phase 2 led to double-blind placebo-controlled trial

Global Phase 3 Pivotal Trial Design Historical Control 8 weeks Baseline 6 weeks Titration 4 weeks Maintenance 13 weeks Titration 4 weeks Open-Label Phase Double-Blind PhaseOpen-Label Phase Trial Details Evaluated the use of oral ganaxolone in children and young adults Global, double-blind, placebo-controlled, clinical trial enrolled 101 patients between the ages of 2 and 19 with a confirmed disease-related CDKL5 gene variant Ages 2-19, ≥16 major motor seizures/month; up to 4 concomitant AEDs Endpoints Primary endpoint of the trial was percent change in 28-day major motor seizure frequency * Non-seizure secondary outcome measures: Behavioral/neuropsychiatric changes correlated with domains of attention & sleep * Major motor seizures were defined as bilateral tonic, generalized tonic-clonic, atonic/drop, bilateral clonic, or focal to bilateral tonic-clonic

Subject Baseline Clinical Characteristics & Prior/Concomitant Medications Baseline seizure burden and AED history highlights unmet need

Ganaxolone Achieved Primary Efficacy Endpoint in Seizure Reduction and Secondary Endpoint in Caregiver Impression of Change Median Percent Reduction 28-day Frequency of Major Motor Seizures = 29.7%* p = 0.002** Caregiver Global Impression of Change in Seizure Intensity / Duration (CGI-CSID) 3032.2% 20 10 4.0% 0 GanaxolonePlacebo *Hodges-Lehman Estimate of Median Difference **Wilcoxon Rank-Sum Test

Marigold Cumulative Response Curve ** ** *p < 0.05 * * * * * Ganaxolone Placebo % of Patients 40 20 0 50 *Fisher's Exact Test % Reduction in Major Motor Seizure Frequency

Consistent Efficacy Signal Across the Broader CDD Population Ganaxolone demonstrated a similar efficacy signal across multiple subgroups related to baseline demographics and seizure frequency. –Supports beneficial effect in the U.S. patient population Percent Reduct ion in M edian M ajor M ot or Seizure Frequency (per 28 days) 35.9% 30 20 10 31.4 % 7.0 % Gan axolon e Placeb o 27.3% 17.5% Percent Reduct ion in M edian M ajor M ot or Seizure Frequency (per 28 days) 4 0 31.8% 30 20 10 0 10 .2% 33.3% Gan axolon e Placeb o Percent Reduct ion in M edian M ajor M ot or Seizure Frequency (per 28 days) 4 0 32.2% 30 20 .9% 20 11.1% 10 35.9% 16.5% 0 -1.4 % U.S.AU/ FR/ IL/ IT/ UKRU/ PL (n =4 1)(n =35)(n =24 ) -10 Fem aleM ale (n =79)(n =21) Gender -7.8 % 0 -10 -4 .1% <3535 - 93>93 (n =32)(n =34 )(n =34 ) Baseline M ajor M ot or Seizure Frequency (p er 28 d ays)

Phase 3 Safety Summary Treatment Emergent Adverse Events (TEAE) Serious Treatment Emergent Adverse Events Preferred Term Placebo (n=51) Ganaxolone (n=50) Any Serious TEAE, n (%) 5 (9.8) 6 (12.0) Bronchitis 0 (0.0) 1 (2.0) Rhinovirus Infection 0 (0.0) 1 (2.0) Urinary Tract Infection 0 (0.0) 1 (2.0) Pneumonia Mycoplasmal 1 (2.0) 0 (0.0) Pneumonia Viral 1 (2.0) 0 (0.0) Respiratory Syncytial Virus Bronchiolitis 1 (2.0) 0 (0.0) Oxygen Saturation Decreased 0 (0.0) 1 (2.0) Food Refusal 0 (0.0) 1 (2.0) Pneumonia Aspiration 0 (0.0) 1 (2.0) Hypoxia 1 (2.0) 0 (0.0) Faecaloma 1 (2.0) 0 (0.0) Hypotonia 1 (2.0) 0 (0.0) Seizure 1 (2.0) 0 (0.0) Unresponsive to Stimuli 1 (2.0) 0 (0.0)

Ganaxolone’s Potential to Provide Durable Seizure Improvements in the Open Label Extension Seizures associated with CDD are often refractory to treatment with existing AEDs and improvements may be short-lived (<3 months)1 Preliminary analysis* of the open-label extension (OLE) provides insights into the extended duration effects of ganaxolone (GNX) in CDD Percent Reduct ion in M edian M ajor M ot or Seizure Frequency (per 28 days) Gan axolon e 60Placeb o (D B) Gan axolon e (OLE) 52.7% n =17 Patients treated with ganaxolone for approximately 12 months experienced a 50 4 0 32.2% 30 20 10 0 Placeb o (D B) 33.3% n =39 4 .0 % 12.7% n =38 37.2% n =36 22.6% n =34 4 4 .5% n =26 35.0 % n =24 29.6% n =20 median 52.7% reduction in major motor seizure frequency Patients transitioning from placebo to ganaxolone demonstrated seizure frequency improvements No new safety findings emerged in the OLE to date Prim ary Endpoint (17 w k s) 1-23-45-67-8 O p e n -La b e l Ga n a xolon e Tim e in OLE (M ont hs) Müller A, et al. Eur. J. Paediatr. Neurol. 2016 ©2020 Marinus Pharmaceuticals. All Rights ReservedI35 *Data as of September 1, 2020

Average Ganaxolone Levels Correlate with Seizure Reduction Logarithms of plasma GNX level and percentage change in major motor seizure frequency were negatively correlated Patients in the Medium and High GNX level groups had an average GNX concentration of 120 ng/mL and a median 43% reduction in seizure frequency –Incidence of CNS-related adverse events was similar across GNX dose level groups Equivalent GNX Level (ng/ m L) Log e Percent Chang e M ajor M ot or Seizure Frequency Equivalent % Chang e in M ajor M ot or Seizure Frequency 5.5 5.0 4 .5 4 .0 3.5 3.0 2.5 * r = -0 .4 99 p = 0 .0 0 1 14 5 4 8 .4 -10 .0 -4 5.4 -66 .9 -79 .9 -8 7.8 Percent Change in M ajor M ot or Seizure Frequency 50 25 0 -25 -50 -75 -10 0 **p = 0 .0 1 3.03.54 .04 .55.05.56 .0 Log e GN X Level (ng / m L) Low (4 0 n g/ m L*) M edium (70 ng/ m L*) H igh (170 ng/ m L*) *Pearson correlat ion Loge percentage change in major motor seizure frequency was calculated as loge(percentage change + 100) n =13n =13n =12 *m ean GNX level w it h in Grou p **Kru sk al-W allis Test ©2020 Marinus Pharmaceuticals. All Rights ReservedI36

Efforts to Improve Ganaxolone Exposure in Chronic Epilepsies Dosing regimen: Marigold Study was the first Phase 3 study of ganaxolone to evaluate three times a day (TID) dosing Predicted pharmacokinetic (PK) curves for TID and two times a day (BID) dosing demonstrate increase trough GNX levels which may provide improved seizure control Dose regimen Cmax (ng/mL) AUC0-24 (ng ∙ h/mL) % time (>100 ng/mL GNX) TID 281 3763 78 BID 286 3135 53 Support the continued study of ganaxolone TID dosing in other epilepsies Formulation development: new oral ganaxolone formulations in development that aim to improve PK properties to better achieve target ganaxolone levels.

Ganaxolone Formulation Work in Progress for Second Generation Candidate Exploring opportunities to improve bioavailability and PK profile Potential expansion into new indications and into new therapeutic areas Targeting IV-to-oral step down for patients that may benefit from continued therapy IV Dosing Oral Dosing Step down IV to oral Pediatric Dosing

 Tuberous Sclerosis Complex

Allo-S as Potential Biomarker Across Various Genetic Epilepsies Scientific literature associates genetic orphan epilepsies with neurosteroid imbalances Marinus has identified abnormal neurosteroid levels in several patient subtypes These findings lead to stratification by Allo-S biomarker in clinical trials

Tuberous Sclerosis Complex CauseDefect or mutation of TSC1 and/or TSC2 genes Symptoms abnormalities Prevalence~25K-40K refractory TSC patients in the U.S.* TreatmentsLimited approved treatments Mechanistic RationalePotential neurosteroid deficiency1 1 diMichele, et al, J. Neuro Neurosurg Psychiatry, 2003 *Failure of two prior antiseizure medications with ongoing, frequent seizures. ©2020 Marinus Pharmaceuticals. All Rights ReservedI41

Unmet Need in TSC Epilepsy and Scientific Rationale for Ganaxolone Epilepsy present in ~90% of individuals affected with TSC Existing treatments fail to control seizures in ~60% of individuals with TSC-associated epilepsy Uncontrolled seizures, especially early in life, may lead to developmental delays and cognitive dysfunction Clear need to evaluate treatments with a differentiated mechanism of action Patients aged 1-14 In collaboration with the TS Alliance and utilization of their Biosample Repository “Many individuals with TSC continue to experience uncontrolled seizures despite a cocktail of multiple antiepileptic drugs. Because new options are always needed, the TSC community welcomes clinical evaluation of new epilepsy treatments” - Kari Luther Rosbeck, President & CEO of the Tuberous Sclerosis Alliance

 PART A Base (4 Weeks) GNX Titration (4 Weeks) GNX Maintenance (8 Weeks) Baseline Period PART B Open-Label Extension (OLE) (24 Weeks) * Available to patients that respond to GNX as defined per protocol OLE Period 2-week taper upon GNX discontinuation Screening Visit Baseline Treatment Visit (if not continuing to Part B) •n = 30 8 - 15 U.S. sites Electronic diaries will be used for data capture At least 8 seizures per month Primary efficacy endpoint: % change in 28-day primary seizure frequency through the end of 12-week treatment period relative to 4-week baseline period Top-line data expected mid 2021 Primary seizure types: focal motor seizures without impairment of consciousness or awareness, focal seizures with impairment of consciousness or awareness, focal seizures evolving to bilateral generalized convulsive seizures, and generalized seizures with a motor component that are countable

 PCDH19 Related Epilepsy

PCDH19-Related Epilepsy CauseInherited mutation of protocadherin 19 (PCDH19) gene. Located on X chromosome Symptoms Early-onset seizures, cognitive and sensory impairment, and psychiatric and behavioral disorders. Seizures last from days to weeks; sensitive to fever Prevalence Affects ~10K children US and EU Predominantly females Genetic testing becoming more readily available Orphan Drug designation TreatmentsNo disease-specific treatments are approved Mechanistic RationaleAssociated with low levels of allopregnanolone1 and potential GABAergic dysfunction 1Gecz, et.al, Human Molecular Genetics, 2015 ©2020 Marinus Pharmaceuticals. All Rights ReservedI45

Seizure Reduction Observed in PCDH19-RE Phase 2 Trial in Patients with Low Allo Levels 25% decrease in median seizure frequency reported in Phase 2 (n=11) Stratification of patients by baseline plasma Allo levels identifies a subpopulation with expected improved efficacy on GNX When comparing seizure frequency at 6 months to baseline: The biomarker+ group (low Allo) significantly improved The biomarker-group (high Allo) deterioration was not statistically significant Clinical data presented at AES 2018 ©2020 Marinus Pharmaceuticals. All Rights ReservedI46

Biomarker Stratified Proof of Concept (POC) Study in PCDH19 Primary efficacy analyses will be conducted using this cohort PCDH19 (all-patients) n~20-22 Low Allo-S Biomarker + High Allo-S Biomarker - R 1:1 R 1:1 Placebo Ganaxolone Up to 600 mg 3x/day Placebo Ganaxolone Up to 600 mg 3x/day Ganaxolone Up to 600 mg 3x/day Pre-baseline Screening Baseline 12 weeksTitration 4 weeks Maintenance 13 weeks Titration 4 weeks Open-Label Phase (52 weeks) * not drawn to scale Trial Details Screening Visit Ages 1-17 with 8 or more seizures in 8 weeks, failed 2 or more AEDs Expect to complete double-blind portion of the trial with ~20-22 patients Stratify patients into one of two biomarker groups based on baseline allopregnanolone sulfate levels and randomized (ganaxolone or placebo) within each stratum Data expected in 1H 2021 ©2020 Marinus Pharmaceuticals. All Rights ReservedI47

 Commercial Opportunity

Commercialization Preparedness Executing research with Payers and Physicians around TPP / Value Proposition Identifying organizational needs for field resources, systems and processes Developing plans to scale up Advocacy, Scientific Affairs and Commercial teams Readying supply chain to support packaging and scale up needs to commercialize Potential for operational leverage across indications within concentrated rare epilepsy care model TPP – Target Product Profile ©2020 Marinus Pharmaceuticals. All Rights ReservedI49

Our Oral Franchise Model is Driven by Ganaxolone Scientific Rationale and Unmet Need in Debilitating Rare Epilepsy Disorders Given CDKL5 and TSC patient seizure burden, overlap of CDKL5 and TSC prescribers, and common market dynamics, we group both indications under a franchise go to market CDKL5 Deficiency Disorder (CDD) model Tuberous Sclerosis Complex (TSC) 4-5K addressable patients in US and 50-100 newborn cases per year1 20-25K addressable US patient population2 Genetic testing in major global markets driving diagnosis rates Severe, difficult to manage patients with high medication reliance and need for more durable options No indicated treatments available or clinical trials conducted addressable patients Overlapping prescribers and similar behavior across each disease state Physicians seeking safe, effective, and durable treatment options Large refractory population despite available treatment options Severe patients still in need of more efficacious medications Given refractory population, opportunity exists for later stage treatments (eg, 3rd line) Jakimeic et. al 2020 NORD (https://rarediseases.org/rare-diseases/tuberous-sclerosis) ©2020 Marinus Pharmaceuticals. All Rights ReservedI50

Our Goal: Build a Sustainable Franchise in Rare Epilepsy Opportunity to expand treated population through future clinical development Phase 2 (TSC) 40,000 patients2 Rare Epilepsy ~163,0005 Phase 3 (CDKL 5) ~5,500 patients1 80-90% refractory3 50-60% refractory3 20-40% refractory4 ~ 4,400 CDKL 5 Patients Addressable Patient Population ~ 20,000 TSC patients ~48,900 Rare Epilepsy Identification of Biomarker Sensitive Population (including PCDH19) Jakimeic et. al 2020 NORD (https://rarediseases.org/rare-diseases/tuberous-sclerosis) Marinus market research Ryan et. al 2015 (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4540245/) Quintana market research

Key Findings from Recently Conducted Market Research Show that Ganaxolone is Well Suited for Broad Clinical Adoption Across Indications Mechanism of Action Ganaxolone’s extrasynaptic mechanism of action well understood and viewed as differentiable TPP Reactions Many HCPs are excited about the opportunity to use ganaxolone, especially for CDD, given favorable reactions to its efficacy and durability data, and safety profile Primary Usage Drivers Disease-specific indication, response rate, and durability of response Ability to be used with antiseizure medications across mechanisms (i.e., sodium channel blockers, GABA transmission inhibitors, cannabidiol) in refractory patients Awareness More Neuros were aware of ganaxolone than any drug in development for CDD or TSC Source: ZS Associates Primary Research and Analysis (N=35 HCP Interviews)

 Intellectual Property

Multiple Layers Of Potential Protection Orphan drug designations for CDD and PCDH19 provide 7 and 10 years regulatory exclusivity in US and EU, respectively. Orphan drug designation for SE provides 7 years regulatory exclusivity in US.

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 Appendix

Details on Baseline Patient Characteristics for Phase 2 SE Trial 1 Low Vascular No NCSE LAC, LEV 200mg (200-600mg) 2 Low Unknown Yes NCSE fPHT, LEV 1,000mg (1000-3000mg) 3 Low Vascular No NCSE LOR, LAC, LEV 600mg (200-600mg) 4 Low Vascular No NCSE LOR, LAC, LEV 600mg (200-600mg) 5 Low Tumor No CSE LOR, LAC, LEV 2,000mg (1000-3000mg) 6 Medium Vascular No NCSE LOR, LAC, LEV 600mg (200-600mg) Drug Overdose / 7MediumYesCSELOR, LEV1,000mg (1000-3000mg) Withdrawal 8 Medium Unknown Yes CSE → NCSE LOR, LAC, LEV 1,000mg (1000-3000mg) 9 Medium Tumor Yes NCSE LAC, LEV, PHT 200mg (100mg) 10 Target Vascular Yes CSE LOR, LAC, VPA 400mg (200-600mg) 11 Target Drug Overdose / Withdrawl No CSE LOR, LAC, LEV 400mg (200-600mg) 12 Target TumorYesNCSELOR, LEV, VPA700mg (1000-3000mg) AutoimmuneNoNCSELOR, LEV1,000mg (1000-3000mg) VascularNoNCSELOR, LAC, LEV, PHT200mg (200-600mg) VascularYesCSELOR, LEV1,000mg (1000-3000mg) TumorNoNCSELOR, LAC, LEV400mg (200-600mg) AutoimmuneNoNCSELOR, fPHT, LAC, LEV, VPA200mg (200-600mg) 13 Target 14 Target 15 Target 16 Target 17 Target *Bolded, underlined IV AED’s were the last ones administered prior to GNX ©2020 Marinus Pharmaceuticals. All Rights ReservedI57

Subject Baseline Demographics & Country Enrollment in Marigold Study (CDD) Demographic Placebo (n=51) Ganaxolone (n=50) Total (n=101) Age, median 7.0 5.0 6.0 Gender, n (%) Male 10 (19.6) 11 (22.0) 21 (20.8) Female 41 (80.4) 39 (78.0) 80 (79.2) Ethnicity, n (%) Hispanic or Latino 6 (11.8) 4 (8.0) 10 (9.9) Not-Hispanic or Latino 43 (84.3) 44 (88.0) 87 (86.1) Unknown 1 (2.0) 1 (2.0) 2 (2.0) Not reported 1 (2.0) 1 (2.0) 2 (2.0) Race, n (%) White 47 (92.2) 46 (92.0) 93 (92.1) Asian 3 (5.9) 2 (4.0) 5 (5.0) Other 1 (2.0) 2 (4.0) 3 (3.0) US IT15 RU14 PL10 UK7 FR 6 AU 6 IL1

Responder Analysis – Marigold Study 100 % of Patients p=0.001* 6057.1% Ganaxolone Placebo Percent Reductions in Major Motor Seizure Frequency 40p=0.064* 23.5%24.5% 20 9.8%10.2% 0 3.9% 75% *Fisher's Exact Test Reduction in Major Motor Seizure Frequency