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): November 12, 2024

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.)

, Radnor, PA
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 2.02. Results of Operations and Financial Condition.

On November 12, 2024, Marinus Pharmaceuticals, Inc. (the “Company”) issued a press release announcing its financial results for the quarter ended September 30, 2024 and certain other information. A copy of the press release is being furnished as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated by reference to this Item 2.02.

The information furnished pursuant to this Item 2.02 shall not be deemed to be “filed” for purposes of Section 18 of the Securities Exchange Act of 1934 (the “Exchange Act”) or otherwise subject to the liabilities of that section, nor shall it be deemed to be incorporated by reference into any of the Company’s filings with the Securities and Exchange Commission under the Exchange Act or the Securities Act of 1933, whether made before or after the date hereof, regardless of any general incorporation language in such a filing, except as expressly set forth by specific reference in such a filing. Except as required by law, the Company undertakes no duty or obligation to publicly update or revise the information so furnished.

Item 9.01. Financial Statements and Exhibits.

(d)Exhibits

Exhibit No.	Description
99.1	Press Release, dated November 12, 2024, of Marinus Pharmaceuticals, Inc.
99.2	Corporate Presentation, dated November 12, 2024.
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: November 12, 2024	/s/ Steven Pfanstiel
	Steven Pfanstiel
	Chief Operating Officer, Chief Financial Officer and Treasurer

EX-99.1

Exhibit 99.1

Marinus Pharmaceuticals Provides Business Update and Reports Third Quarter 2024 Financial Results

● ZTALMY^® (ganaxolone) Q3 2024 net product revenue of $8.5 million representing growth of 56% versus Q3 2023

● Narrowing full year 2024 ZTALMY net product revenue guidance to $33 to $34 million

● Reported results from Phase 3 TrustTSC trial and commenced process to explore strategic alternatives

● Marinus continues to support the commercial growth of ZTALMY; further ganaxolone clinical development has been suspended

● Scheduled to meet with FDA Q4 2024 to discuss a potential path forward for IV ganaxolone in refractory status epilepticus  

● Cost reduction plans implemented with cash runway expected into Q2 2025; cash and cash equivalents of $42.2 million as of September 30, 2024

RADNOR, Pa. – November 12, 2024 –Marinus Pharmaceuticals, Inc. (Nasdaq: MRNS), a pharmaceutical company dedicated to the development of innovative therapeutics to treat seizure disorders, today reported business highlights and financial results for the third quarter ended September 30, 2024.

“We are pleased to see continued commercial growth of ZTALMY with more than 200 patients active on therapy and a steady increase in demand,” said Scott Braunstein, M.D., Chairman and Chief Executive Officer of Marinus. “In 2024, our Phase 3 data in status epilepticus and tuberous sclerosis complex showed meaningful clinical activity in certain refractory patients, however, the trials did not meet the thresholds for statistical significance. Given this outcome, we have made the difficult decision to explore strategic alternatives with the goal of maximizing stockholder value while supporting the growth of ZTALMY for patients with CDKL5 deficiency disorder (CDD).”

Dr. Braunstein continued, “I extend my deepest gratitude to our dedicated employees for their significant contributions to our work, and to the patients and clinicians who participated in our trials. We are proud to have delivered the first-and-only FDA-approved treatment for patients with seizures associated with CDD and hope that our research will serve as a foundation for future innovations in areas of high unmet need.”

ZTALMY^® (ganaxolone) Oral Suspension CV

● Generated net product revenue of $8.5 million for the third quarter of 2024representing 56% growth versus the third quarter of 2023.

● Narrowing full year 2024 net product revenue guidance to $33 to $34 million from a range of $33 to $35 million.

● Announced issuance of new U.S. patent for ZTALMY oral titration regimens covering the treatment of a range of epilepsies, expiring September 2042.

Clinical Updates

● The U.S. Food and Drug Administration (FDA) granted Marinus a Type C meeting, scheduled for the fourth quarter of 2024, to discuss a potential path forward for intravenous (IV) ganaxolone in refractory status epilepticus (RSE).

● Presented data from the Phase 3 RAISE trial evaluating IV ganaxolone for the treatment of RSE at the Neurocritical Care Society Annual Meeting in October 2024.

● Announced topline results from the Phase 3 TrustTSC trial of oral ganaxolone in tuberous sclerosis complex (TSC) whereby the trial did not achieve statistical significance in the primary endpoint.

● Marinus will continue to support the commercial growth of ZTALMY and activities required by the FDA and European Medicines Agency specific to post-approval commitments related to the CDD indication.

Ganaxolone development in the RAISE trial has been supported in part by the Department of Health and Human Services; Administration for Strategic Preparedness and Response; Biomedical Advanced Research and Development Authority (BARDA) under contract number 75A50120C00159.

General Business and Financial Update

● Marinus has commenced a process to explore strategic alternatives with the goal of maximizing value for its stockholders and has engaged Barclays as an advisor to assist in reviewing its strategic alternatives.

● Full year 2024 guidance has been narrowed with projected ZTALMY net product revenue between $33 and $34 million and combined selling, general and administrative (SG&A) and research and development (R&D) expenses in the range of approximately $135 to $138 million, including stock-based compensation expense of approximately $20 million.

● Cost reduction activities were initiated in the fourth quarter of 2024, including suspending further ganaxolone clinical development and a workforce reduction of approximately 45%.

● Through the execution of the cost reduction plans, the Company had cash and cash equivalents of $42.2 million as of September 30, 2024, to fund the Company’s operating expenses and capital expenditure requirements into the second quarter of 2025.

Financial Results

● Recognized $8.5 million and $23.9 million in net product revenue for the three and nine months ended September 30, 2024, respectively, as compared to $5.4 million and $13.0 million for the same periods in the prior year, respectively.

● Recognized $0.1 million and $0.3 million in Biomedical Advanced Research and Development Authority (BARDA) federal contract revenue for the three and nine months ended September 30, 2024, respectively, as compared to $1.9 million and $10.8 million for the same periods in the prior year, respectively. The decrease was primarily driven by activity associated with the start-up of the API onshoring initiative in the first quarter of 2023 and completion of the BARDA base period funding in the fourth quarter of 2023.

● R&D expenses were $16.3 million and $61.3 million for the three and nine months ended September 30, 2024, respectively, as compared to $23.7 million and $73.0 million for the same periods in the prior year, respectively. The reduction was due primarily to reduced costs in 2024 associated with the RAISE trial completion and costs associated with start-up of the API onshoring effort in the first quarter of 2023.

● SG&A expenses were $12.6 million and $47.9 million for the three and nine months ended September 30, 2024, respectively, as compared to $14.9 million and $45.8 million for the same periods in the prior year, respectively. The primary drivers of the decrease for the three month period were decreased personnel and consulting expenses, while the drivers of the increase for the nine month period were increased stock-based compensation expense and commercial expense.

● The Company had net losses of $24.2 million and $98.7 million for the three and nine months ended September 30, 2024, respectively; cash used in operating activities decreased to $87.8 million for the nine months ended September 30, 2024, compared to $91.0 million for the same period a year ago.

● At September 30, 2024, the Company had cash and cash equivalents of $42.2 million, compared to cash, cash equivalents and short-term investments of $150.3 million at December 31, 2023.

Readers are referred to, and encouraged to read in its entirety, the Company’s Quarterly Report on Form 10-Q for the quarterly period ended September 30, 2024, to be filed with the Securities and Exchange Commission, which includes further detail on the Company’s business plans, operations, financial condition, and results of operations.

Selected Financial Data (in thousands, except share and per share amounts)

	September 30, 2024 (unaudited)		December 31, 2023
ASSETS
Cash and cash equivalents	$	42,184	$	120,572
Short-term investments		-		29,716
Other assets		21,440		20,620
Total assets	$	63,624	$	170,908
LIABILITIES AND STOCKHOLDERS’ (DEFICIT) EQUITY
Current liabilities	$	34,504	$	40,624
Long term debt, net		41,713		61,423
Revenue interest financing payable, net		36,039		33,766
Other long-term liabilities		18,108		18,330
Total liabilities		130,364		154,143
Total stockholders’ (deficit) equity		(66,740)		16,765
Total liabilities and stockholders’ (deficit) equity	$	63,624	$	170,908

	Three Months Ended September 30,						Six Months Ended September 30,
	2024 (Unaudited)			2023 (Unaudited)			2024 (Unaudited)			2023 (Unaudited)
Revenue:
Product revenue, net	$	8,468		$	5,429		$	23,928		$	13,010
Federal contract revenue		56			1,891			295			10,753
Collaboration revenue		17			18			53			36
Total revenue		8,541			7,338			24,276			23,799
Expenses:
Research and development		16,334			23,661			61,349			73,006
Selling, general and administrative		12,573			14,868			47,909			45,794
Restructuring Costs		-			-			1,950			-
Cost of product revenue		714			455			2,205			1,047
Total expenses:		29,621			38,984			113,413			119,847
Loss from operations		(21,080	)		(31,646	)		(89,137	)		(96,048	)
Interest income		598			1,895			3,169			6,366
Interest expense		(3,843	)		(4,242	)		(12,806	)		(12,597	)
Other income, net		100			1,021			52			1,105
Loss before income taxes		(24,225	)		(32,972	)		(98,722	)		(101,174	)
Benefit for income taxes		-			-			-			1,538
Net loss applicable to common shareholders	$	(24,225	)	$	(32,972	)	$	(98,722	)	$	(99,636	)
Per share information:
Net loss per share of common stock—basic and diluted	$	(0.42	)	$	(0.61	)	$	(1.73	)	$	(1.89)
Basic and diluted weighted average shares outstanding		57,229,229			53,920,109			57,049,038			52,755,114
Other comprehensive loss
Unrealized gain (loss) on available-for-sale securities		-			43			20			(71)
Total comprehensive loss	$	(24,225	)	$	(32,929	)	$	(98,702	)	$	(99,707)

About Marinus Pharmaceuticals

Marinus is a commercial-stage pharmaceutical company dedicated to the development of innovative therapeutics for seizure disorders. The Company’s product, ZTALMY^® (ganaxolone) oral suspension CV, is an FDA-approved prescription medication introduced in the U.S. in 2022. For more information, please visit www.marinuspharma.com and follow us on LinkedIn, X and Facebook.

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, our expectations regarding the review and exploration of strategic alternatives and their potential impact on stockholder value; our expectations regarding the future of the company’s operations; our net product revenue and other financial guidance and projections; statements regarding our expected clinical development plans, enrollment in our clinical trials, and regulatory communications, and the timing thereof; our expected cash runway; our expectations and beliefs regarding the FDA and EMA with respect to our product candidates; our expectations regarding our cost reduction plans; the potential safety and efficacy of ganaxolone; and other statements regarding the company's future operations, financial performance, financial position, prospects, objectives and other future event.

Forward-looking statements in this press 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, the risk that exploration of strategic alternatives may not result in any definitive transaction or enhance stockholder value and may create a distraction or uncertainty that may adversely affect our operating results, business, or investor perceptions; uncertainties regarding future costs and expenses; Marinus’ ability to continue as a going concern; Marinus’ ability to maintain compliance with its debt covenants and risks and uncertainties regarding the ability to do; unexpected market acceptance, payor coverage or future prescriptions and revenue generated by ZTALMY; the pricing and reimbursement process can be time consuming and may delay commercialization of ZTALMY in one or more European countries; our dependence on Orion to commercialize ZTALMY in Europe pursuant to the exclusive collaboration agreement; unexpected actions by the FDA or other regulatory agencies with respect to our products; competitive conditions and unexpected adverse events or patient outcomes from being treated with ZTALMY, the company’s cash and cash equivalents may not be sufficient to support its operating plan for as long as anticipated; our ability to comply with the FDA’s requirement for additional post-marketing studies in the required time frames; the size and growth potential of the markets for the company’s products, and the company’s ability to service those markets; the company’s expectations, projections and estimates regarding expenses, future revenue, capital requirements, and the availability of and the need for additional financing; delays, interruptions or failures in the manufacture and supply of our product; the company’s ability to obtain additional funding to support its programs; and the company’s ability to protect its intellectual property. This list is not exhaustive and these and other risks are described in our periodic reports, including the annual report on Form 10-K, quarterly reports on Form 10-Q and current reports on Form 8-K, filed with or furnished to the Securities and Exchange Commission and available atwww.sec.gov. Any forward-looking statements that we make in this press release speak only as of the date of this press release. We assume no obligation to update forward-looking statements whether as a result of new information, future events or otherwise, after the date of this press release.

Company Contacts

Investors

Sonya WeigleChief People and Investor Relations Officer

Marinus Pharmaceuticals, Inc.

sweigle@marinuspharma.com

Media

Molly Cameron
Director, Corporate Communications & Investor Relations

Marinus Pharmaceuticals, Inc.

mcameron@marinuspharma.com

EX-99.2

Exhibit 99.2

Nasdaq: MRNS @MarinusPharma Photo Credit: Kelly Crews Photography Ryan (center) Living with CDKL5 deficiency disorder Corporate Presentation November 2024

©2024 Marinus Pharmaceuticals. All Rights Reserved I 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 expectations regarding the review and exploration of strategic alternatives and their potential impact on stockholder value; our expectations regarding the future of the company’s operations; our net product revenue and other financial guidance and projections; statements regarding our expected clinical development plans, enrollment in our clinical trials, and regulatory communications, and the timing thereof; our expected cash runway; our expectations and beliefs regarding the FDA and EMA with respect to our product candidates; our expectations regarding our cost reduction plans; the potential safety and efficacy of ganaxolone; and other statements regarding the company's future operations, financial performance, financial position, prospects, objectives and other future event. 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, the risk that exploration of strategic alternatives may not result in any definitive transaction or enhance stockholder value and may create a distraction or uncertainty that may adversely affect our operating results, business, or investor perceptions; uncertainties regarding future costs and expenses; Marinus’ ability to continue as a going concern; Marinus’ ability to maintain compliance with its debt covenants and risks and uncertainties regarding the ability to do; unexpected market acceptance, payor coverage or future prescriptions and revenue generated by ZTALMY; the pricing and reimbursement process can be time consuming and may delay commercialization of ZTALMY in one or more European countries; our dependence on Orion to commercialize ZTALMY in Europe pursuant to the exclusive collaboration agreement; unexpected actions by the FDA or other regulatory agencies with respect to our products; competitive conditions and unexpected adverse events or patient outcomes from being treated with ZTALMY, the company’s cash and cash equivalents may not be sufficient to support its operating plan for as long as anticipated; our ability to comply with the FDA’s requirement for additional post-marketing studies in the required time frames; the size and growth potential of the markets for the company’s products, and the company’s ability to service those markets; the company’s expectations, projections and estimates regarding expenses, future revenue, capital requirements, and the availability of and the need for additional financing; delays, interruptions or failures in the manufacture and supply of our product; the company’s ability to obtain additional funding to support its programs; and the company’s ability to protect its intellectual property. 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 our business in general, see filings we have 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. Safe Harbor Statement 2

©2024 Marinus Pharmaceuticals. All Rights Reserved I Ganaxolone Engages Both Synaptic and Extra-synaptic GABAA Receptors 3 Ganaxolone is a neuroactive steroid that targets binding sites on GABAA receptors that are distinct from the benzodiazepine site and other GABAergic molecules.1-3 Ganaxolone modulates both synaptic and extrasynaptic GABAA receptors to increase inhibitory tone1-5 ➢ Potentiates dual inhibitory signaling, transient (phasic) and continuous (tonic)1,3 BZD, benzodiazepine; GNX, ganaxolone 1. Reddy DS and Woodward R. Drugs Fut. 2004;29(3):227-242. 2. Reddy DS, Estes WA. Trends Pharmacol Sci. 2016;37(7):543-561. 3. Carver CM, Reddy DS. Psychopharmacology (Berl). 2013;230(2):151-188. 4. Reddy DS. Front Cell Neurosci. 2013;7:115. 5. Reddy DS, Rogawski MA. Jasper's Basic Mechanisms of the Epilepsies [Internet]. 4th edition; 6. Paul SM, Purdy RH. Neuroactive steroids, Faseb J 1992; 6(6):2311-22.

ZTALMY® Clinical and Commercial Overview Not for promotional use

©2024 Marinus Pharmaceuticals. All Rights Reserved I ZTALMY® Has the Potential to Significantly Advance Epilepsy Treatment 5 Differentiated MOA addresses unmet need Well-characterized safety profile FDA-approved in CDD Established commercial infrastructure supports continued expansion and adoption Significant commercial opportunity CDD: CDKL5 deficiency disorder; MOA: mechanism of action

©2024 Marinus Pharmaceuticals. All Rights Reserved I 6 Ganaxolone Placebo 0 10 20 30 40 Median Percent Reduction 28-day Frequency of Major Motor Seizures 30.7% 6.9% *Wilcoxon Rank-Sum Test **Hodges-Lehman Estimate of Median Dif erence Patients taking ganaxolone experienced a significant reduction in seizure frequency Ganaxolone reduced the frequency of monthly major motor seizures by a median of 30.7% compared with 6.9% for placebo (p=0.0036)* Δ = 27.1% (47.9 - 9.6)** Phase 3 CDD Marigold Trial and Open Label Extension Data Not for promotional use Patients who remained in the clinical trial at 2 years experienced sustained reduction in MMSF1 ► Following the pivotal trial, 88 out of 101 patients entered an open-label extension study to evaluate the ongoing safety and efficacy of ZTALMY.1 ► The primary objective of the OLE was to collect additional safety and tolerability data. Safety findings were consistent with the double-blind phase; no new safety findings had emerged at the time of analysis. 1,2 ► Additional efficacy assessments were also performed. Open-label design and small sample size preclude conclusions about efficacy. Reduction in monthly major motor seizure frequency through 2 years of the OLE*** Patients achieved average seizure reductions of approximately 50% at two years of treatment ***Data as of June 30, 2022 1. Data on file. Marinus Pharmaceuticals, Inc. 2. Specchio N, Amin S, Hulihan J, et al. Extended duration safety and efficacy of ganaxolone for the treatment of CDKL5 deficiency disorder: preliminary open-label extension analysis (Marigold Study). American Epilepsy Society. Dec 4-8, 2020. Virtual conference. Safety Summary ► The most frequent adverse events (AEs) reported by both groups (ganaxolone vs placebo) during the double-blind were somnolence (36% vs 16%), pyrexia (18% vs 8%), and upper respiratory tract infection (10% vs 6%). ► Serious treatment-emergent AEs (TEAEs) were reported in 12% and 10% of ganaxolone-and placebo-treated patients, respectively, during the DB phase. Marigold data published in The Lancet Neurology OLE data published in Epilepsia First international CDKL5 guidelines published in Frontiers in Neurology

©2024 Marinus Pharmaceuticals. All Rights Reserved I ZTALMY® Performance Metrics and Growth Drivers 7 Net product revenue of $8.5M for the third quarter of 2024 56% growth from Q3 2023 Continued strong new patient enrollments Continued growth of new prescribers driving demand Achieved profitability on the ZTALMY commercial investment in Q1 2024, ahead of original target Favorable reimbursement dynamics across all payers, including both commercial and government programs Not for promotional use Full year 2024 expected net product revenue: $33M-$34M Growth Opportunities: • >1,000 CDD patients identified through third-party data sources • Potential indication expansion • Ex-U.S. launches

©2024 Marinus Pharmaceuticals. All Rights Reserved I A Comprehensive Commercial Strategy to Grow the ZTALMY® Brand 8 Patient identification Activate the caregiver community Focused education to HCPs to establish ZTALMY as the standard of care for CDD seizure management Continuously enhance the patient experience • Elevate by educating HCPs on the importance of determining the genetic etiology of patients with refractory epilepsy syndromes • Increased investment in third party data expected to allow targeting of approximately 2x more CDD patients • Inspire through newly added “Shining Moments ” educational programing delivered directly to the caregiver community focused on ZTALMY and the CDD community • Promotional education targeted to HCPs with a high propensity of having CDD patients and prescribing ZTALMY • Data driven analytics and HCP segmentation strategies to deliver the right message, to the right HCP, at the right time • Refine the ZTALMYOne patient support program to meet the evolving needs of the CDD community Drive best in class practices, establish Marinus as a leader in refractory epilepsy, and build capabilities for future launches Not for promotional use

©2024 Marinus Pharmaceuticals. All Rights Reserved I Driving Global Access of ZTALMY® (ganaxolone) 9 Europe: Collaboration agreement with Orion Corporation for ganaxolone • Development, commercial and sales milestones1 ; tiered royalties in the low double-digits up to the high teens (oral suspension) and low 20s (IV) • Marinus is eligible to receive a €10 million payment on achievement of certain CDD launch milestones China: Collaboration agreement with Tenacia Biotechnology for ganaxolone • Development, commercial and sales milestones2 ; tiered double-digit royalties MENA: Distribution agreement with Biologix Fzco for ganaxolone • Revenue sharing arrangement with regulatory milestones Marinus Access Program: Expands global access to ZTALMY in non-partnered markets for appropriate patients with seizures associated with CDD • Revenue began in Q3 2024 through distribution agreement with Uniphar Group 1Subject to achievement of certain clinical and commercial launch milestones and annualized sales thresholds for the oral and IV products 2Subject to achievement of regulatory approvals for CDD

Phase 3 TrustTSC Topline Trial Results

©2024 Marinus Pharmaceuticals. All Rights Reserved I Phase 3 Trial Overview 11 ► Enrolled 129 patients across sites in the U.S., Western Europe, Canada, Israel, Australia and China ► Primary Endpoint: Percent change in 28-day TSC-associated seizure frequency during 16-week treatment period compared to baseline ► Key Secondary Endpoints: Percent change in TSC-associated seizure frequency during 12-week maintenance period, 50% responder rate, and clinical global impression Ganaxolone Placebo Baseline (4 weeks) Titration (28 days) Maintenance (12 weeks) Eligible Patients with TSC R 1:1 Primary Endpoint Analysis Open-label Ganaxolone Double-blind Phase

©2024 Marinus Pharmaceuticals. All Rights Reserved I TrustTSC Topline Results 12 Primary Endpoint Responder curve*: Ganaxolone was generally well-tolerated with a safety profile consistent with previous clinical trials. The most frequent adverse event was somnolence: 28.1% for ganaxolone compared with 16.9% for placebo. Individual patient outcomes: *Nominal p-values

Second Generation Product Development

©2024 Marinus Pharmaceuticals. All Rights Reserved I Second Generation Ganaxolone - Prodrug 14 Goals Target Oral Pharmacokinetic Profile Increase efficacy Consistent delivery to achieve target plasma concentration Improve tolerability Optimize PK profile to reduce Cmax-related adverse effects Reduce dosing frequency More sustained exposure to allow once- or twice-daily dosing Lower cost of goods Better absorption to reduce API requirements per dose Enhance IP protection Improve formulation characteristics to provide opportunity for new IP AUC Cmax Tmax MEC MTC Current profile Target profile Increase the proportion of time the plasma level exceeds a minimally effective concentration (MEC) Avoid a significant increase in peak level (Cmax) that would exceed the maximum tolerated concentration (MTC) • Prodrug candidate identified • IND-enabling work estimated to take 12-15 months to complete • IP filed in 2022

©2024 Marinus Pharmaceuticals. All Rights Reserved I Average Ganaxolone Levels Correlate with Seizure Reduction 15 • Logarithms of plasma ganaxolone level and percentage change in major motor seizure frequency were negatively correlated • Patients in the Medium and High ganaxolone level groups had an average ganaxolone concentration of 120 ng/mL and a median 38.5% reduction in seizure frequency • Incidence of CNS-related adverse events was similar across ganaxolone dose level groups Loge percentage change in major motor seizure frequency was calculated as loge (percentage change + 100) 3.0 3.5 4.0 4.5 5.0 5.5 6.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 Loge GNX Level (ng/mL) Loge Percent Change Major Motor Seizure Frequency Equivalent % Change in Major Motor Seizure Frequency r = -0.512 p = 0.001 *Pearson correlation * 145 48.4 -10.0 -45.4 -66.9 -79.9 -87.8 Equivalent GNX Level (ng/mL) 20.1 33.1 54.6 90.0 148 245 403 Low (40 ng/m L*) Medium (70 ng/m L*) High (170 ng/m L*) -100 -75 -50 -25 0 25 50 75 100 Percent Change in Major Motor Seizure Frequency **p = 0.01 *m ean GNX level w it h in Grou p **Kru skal-W allis Test n =13 n =13 n =12 Goal of reformulation is to drive consistent plasma ganaxolone levels to the mid- and upper-end of the target range

©2024 Marinus Pharmaceuticals. All Rights Reserved I Ganaxolone Prodrug Program Overview 16 0 2 4 6 8 0 50 100 150 200 Time (hr) ng/ml PO GNX Formed FC-13138 0-8 hrs 0 10 20 30 40 0 50 100 150 200 250 Time (hr) ng/ml PO GNX Formed FC-13138 0-48 hrs ► Ganaxolone prodrug IND readiness requires 12-15 month investment; near-term investment in analytical chemistry development work ► Prodrug compound readily converts to ganaxolone in vivo in dog following single oral administration (figures on right) ► Preferred synthesis route ready for non-GMP tox scale-up ► Salt screening nearly complete and shows ideal profile at low pH for improved solubility for oral administration ► Early PK work supports QD or BID dosing and the ability to achieve higher steady state serum concentrations.

Phase 3 RAISE Topline Trial Results

©2024 Marinus Pharmaceuticals. All Rights Reserved I Status Epilepticus Overview 18 Status Epilepticus = Condition resulting from either the failure of the mechanisms responsible for seizure termination or from the initiation of mechanisms which lead to: • abnormally prolonged seizures (after time point t 1 ) • can have long-term consequences (after time point t 2 ) 1. DeLorenzo RJ et al 1995 J Clin Neurophysiol 2. Naylor DE. Epilepsia Open. 2023 3. Rossetti AO, et al. J Neurol Neurosurg Psychiatry. 2006 4. Jayalakshmi S, et al. Seizure. 2015 5. Penberthy LT, et al. Seizure. 2005 6. Guterman EL, et al. JAMA Neurol 2021 • Disabling cognitive deficits3 • 2.9x increased risk for development of epilepsy3 Associated with significant morbidity: • Underlying SE etiology3 • More refractory SE4 • Therapeutic coma exposure3 • Increased age3 • Substantial direct healthcare cost5 especially as SE progresses6 Incidence of SE in the United States: ~150,000 SE episodes per year1 • Disabling cognitive deficits2 • Increased risk for development of epilepsy2 Increased mortality associated with: Significant healthcare utilization:

©2024 Marinus Pharmaceuticals. All Rights Reserved I RAISE: Phase 3 Trial in Refractory Status Epilepticus 19 STUDY POPULATION INTERVENTION CO-PRIMARY ENDPOINTS KEY SECONDARY ENDPOINTS Onset of Action: Proportion of patients with SE cessation within 30 minutes Durability of Effect: Proportion of patients with no progression to IV anesthesia for 36 hours Onset of Action: Time to SE cessation Durability of Effect: No progression to IV anesthesia for 72 hours Status epilepticus patients aged ≥12 years who have failed 2 or more antiseizure treatments for the acute treatment of SE* Background Standard of Care + IV Ganaxolone 1:1 randomization Background Standard of Care + Placebo DOSING REGIMEN

©2024 Marinus Pharmaceuticals. All Rights Reserved I RAISE Topline Results: Baseline Patient Characteristics 20 *Safety population (unless otherwise noted) A ITT population Baseline Characteristics* Placebo (n = 49) IV Ganaxolone (n = 51) Age (years), median (range) 59 (15 – 90) 60 (16 – 88) Male sex, no. (%) 30 (61.2) 30 (58.8) Mechanical ventilation prior to IP initiation, no. (%)A 18 (38.3) 21 (42.9) Baseline STESS score, median (IQR) Score 0-2, no. % (Favorable) Score 3-6, no. % (Unfavorable) Unknown 3 (1, 4) 22 (44.9) 25 (51.0) 2 (4.1) 3 (2, 5) 14 (27.5) 34 (66.7) 3 (5.8) Number of failed ASMs, mean (SD) 3.1 (1.3) 3.4 (1.7) Seizure burden (%), mean (SD) 30 (30) 37 (32) Duration of status epilepticus (hr), mean (SD) 32.8 (35.6) 42.4 (58.5) Baseline Characteristics* Continued Placebo (n = 49) IV Ganaxolone (n = 51) Status epilepticus subtype – % With prominent motor symptoms 11 (22.4) 15 (29.4) Without prominent motor symptoms 38 (77.6) 35 (68.6) Primary etiology of status epilepticus Exacerbation of underlying epilepsy 21 (42.9) 15 (29.4) ICH or IVH 5 (10.2) 4 (7.8) Head trauma 5 (10.2) 3 (5.9) Ischemic stroke 3 (6.1) 4 (7.8) Cerebral tumor 3 (6.1) 12 (23.5) CNS infection 1 (2.0) 4 (7.8) Inflammation/autoimmune disease 0 (0) 2 (3.9) Other 3 (6.1) 4 (7.8) Unknown 8 (16.3) 3 (5.9) Demographic data indicate imbalance in several baseline characteristics

©2024 Marinus Pharmaceuticals. All Rights Reserved I RAISE Topline Results: Co-Primary Endpoints 21 Proportion of patients with no progression to IV anesthesia for 36 hours Proportion of patients with SE cessation within 30 minutes without medications for the acute treatment of SE IV Ganaxolone (n = 49) Placebo (n = 47) 0 20 40 60 80 100 13 80 Percent of Patients p<0.0001 IV Ganaxolone (n = 49) Placebo (n = 47) 0 20 40 60 80 100 51 63 Percent of Patients p=0.1619 The incidence of serious adverse events was similar between the treatment and placebo arms (n=19 for IV ganaxolone, n=18 for placebo), with hypotension being more commonly seen in the IV ganaxolone arm. Median time to SE Cessation*: IV ganaxolone: 4.2 minutes Placebo: 307.2 minutes nominal p<0.0001 *Time to SE cessation after study drug administration on top of background standard of care, investigators could choose to escalate background standard of care treatment at any point to manage patient care.

©2024 Marinus Pharmaceuticals. All Rights Reserved I RAISE Topline Results: EEG Secondary Endpoint 22 Median percent reduction in EEG seizure burden - hours 1-36* Ganaxolone (N=43) Placebo (N=39) EEG seizure burden is a potential measure of durability of effect *Data reported is the pre-anesthesia seizure burden, with EEG seizure burden after the initiation of IV anesthesia imputed as the mean hourly seizure burden from the start of the study drug up to the hour prior to IV anesthesia 93% 36% 0.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0% 90.0% 100.0% p=0.003** **Nominal p-value

Financial Update

©2024 Marinus Pharmaceuticals. All Rights Reserved I Financial Overview 24 2024 Full Year Guidance Financial Summary (at Sept. 30, 2024): • $42.2 million in cash and cash equivalents • Cash runway into Q2 2025 • 55.2 million shares outstanding; 67.9 million shares outstanding on a fully dilutive basis3 • $56.2 million of outstanding debt, matures May 2026 1 Reflects combined SG&A and R&D expenses. 2 Non-cash Stock-Based Compensation (SBC) expense, included in note (1). 3 Fully dilutive total includes impact of pre-funded warrants and outstanding stock options and RSU’s Guidance Full Year 2024 ZTALMY Net Revenue $33 - $34 million SG&A & R&D1 $135 - $138 million SBC2 ~$20 million Analyst Coverage*: Cantor Fitzgerald: Charles C. Duncan, Ph.D. EF Hutton: Jason Kolbert H.C. Wainwright & Co: Douglas Tsao Jefferies: Andrew Tsai JMP Securities: Jason N. Butler, Ph.D. Leerink Partners: Marc Goodman RBC: Brian Abrahams, M.D. RW Baird: Brian Skorney T.D. Cowen: Joseph Thome, Ph.D. Truist: Joon Lee, M.D., Ph.D. *Note: Opinions, estimates, and forecasts of the individual analysts regarding Marinus do not represent opinions, estimates, and forecasts of Marinus. The listing above does not imply endorsement or concurrent with their information, conclusions, or recommendations. Nasdaq: MRNS

Intellectual Property

©2024 Marinus Pharmaceuticals. All Rights Reserved I Multiple Layers Of Potential Protection 26 Orphan drug designations for CDD and PCDH19 provide 7 and 10 years regulatory exclusivity in U.S. and EU, respectively. Orphan drug designation for SE provides 7 years regulatory exclusivity in U.S. U.S. Patents/ Patent Applications Expiration Date CDKL5 Deficiency Disorder Method of Use Patent granted (licensed) for method of treating CDKL5 deficiency disorder 2037 Application pending on dosing regimen 2038/2041/2042 Formulation Patents granted (oral suspension) 2031 (if PTE granted) Epilepsy Method of Use Patent granted on oral titration regimen 2042 Applications pending on oral titration regimens 2042 Formulation Patents granted (oral suspension) 2031 (if PTE granted) Second Generation Ganaxolone Prodrug Application pending on ganaxolone prodrug 2042/2043 Status Epilepticus Method of Use Patent granted on clinical regimen 2040 Patent granted on clinical regimen using broader ganaxolone dosing 2040 Applications pending on dosing regimens for SRSE and ESE 2041/2042 Formulation Licensed Captisol® patents Through 2033 Applications pending on IV formulation 2036

XML

Document and Entity Information	Nov. 12, 2024
Document and Entity Information [Abstract]
Document Type	8-K
Document Period End Date	Nov. 12, 2024
Entity File Number	001-36576
Entity Registrant Name	Marinus Pharmaceuticals, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-0198082
Entity Address State Or Province	PA
Entity Address, Address Line One	5 Radnor Corporate Center
Entity Address, Adress Line Two	Suite 500
Entity Address, Address Line Three	100 Matsonford Rd
Entity Address, City or Town	Radnor
Entity Address, Postal Zip Code	19087
City Area Code	484
Local Phone Number	801-4670
Title of 12(b) Security	Common Stock, par value $0.001
Trading Symbol	MRNS
Security Exchange Name	NASDAQ
Entity Emerging Growth Company	false
Entity Central Index Key	0001267813
Amendment Flag	false
Written Communications	false
Soliciting Material	false
Pre-commencement Tender Offer	false
Pre-commencement Issuer Tender Offer	false