Marinus Pharmaceuticals : Corporate Overview Slide Deck

Ryan (center)

Living with CDKL5 deficiency disorder

Corporate Presentation

May 2024

Nasdaq: MRNS

@MarinusPharma

Photo Credit: Kelly Crews Photography

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 ability to continue as a going concern; our expected revenue and expenses; our commercialization plans for ZTALMY® and clinical development plans for ganaxolone, and the expected timing thereof; the clinical development schedule and milestones; expected dosing in our clinical trials; 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; the potential safety and efficacy and therapeutic potential of ganaxolone; timing and expectations regarding the potential benefits ZTALMY will provide for patients and physicians; timing and expectations regarding regulatory communications and submissions; expectations regarding our agreement with BARDA; expectations regarding our current and contemplated collaborations with ex-US partners, including the potential benefits and timing thereof; expectations regarding the potential market opportunities for our product candidates; expectations regarding patient populations; expectations regarding potential commercial alliances; expectations regarding our cash flow, cash projections and cash runway; expectations regarding the continued uptake of ZTALMY; expectations regarding the impact of on-going scientific and clinical research investments on our product candidates; expectations regarding operating margins; plans for commercial investments; plans to leverage existing our infrastructure and knowledge; our plans for the global access program and the expected benefits and timing thereof; and our expectations regarding future opportunities of oral and IV ganaxolone. 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 patient and physician acceptance of ZTALMY; our ability to obtain adequate market access for ZTALMY; our ability to comply with the U.S. Food and Drug Administration's ("FDA") requirement for additional post-market studies in the required timeframes; the timing of regulatory filings; the potential that regulatory authorities, including the FDA and the European Medicines Agency ("EMA"), may not grant or may delay approval for our product candidates; uncertainties and delays relating to the design, enrollment, completion, and 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 EMA 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 candidates; our ability to obtain, maintain, protect and defend intellectual property for our product candidates; the potential negative impact of third party patents on our collaborators' or our ability to commercialize ganaxolone; delays, interruptions or failures in the manufacture and supply of our product candidates; the size and growth potential of the markets for our product candidates, and our ability to service those markets; our cash and cash equivalents may not be sufficient to support our operating plan for as long as anticipated; our expectations, projections and estimates regarding expenses, future revenue, capital requirements, and the availability of and the need for additional financing; our ability to obtain additional funding to support our commercial and clinical development programs; our dependence on ex-US partners to commercialize ZTALMY outside of the US; the potential for our ex-US partners to breach our collaboration agreements or terminate the agreements; 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 candidates. 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.

©2024 Marinus Pharmaceuticals. All Rights Reserved I

2

Ganaxolone Development Pipeline

Ganaxolone is a positive allosteric GABAA receptor modulator with a well-defined MOA designed to treat patients suffering from seizure disorders.

Ganaxolone is designed to modulate both synaptic and extrasynaptic GABAA receptors to calm over-excited neurons.

Oral Suspension

Intravenous

Oral Suspension

Oral Suspension

Phase 1

Phase 2

CDKL5 Deficiency Disorder

Refractory Status Epilepticus

RAISE Trial

Tuberous Sclerosis Complex

TrustTSC Trial

Developmental Epileptic

Encephalopathies

Including Lennox-Gastaut Syndrome

Phase 3

Approved

FDA & EMA approved

Anticipated Milestones

Topline data early summer 2024

Topline data first half of Q4 2024

Trial to begin 1H 2025

Ongoing trial

Planned future trial

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3

Significant Near-term Milestones Build on Commercial Success

Program	Indication	1H 2024	2H 2024	1H 2025	2H 2025
	CDKL5 deficiency	Achieved
	disorder	profitability*
	Tuberous sclerosis	Complete Phase 3	Phase 3 TrustTSC	Potential filing for FDA	Potential Launch
	complex	TrustTSC enrollment	readout	Approval
	Developmental and			Begin enrollment of
	epileptic
			Phase 2 trial
	Encephalopathies
IV Ganaxolone	Refractory status	Phase 3 RAISE	Phase 3 RAISE
enrollment
epilepticus	readout
	completed
Second-Gen	Lennox-Gastaut				IND Expected
Program	syndrome

Two Topline Data Readouts Expected Before Year-End

*on ZTALMY commercial investment

©2024 Marinus Pharmaceuticals. All Rights Reserved I

4

Commercial Overview

Not for promotional use

ZTALMY® Has the Potential to Significantly Advance Epilepsy Treatment

FDA-approved in CDD

Well-characterized safety profile

Differentiated MOA addresses unmet need

CDD: CDKL5 deficiency disorder; MOA: mechanism of action

Scalable commercial infrastructure supports rapid expansion and adoption

Significant commercial opportunity

©2024 Marinus Pharmaceuticals. All Rights Reserved I

6

ZTALMY® Performance Metrics

and Growth Drivers

U.S. net product revenue of $7.5M for the first quarter of 2024

>125% growth from Q1 2023

Continued strong new patient

enrollments

Continued growth of new prescribers driving demand

Increased full year 2024 expected U.S. net product revenue to

$33M-$35M

Favorable reimbursement

dynamics across all payers, including both commercial and government programs

Achieved profitability on the ZTALMY commercial investment in Q1 2024, ahead of original target

Growth Opportunities:

• >1,000 CDD patients identified through third-party data sources
• Indication expansion, including TSC
• Ex-U.S.launches (EU, MENA, China)

Not for promotional use

©2024 Marinus Pharmaceuticals. All Rights Reserved I

7

Tuberous Sclerosis Complex

"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

Tuberous Sclerosis Complex (TSC)

CAUSE		•	Defect or mutation of TSC1 and/or TSC2 genes
INCIDENCE		•	~1 in 6,000 live births1
COMMON		•	Seizures, cognitive impairment, behavioral difficulties, skin/kidney/lung abnormalities, etc.
SYMPTOMS
EPILEPSY IN TSC		• Occurs in ~80-90% of those with TSC2
	•	Seizures typically begin within first year of life (infantile spasms and/or focal seizures)2

TSC is one of the most common genetic epilepsies often

exhibiting highly refractory seizures despite existing therapies

1. Hasbani DM & Crino PB 2018 Hand. Clin. Neurol.
2. Chu-ShoreCJ et al.2010 Epilepsia

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9

TSC Phase 2 Trial Results

Primary Endpoint Results:

16.6% median reduction in TSC-associated seizures

	100
inreductionPercent frequencyseizureassociated	80
60
	40
	20
	0
	-20	16.6%
	-40
	-60
TSC-	-80
-100
	-200
		=median

Secondary and

Exploratory Analyses

reductionPercentin focal frequencyseizure(median)	30	patientsofPercent		Proportion of patients with a ≥50% reduction
0		in TSC-associated seizure frequency
	25.2 %		50
			45
	20		40			36.4%
			35	30.4 %
			30		25.0 %
			25
	10
		20
			15
			10
			5
	Subjects with		0	Intent to Treat *
			+Cannabidiol +Everolimus
	Focal Seizure Types			(n=23)	(n=12)	(n=11)
	(n=19)			* Secondary endpoint

The most common adverse events (AEs) reported were somnolence, sedation and fatigue

17.4% (n=4) of patients discontinued due to AEs (total discontinuation rate: 26% (n=6))

74% (n=17) of patients reported somnolence-related AEs

52% (n=12) of patients required dose adjustments

One treatment-related serious adverse event (AE) of seizure was reported in the trial

©2024 Marinus Pharmaceuticals. All Rights Reserved I 10