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January 2026 NEXT GENERATION RNA MEDICINES JP Morgan Healthcare Conference
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2© 2026 Arcturus Therapeutics, Inc. Forward Looking Statements This presentation contains forward-looking statements. These statements relate to future events and involve known and unknown risks, uncertainties and other factors which may cause our actual results, performance or achievements to be materially different from any future performances or achievements expressed or implied by the forward-looking statements. Each of these statements is based only on current information, assumptions and expectations that are inherently subject to change and involve a number of risks and uncertainties. Forward-looking statements include, but are not limited to, statements about: our strategy, future operations, collaborations, the likelihood of success (including safety and efficacy) and promise of our pipeline, the development, manufacture or commercialization of our pipeline and partnered pipeline assets, the likelihood of success of, and achievement of revenues from, our partnered programs, the planned initiation, design or completion of clinical trials the likelihood that we will obtain clearance from regulatory authorities to proceed with planned clinical trials, the ability to enroll subjects in clinical trials, the timing for receipt of data, the likelihood that preclinical or clinical data will be predictive of future clinical results, the likelihood that clinical data will be sufficient for regulatory approval or completed in time to submit an application for regulatory approval within a particular timeframe, the anticipated timing for regulatory submissions, the timing of, and expectations for, any results of any preclinical or clinical studies or regulatory approvals, the potential administration regimen or dosage, or ability to administer multiple doses of, any of our drug candidates, our manufacturing methods and technologies (including purification, lyophilization and stability of our products), the likelihood that a patent will issue from any patent application, our current cash position and adequacy of our capital to support future operations, and any statements other than statements of historical fact. In some cases, you can identify forward-looking statements by terms such as “may,” “will,” “should,” “could,” “would,” “expects,” “plans,” “anticipates,” “believes,” “estimates,” “projects,” “predicts,” “potential” and similar expressions (including the negative thereof) intended to identify forward looking statements. Arcturus may not actually achieve the plans, carry out the intentions or meet the expectations or projections disclosed in any forward- looking statements such as the foregoing, and you should not place undue reliance on such forward-looking statements. The forward-looking statements contained or implied in this presentation are subject to other risks and uncertainties, including those discussed under the heading "Risk Factors" in Arcturus’ most recent Annual Report on Form 10-K with the SEC and in other filings that Arcturus makes with the SEC. Except as otherwise required by law, we disclaim any intention or obligation to update or revise any forward-looking statements, which speak only as of the date they were made, whether as a result of new information, future events or circumstances or otherwise. Trademark Attribution: The Arcturus logo and other trademarks of Arcturus appearing in this presentation are the property of Arcturus. All other trademarks, services marks, and trade names in this presentation are the property of their respective owners.
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3© 2026 Arcturus Therapeutics, Inc. Arcturus Therapeutics Nasdaq: ARCT mRNA Therapeutic Candidates Headquarters: San Diego, CA Employees: 100 Founded: 2013 ARCT-810 (LUNAR-OTC) Ornithine Transcarbamylase Deficiency ARCT-032 (LUNAR-CF) Cystic Fibrosis STARR® mRNA Vaccines KOSTAIVE® Approved in Japan, UK, EU LUNAR-H5N1 U.S. Pandemic Flu PARTNERS
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4© 2026 Arcturus Therapeutics, Inc. Broad Intellectual Property Portfolio Proprietary mRNA Technologies Driving Therapeutic Programs 500+ Patents & Patent Applications mRNA Technology • mRNA for protein replacement • Self-amplifying mRNA (STARR®) low-dose vaccine technology Manufacturing Know-How • Drug Substance Production (mRNA & STARR® mRNA) • mRNA Purification • Drug Product Production (LUNAR ® Lipids + mRNA) • Fill Finish / Lyophilization LUNAR® Delivery • Hepatocytes – intravenous • Myocytes – intramuscular • Airway Cells – inhaled
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5© 2026 Arcturus Therapeutics, Inc. Proprietary, Biodegradable, Optimized for Each Cell Type LUNAR® Lipid Nanoparticle Delivery Technology LUNAR® interacts with cell membrane LUNAR® internalized inside endosome mRNA release via engineered endosomolysis mRNA translates into protein of interest
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6© 2026 Arcturus Therapeutics, Inc. Pipeline of Arcturus-Owned mRNA Therapeutic Candidates Upcoming MilestoneFunded ByCandidate Indication Global Prevalence Pivotal Trial Strategy Alignment with Regulatory Agencies H1 2026 LUNAR®-OTC (ARCT-810) Ornithine Transcarbamylase Deficiency (OTC) >10,000Hepatic Phase 2 12-Week Study Initiation H1 2026 LUNAR®-CF (ARCT-032) Cystic Fibrosis >100,000Respiratory Franchise Each Arcturus-Owned Program Represents a Significant Commercial Opportunity
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LUNAR-CF (ARCT-032) Inhaled mRNA Therapeutic Candidate for Cystic Fibrosis
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8© 2026 Arcturus Therapeutics, Inc. ARCT-032 Background An inhaled mRNA therapeutic that can build new CFTR protein in the lung cells of individuals with CF is desired Arcturus is preparing to initiate a Phase 2, fourth cohort, study in ~20 CF participants with daily treatment over a period of 12 weeks ARCT-032 received Rare Pediatric Disease Designation and Orphan Drug Designation from the U.S. FDA and Orphan Medicinal Product Designation from the European Commission (EC) The Cystic Fibrosis Foundation has committed ~$25 Million to ARCT-032 Presently in Phase 2 studies, ARCT-032 has been generally safe and well tolerated to date
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9© 2026 Arcturus Therapeutics, Inc. ARCT-032 Market Opportunity Cystic Fibrosis Cystic Fibrosis >100,000 worldwide prevalence Caused by mutations in the CFTR gene, resulting in poor chloride transport and dehydrated, sticky mucus in the airways Chronic airway obstruction leads to infection and inflammation, which causes progressive airway damage and ultimately, respiratory failure Unmet Medical Need LUNAR-CF Aims to Restore CFTR Function An mRNA replacement therapy has the potential to produce wild-type CFTR in the lungs of CF patients, independent of genotype Effective CFTR modulators are not approved for treatment of all people with CF Standard of care therapies do not prevent chronic, progressive loss of lung function that ultimately requires lung transplantation or leads to early death Functional CFTR protein can restore chloride efflux in the airways, reducing mucus accumulation and airway damage and minimizing the progressive respiratory impairment observed in people with CF
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10© 2026 Arcturus Therapeutics, Inc. ARCT-032 Initial Target Population Class I CF No treatment option available other than symptomatic care Class I CF Patients ~10,000 Class I CF patients globally Class I nonsense mutations result in no production of CFTR protein At risk of developing severe lung disease Unmet Medical Need Potential Uptake Rapid adoption is expected among people with CF who carry ineligible mutations or who are modulator intolerant due to the significant unmet need in this population Estimated 15% of people with Cystic Fibrosis are potential candidates for ARCT-032 10% with ineligible Class I mutations Up to 5% of patients with incomplete response or unacceptable side effects to CFTR modulators Ineligibility for CFTR modulators is the greatest area of unmet need in CF Those with incomplete response to CFTR modulators represent an important potential patient population The ~10,000 Class I CF Patient Population Represents the Highest Unmet Need
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11© 2026 Arcturus Therapeutics, Inc. ARCT-032 Clinical Summary Phase 1 Study in Healthy Volunteers • N = 32 across 4 ascending single-dose cohorts • Safety, tolerability and PK data supported transition to Phase 1b study Phase 1b Study in Adults with Cystic Fibrosis • N=7; Each CF participant received two administrations of ARCT-032 • Safety, tolerability and PK data supported transition to Phase 2 study Phase 2 Study in CF Participants who do not qualify for or benefit from CFTR modulator therapy • Multiple ascending dose, open-label study • Safety, tolerability, PK and efficacy at 3 dose levels (5mg, 10mg, 15mg) • Each participant receives daily treatments of ARCT-032 over a period of 28 days 11 New 12-Week Study Enrolling a Fourth Cohort Up to 20 CF Participants is Planned to Begin H1 2026
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12© 2026 Arcturus Therapeutics, Inc. ARCT-032 Phase 2 Objectives • Establish safety, tolerability, efficacy in adults with CF who are not on CFTR modulator therapy Phase 2 Safety and Tolerability Study (Cohorts 1, 2, 3) • Open-Label, multicenter, multiple ascending dose study • Daily inhaled treatments of ARCT-032 over a period of 28 days • First cohort (N = 3; 5 mg) completed dosing • Second cohort (N = 6; 10 mg) completed dosing • Third cohort (N = 4; 15 mg) dosing phase near completion Phase 2 Safety and Preliminary Efficacy Study (Cohort 4) • Open-label, multicenter, N = 20, Dose = 10 or 15 mg • Daily inhaled treatments of ARCT-032 over a period of 12 Weeks • Planned initiation 1H 2026
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13© 2026 Arcturus Therapeutics, Inc. ARCT-032 Phase 2 Interim Data 13
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14© 2026 Arcturus Therapeutics, Inc. Mucus Plug Reduction is Important Arcturus evaluated mucus plug reduction after 28 days of treatment with ARCT-032 High-Resolution CT Scans were analyzed utilizing Thirona’s FDA 510(k)-cleared AI Technology Lung structure changes are important predictor and precursor of lung function improvements • Studies1 have shown lung structural abnormalities in subjects with CF are associated with lower FEV1 lung function scores over the next 10 years of their life • Mucus plugging are among the most predictive of lower FEV1 function • Chest HRCT scans can provide an early readout of likely long-term success for CF patients Mucus Plug Reduction Interim Results • No mucus plug reduction observed at the 5 mg dose level (first cohort) • Significant mucus plug reductions observed at the 10 mg dose level (second cohort) • Third cohort (15 mg) is ongoing, near completion of dosing phase 1. Turkovic L, Caudri D, Rosenow T, et al. Structural determinants of long-term functional outcomes in young children with cystic fibrosis. Eur Respir J 2020; 55: 1900748 [https://doi.org/ 10.1183/13993003.00748-2019].
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15© 2026 Arcturus Therapeutics, Inc. Cohort 2: Mucus Reduction Summary 4 out of 6 participants in Cohort 2 exhibited Mucus Reduction (each received 10 mg ARCT-032 daily for 28d) Averaging the four participants that exhibited Mucus Reduction (Patients 2, 4, 6, 5): • 27.8% Reduction in Number of Mucus Plugs • 32.6% Reduction in Mucus Volume After 28 daily doses (10 mg) of ARCT-032: Reduction of mucus plugs and mucus volume is encouraging Subject Number Dose (mg) Number of Mucus Plugs % Change @ Day 28 Mucus Volume (mL) % Change @ Day 28 2 10 -38.5% -67.4% 4 10 -34.9% -27.5% 6 10 -28.5% -29.5% 5 10 -9.1% -6.1% 3 10 23.8% 9.1% 1 10 25.6% 60.9%
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16© 2026 Arcturus Therapeutics, Inc. HRCT Imaging Background Example of Adult Healthy Lung Example of Adult Class I CF Lung Mucus plugs are colored red
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17© 2026 Arcturus Therapeutics, Inc. HRCT Scans of Selected Class I CF Participants Cohort 2: Patient 2 Cohort 2: Patient 5 Reduction of mucus plugs after 28 days of treatment with ARCT-032
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18© 2026 Arcturus Therapeutics, Inc. ARCT-032: Summary of Phase 2 Interim Data • ARCT-032 continues to be safe and well tolerated at all tested dose levels • Meaningful trends of clinical activity observed via high HRCT scans – After 28 days of treatment with ARCT-032 (10 mg), 4 out of 6 Class I CF participants exhibited encouraging reduction in numbers of mucus plugs and mucus volume • Larger (N = 20) and longer duration (12 wks) study is planned to begin H1 2026 – The HRCT mucus reduction and supporting lung function data from the second cohort (10 mg), combined with additional data collected from the ongoing third cohort (15 mg), will guide dose selection 1Reference https://ir.arcturusrx.com/static-files/48940714-0106-400d-a4a9-15acb88da82e for full Phase 2 interim data presentation
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LUNAR-OTC (ARCT-810) Systemically Delivered mRNA for Ornithine Transcarbamylase (OTC) Deficiency
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20© 2026 Arcturus Therapeutics, Inc. ARCT-810 Market Opportunity Ornithine Transcarbamylase (OTC) Deficiency The most common urea cycle disorder Unmet Medical Need LUNAR-OTC Aims to Restore Enzyme Function Establishing expression of OTC enzyme in liver has potential to restore urea cycle activity to detoxify ammonia, preventing neurological damage and potentially removing need for liver transplantation The urea cycle converts neurotoxic ammonia to water-soluble urea that can be excreted in urine Deficiency in OTC causes elevated blood ammonia, which can lead to progressive neurological damage, coma, and death Present standard of care involves a strict diet (low protein, high fluid intake) plus ammonia scavengers Present standard of care does not effectively prevent life- threatening spikes of ammonia Severe OTC Deficiency patients are referred for liver transplant, currently the only cure ~10,000 prevalence in U.S./ EU
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21© 2026 Arcturus Therapeutics, Inc. ARCT-810 Clinical Summary 21 aaaaa aa Phase 1 Study in Healthy Volunteers • Completed dosing up to 0.4 mg/kg, total participants N = 24, generally safe and well tolerated Phase 1b Single Ascending Dose Study in OTCD Adults • Completed enrollment and dosing of all cohorts (N=16) • Dose cohorts were 0.2, 0.3, 0.4 and 0.5 mg/kg; no serious or severe adverse events Phase 2 (UK & EU) Single and Multiple Ascending Dose, Placebo- controlled Study in OTCD Adolescents & Adults • Completed enrollment of 8 participants at the 0.3 mg/kg dose level • Up to 6 bi-weekly doses for each participant with the following endpoints ‒ Primary Endpoints: Safety and tolerability ‒ Secondary Endpoints: PK and PD (ureagenesis assay, plasma ammonia: 24-hr profile and peak level) ‒ Exploratory Endpoints: Plasma amino acids and OTC enzyme activity; urine orotic acid ARCT-810 received Orphan Drug Designation, Fast Track Designation & Rare Pediatric Disease Designation from the U.S. FDA and Orphan Medicinal Product Designation from the European Commission (EC) Phase 2 Ongoing Open Label Study (U.S.) • Enrolling adults and adolescent participants with more severe disease • Multiple dose levels to be evaluated • Each participant is expected to receive five intravenous infusions administered over two months
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22© 2026 Arcturus Therapeutics, Inc. ARCT-810: European and U.S. Phase 2 Trials Objectives • Establish safety and tolerability in OTC deficient adolescents and adults • Evaluate biomarker responses – glutamine, ammonia, ureagenesis European Phase 2 Study – Completed (N = 8; 6 ARCT-810 / 2 placebo) • Randomized, placebo-controlled • 0.3 mg/kg ARCT-810; up to six biweekly IV infusions • Entry criteria: Patients with stable disease U.S. Phase 2 Study – Ongoing (up to N = 6) • Open-label, multiple ascending dose study • 0.3 mg/kg and 0.5 mg/kg; five biweekly IV infusions of ARCT-810 • Entry criteria: Patients with more severe disease • More frequent and optimized biomarker timepoints • Includes 15N-ureagenesis assay
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23© 2026 Arcturus Therapeutics, Inc. ARCT-810 Phase 2 Interim Data 23
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24© 2026 Arcturus Therapeutics, Inc. 500 600 700 800 900 1000 0 20 40 60 80 100 120 140 160 Mean Glutamine (umol/L) Study Day Phase 2 (EU - 6 dose) ARCT-810 Final Dose Day 71 Glutamine Normalization Following ARCT-810 Administration Glutamine normal values range from ~400 to 800 umol/L Interim data show significant reduction in glutamine levels following ARCT-810 administration High glutamine levels are normalized during treatment course Approximately one month after the final dose, glutamine levels elevate above normal Glutamine Normal Range 500 600 700 800 900 1000 1100 1200 1300 0 10 20 30 40 50 60 70 80 90 Glutamine (umol/L) Study Day Phase 2 (US - 5 dose) (Interim) 101-002 (0.5 mg/kg) 101-003 (0.3 mg/kg) 101-004 (0.5 mg/kg) Final Dose Day 57 Glutamine Normal Range
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25© 2026 Arcturus Therapeutics, Inc. ARCT-810 Significantly Increases 15N-Ureagenesis Mean Relative Ureagenesis Function (RUF) increased +14.7% from baseline to 28 days post-fifth dose-- from 29.0% (SD 9.1%) to 43.7% (SD 21.7%) Mean RUF increase is statistically significant -- p-value = 0.026, LMM analysis Two of three participants achieved > 50% RUF Data suggest ARCT-810 progressively increases functional OTC enzyme in the liver resulting in improved urea cycle function Encouraging 15N-Ureagenesis data provide additional support and confidence in the favorable glutamine results Interim Phase 2 Data U.S. Open Label Study (N = 3):
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26© 2026 Arcturus Therapeutics, Inc. ARCT-810: Ammonia Stable and Within Normal Range Ammonia levels stabilized within normal range following two administrations of ARCT-810 and remained stable for approximately 28 days after completion of dosing Ammonia data add robustness to the favorable glutamine and ureagenesis data 0 20 40 60 80 100 120 1 15 29 43 57 71 85 99 113 127 141 155 Mean Ammonia (umol/L) Study Day Placebo, n=2 ARCT-810 (0.3 mg/kg), n=6 0 20 40 60 80 100 120 1 15 29 43 57 71 85 Mean Ammonia (umol/L) Study Day ARCT-810 (0.3 or 0.5 mg/kg), n=3 REF ≤72 μmol/L Hyperammonemia ≥100 μmol/L REF ≤72 μmol/L Hyperammonemia ≥100 μmol/L Interim Phase 2 (U.S.)Phase 2 (Europe)
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27© 2026 Arcturus Therapeutics, Inc. ARCT-810: Summary of Phase 2 Interim Data1 • Significant and consistent reduction in glutamine levels in both Phase 2 studies – from abnormal to normal levels • Significant increase in 15N-ureagenesis in the U.S. Phase 2 study – additional evidence of urea cycle improvement • Ammonia – stable and within normal range • ARCT-810 continues to be safe and well tolerated at all tested dose levels Planned alignment with regulatory agencies around pivotal trial strategy for both severe pediatric and stable adult populations – H1 2026 1Reference https://ir.arcturusrx.com/static-files/f01ce22c-25cd-4886-850d-18e8db4484b8 for full Phase 2 interim data presentation
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28© 2026 Arcturus Therapeutics, Inc. Key Near Term Objectives H1 2026 ARCT-810 (OTC Deficiency) Establish clarity and alignment with FDA on the regulatory development paths • For severe pediatric OTC Deficient patients (0-6 years of age) • For OTC deficient adolescents and adults with stable disease ARCT-032 (CF) Receive approval to proceed with the Phase 2 fourth cohort (N = 20) • Initiate enrollment and dosing of daily treatment for 12-weeks Arcturus mRNA Therapeutic Clinical Programs
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29© 2026 Arcturus Therapeutics, Inc. 29 Q & A