Vamorolone

Data Demonstrate Vamorolone’s Balanced Corticosteroid Pro On-Target Glucocorticoid Activity and Without Evidence of Significant Immunosuppressive Activity at Clinical Doses CORAL GABLES, Fla., June 30, 2026 (GLOBE NEWSWIRE) -- Catalyst Pharmaceuticals, Inc. ("Catalyst") (Nasdaq: CPRX), a commercial-stage biopharmaceutical company focused on in-licensing, developing, and commercializing novel medicines for patients living with rare and difficult-to-treat diseases, today announced topline results from a two-part Phase 1 clinical study of vamorolone in healthy adult volunteers. The study demonstrated balanced corticosteroid activity with expected cortisol suppression and no evidence of significant immunosuppressive activity at clinical doses. These findings suggest that vamorolone delivers glucocorticoid and anti-inflammatory activity, while avoiding significant immunosuppressant effects, supporting its potential use as a treatment across a broad range of chronic inflammatory rare diseases. Key Highlights and Readouts: Overall study design A two-part (referred to as Parts A and B) Phase 1 study was conducted in healthy adult volunteers The primary purpose of Part A was to assess equipotency between deflazacort and vamorolone to help address the clinical case in which a patient might experience differential cortisol effects when switching from deflazacort to vamorolone The primary purpose of Part B was to evaluate ascending doses of vamorolone to assess vamorolone’s clinical immunosuppressive potential in consideration of potential life cycle management indications The study evaluated cortisol suppression, anti-inflammatory activity, and immunosuppressive effects across clinical and supratherapeutic doses Part A: Vamorolone vs. deflazacort (equipotency assessment) 24 healthy adults were enrolled in a randomized, single-center, crossover study Single doses of vamorolone (300 mg) and deflazacort (0.9 mg/kg) were evaluated Both agents demonstrated expected on-target glucocorticoid receptor activity, including cortisol suppression, leukocyte redistribution, and effects on functional immune biomarkers Similar time to onset was observed for both treatments (approximately 2–4 hours post-dose) Comparable cortisol suppression was observed at clinical doses Vamorolone demonstrated less pronounced immunosuppressive biomarker effects compared with deflazacort “By demonstrating similar cortisol suppression at label-based clinical doses of vamorolone and deflazacort, these data support the currently labeled dosing of vamorolone in the treatment of DMD and do not suggest the need for other dosing considerations when switching patients from deflazacort to vamorolone,” said William Andrews, MD, Chief Medical Officer of Catalyst Pharmaceuticals. “Moreover, vamorolone achieved robust glucocorticoid and anti-inflammatory activity without evidence of significant immunosuppression at clinical doses.” Part B: Ascending dose evaluation of immunosuppressive potential 36 healthy volunteers received vamorolone at doses of 9, 27, or 40 mg/kg once daily for seven days Immune biomarkers and cellular markers were evaluated through Day 21 Clinically relevant immunosuppressive effects were observed only at the highest dose level (40 mg/kg/day) No relevant immunosuppressive effects observed at lower dose levels (9 or 27 mg/kg/day) Immunosuppressive effects increased with repeated dosing at 40 mg/kg/day and persisted after treatment cessation “As the 40 mg/kg/day dose is above currently approved vamorolone dosing and higher than doses previously studied in clinical trials, these findings suggest that clinically meaningful immunosuppression with vamorolone is unlikely at clinically relevant doses,” Dr. Andrews added. “The prospect of this favorable pro and anti-inflammatory activity without clinically meaningful immunosuppression at clinically relevant doses—has the potential to distinguish vamorolone from conventional corticosteroids. Additionally, this pro support vamorolone’s potential utility across a broad range of chronically inflammatory rare diseases.” About Catalyst Pharmaceuticals, Inc. Catalyst Pharmaceuticals, Inc. (Nasdaq: CPRX) is a biopharmaceutical company committed to improving the lives of patients with rare diseases. With a proven track record of bringing life-changing treatments to the market, we focus on in-licensing, commercializing, and developing innovative therapies. Guided by our deep commitment to patient care, we prioritize accessibility, ensuring patients receive the care they need through a comprehensive suite of support services designed to provide seamless access and ongoing assistance. Catalyst maintains a well-established U.S. presence, which remains the cornerstone of our commercial strategy, while continuously evaluating strategic opportunities to expand our global footprint. Catalyst, headquartered in Coral Gables, Fla., has been recognized by Forbes as one of America’s Most Successful Companies in 2023, 2024, and 2025, and on the 2025 Deloitte Technology Fast 500™ list as one of North America’s Fastest-Growing Companies. For more information, please visit Catalyst's website at . Forward-Looking Statements This press release contains forward-looking statements, as that term is defined in the Private Securities Litigation Reform Act of 1995. Forward-looking statements involve known and unknown risks and uncertainties, which may cause Catalyst's actual results in future periods to differ materially from forecasted results. A number of factors, including (i) whether vamorolone can be developed and successfully commercialized in the future for the treatment of other chronic inflammatory rare diseases, and (ii) those factors described in Catalyst's Annual Report on Form 10-K for the 2025 fiscal year and its subsequent filings with the U.S. Securities and Exchange Commission (“SEC”), could adversely affect Catalyst. Copies of Catalyst's filings with the SEC are available from the SEC, may be found on Catalyst's website, or may be obtained upon request from Catalyst. Catalyst does not undertake any obligation to update the information contained herein, which speaks only as of this date. CONTACT: Contact Information: Investor Contact Melissa Kendis, Catalyst Pharmaceuticals, Inc. (305) 420-3200 IR@catalystpharma.com Media Contact Ignacio Guerrero-Ros, Ph.D., Russo Partners, LLC (646) 249-6817 Ignacio.Guerrero-Ros@russopartnersllc.com

Pratteln, Switzerland, June 2, 2026 – Santhera Pharmaceuticals (SIX: SANN) today notes that AGAMREE has been granted Orphan Drug Designation (ODD) and Global Innovative Products on Fast Track (GIFT) designation by South Korea’s Ministry of Food and Drug Safety (MFDS) for the treatment of Duchenne muscular dystrophy (DMD). These designations recognize the significant unmet medical need among DMD patients in South Korea, where no alternative treatment is currently available. The GIFT designation is a priority review pathway that may shorten the standard regulatory review timeline from 120 to 90 working days, potentially accelerating access to AGAMREE for patients living with this debilitating disease. Nxera plans to submit a Marketing Authorization Application in South Korea during 2026. Licensing partner Nxera Pharma Co., Ltd. (“Nxera”) holds exclusive rights to AGAMREE for Japan, South Korea, Australia, and New Zealand under a licensing agreement entered into in January 2026 . Santhera will receive sales and milestone payments and royalties on net sales of AGAMREE in the licensed territories. About AGAMREE® (vamorolone) AGAMREE is a dissociative corticosteroid approved for the treatment of Duchenne muscular dystrophy (DMD). It binds selectively to the glucocorticoid receptor and triggers anti-inflammatory activity through inhibition of NF‑κB-mediated gene transcription, while inducing reduced transactivation of other genes 1 . AGAMREE is not a substrate for 11‑β-hydroxysteroid dehydrogenase (11β-HSD) enzymes, which are involved in the local amplification of glucocorticoid activity in tissues and have been implicated in corticosteroid-associated toxicity 2,3 . This pharmacological pro the basis for its classification as a dissociative corticosteroid, designed to preserve anti-inflammatory efficacy while reducing the systemic effects associated with long-term conventional corticosteroid therapy 1–3 . In the pivotal Phase 2b VISION-DMD study, AGAMREE met its primary endpoint, demonstrating a statistically significant improvement in Time to Stand (TTSTAND) velocity versus placebo at 24 weeks (p = 0.002) 4 . The most commonly reported adverse reactions were cushingoid features, vomiting, weight increase, increased appetite, and irritability; most were mild to moderate in severity 1 . Long-term data from up to eight years of AGAMREE treatment were presented at the Muscular Dystrophy Association (MDA) Clinical & Scientific Conference in March 2026 5,6 . In propensity-matched analyses, AGAMREE demonstrated durable efficacy comparable to standard-of-care corticosteroids and a differentiated safety profile: a lower incidence of vertebral fractures versus deflazacort-treated cohorts (8.1% vs 41.9%; p = 0.0082) 5 ; maintained normal growth trajectory with a mean height advantage of 12.17 cm versus conventional corticosteroids (p < 0.0001) 5,6 , and a lower incidence of cataracts versus deflazacort (p = 0.015), with no observed cases of glaucoma 5 . ▼ This medicinal product is subject to additional monitoring. This will allow quick identification of new safety information. Healthcare professionals are asked to report any suspected adverse reactions. References AGAMREE (vamorolone) Summary of Product Characteristics. European Medicines Agency; authorised 14 December 2023. Link Heier CR, Damsker JM, Yu Q, et al. VBP15, a novel anti-inflammatory and membrane-stabilizer, improves muscular dystrophy without side effects. Life Sci Alliance. 2019;2(1):e201800186. Link Reeves EKM, Hoffman EP, Nagaraju K, et al. VBP15: preclinical characterization of a novel anti-inflammatory delta 9,11 steroid. Bioorg Med Chem. 2013;21(8):2241–2249. Link Dang UJ, Damsker JM, Guglieri M, et al. Efficacy and safety of vamorolone over 48 weeks in boys with Duchenne muscular dystrophy (VISION-DMD). Neurology. 2024;102(5):e208112. Link Guglieri M, et al. Long-term impact of vamorolone on bone health compared to standard of care glucocorticoids in boys with Duchenne muscular dystrophy. Poster 62S, MDA Clinical & Scientific Conference 2026. Link McDonald CM, et al. Comparative analysis of long-term effectiveness of vamorolone versus standard of care glucocorticoid treatment in boys with Duchenne muscular dystrophy. Poster 23S, MDA Clinical & Scientific Conference 2026. Link About Santhera Santhera Pharmaceuticals (SIX: SANN) is a Swiss specialty pharmaceutical company focused on the development and commercialization of innovative medicines for rare neuromuscular diseases with high unmet medical need. The Company has an exclusive license from ReveraGen for all indications worldwide to AGAMREE® (vamorolone), a dissociative steroid with novel mode of action, which was investigated in a pivotal study in patients with Duchenne muscular dystrophy (DMD) as an alternative to standard corticosteroids. AGAMREE for the treatment of DMD is approved in the U.S. by the Food and Drug Administration (FDA), in the EU by the European Commission (EC), in the UK by the Medicines and Healthcare products Regulatory Agency (MHRA), in Switzerland by Swissmedic, in China by the National Medical Products Administration (NMPA), in Hong Kong by the Department of Health (DoH) and in Canada by Health Canada. Santhera has out-licensed the rights to AGAMREE as follows: to Catalyst Pharmaceuticals for North America; to Sperogenix Therapeutics for China and certain countries in Southeast Asia; and to Nxera Pharma for Japan, South Korea, Australia, and New Zealand. For further information, please visit . AGAMREE® is a trademark of Santhera Pharmaceuticals. For further information, please contact: Santhera Catherine Isted, Chief Financial Officer: IR@santhera.com ICR Healthcare: Santhera@icrhealthcare.com Stifel +44 (0)20 7710 7600 Brough Ransom, Charles Hoare, Fred Walsh Octavian +41 (0)44 520 1588 Serge Monnerat, Marius Zuberbuehler Disclaimer / Forward-looking statements This communication does not constitute an offer or invitation to subscribe for or purchase any securities of Santhera Pharmaceuticals Holding AG. This publication may contain certain forward-looking statements concerning the Company and its business. Such statements involve certain risks, uncertainties and other factors which could cause the actual results, financial condition, performance or achievements of the Company to be materially different from those expressed or implied by such statements. Readers should therefore not place undue reliance on these statements, particularly not in connection with any contract or investment decision. The Company disclaims any obligation to update these forward-looking statements. # # # Attachment 260602 Santhera Nxera ODD South Korea FINAL Eng (1)