Readout to Include One-Year Cohort 1 Results and Early Cohort 2 Data; Webcast Conference Call Planned to Review RIDGE-1 Data at ASGCT Additional Presentations at ASGCT Showcase Tenaya’s Work with Patients to Advance Gene Therapy and Early-Stage Pipeline Innovations in Cardiac Gene Editing  SOUTH SAN FRANCISCO, Calif., April 27, 2026 (GLOBE NEWSWIRE) — Tenaya Therapeutics, Inc. (NASDAQ: TNYA), a clinical-stage biotechnology company with a mission to discover, develop and deliver potentially curative therapies that address the underlying causes of heart disease, today announced the acceptance of multiple abstracts for presentation at the American Society of Gene and Cell Therapy (ASGCT) Annual Meeting, taking place May 11-15, 2026, in Boston, Massachusetts. Of note, new clinical data from both dose cohorts of the RIDGE-1 Phase 1b/2 trial of TN-401 will be featured as a late-breaking oral presentation. TN-401 is being developed for the potential treatment of adults with arrhythmogenic right ventricular cardiomyopathy (ARVC), a form of arrhythmogenic cardiomyopathy (ACM) that primarily impacts the right ventricle, caused by mutations in the plakophilin-2 (PKP2) gene. PKP2 gene mutations result in insufficient levels of critical proteins needed to maintain the structural integrity and cell-to-cell electrical signaling of heart muscle cells. TN-401 gene replacement therapy is designed to address the underlying cause of disease by delivering a functional PKP2 gene into heart muscle cells using an adeno associated virus serotype 9 (AAV9) capsid. The ASGCT presentation will include new safety, biopsy and efficacy data from patients treated at both the 3E13 vg/kg and 6E13 vg/kg dose levels. Details of the TN-401 clinical data presentation are as follows: Presentation Date & Time: Friday, May 15, 2026, from 8:00 am – 9:00 am EDT Abstract Title: Interim Data from RIDGE-1: A Phase 1b/2 Interventional Study to Evaluate Safety and Efficacy of TN-401, an AAV9 Investigational Gene Replacement Therapy, in Adults with PKP2-Associated Arrhythmogenic Right Ventricular Cardiomyopathy Location: Westin Seaport Commonwealth Ballroom ABC (Concourse Level)Presenting Author: John Giudicessi, M.D., Departments of Cardiovascular Medicine and Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, New York Two other Tenaya abstracts have been accepted for poster presentations during ASGCT 2026. The first poster will detail results of a survey exploring parental perceptions of gene therapy treatment for children with cardiomyopathies conducted in partnership with DDC Clinic and the patient advocacy group, Children’s Cardiomyopathy Foundation. Presentation Session Date & Time: Tuesday, May 12, 2026, from 5:00 pm – 6:30 pm EDT Abstract Title: Perceptions and attitudes towards gene replacement therapy in parents of children with cardiomyopathy (#1372)Location: MCEC Exhibit and Poster HallPresenting Author: Kimberly Cohee, Executive Director, Patient Advocacy at Tenaya The second poster accepted for presentation builds on research previously presented for TN-501, a gene editing therapeutic candidate intended for the treatment of PLN-R14del-associated dilated cardiomyopathy (DCM). TN-501 is uniquely designed to specifically inactivate the pathogenic phosolamban (PLN) R14del allele while preserving healthy function. Presentation Session Date & Time: Thursday, May 14, 2026, from 5:00 pm – 6:30 pm EDTAbstract Title: Development of TN-501, an AAV-Delivered Gene Editing Therapy for PLN-R14del Cardiomyopathy (#3432) Location: MCEC Exhibit and Poster HallPresenting Author: Huanyu Zhou, PhD, Associate Director, Gene Therapy at Tenaya Therapeutics The posters presented at ASGCT will be available in the “Our Science” section of the company’s website at the time of the live presentation. Conference Call and WebcastTenaya management plans to host a webcast conference call to discuss the TN-401 data being presented at the upcoming ASGCT Annual Meeting 2026. Details will be posted to the “Events & Presentations” page in the investor section of the Tenaya website at www.tenayatherapeutics.com. About PKP2-Associated ARVCPlakophilin-2 (PKP2) mutations are the most common genetic cause of arrhythmogenic right ventricular cardiomyopathy (ARVC, also known as arrhythmogenic cardiomyopathy or ACM), occurring in approximately 40 percent of the overall ARVC population. The prevalence of PKP2-associated ARVC is estimated at more than 70,000 people in the U.S. alone. In PKP2-associated ARVC, mutations of the PKP2 gene results in insufficient expression of a protein needed for the proper functioning of the desmosomal complex that maintains physical connections and electrical signaling between heart muscle cells. As the desmosome structure degrades, cardiac muscle cells are replaced by fibrofatty tissue and electrical impulses in the heart become unstable, resulting in irregular heart rhythms that can be fatal. ARVC symptoms include arrhythmias, palpitations, lightheadedness, dizziness and fainting. It is typically diagnosed before age 40, and sudden cardiac arrest due to life-threatening ventricular arrhythmias is frequently the first manifestation of disease. Current treatments include anti-arrhythmic medications, implantable cardioverter-defibrillators (ICDs) and ablation procedures, which do not address the underlying genetic cause of disease. About TN-401 Gene Therapy and the RIDGE-1 Clinical TrialTN-401 is an investigational AAV9-based gene therapy being developed for the treatment of ARVC due to mutations in the PKP2 gene. AAV9 was selected as the vector for delivery of Tenaya’s PKP2 gene therapy based on its extensive clinical and commercial safety record and demonstrated ability to target heart muscle cells. TN-401 has received Orphan Drug and Fast Track Designations from the U.S. Food and Drug Administration. Tenaya’s development of TN-401 is supported in part by a grant from the California Institute for Regenerative Medicines (CIRM). The RIDGE-1 Phase 1b/2 clinical trial of TN-401 in patients with PKP2-associated ARVC is a multi-center, open-label, dose escalation study being conducted in the U.S. and UK. RIDGE-1 is intended to assess the safety, tolerability and preliminary clinical efficacy of a one-time intravenous infusion of TN-401. RIDGE-1 will seek to enroll up to fifteen adults who have been diagnosed with PKP2-associated ARVC, have an ICD and have high counts of premature ventricular contractions (PVCs) during screening, indicating electrical instability and increased risk of fatal arrhythmias. To learn more about gene therapy for ARVC and the RIDGE-1 clinical trial, please visit ARVCstudies.com or ClinicalTrials.gov (NCT06228924). About Tenaya TherapeuticsTenaya Therapeutics is a clinical-stage biotechnology company committed to a bold mission: to discover, develop and deliver potentially curative therapies that address the underlying drivers of heart disease. Tenaya’s pipeline includes clinical-stage candidates TN-201, a gene therapy for MYBPC3-associated hypertrophic cardiomyopathy (HCM) and TN-401, a gene therapy for PKP2-associated arrhythmogenic right ventricular cardiomyopathy (ARVC) and TN-301, a clinical-stage small molecule HDAC6 inhibitor for the potential treatment of heart failure and related cardio/muscular disease, such as Duchenne’s muscular dystrophy. Tenaya has employed a suite of integrated internal capabilities, including modality agnostic target validation, capsid engineering and manufacturing, to generate a portfolio of novel medicines based on genetic insights, including multiple early-stage programs in preclinical development aimed at the treatment of both rare genetic disorders and more prevalent heart conditions. Tenaya is also leveraging this expertise through a research collaboration with Alnylam Pharmaceuticals to discover novel human genetic targets for the potential development of disease-modifying treatments for cardiovascular diseases. For more information, visit www.tenayatherapeutics.com. Forward-Looking StatementsThis press release contains forward-looking statements as that term is defined in Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. Statements in this press release that are not purely historical are forward-looking statements. Words such as “planned,” “potential,” “will,” and similar expressions are intended to identify forward-looking statements. Such forward-looking statements include, among other things, the therapeutic potential of TN-401 as a treatment for ARVC caused by mutations in the PKP2 gene; the timing and content of the RIDGE-1 data presentation and related conference call, as well as Tenaya’s other ASGCT poster presentations; and TN-501 as a potential treatment for PLN R14del-associated DCM. The forward-looking statements contained herein are based upon Tenaya’s current expectations and involve assumptions that may never materialize or may prove to be incorrect. These forward-looking statements are neither promises nor guarantees and are subject to a variety of risks and uncertainties, including but not limited to: availability of data at the referenced times; the timing and progress of RIDGE-1 and Tenaya’s other ongoing clinical trials; the potential failure of Tenaya’s product candidates to demonstrate safety and/or efficacy in clinical testing; the potential for any clinical trial results to differ from preclinical, interim, preliminary, topline or expected results; risks associated with the process of discovering, developing and commercializing therapies that are safe and effective for use as human therapeutics; Tenaya’s ability to develop, initiate or complete preclinical studies and clinical trials, and obtain approvals, for any of its product candidates; Tenaya’s continuing compliance with applicable legal and regulatory requirements; Tenaya’s ability to raise any additional funding it will need to continue to pursue its business and product development plans; Tenaya’s reliance on third parties; Tenaya’s manufacturing, commercialization and marketing capabilities and strategy; the loss of key scientific or management personnel; competition in the industry in which Tenaya operates; Tenaya’s ability to obtain and maintain intellectual property protection for its product candidates; general economic and market conditions; and other risks. Information regarding the foregoing and additional risks may be found in the section entitled “Risk Factors” in documents that Tenaya files from time to time with the Securities and Exchange Commission. These forward-looking statements are made as of the date of this press release, and Tenaya assumes no obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law. Tenaya ContactsMichelle CorralVP, Corporate Communications and Investor RelationsIR@tenayathera.com InvestorsAnne-Marie FieldsPrecision AQannemarie.fields@precisionaq.com MediaWendy RyanTen Bridge Communicationswendy@tenbridgecommunications.com