• SECN-15 constitutes promising new therapeutic option by enhancing anti-tumor immunity and overcoming resistance to checkpoint inhibitors
• Preclinical data substantiate enhanced anti-tumor immunity in monotherapy as well as in combination therapy setting
• New findings underline reprogramming mechanism in tumoral endothelial cells from angiogenic to immune-permissive, interferon-responsive state through NRP1 knockdown activity

Martinsried (Munich), Germany, April 17, 2026 - Secarna Pharmaceuticals GmbH & Co. KG, a company redefining the discovery and development of best-in-class oligonucleotide therapeutics today announced that additional preclinical data for its proprietary antisense oligonucleotide (ASO) SECN-15 will be presented in a poster session at the American Association for Cancer Research (AACR) Annual Meeting 2026 in San Diego, CA, USA, on Monday, April 20, 2026.

Poster Highlights
The poster outlines the potential of SECN-15 as a high-affinity ASO designed to selectively downregulate Neuropilin-1 (NRP1) expression, a promising target in oncology with the potential to break resistance to immune checkpoint inhibitors (ICIs). Elevated NRP1 expression correlates with poor prognosis across multiple solid tumors and is associated with epithelial-mesenchymal transition (EMT), angiogenesis, fibrosis and the establishment of an immunosuppressive tumor microenvironment – key processes that drive tumor progression and resistance to currently approved immunotherapies. SECN-15 demonstrates strong anti-tumor efficacy both as monotherapy and in combination with ICIs in mouse tumor models, where ICIs only show limited efficacy. Knockdown of NRP1 in tumor endothelial cells is associated with reprogramming from an angiogenic to an immune-permissive, interferon-responsive state supporting a potential role in modulating the tumor microenvironment to enhance anti-tumor immunity.

A single systemic dose of SECN-15 resulted in a sustained reduction of soluble NRP1 levels in vivo for at least 28 days, supporting durable target engagement and suggesting the potential for extended dosing intervals in clinical development. Soluble NRP1 levels in plasma will serve as a reliable and easily measurable biomarker for assessing NRP1 knockdown in subsequent clinical trials. Gastric cancer, a tumor type in which high NRP1 expression is linked to highly inferior outcomes, has been identified as potential lead indication for a planned clinical Phase I/II trial. IND-enabling studies are currently underway to advance SECN-15 into clinical development.

“We are very pleased to present additional preclinical and translational data from our lead program SECN-15 in a poster presentation at the AACR Annual Meeting 2026,” said Richard Klar, PhD, Chief Research Officer of Secarna Pharmaceuticals. “As we continue our preparations for the first-in-human clinical trials, these additional findings reinforce our approach to establish SECN-15 as promising new therapeutic strategy to target solid tumors.”

Poster Presentation Details
Title: SECN-15: Antisense oligonucleotide-mediated Neuropilin-1 suppression enhances anti-tumor immunity and overcomes checkpoint inhibitor resistance in solid tumors
Presenting Author: Richard Klar, PhD, Chief Research Officer, Secarna Pharmaceuticals
Session Title: Modifiers of Inflammation and the Tumor Microenvironment
Session Date: April 20, 2026
Session Time: 2:00 pm – 5:00 pm PDT
Location: Poster Section 10
Poster Board Number: 22
Presentation Number: 2912

About Secarna Pharmaceuticals

Secarna Pharmaceuticals is a biopharmaceutical company redefining the discovery and development of best-in-class oligonucleotide therapeutics, offering hope to patients facing conditions that are beyond the reach of current approaches and modalities. With the Company’s proprietary AI-empowered OligoCreator® platform, which includes multiple delivery technologies, Secarna identifies and characterizes oligonucleotide therapeutics with unparalleled speed and excellent safety and efficacy. By delivering these novel therapeutics to the cells, organs, or tissues where they are needed, targeted oligonucleotide therapies have the potential to revolutionize treatments for a wide range of difficult-to-treat disorders. Secarna’s unique OligoCreator® platform is leveraged to transform untreatable conditions into treatable ones, profoundly changing the future of medicine. www.secarna.com