AFRRI/NIAID Designs Proprietary PBI-BM2.5 Protocol to Evaluate Valion Bio's (NASDAQ: VBIO) Entolimod as the First and Only Treatment for GI-ARS

AFRRI/NIAID partnership and validated animal models significantly derisk regulatory and commercial advancement of Company's lead candidate

Positive momentum further positions Entolimod as a potential first and only treatment for GI-ARS, representing a multi-billion-dollar commercial opportunity

SAN ANTONIO, June 25, 2026 /PRNewswire/ -- Valion Bio, Inc. (Nasdaq: VBIO) ("Valion Bio" or the "Company") today announced that the Armed Forces Radiobiology Research Institute ("AFRRI"), a division of the U.S. Department of War ("DoW"), in partnership with the National Institute of Allergy and Infectious Diseases ("NIAID"), has completed design of the survival efficacy protocol that will be used to evaluate the Company's lead candidate, Entolimod™, for the treatment of Gastrointestinal Acute Radiation Syndrome ("GI-ARS").

The final AFRRI/NIAID protocol design for Entolimod emanates from the Company's previously announced non-clinical evaluation agreement with NIAID, and closely follows the U.S. House Armed Services Committee's direction to the DoW to develop a resources and fielding plan for prioritizing radiation/nuclear countermeasures that, like Entolimod, are both prophylactic (pre-exposure) and therapeutic (post-exposure).

Currently, no U.S. Food and Drug Administration ("FDA")-approved medical countermeasures exist to mitigate GI-ARS; representing a critical therapeutic and commercial gap in a market driven by U.S. government emergency preparedness requirements. The AFRRI/NIAID-selected partial body irradiation with 2.5% bone marrow sparing/shielding ("PBI-BM2.5") at lethal radiation dose (LD50/30 of 14.6 Gy) murine model to evaluate Entolimod is scientifically rigorous and meets the FDA's Animal Rule criteria, which allows the Agency to approve new drugs and biological products based on animal efficacy studies when human clinical trials are unethical or not feasible, such as in the case of internal radioactive contamination.^1,2,3

Entolimod is a recombinant deletion variant of Salmonella FliC flagellin engineered to activate TLR5 selectively. Upon engagement, Entolimod triggers specific pathways that ultimately promote multi-tissue cytoprotection and inhibit apoptosis in radiosensitive hematopoietic and gastrointestinal tissues. By utilizing a proprietary murine model that spares only 2.5% of bone marrow (one hind leg and tail) from a lethal radiation dose, the study will isolate GI pathophysiology from overwhelming hematopoietic failure — creating a cleaner efficacy signal for a mechanism targeting intestinal epithelial recovery and immune restoration.

Valion Bio CEO, Michael Handley, said, "The AFRRI protocol finalization represents a key inflection point for Entolimod as a radiation/nuclear countermeasure and for Valion as a company. We are now positioned to generate the high-quality non-clinical efficacy data that the FDA and the government require to support future licensure under the Animal Rule. The gastrointestinal subsyndrome of ARS is the market's greatest unmet need—it is lethal, it is currently untreated, and it is precisely where Entolimod's TLR5 agonist mechanism has the greatest potential to differentiate from incumbent G-CSF therapy."

This Entolimod protocol advancement comes as the broader ARS medical countermeasures market accelerates, with global market valuations reaching an estimated $5.47 billion by 2025 and projected to expand to $7.80 billion by 2032, growing at a compound annual growth rate of 5.2%. North America, where government stockpiling and biodefense spending concentrate, accounts for 46% of market revenue.⁴

Sources

¹ Vidya P. Kumar, Kefale Wuddie, Alena Tsioplaya, Alia Weaver, Gregory P. Holmes-Hampton, and Sanchita P. Ghosh "Development of a Multi-Organ Radiation Injury Model with Precise Dosimetry with Focus on GI-ARS," Radiation Research 201(1), 19-34, (28 November 2023). https://doi.org/10.1667/RADE-23-00068.1

² Krivokrysenko VI, Toshkov IA, Gleiberman AS, Krasnov P, Shyshynova I, Bespalov I, Maitra RK, Narizhneva NV, Singh VK, Whitnall MH, Purmal AA, Shakhov AN, Gudkov AV, Feinstein E "The Toll-Like Receptor 5 Agonist Entolimod Mitigates Lethal Acute Radiation Syndrome in Non-Human Primates," PLoS One (14 September 2015). https://doi.org/10.1371/journal.pone.0135388.

³ FDA "Animal Rule Information" https://www.fda.gov/emergency-preparedness-and-response/preparedness-research/animal-rule-information

⁴ CoherentMI "Acute Radiation Syndrome Market Size and Share Analysis – Growth Trends and Forecasts" ^{https://www.coherentmi.com/industry-reports/acute-radiation-syndrome-market}

About Valion Bio, Inc.

Valion Bio, Inc. (Nasdaq: VBIO), the new corporate identity of Tivic Health Systems, Inc., is developing biologics that activate innate immune pathways for cytoprotection and modulate immune responses in conditions driven by radiation, disease, and immune dysregulation. The Company's lead candidate, Entolimod for acute radiation syndrome (ARS), has been extensively studied and has demonstrated survival benefits and improved tissue recovery in animal models under the FDA's Animal Rule. Entolimod is a novel Toll-like receptor 5 (TLR5) agonist that activates NF-κB signaling pathways to protect cells from damage and stimulate immune responses. Entolimod for ARS has received Fast Track and Orphan Drug designations from the U.S. Food and Drug Administration. Valion Bio is also advancing Entolasta, a next-generation TLR5 agonist designed for potential broader therapeutic applications, including oncology supportive care. Valion Bio's wholly owned subsidiary, Velocity Bioworks, a contract development and manufacturing organization (CDMO), currently provides biomanufacturing services to Valion, and is working towards providing services to third-party biotech companies in the future. For more information, visit www.valionbio.com.

Forward-Looking Statements

This press release may contain "forward-looking statements" that are subject to substantial risks and uncertainties. All statements, other than statements of historical fact, contained in this press release are forward-looking statements. Forward-looking statements contained in this press release may be identified by the use of words such as "anticipate," "believe," "con template," "could," "estimate," "expect," "intend," "seek," "may," "might," "plan," "potential," "predict," "project," "target," "aim," "should," "will," "would," or the negative of these words or other similar expressions, although not all forward-looking statements contain these words. Forward-looking statements are based on Valion Bio, Inc.'s current expectations and are subject to inherent uncertainties, risks, and assumptions that are difficult to predict. Further, certain forward-looking statements are based on assumptions as to future events that may not prove to be accurate, including as a result of the company's interactions with and guidance from the FDA and other regulatory authorities; the continued interest of BARDA and other U.S. government agencies in Entolimod; the ability of the company to achieve the expected benefits from the acquisition of development and manufacturing assets within expected time frames or at all; changes to the company's relationship with its partners; failure to obtain FDA or similar clearances or approvals and noncompliance with FDA or similar regulations, including related to the Animal Rule; the company's future development of Entolimod or Entolasta; changes to the company's business strategy; timing and success of pre-clinical and clinical trials and study results; regulatory requirements and pathways for approval; the company's ability to successfully commercialize its product candidates in the future; changes in the markets and industries in which the company does business; consummation of any strategic transactions; the company's need for, and ability to secure when needed, additional working capital; the company's ability to maintain its Nasdaq listing; and changes in tariffs, inflation, legal, regulatory, political and economic risks. Accordingly, you are cautioned not to place undue reliance on such forward-looking statements. For a discussion of risks and uncertainties relevant to the company, and other important factors, see Valion Bio's filings with the SEC, including, its Annual Report on Form 10-K for the year ended December 31, 2025, filed with the SEC on March 30, 2026, under the heading "Risk Factors", as well as the company's subsequent filings with the SEC. Forward-looking statements contained in this press release are made as of this date, and the company undertakes no duty to update such information except as required by applicable law.

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SOURCE Valion Bio, Inc.