Once-Weekly Intranasal Potential: Preclinical PK data demonstrate single-dose drug levels sustained above designed therapeutic concentrations for up to 7 days in nasal mucosal and lung tissue.

Addressing Endemic Coronaviruses: DCOY-CoV is designed to protect against endemic human coronaviruses (OC43, 229E, NL63, HKU1, and SARS-CoV-2), in people at high risk of serious illness including the more than 20 million high-risk immunocompromised and 15 million COPD patients in the U.S. and Europe.

Symposium Showcase: Chief Technology Officer Dr. Michael Lipp presenting initial PK dataset today, September 29 at the Boulder Peptide Symposium's Peptide Showcase.

CAMBRIDGE, Mass., Sept. 29, 2026 /PRNewswire/ -- Decoy Therapeutics, Inc. (NASDAQ: DCOY), a biotechnology company pioneering Designable Multi-Antivirals (D-MAVs™), today announced preclinical pharmacokinetic (PK) data supporting once-weekly intranasal administration for its lead program, DCOY-CoV. Results demonstrate that a single intranasal dose maintains therapeutic drug concentrations in both upper respiratory mucosal tissues and deep lung tissue for up to seven days.

Dr. Michael Lipp, Chief Technology Officer and Co-Founder of Decoy Therapeutics, will present these data today, September 29 at the Boulder Peptide Symposium's Peptide Showcase in Napa Valley, California. 

Preclinical PK Breakthrough Data: Extended Tissue Retention

Using a design concept analogous to the once-weekly GLP-1 subcutaneous therapies, Decoy leveraged lipid- and peptide-conjugate engineering through its proprietary IMP³ACT™ platform, constructing DCOY-CoV for extended tissue residence. In preclinical studies, a single intranasal dose showed:

• Sustained Therapeutic Coverage: drug levels remained above designed antiviral concentrations for seven days post-dose.
• Deep Lung & Respiratory Protection: High persistence in lung tissue supports protection against lower respiratory tract infections, the primary cause of severe coronavirus-related morbidity.
• Compliance-Driven Design: Once-weekly intranasal delivery overcomes compliance barriers inherent in daily oral or inhaled regimens.

"Most antivirals are built for a single virus, but a D-MAV targets conserved fusion mechanisms shared across viral families," said Rick Pierce, Chief Executive Officer of Decoy Therapeutics. "Two of the biggest drivers of real-world therapeutic value are patient compliance and convenience. A single drug that covers multiple coronaviruses and requires only once-weekly administration directly addresses both."

High Unmet Need in 20 Million+ High-Risk Patients

While common cold coronaviruses cause mild symptoms in healthy individuals, endemic coronaviruses can pose severe health risks for an estimated 20 million immunocompromised or otherwise high-risk individuals across the U.S. and Europe, and for the more than 15 million Americans living with Chronic Obstructive Pulmonary Disease (COPD). Respiratory viruses can lead to:   

• Severe COPD Flare-ups: Respiratory viruses are detected in ~40% of COPD flare-ups requiring hospital or emergency care. People with COPD hospitalized with a viral respiratory infection have 50% higher odds of ICU admission and 90% higher odds of mechanical ventilation than those without a virus.
• High Mortality in Transplant & Vulnerable Cohorts: 30-day mortality among hospitalized adults with endemic coronaviruses reaches up to 25%. In stem cell transplant recipients, progression to lower respiratory tract infection during the 2024-2025 respiratory season.10% to 30% mortality rate. COVID-19 alone was associated with an estimated 34,000 to 53,000 US deaths during the 2024-2025 respiratory season.
• Economic Cost: These viruses can be very expensive for the healthcare system. For example, total U.S. COPD direct medical cost is about $50 billion a year, and a single hospitalized flare-up can cost more than $18,000.

Apart from COVID-19, there are currently no FDA-approved antiviral treatments or prophylactics for endemic human coronaviruses.

"What we are working toward is a self-administered dose you take once and stop thinking about for the rest of the week," said Dr. Barbara Hibner, Chief Scientific Officer and Co-Founder of Decoy Therapeutics. "For fragile patients where a common respiratory virus can cause irreversible lung damage, once-weekly protective coverage represents a crucial breakthrough." 

Program Timeline DCOY-CoV is expected to enter clinical trials in 2027.

About Decoy Therapeutics, Inc.
Decoy Therapeutics (NASDAQ: DCOY) is a biotechnology company developing Designable Multi-Antivirals (D-MAVs™) powered by its proprietary IMP³ACT™ platform. By combining generative AI structural design with advanced peptide-conjugate chemistry, Decoy creates single therapeutics that target conserved viral entry machinery across entire viral families. Decoy's pipeline includes programs targeting endemic coronaviruses (COVID-19, MERS), paramyxoviruses (RSV, hPIV, Nipah, Measles), and filoviruses (Ebola, Marburg). For more information, visit decoytx.com. 

Forward-Looking Statements
This press release contains "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995 regarding Decoy, including expected achievement of milestones for its lead asset and future prospects of Decoy. These statements may discuss goals, intentions and expectations as to future plans, trends, events, results of operations or financial condition, or otherwise, based on current beliefs of the management of Decoy, as well as assumptions made by, and information currently available to, management. Forward-looking statements generally include statements that are predictive in nature and depend upon or refer to future events or conditions, and include words such as "may," "will," "can," "should," "would," "expect," "anticipate," "plan," "likely," "believe," "estimate," "project," "intend," and other similar expressions. Statements that are not historical facts are forward-looking statements. Forward-looking statements are based on current beliefs and assumptions that are subject to risks and uncertainties and are not guarantees of future performance. Actual results could differ materially from those contained in any forward-looking statement as a result of various factors, including, without limitation: the risk that the Company will not obtain sufficient financing to execute on their business plans and risks related to Decoy's products and development plans, including unanticipated issues with any IND application process and the potential of the IMP³ACT™ platform. Readers are urged to carefully review and consider the various disclosures made by the Company in its reports filed with the SEC, including its Annual Report on Form 10-K for the fiscal year ended December 31, 2025, as revised or supplemented by its Quarterly Reports on Form 10-Q and other documents filed with the SEC. If one or more of these risks or uncertainties materialize, or if the underlying assumptions prove incorrect, Decoy's actual results may vary materially from those expected or projected.

Business Development Contact:
Peter Marschel, Chief Business Officer
Email: peter@decoytx.com | Phone: 617-943-6305

Media Relations Contact:
Tara Mulloy, TMC Studio
Email: tara@tmc-studio.com | Phone: 978-855-5219

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SOURCE Decoy Therapeutics, Inc.