Engineered ACE2 decoy in dry powder form for inhalation: A novel therapy for SARS-CoV-2 variants

Takaaki Ito; Tatsuya Suzuki; Yusuke Sakai; Keisuke Nishioka; Yumi Itoh; Kentarou Sakamoto; Nariko Ikemura; Satoaki Matoba; Yasunari Kanda; Junichi Takagi; Toru Okamoto; Kohei Tahara; Atsushi Hoshino

doi:10.1016/j.omtm.2025.101459

Engineered ACE2 decoy in dry powder form for inhalation: A novel therapy for SARS-CoV-2 variants

Mol Ther Methods Clin Dev. 2025 Mar 31;33(2):101459. doi: 10.1016/j.omtm.2025.101459. eCollection 2025 Jun 12.

Authors

Takaaki Ito¹, Tatsuya Suzuki^{2

3}, Yusuke Sakai⁴, Keisuke Nishioka⁵, Yumi Itoh^{2

3}, Kentarou Sakamoto⁶, Nariko Ikemura⁷, Satoaki Matoba⁷, Yasunari Kanda⁸, Junichi Takagi^{6

9}, Toru Okamoto^{2

3}, Kohei Tahara^{1

10}, Atsushi Hoshino⁷

Affiliations

¹ Laboratory of Pharmaceutical Engineering, Gifu Pharmaceutical University, Gifu 501-1196, Japan.
² Department of Microbiology, Juntendo University School of Medicine, Tokyo 113-8421, Japan.
³ Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan.
⁴ Department of Pathology, National Institute of Infectious Diseases, Tokyo 208-0011, Japan.
⁵ Department of Infectious Diseases, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
⁶ Laboratory for Protein Synthesis and Expression, Institute for Protein Research, Osaka University, Osaka 565-0871, Japan.
⁷ Department of Cardiovascular Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
⁸ Division of Pharmacology, National Institute of Health Sciences, Kanagawa 210-9501, Japan.
⁹ Center for Infectious Disease Education and Research, Osaka University, Osaka 565-0871, Japan.
¹⁰ Laboratory of Nanofiber Technology, Gifu Pharmaceutical University, Gifu 501-1196, Japan.

Abstract

The persistent threat of SARS-CoV-2 and the emergence of new variants has prompted the development of a novel, easily administered modality that can overcome viral mutations. The engineered ACE2 decoy shows neutralizing activity comparable to monoclonal antibodies and is broadly effective against SARS-CoV-2 variants and ACE2-utilizing sarbecoviruses. In addition to intravenous administration, this decoy has shown antiviral efficacy through nebulized aerosol inhalation in murine and primate models, offering a dose-sparing advantage. Clinically, dry powder formulation is ideal for convenience and storage but poses challenges for protein biologics. This study developed a freeze-dried spray formulation of the ACE2 decoy for inhalation. The trehalose and leucine-based excipient maintained neutralizing activity and prevented aggregate formation. The dry powder showed aerodynamic distribution from bronchi to alveoli, aiding protection against SARS-CoV-2 infections. Neutralizing activity, structural stability, and powder dispersibility were preserved after 6 months of storage. In a mouse model of SARS-CoV-2 infection, significant reductions in viral replication and lung pathology were observed with intratracheal administration 24 h post-infection. The ACE2 decoy retained activity against recent JN.1 and current KP.3 strains, confirming its robust efficacy against viral mutations. This ACE2 decoy powder inhalant is a self-administered, next-generation treatment addressing the ongoing immune-evading evolution of SARS-CoV-2.

Keywords: ACE2 decoy; SARS-CoV-2; dry powder formulation; escape mutations; variants.