[News Release] VLP Therapeutics Japan reports safety, immunogenicity, and optimal dosing of VLPCOV-02, a SARS-CoV-2 saRNA vaccine with modified 5-methylcytosine base [iScience]

VLP Therapeutics Japan, Inc. (VLPT Japan) researchers and their colleagues at the National Institutes of Biomedical Innovation, Health and Nutrition (NIBN) in Japan published a paper in iScience online reporting safety, immunogenicity, and optimal dosing of VLPCOV-02, a SARS-CoV-2 saRNA vaccine with modified 5-methylcytosine base. This research was supported by AMED under Grant Number JP21nf0101627.

• Authors: Masayuki Aboshi, Daisuke Kawakami, Kaoru Kono, Ayae Nishiyama, Takuto Nogimori, Yuko Sunada, Kenta Matsuda, Takashi Sekida, Shigeru Suga, Jonathan F. Smith, Nobuaki Sato, Takuya Yamamoto, Wataru Akahata* (*Corresponding author)
• DOI: 10.1016/j.isci.2026.114766
• URL: https://www.cell.com/iscience/fulltext/S2589-0042(26)00141-0
• Published online: 21 January 2026
• Abstract: Variant-adapted vaccines are becoming increasingly important for continued COVID-19 prevention. Part 1 of the phase 1/2 study with VLPCOV-02, a lipid nanoparticle-encapsulated, self-amplifying RNA (saRNA) vaccine with a modified 5-methylcytosine (5 mC) base, demonstrated lower reactogenicity and incidence of adverse events, and induction of antibody responses. We report results of part 2 with an expanded number of participants (N = 323 [3 μg VLPCOV-02: 53 non-elderly and 54 elderly; 7.5 μg VLPCOV-02: 55 non-elderly and 55 elderly; 30 μg Comirnaty ready to use: 52 non-elderly and 54 elderly]) to determine the optimal dose level. VLPCOV-02 induced robust immunoglobulin G titers against receptor-binding domain and neutralizing antibody titers against all variants of SARS-CoV-2 tested, and induced CD4+ and CD8+ T cell responses. These results indicate that the incorporation of a modified 5 mC base improves the safety profile of the saRNA vaccine without compromising immunogenicity, supporting further development of this platform as a booster vaccine.

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About VLP Therapeutics: VLP Therapeutics, Inc. (VLPT), co-founded in 2013 by Drs. Wataru Akahata, Ryuji Ueno, and Sachiko Kuno, is a Maryland, US-based biotech company with a mission to address unmet medical needs worldwide and expand the frontiers of vaccine treatment. VLPT is currently engaged in research and development of a cancer treatment vaccine as well as prophylactic vaccines against infectious diseases including malaria and dengue.

About VLP Therapeutics Japan: VLP Therapeutics Japan, Inc. (VLPT Japan), founded in 2020 by Dr. Wataru Akahata originally as a wholly owned subsidiary of US-based VLP Therapeutics, Inc., is a Tokyo-based biotech company. VLPT Japan is currently engaged in research and development of prophylactic vaccines against infectious diseases, including COVID-19, influenza, and dengue. The COVID-19 project is funded by the Japan Agency for Medical Research and Development (AMED) and the Japanese Ministry of Health, Labour and Welfare.