TOKYO -- A new type of coronavirus vaccine that requires less than one-tenth the dosage of existing shots made by Pfizer and others is nearing clinical trials in Japan, with the developer hoping to counter new variants of the virus.
U.S.-based VLP Therapeutics will apply for Japanese approval by June, and aims to start clinical trials by the summer. The first phase would involve dozens of participants at Oita University Hospital.
The vaccine uses messenger RNA (mRNA), which is also used in the Pfizer/BioNTech vaccine. The messenger RNA instructs cells to produce a protein found in the coronavirus. This protein stimulates an immune response against the virus.
But mRNA breaks down easily in the body, requiring a sufficient amount to be injected in each shot. VLP's experimental vaccine tries to solve this problem by including instructions in the mRNA for replicating itself.
VLP estimates that the dosage required per person would be 1 to 10 micrograms, which is 1% to 10% the amount required for other RNA-based vaccines. In theory, Japan's entire population would require about 130 grams to 1,300 grams.
VLP aims to move on to a phase two study as early as the end of this year, then conduct a large-scale phase three trial in 2022. If the clinical trials go well, Fujifilm would produce the vaccine.
VLP was founded in 2013 by Wataru Akahata, a vaccine researcher at the U.S. National Institutes of Health. The startup is backed by investors including Japanese trading house Sojitz and Miyako Capital. It has also been supported by the Japan Agency for Medical Research and Development since fiscal 2020.
Animal experiments showed that VLP's vaccine is effective against the South Africa and Brazil variants of the coronavirus, according to the company. "If safe, highly effective vaccines can be manufactured domestically, it will be easier to respond if a troublesome variant appears in Japan," Akahata said.
Similar vaccines have been developed in the U.S. and the U.K. U.S.-based Arcturus Therapeutics and others are planning to start a phase three clinical trial by June, involving over 10,000 participants. Phase one and two trials in the U.S. and Singapore reportedly showed promising results. The U.K.'s Imperial College London has started a second phase trial.
For regulators, these vaccines pose a new challenge for evaluating safety.
"If self-replication of mRNA continues excessively, it risks causing unexpected side effects," said Keiji Itaka, professor at Tokyo Medical and Dental University.