CSL, Arcturus get first approval for self-assembling RNA jab

Japan’s medicines regulator has approved the first vaccine based on self-assembling RNA, a spin on the mRNA technology used in current shots, which is designed to deliver greater efficacy with a lower dose.

The Ministry of Health, Labour and Welfare (MHLW) gave the green light to CSL and Arcturus’ COVID-19 vaccine ARCT-154 – also known as Lunar-COV19 – which will be commercialised in Japan by partner Meiji Seika Pharma. Japan is the first country to clear the saRNA vaccine, which has also been filed for approval in Europe.

The lipid nanoparticle-formulated shot, given in two doses 28 days apart, has been shown to be effective against multiple ancestral strains of SARS-CoV-2, the virus that caused COVID-19. In phase 3 trials, it showed more than 95% efficacy in the prevention of severe COVID infections.

saRNA vaccines rely on RNA-dependent RNA polymerases (RDRP) derived from RNA viruses to amplify the delivered RNA, increasing the production of antigen proteins in the body. Studies suggest the approach can improve the durability of protection, in part because it prolongs the stimulation of antigen-presenting cells (APCs) important for long-term immunity.

CSL’s Seqirus subsidiary bought into the ARCT-154 programme last year as part of a wide-ranging collaboration for saRNA vaccines spanning COVID-19, influenza and other respiratory infections that included an upfront payment of $200 million and more than $4 billion in potential milestones.

The bottom has largely dropped out of the market for COVID-19 vaccines, with the two top producers of mRNA-based shots – Pfizer/BioNTech and Moderna – both reporting lowered sales expectations this year that could get worse in 2024 before stabilising in 2025 and beyond.

ARCT-154 targets ancestral variants of the coronavirus, so will likely not be an option for current vaccination campaigns. Nevertheless, the MHLW is an important milestone for the saRNA field and the Arcturus/CSL alliance, which has candidates against other variants in phase 3 testing – including the prevailing XBB.1.5 strain – as well as season and pandemic flu candidates in early development.

The approval “marks a historic and exciting milestone as the first [saRNA] vaccine in the world to be registered, and supports CSL’s promise to protect global public health,” said Jonathan Edelman, head of the company’s vaccines innovation unit.

“We are committed to working with health authorities around the world to ensure this important vaccine technology will be available to people at risk for COVID-19.”

Photo by Tianshu Liu on Unsplash