First self-amplifying mRNA vaccine reaches Europe
Arcturus Therapeutics and CSL's COVID-19 vaccine Kostaive has been approved for marketing in the EU, becoming the first based on self-amplifying mRNA (sa-mRNA) to clear that threshold.
While entering a market that has reduced dramatically in size since the end of the pandemic, Kostaive is being billed as a technological advance on current mRNA shots like Moderna's Spikevax and Pfizer/BioNTech's Comirnaty as it stimulates longer-lasting immunity.
Unlike regular mRNA vaccines, sa-mRNA vaccines – as their name suggests – instruct the body to make more mRNA and protein to boost the immune response, rather than relying on a finite dose which results in protection waning over time.
Arcturus and CSL say they have clinical trial data showing Kostaive (formerly ARCT-154) offers superior immunogenicity and antibody persistence for up to 12 months post-vaccination compared to conventional mRNA jabs. It is targeted at the JN.1 subtype of Omicron variant BA.2.86, which is still one of the main strains currently circulating 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.
The EU isn't the first market where Kostaive is approved. It has also been given the green light in Japan, where it is being distributed by Meiji Seika Pharma and started rolling out in the 2024/25 COVID-19 immunisation campaign.
The first sa-mRNA vaccine to reach any market was Gennova Biopharmaceuticals' Gemcovac, which was launched in India in 2022 on the back of an emergency approval as the pandemic was still in full swing.
A launch in Europe isn't imminent, however, as CSL wants to make changes to Kostaive's formulation to "better meet the needs of healthcare professionals and their patients," according to Jonathan Edelman, head of CSL's vaccine innovations unit.
"As COVID-19 remains an unpredictable global threat, CSL is dedicated to completing these technical enhancements and making this innovative vaccine available in Europe as soon as possible," he added.
CSL licensed rights to the Arcturus-developed vaccine in 2022, paying $200 million upfront to access the San Diego, US-based biotech's sa-mRNA platform for COVID-19 as well as other respiratory diseases including influenza.
Arcturus said at the time it was eligible to receive more than $4.3 billion in milestone payments if certain development and commercial objectives were met, plus a 40% net profit share for COVID-19 vaccines.
