Nature Communications Publishes Key Data on CSL and Arcturus Therapeutics' COVID-19 Vaccine

Recent data confirm the effectiveness of ARCT-154, the first self-amplifying (sa-mRNA) COVID-19 vaccine approved for adults in Japan. This vaccine has shown superior immunogenicity against the Omicron BA 4/5 variant compared to traditional mRNA COVID-19 vaccine boosters and has demonstrated longer-lasting immunity.

CSL, a global biotechnology firm, and Arcturus Therapeutics recently announced that their study results have been published in Nature Communications. The study evaluated the safety, immunogenicity, and efficacy of ARCT-154, a novel sa-mRNA COVID-19 vaccine. The article, titled "Safety and immunogenicity and efficacy of the self-amplifying mRNA ARCT-154 COVID-19; pooled phase 1, 2, 3a, and 3b randomized, controlled trials," provided compelling evidence on the vaccine’s potential.

The study revealed that two doses of 5 μg ARCT-154 were well-tolerated, immunogenic, and offered significant protection against various COVID-19 strains. The vaccine exhibited 100% efficacy in preventing severe COVID-19 among healthy individuals aged 18-59 and over 90% efficacy in those at higher risk due to comorbidities or advanced age.

Jon Edelman, M.D., Senior Vice President of CSL's Vaccines Innovation Unit, remarked on the significance of the findings, underscoring the potential of the sa-mRNA vaccine in public health protection. Pad Chivukula, Ph.D., Chief Scientific Officer of Arcturus Therapeutics, also expressed satisfaction with the publication in Nature Communications, emphasizing the collaborative effort between Arcturus and CSL in advancing innovative technologies to combat COVID-19.

The integrated study included observer-blind, randomized, controlled trials across phase 1, 2, 3a, and 3b, involving adults aged 18 and above. Participants received either two doses of ARCT-154 or a saline placebo, administered 28 days apart. The study stratified participants by age and risk of severe COVID-19 before randomizing them to vaccine or placebo groups. The primary endpoints were vaccine efficacy up to two months after the second dose, reactogenicity within seven days of each dose, safety within 28 days, and immunogenicity measured 28 days post-vaccination.

From August 15 to January 12, 2023, 1,001 participants were randomized in the phase 1/2/3a study, and 16,100 participants in the phase 3b study. The findings confirmed ARCT-154's safety and tolerability, with most adverse events being mild or moderate. Both vaccine and placebo groups reported similar rates of related or severe adverse events. The phase 3b study further validated these observations.

Four weeks after the second dose, the neutralizing antibody seroconversion rate was 94.1%. The study identified 640 confirmed COVID-19 cases eligible for analysis, including 43 severe cases and 10 deaths. ARCT-154 demonstrated 56.6% efficacy against any COVID-19, 95.3% efficacy against severe COVID-19, and 86.5% efficacy against COVID-19-related deaths. For severe COVID-19, the efficacy was 100% in healthy 18-59-year-olds and 91.9% in those with comorbidities. In individuals aged 60 and above, the vaccine showed 54.3% efficacy against any severity of COVID-19 and 94.4% efficacy against severe disease.

The study was co-funded by Vinbiocare Biotechnology Joint Stock Company and Arcturus Therapeutics. The ARCT-154 vaccine utilizes sa-mRNA technology, which instructs the body to produce more mRNA and protein, thereby enhancing the immune response.

CSL, established in 1916, is a global biotechnology leader, providing lifesaving products to patients in over 100 countries. Arcturus Therapeutics, founded in 2013, focuses on mRNA medicines and vaccines, including the world's first approved sa-mRNA COVID-19 vaccine. The company leverages its extensive RNA therapeutics platforms to develop innovative treatments for various diseases.