Nature Communications Publishes Pivotal Data Demonstrating Efficacy and Tolerability of CSL and Arcturus Therapeutics’ COVID-19 Vaccine

Global biotechnology leader CSL (ASX:CSL; USOTC:CSLLY) and Arcturus Therapeutics (Nasdaq: ARCT) today announce Nature Communications has published results from an integrated phase 1/2/3a/3b study evaluating the safety, immunogenicity, and efficacy of ARCT-154, a novel self-amplifying (sa-mRNA) COVID-19 vaccine and the world’s first approved sa-mRNA COVID-19 vaccine.

The results demonstrate that two 5 μg doses of ARCT-154, sa-mRNA vaccine, were well-tolerated, immunogenic and provided significant protection against multiple strains of COVID-19. The efficacy of ARCT-154 against severe COVID-19 was 100 percent in healthy persons aged 18-59 and more than 90 percent in persons at risk of severe consequences of the disease due to co-morbidities or older age.

“The results published in Nature Communications demonstrate the efficacy and tolerability of ARCT-154 and add to a growing body of evidence that our sa-mRNA vaccine has the potential to provide significant protection against the pervasive virus, reinforcing our promise to protect public health,” said Jon Edelman, M.D., Senior Vice President, Vaccines Innovation Unit, CSL.

“We are thrilled that the results of the ARCT-154 study have been published in the highly respected journal Nature Communications,” said Pad Chivukula, Ph.D., Chief Scientific Officer of Arcturus Therapeutics. “These data and the approval in Japan highlight the strength of our and CSL’s commitment to delivering innovative technology that protects the public from COVID-19.”

The Nature Communications article titled, “Safety, immunogenicity and efficacy of the self-amplifying mRNA ARCT-154 COVID-19 vaccine: pooled phase 1, 2, 3a and 3b randomized, controlled trials” was published online.

About the study

During the observer-blind, randomized, controlled phase 1, 2, 3a and 3b integrated study, adults ≥18 years old receive two 5 μg doses of ARCT-154 or saline placebo 28 days apart. Phase 2/3a/3b participants were stratified by age (< 60 or ≥ 60 years of age) and by risk of severe COVID-19 prior to being randomized 3:1 (phase 1/2/3a) or 1:1 (phase 3b) to vaccine or placebo groups. The primary endpoints were vaccine efficacy up to 2 months after dose 2, reactogenicity within up to 7 days of each dose, safety within up to 28 days after each dose, and immunogenicity measured 28 days after each dose. From August 15 to January 12, 2023, 1,001 participants were randomized (748 ARCT-154 and 253 placebo) in the integrated phase 1/2/3a study, and 16,100 participants (8,056 ARCT-154 and 8,044 placebo) in the phase 3b study.