26 January 2022 - - US-based messenger RNA medicines company Arcturus Therapeutics Holdings Inc. (NASDAQ: ARCT) has received new data from clinical development programs for ARCT-154 and ARCT-165, its investigational, next-generation, self-amplifying mRNA vaccine candidates targeting variants of concern, the company said.

New data from the Phase 1/2 booster trial, sponsored by Arcturus and currently ongoing in US and Singapore, demonstrated that ARCT-154 and ARCT-165, when administered in low doses (5 mcg) at least five months following initial vaccination with Comirnaty, yielded robust increases of 54- and 47-fold, respectively, in neutralizing antibody responses against the Omicron variant.

These findings provide additional data to recently updated results from the Phase 1/2 demonstrating robust neutralizing antibody responses against SARS-CoV-2 D614G strain as well as several variants of concern, and is expected to support the expansion of clinical development of the candidates to evaluate their potential as booster vaccines.

Twenty four participants, divided equally in the ARCT-154 and ARCT-165 booster groups, received 5 micrograms of ARCT-154 or ARCT-165 following primary vaccination with Comirnaty at least 5 months earlier.

All participants in the booster trial were below 65 years of age at the time of receiving the booster dose.

Figure 1 shows the neutralizing antibody geometric mean titers against the Omicron strain for the ARCT-154 and the ARCT-165 groups on Day 29 post-boost compared to pre-boost titer, as measured by an exploratory microneutralization titer assay (Moore Laboratory, National Institute for Communicable Diseases and University of the Witwatersrand, South Africa).

Founded in 2013 and based in San Diego, California, Arcturus Therapeutics Holdings Inc. (NASDAQ: ARCT) is a clinical-stage mRNA medicines and vaccines company with enabling technologies: LUNAR lipid-mediated delivery, STARR mRNA Technology and mRNA drug substance along with drug product manufacturing expertise.

Arcturus' diverse pipeline of RNA therapeutic and vaccine candidates includes mRNA vaccine programs for SARS-CoV-2 (COVID-19) and influenza, and other programs to potentially treat ornithine transcarbamylase deficiency, and cystic fibrosis along with partnered programs including glycogen storage disease type III (GSD III), hepatitis B virus, and non-alcoholic steatohepatitis.

Arcturus' versatile RNA therapeutics platforms can be applied toward multiple types of nucleic acid medicines including messenger RNA, small interfering RNA, replicon RNA, antisense RNA, microRNA, DNA, and gene editing therapeutics.

Arcturus' technologies are covered by its extensive patent portfolio (with patents and patent applications issued in the US, Europe, Japan, China and other countries).