Benzinga | Jan 25, 2022 08:09AM EST

Arcturus Therapeutics Reports New Data Demonstrating Neutralizing Antibody Immune Response To The SARS-CoV-2 Omicron Variant From ARCT-154 And ARCT-165 Booster Clinical Trial

Arcturus Therapeutics Holdings Inc. ((the &ldquo, Company&rdquo, , &ldquo, Arcturus&rdquo, , NASDAQ:ARCT), a leading clinical-stage messenger RNA medicines company focused on the development of infectious disease vaccines and significant opportunities within liver and respiratory rare diseases, today announced 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.

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Figure 1: Pseudovirus (Omicron variant, research use) MNT assay results. Antibody titers corresponding to 50% viral inhibition (ID50) in trial participants at Day 1 (prior to boosting) and Day 29 after boosting with ARCT-154 (left; n = 12/12) and ARCT-165 (right; n = 12/12). The bar graphs show the geometric means of neutralization titers, with 95% confidence intervals. The multiples are fold rises of neutralizing antibody titers on Day 29 over Day 1 values. ID?50: half-maximal inhibitory dose; LLOQ: lower limit of quantitation. (Graphic: Business Wire)

New data from the Phase 1/2 booster trial, sponsored by Arcturus and currently ongoing in U.S. 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(r), 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.

"Arcturus' lower dose STARR(tm) self-amplifying mRNA vaccine technology continues to generate highly encouraging clinical booster data, increasing the platform's potential to address endemic markets for COVID and other infectious diseases," said Joseph Payne, President and CEO of Arcturus Therapeutics. "Demonstration of high levels of neutralizing antibody responses against a broad range of variants, including Omicron, suggests that our self-amplifying mRNA vaccine platform has the potential to combat not only the present variants of concern, but also emerging variants of SARS-CoV-2."

Twenty four (24) 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(r) 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 (MNT) assay (Moore Laboratory, National Institute for Communicable Diseases and University of the Witwatersrand, South Africa).