Arcturus Therapeutics Received Approval from Singapore Health Sciences Authority to Proceed with Phase 2 Study of ARCT-021 (LUNAR-COV19) Vaccine Candidate and Provides New and Updated Clinical and Preclinical Data - Seite 2

Summary of Phase 1/2 Interim Clinical Data
Participant Description

• 106 participants; 78 received ARCT-021; 28 received placebo
• 44 participants received ARCT-021 at doses selected for Phase 2 – 27 young adults (≤ 55 years), and 17 older adults (> 55 years)
• 34 participants (22 young adults; 12 older adults) received a single administration of 5 µg
• 10 participants (5 young adults, 5 older adults) received a single administration of 7.5 µg
• 24 participants (12 young adults, 12 older adults) received a prime-boost regimen (5 µg x 2)

Safety and Tolerability

• No safety concerns identified
• No participants have withdrawn from the study; all participants completed all doses
• All adverse events except 2 were mild or moderate at doses selected for Phase 2
  • Transient, asymptomatic Grade 3 lymphopenia seen in one participant. Lymphopenia has been observed with other RNA vaccines.
  • Transient Grade 3 fatigue and myalgia observed following second injection in one older adult.
• Only serious adverse event (SAE) was in a placebo participant

Immunogenicity

• All (44/44) subjects receiving the 5µg or7.5 µg dose had humoral immune responses for binding (Luminex) and/or neutralizing antibodies (PRNT50)
  • Binding antibody titers peaked through Day 43 for 5 µg and 7.5 µg single administration groups, and Day 57 for 5 µg prime-boost groups.
  • Peak geometric mean binding antibody titers: 4,959 (5 µg single shot); 6,749 (7.5 µg single shot); 16,642 (5 µg prime-boost); placebo less than 400.
  • Responder peak geometric mean neutralizing antibody titers of 32, 33 and 46, following 5 µg single dose, 7.5 µg single dose and 5 µg prime-boost participants, respectively.
  • Neutralizing antibody titers in convalescent sera ranged from 12 to 1818.

• Cellular immune responses to SARS-COV-2 peptide pools evident by Day 15 for 5 µg and 7.5 µg doses
  • PBMC ELISpot responses detected at Day 15.
  • CD8+ and CD4+ T cell responses shown on cytokine staining (IFN-ϒ) at Day 29 following single dose at 5 µg and 7.5 µg and sustained at 2 weeks following boost at 5 µg.
  • Th1 dominant CD4+ response following single dose and prime boost regimens.

New Preclinical Data Supports Protection from SARS-CoV-2