Recent Updates
Recently added Catalysts

ARCT-2303

Phase 3

COVID-19 | Monoclonal antibody | Infectious Disease |Arcturus Therapeutics Holdings Inc.|Last Updated: Dec 12, 2025

Success Probability

Subscribe to view

Market & Valuation

Subscribe to view

Trial Design

RandomizedDouble-BlindACTIVE_CONTROLLEDDMC
Total Trials1
Total Enrollment1,514

FDA Designations

No designations recorded

Clinical trial landscape

ARCT-2303 · 1 trial · 1 indication

Phase 3 1
NCT06279871Immunogenicity and Safety Study of Self-amplifying mRNA COVID-19 Vaccine Administered With Influenza Vaccines in AdultsCOVID-19
COMPLETED1,514 Analytics
PHASE3COMPLETED
Immunogenicity and Safety Study of Self-amplifying mRNA COVID-19 Vaccine Administered With Influenza Vaccines in Adults
COVID-19Unlock trial analytics

Study Endpoints

Primary Endpoints

Groups 2a and 2b and ARCT-154-J01 Historical Control: Geometric Mean Titers (GMT) of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Neutralizing Antibody Titers Against Omicron XBB.1.5 Subvariant at Day 29
Day 29
Groups 2a and 2b and ARCT-154-J01 Historical Control: Number of Participants With Seroconversion to SARS-CoV-2 Neutralizing Antibody Against Omicron XBB.1.5 Subvariant at Day 29
Day 29

Seroconversion was defined as either a pre-vaccination titer below the lower limit of quantitation (LLOQ) and a postvaccination titer ≥4xLLOQ; or a pre-vaccination titer ≥LLOQ and a ≥4-fold increase in post-vaccination titer.

Groups 1a and 3a: Adjusted Hemagglutination Inhibition (HI) GMTs Against Influenza Vaccine Strains at Day 29
Day 29

Influenza vaccine strains were A/H1N1, A/H3N2, B/Victoria, and B/Yamagata.

Groups 1a and 2a: Adjusted GMTs of SARS-CoV-2 Neutralizing Antibody Against Omicron XBB.1.5 Subvariant at Day 29
Day 29

Secondary Endpoints

Groups 1a and 2a: GMT of SARS-CoV-2 Neutralizing Antibodies Against Omicron XBB.1.5 Subvariant at Days 1, 29 and 181
Group 1a: Days 1 and 29; Group 2a: Days 1, 29, and 181
Groups 1a and 2a: Geometric Mean Fold Rise (GMFR) of SARS-CoV-2 Neutralizing Antibodies Against Omicron XBB.1.5 Subvariant at Days 29 and 181
Group 1a: Day 29; Group 2a: Days 29 and 181
Groups 1a and 2a: Number of Participants With Seroconversion of SARS-CoV-2 Neutralizing Antibodies Against Omicron XBB.1.5 Subvariant at Day 29
Day 29
Unlock Study Endpoints

Study Design & Arms

AllocationRANDOMIZED
MaskingQUADRUPLE
ModelPARALLEL
PurposePREVENTION

Treatment Arms

ArmTypeDescription
Group 1a (ARCT-2303/Influenza vaccine)EXPERIMENTALParticipants will receive one 0.5-mL IM (intramuscular) dose of ARCT-2303 and one 0.5-mL IM dose of influenza vaccine on Day 1 followed by a 0.5-mL IM dose of placebo on Day 29.
Group 2a (ARCT-2303)EXPERIMENTALParticipants will receive one 0.5-mL IM dose of ARCT-2303 and one 0.5-mL IM dose of placebo on Day 1 followed by a 0.5-mL IM dose of influenza vaccine on Day 29.
Group 3a (Influenza vaccine)ACTIVE_COMPARATORParticipants will receive one 0.5-mL IM dose of influenza vaccine and one 0.5-mL IM dose of placebo on Day 1 followed by a 0.5-mL IM dose of ARCT-2303 on Day 29.
Group 1b (ARCT-2303/ Influenza vaccine)EXPERIMENTALParticipants will receive one 0.5-mL IM dose of ARCT-2303 and one 0.5-mL IM dose of influenza vaccine on Day 1 followed by a 0.5-mL IM dose of placebo on Day 29.
Group 2b (ARCT-2303)EXPERIMENTALParticipants will receive one 0.5-mL IM dose of ARCT-2303 and one 0.5-mL IM dose of placebo on Day 1 followed by a 0.5-mL IM dose of influenza vaccine on Day 29.
Group 3b (Influenza vaccine)ACTIVE_COMPARATORParticipants will receive one 0.5-mL IM dose of influenza vaccine and one 0.5-mL IM dose of placebo on Day 1 followed by a 0.5-mL IM dose of ARCT-2303 on Day 29.

Interventions

NameTypeDescription
ARCT-2303BIOLOGICALSelf-Amplifying RNA COVID-19 vaccine (Omicron XBB.1.5)
Influenza vaccineBIOLOGICALLicensed cell-based influenza vaccine
Influenza vaccine, adjuvantedBIOLOGICALLicensed influenza vaccine, adjuvanted
PlaceboOTHER0.9% saline
Unlock Study Design Details

Eligibility Criteria

Age Range18 Years to N/A
SexALL
Healthy VolunteersYes
Study Sites29

Inclusion Criteria: 1, Individuals are male, female, or transgender adults ≥18 years of age. 2\. Healthy participants or participants with pre-existing stable medical conditions. 3\. Participant or legally authorized representatives must freely provide documented informed consent prior to study p...

Countries:AustraliaCosta RicaHondurasPhilippines
Unlock Eligibility Criteria

Frequently asked questions about ARCT-2303

What is ARCT-2303 used for?

ARCT-2303 is an investigational self-amplifying mRNA COVID-19 vaccine being developed for the prevention of COVID-19. It is currently in Phase 3 clinical development and is not yet approved by regulatory authorities.

Who makes ARCT-2303?

ARCT-2303 is being developed by Arcturus Therapeutics Holdings Inc., a biopharmaceutical company traded on the Nasdaq under the ticker symbol ARCT. The company is conducting clinical trials to evaluate the vaccine's safety and immunogenicity.

What phase is ARCT-2303 in?

ARCT-2303 is in Phase 3 clinical development as an investigational COVID-19 vaccine. It has completed one Phase 3 trial and is not yet approved for use, meaning it remains under clinical investigation.

What clinical trials is ARCT-2303 in?

ARCT-2303 has been studied in a completed Phase 3 clinical trial with the identifier NCT06279871. This trial evaluated the immunogenicity and safety of the vaccine when administered with influenza vaccines in adults, enrolling 1,514 participants across Australia, Costa Rica, Honduras, and the Philippines.

Is ARCT-2303 a monoclonal antibody?

No, ARCT-2303 is not a monoclonal antibody. It is a self-amplifying mRNA vaccine designed to induce an immune response against COVID-19. The modality classification as a monoclonal antibody in some databases is incorrect based on the available trial information.