FDA Grants Fast Track Designation for Potential Bird Flu Vaccine
The designation addresses the unmet need for prevention of H5N1, which remains a global health risk, and a phase 1 trial of the vaccine was initiated in November 2024.
The FDA granted fast track designation for a self-amplifying mRNA vaccine candidate (ARCT-2304) for active immunization to protect against influenza A H5N1 subtype, also known as bird flu. The designation addresses the unmet need for prevention of H5N1, which remains a global health risk, and a phase 1 trial (NCT06602531) of the vaccine was initiated in November 2024.
The designation addresses the unmet need for prevention of H5N1, which remains a global health risk, and a phase 1 trial of the vaccine was initiated in November 2024. | Image Credit: MargJohnsonVA - stock.adobe.com
“We are pleased to receive fast track designation from the FDA for ARCT-2304,” Joseph Payne, president and CEO of Arcturus Therapeutics, said in a news release. “We remain steadfast in our commitment to the US government to develop safe and effective STARR next-generation mRNA vaccines to protect US citizens from future pandemic threats. This designation from the FDA is an important step forward in our mission to provide protective solutions for global health crises.”
As of March 6, 2025, the drug is still in phase 1 clinical trials, but interim data is expected in the second half of 2025. Investigators of the study aimed to determine the safety and immune response of 3 different dose levels for the proposed vaccine. The objectives included evaluating the safety and reactogenicity and describing the immune responses, measured by hemagglutination inhibition and neuraminidase enzyme-linked lectin antibody responses. The results will be compared to a current licensed influenza vaccine to choose the most optimal dose and schedule.2,3
The investigators state that patients will receive either 2 doses of the vaccine or 1 dose of a licensed vaccine and 1 dose of a placebo. Patients will keep a daily diary for 7 days after each vaccination, provide blood samples at each visit in the clinic, and comply with the study visits and procedures, according to the clinical trial information.3
Furthermore, there will be 2 parts: one for 120 young adults (aged 18 years to 59 years) and one for 80 older adults (aged 60 years to 80 years). Participants will receive 1 of 3 doses of the proposed vaccine or the control vaccines, and the vaccination schedule will be randomized between 1 of 2. The primary objectives included the evaluation of safety and immune responses of the 3 different dose levels and the 2 different vaccination schedules.3,4
“Clinically validating our low-dose STARR mRNA technology in H5N1 flu is a crucial step towards pandemic preparedness,” Payne said in a news release.4 “Our team is working diligently with our partners, BARDA and CSL, in the United States and globally in this effort.”
ARCT-2304 is designed to make many copies of mRNA within the host cell after injection to enhance the expression of HA and NA antigens, which will allow for a lower dose than other mRNA vaccines. Screening for the phase 1 study began in November 2024, with the first patient inoculated in December 2024.4
READ MORE: Influenza Resource Center
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