New Regulatory Filings Advance Moderna's mRNA-1345 RSV Vaccine

Today, the biotechnology company Moderna, Inc. announced key regulatory submissions for their respiratory syncytial virus (RSV) vaccine, mRNA-1345. The vaccine candidate utilizes Moderna’s pioneering messenger RNA technology, and is intended to prevent RSV-associated lower respiratory tract disease (RSV-LRTD) in adults 60 years and older.

Moderna submitted marketing authorization applications for mRNA-1345 with the European Medicines Agency (EMA), Swissmedic in Switzerland, and the Therapeutic Goods Administration (TGA) in Australia. Additionally, Moderna began the rolling submission process for US Food and Drug Administration (FDA) Biologics License Application (BLA).

In January 2023, the FDA granted Breakthrough Therapy Designation to mRNA-1345; the vaccine candidate had previously received an FDA Fast Track designation in August 2021. In Australia, mRNA-1345 was approved for Priority Determination in April 2023, and the TGA submission will thus be evaluated under the Priority Pathway.

“We are proud to announce these filings for the use of our RSV vaccine candidate, mRNA-1345, in the European Union, Switzerland, Australia, and the US.” said Moderna CEO Stéphane Bancel. “RSV is a major cause of lower respiratory tract infections in older adults and can cause a significant burden to health systems through hospitalizations and emergency care admissions.”

The regulatory submissions were based upon positive data from the ConquerRSV study, a randomized, double-blind, placebo-controlled study of 37,000 adults across 22 countries. The primary study endpoints were based upon 2 definitions of RSV-LRTD, determined by either 2 or more symptoms or 3 or more symptoms.

The trial met both primary efficacy endpoints, with a vaccine efficacy of 83.7% against RSV-LRTD as defined as 2 or more symptoms, and 82.4% protective against RSV-LRTD defined as 3 or more symptoms. The participants were 60 years or older, and tolerated mRNA-1345 with a favorable safety profile. Most adverse reactions were mild to moderate in severity, and the most commonly reported events were injection site pain, fatigue, headache, myalgia, and arthralgia.

mRNA-1345 contains a single mRNA sequence encoding for a stabilized prefusion F glycoprotein, and the same lipid nanoparticles as Moderna’s COVID-19 vaccines. “The F glycoprotein is on the surface of the virus and is required for infection by helping the virus to enter host cells,” Moderna explained in a statement. “It exists in two states, prefusion and postfusion. The prefusion conformation is a significant target of potent neutralizing antibodies, and the protein sequences are largely similar across both RSV-A and RSV-B subtypes.”

RSV a common respiratory virus that typically causes mild, cold-like symptoms. While most people recover within 2 weeks, older adults are susceptible to severe and even fatal infection. Because RSV primarily affects the lungs and breathing passages, disease severity can increase with age and comorbidities such as chronic obstructive pulmonary disease, asthma, and congestive heart failure. Additionally, adults living in nursing homes or long-term care facilities are at higher risk for adverse RSV disease outcomes.

Infants and young children are also vulnerable to severe or fatal RSV disease, due in large part to their smaller breathing tubes, which fill with fluid more rapidly than in healthy adults. There are no pediatric RSV vaccines, but Moderna is evaluating mRNA-1345 in this population in an ongoing phase 1 clinical trial.

After having no RSV vaccine since the virus was discovered in 1956, this year has seen a flurry of RSV vaccine candidates and approvals. Last week, CDC Director Rochelle P. Walensky, MD, MPH, recommended the use of GSK and Pfizer’s respective RSV vaccines for individuals 60 years and older. On May 3, GSK’s RSV vaccine Arexvy (RSVPreF3 +AS01E) became the world’s first approved RSV vaccine. Within the month, the FDA approved Pfizer’s Abrysvo (bivalent RSV prefusion F; RSVpreF) for the same patient population.

"Our mRNA platform has allowed us to move from initial clinical testing to our first international phase 3 trial to initiation of regulatory submissions for mRNA-1345 in just 2 years, enabling us to tackle this pervasive public health burden with speed and clinical rigor,” Bancel said. “mRNA-1345 represents the second product coming from our mRNA platform to seek global approval, and with recent positive data in rare disease and cancer, we expect more in the future—further demonstrating the tremendous potential of mRNA to combat disease.”

Will Moderna’s mRNA-1345 be the world’s third RSV vaccine? Contagion is actively following the RSV disease space. Check back soon for updates, or catch up with our past coverage here.