Moderna RSV Vaccine for Seniors Meets Primary Endpoints for its Phase 3 Trial

Moderna announced today that its investigational RSV vaccine demonstrated an efficacy of 83.7% against RSV-associated lower respiratory tract disease (RSV-LRTD) in its ConquerRSV phase 3 trial.

"Today's results represent an important step forward in preventing lower respiratory disease due to RSV in adults 60 years of age and older. These data are encouraging, and represent the second demonstration of positive phase 3 trial results from our mRNA infectious disease vaccine platform after, Spikevax, our COVID-19 vaccine. We look forward to publishing the full data set and sharing the results at an upcoming infectious disease medical conference," Moderna Chief Executive Officer Stéphane Bancel said in a statement.

What the Data Says
The ConquerRSV trial is a randomized, double-blind, placebo-controlled study of approximately 37,000 adults 60 years or older in 22 countries, including the United States. The primary efficacy endpoints were based on two definitions of RSV-LRTD defined as either two or more symptoms, or three or more symptoms of disease.

The interim analysis was based on 64 cases of RSV-LRTD with two or more symptoms, of which 55 occurred in the placebo group and 9 occurred in the mRNA-1345 group, and 20 cases of RSV-LRTD with three or more symptoms, of which 17 cases were observed in the placebo group compared with three cases observed in the mRNA-1345 group.

The other primary efficacy endpoint against RSV-LRTD defined by three or more symptoms was also met, with a VE of 82.4% (96.36% CI: 34.8%, 95.3%; p=0.0078). The trial is ongoing, and additional efficacy analyses are planned as cases accrue, including for severe RSV.

The company reported that the mRNA-1345 vaccine was well tolerated with no safety concerns identified. To date most solicited adverse reactions were mild or moderate and the most commonly reported solicited adverse reactions in the mRNA-1345 group were injection site pain, fatigue, headache, myalgia, and arthralgia.

The overall rate of severe (Grade 3 or greater) solicited systemic adverse reactions was 4.0% for mRNA-1345 and 2.8% for placebo. The overall rate of Grade 3 or greater solicited local adverse reactions was 3.2% for mRNA-1345 and 1.7% for placebo. The study is ongoing, and an updated analysis of safety and tolerability will be provided at the time of regulatory submission.

The vaccine is made up of a single mRNA sequence encoding for a stabilized prefusion F glycoprotein. The vaccine uses the same lipid nanoparticles (LNPs) as in the Moderna 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. It exists in two states, prefusion and postfusion. The prefusion conformation is a significant target of potent neutralizing antibodies and is highly conserved across both RSV-A and RSV-B subtypes.

According to the Centers for Disease Control and Prevention, it is estimated that between 60,000-120,000 older adults in the United States are hospitalized and 6,000-10,000 of them die due to RSV infection.

To date, there are no approved vaccines or therapies for RSV.

The company continues to utilize its mRNA pipeline for a variety of respiratory and latent viruses, and recently provided an update to their portfolio.