Moderna RSV Vaccine Granted FDA Breakthrough Therapy Status

Two weeks ago, Moderna reported topline data from its ConquerRSV phase 3 trial for its investigational RSV vaccine, mRNA-1345, demonstrating it had an 83.7% vaccine efficacy against RSV-associated lower respiratory tract disease (RSV-LRTD).

Yesterday, the company announced it had been granted breakthrough therapy designation for the vaccine from the FDA for the prevention of RSV-LRTD in adults aged 60 years or older.

"The FDA's breakthrough designation for mRNA-1345 further emphasizes the significant health impact of RSV in older adults and the high unmet need," Moderna CEO Stéphane Bancel said in a statement. "With this designation, we look forward to productive conversations with the FDA in the hopes of bringing our RSV vaccine candidate for older adults to the market safely and quickly.”

The Trials Results
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 company said their mRNA platform has now demonstrated two positive phase 3 infectious disease trial results. “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,” Bancel said in a previous statement.