REDWOOD CITY, Calif.--(BUSINESS WIRE)-- Meissa Vaccines (“Meissa”), a clinical-stage biotechnology company developing vaccines to prevent viral respiratory infections, today announced positive safety and immunogenicity data for MV-012-968, Meissa’s intranasal live attenuated RSV vaccine candidate, from a clinical study in RSV-naïve (seronegative) participants between the ages of six and 36 months. Meissa is developing MV-012-968 as a needle-free, adjuvant-free vaccine to protect infants and toddlers from respiratory syncytial virus (RSV).

“With this outstanding safety and robust serum antibody response, we believe Meissa’s live attenuated vaccine has the potential to be a best-in-class solution to protect infants and toddlers from RSV, and we are now preparing to advance MV-012-968 into a Phase 2/3 clinical trial next year,” said Martin Moore, Ph.D., cofounder and Chief Scientific Officer, Meissa Vaccines. “These data also demonstrate the power of our AttenBlock platform to generate live attenuated vaccines with outstanding safety and immunogenicity – something that we’ve not seen with other platforms.”

The study enrolled 79 participants at multiple sites in the U.S. to evaluate the safety and immunogenicity of MV-012-968 (ClinicalTrials.gov Identifier: NCT04909021). Doses ranged from one dose of 10³ PFU to two doses of 10⁷ PFU, 28 days apart. At the highest dose tested, no serious adverse events related to vaccination were reported with no evidence of any lower respiratory tract symptoms, no Grade 2 or 3 fever observed, and low level, transient vaccine shedding detected. Solicited symptoms were generally mild, were not temporally associated with vaccine virus shedding, and did not differ in incidence from the placebo group. All RSV-naïve infants and toddlers demonstrated a vaccine response to two doses of 10⁷ PFU. Serum neutralizing antibody responses to MV-012-968 were robust and comparable to the response seen with previous live attenuated RSV vaccine candidates that demonstrated high efficacy against medically-attended RSV disease. Moreover, MV-012-968 demonstrated significantly greater tolerability to date compared to these previous candidates.¹

Peter Wright, M.D., a pediatric infectious disease specialist, Professor of Pediatrics at Dartmouth Geisel School of Medicine, and a scientific advisor to Meissa, said, “While passive immunization strategies such as monoclonal antibodies and maternal immunization can protect infants against RSV, the duration of protection is limited. Active immunization with a pediatric live attenuated RSV vaccine offers the possibility of greater protection and even limiting transmission. These goals have been hampered over the years by the challenge of balancing attenuation and potency. We suspect that locally stimulated immunity in the respiratory tract by a topically presented vaccine will be a component of a truly successful immunization strategy. Now with next-generation vaccine technologies like Meissa’s, I am excited for the potential of a pediatric live attenuated RSV vaccine to advance and protect infants and toddlers. Meissa’s Phase 1 data are compelling and are consistent with strong preclinical data demonstrating potency despite heavy attenuation.”

1. Karron et.al. Am J Respir Crit Care Med, 2021

About RSV

Respiratory syncytial virus (RSV) is a leading cause of respiratory infections such as bronchiolitis and viral pneumonia in infants. In the United States, approximately 1% of infants are hospitalized because of RSV each year. Globally, in children under 5 years of age, RSV causes more than 66,000 deaths per year and approximately three million hospitalizations (Anderson 2013). Since the discovery of RSV in 1956, no vaccine has been approved for prevention.

About Meissa Vaccines

Meissa Vaccines was founded with innovative technologies to generate safe and effective vaccines and a mission to protect people everywhere from life-threatening respiratory viruses. Meissa is advancing intranasal, live attenuated vaccine candidates against respiratory syncytial virus (RSV), SARS-CoV-2 (COVID-19), and human metapneumovirus (hMPV). These vaccine candidates have been developed using the company’s proprietary AttenuBlock^TM platform, which includes codon deoptimization and technologies exclusively licensed from Emory University and Children’s Healthcare of Atlanta. Meissa’s live attenuated vaccine candidates are formulated to be delivered as an adjuvant-free, needle-free dose and are designed to generate a strong, durable immune response to prevent infection and disease and be part of the global solution to controlling respiratory viruses. Meissa is headquartered in Redwood City, California. For more information, please visit www.meissavaccines.com.

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