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Meissa Announces 1st Dosing in Phase 2 Study of Intranasal Live Attenuated Vaccine Candidate for RSV

- The randomized, double-blind, placebo-controlled challenge study is designed to evaluate safety and prophylactic efficacy of MV-012-968 against symptomatic respiratory syncytial virus (RSV)

- Previous clinical data shows MV-012-968 is well-tolerated, heavily attenuated, and induces an RSV-specific mucosal IgA response in healthy seropositive adults and pediatric participants

REDWOOD CITY, Calif., January 21, 2021 – Meissa Vaccines (“Meissa”), a biotechnology company developing vaccines to prevent viral respiratory infections, announced today that the first adult participants have been dosed in a Phase 2 study of MV-012-968, the company’s intranasal live attenuated vaccine candidate against respiratory syncytial virus (RSV). Meissa is developing MV-012-968, an intranasal (needle-free), live attenuated vaccine candidate, to protect infants and at-risk, older adults from RSV.

The Phase 2 study is designed as a randomized, double-blind, placebo-controlled study to evaluate the safety and prophylactic efficacy of a single intranasal dose of MV-012-968 against symptomatic RSV infection in a virus challenge model. The company plans to enroll up to 70 adult participants, between ages 18 and 45 years, in the U.K. with the support of hVIVO, part of Open Orphan plc, the industry leading services provider of viral challenge studies. The identifier is NCT04690335.

Data from a completed Phase 1a study ( Identifier NCT04227210) showed a 10^6 PFU dose of MV-012-968 was safe and well-tolerated among healthy RSV sero-low adults and resulted in no detectable shed vaccine virus nasally, indicating heavy attenuation, and yet induced RSV-specific mucosal IgA in the majority of vaccine recipients, despite pre-existing immunity to RSV.

Preliminary data from a Phase 1b study in sero-positive pediatric participants ( Identifier NCT04444284) showed that a single dose of either 10^4 or 10^5 PFU of MV-012-968 was well-tolerated, did not result in detectable shed vaccine virus, and stimulated RSV-specific mucosal IgA. Meissa plans to initiate a Phase 1c study in sero-negative infants in the first half of this year.

“We now have supportive clinical data in adult and pediatric populations showing our intranasal live attenuated vaccine candidate for RSV is well-tolerated and induces mucosal IgA, an important mechanism to protect against RSV infection,” said Martin Moore, Ph.D., CEO and Cofounder of Meissa. “These two clinical studies, the Phase 2 challenge in sero-positive adults and the Phase 1c in sero-negative infants, are key milestones in developing a safe and effective RSV vaccine, which is a significant global health priority that could save thousands of lives and help millions of patients around the world.”

"Meissa and hVIVO share the same vision of using challenge studies to accelerate development of potential vaccines for infectious diseases, such as RSV,” said Cathal Friel, Executive Chairman and Cofounder of Open Orphan plc. “hVIVO is the only company globally offering the capability to conduct an RSV human challenge study, and we are pleased to have been selected to run this study by an organization with world-class expertise in vaccine development."

About MV-012-968

MV-012-968 was generated using the company’s proprietary AttenuBlockTM synthetic biology platform with the goal of creating safe, potent, stable, and cost-effective intranasal vaccines. Meissa’s AttenuBlock platform incorporates 10 years of research and development at Emory University, where researchers employed rational and precise codon deoptimization and other genetic strategies to produce hundreds of targeted mutations into the RSV genome, providing exquisite control over viral protein expression (Nature Communications, 2016). The AttenuBlock platform can potentially solve challenging obstacles in modern vaccinology such as suboptimal immune responses, over- and under-attenuation, and vaccine genetic stability.

About RSV

RSV is the leading cause of infant hospitalization in the United States and is considered the “missing” mandatory pediatric vaccine. RSV is also a significant cause of morbidity and mortality in at-risk adults and the elderly. In the United States, approximately 1% of infants are hospitalized by RSV each year. Globally, RSV causes more than 66,000 deaths per year and approximately three million hospitalizations in children less than five years of age (Anderson 2013).

About Meissa Vaccines

Meissa Vaccines was founded with a mission to protect people everywhere from deadly respiratory viruses and a commitment to develop innovative technologies capable of delivering effective vaccines at a global scale. Meissa is advancing live attenuated vaccine candidates against life threatening respiratory viruses, including 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 synthetic biology platform, which includes codon deoptimization and technologies exclusively licensed from Emory University and Children’s Healthcare of Atlanta. Meissa’s vaccine candidates are formulated to be delivered as a single, intranasal, adjuvant-free, needle-free dose and are designed to prevent infection and disease and generate a strong, durable immune response. Meissa is headquartered in Redwood City, Calif.


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