Novavax’s RSV vaccine fails second Phase III trial, further shrinking its pathways to success

Following the news on 28 February 2019 that Novavax’s respiratory syncytial virus (RSV) disease vaccine for infants – ResVax – did not meet its primary Phase III endpoint,

Paul Jeng, PhD, Pharma Analyst at GlobalData, a leading data and analytics company, offers his view on the future prospects for ResVax in RSV prevention:

“This is the second Phase III trial of ResVax to miss primary efficacy objectives, following disappointing results from a 2016 study to prevent RSV-associated lower respiratory tract infections (LRTI) in elderly adults.

“As a silver lining, ResVax did meet its secondary trial objectives, with 44% and 48% efficacy against RSV LRTI hospitalizations and severe hypoxemia, respectively. If the vaccine is ultimately cost-effective, it may find a commercial window as a preventative measure against the most serious consequences of RSV infection. Novavax can also continue its early-stage development of ResVax in young children as a pediatric vaccine.

“A successful vaccine for prevention of serious RSV infections in infants has been elusive to drug developers due to issues with suboptimal neonatal immune response and challenges in vaccine antigen selection. However, the competition to establish a first-to-market advantage will grow stronger as other RSV vaccines, including Janssen’s Phase II vaccine (Ad26.RSV.preF) that encodes a pre-fusion F protein, advance through clinical trials.

“Moreover, AstraZeneca and Sanofi’s prophylactic monoclonal antibody, MEDI8897, recently received an FDA Breakthrough Therapy Designation and is positioned for a pivotal Phase III study, with potential to cut into future RSV market share. Novavax’s best case scenarios for ResVax now include a longer approval horizon or more restricted target patient population than initially anticipated.”

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