Significant Enrollment Milestone Met in Phase 3 Trial of Novavax's RSV Vaccine

Novavax, a clinical-stage biotechnology company, has just announced that it has reached a significant enrollment milestone for their clinical phase 3 trial, dubbed Prepare, regarding their vaccine candidate for the prevention of respiratory syncytial virus (RSV) in infants via maternal immunization.

A total of 4,600 healthy, pregnant women in their third trimester have been enrolled in the global Prepare trial, which was first initiated in December 2015; to date, at least 3,000 of participants have received the RSV F protein recombinant nanoparticle vaccine (RSV F Vaccine).

The primary objective of the trial is to assess the safety and efficacy of maternal immunization with the RSV F vaccine “against medically significant RSV-positive lower respiratory tract infection (LRTI) in infants through a minimum of the first 90 days of life and up through the first 6 months of life,” a recent press release reads.

“Reaching this enrollment target for the Prepare trial is a significant milestone in the advancement of our RSV F Vaccine franchise,” Novavax, Inc.’s president and CEO Stanley C. Erck, said in a recent statement. “RSV remains an urgent global unmet need due to the mortality and morbidity associated with RSV disease in infants and the absence of a vaccine to prevent such disease.”

RSV is very common among children; in fact, the Centers for Disease Control and Prevention (CDC) reports that most children have had RSV infections by their second birthday. While symptoms are usually mild—runny nose, coughing, sneezing, fever, wheezing, and decreased appetite—and pass within a week or 2, more severe cases of the virus can result in bronchiolitis or pneumonia, which could have serious implications for young infants or older adults.

More than 57,000 children under the age of 5 in the United States require hospitalization for RSV each year, and currently, there is no vaccine available to protect these individuals from infection.

“While mortality related to RSV in infants is low in industrialized countries, in the developing world, RSV is second only to malaria as a cause of infant death,” Erck told Contagion^® in a recent interview. “Since the infant immune system is immature and would require several vaccine doses to mount an effective immune response, Novavax’s strategy is to provide protection to the infant under 6 months of age with antibodies produced by immunizing the mother and passed to the developing fetus through the placenta—a natural physiologic process that has been shown to be effective against tetanus, pertussis, and influenza.”

After the last infant born to the 4,600 women enrolled in trial has been followed for the duration of 6 months, Novavax will begin a prespecified interim efficacy analysis. If the results of the analysis are favorable, the trial will conclude without further enrollment. Novavax will then file a biologics license application with the US Food and Drug Administration, in addition to a marketing authorization application with the European Medicines Agency by the first quarter of 2020.

As the vaccine had already been granted Fast Track Designation by the FDA, it could potentially be eligible for priority review of the BLA, which would cut the standard FDA review process by 4 months.