Novavax Announces Positive Top-Line Results From Phase 1 Clinical Trial of RSV Vaccine Candidate in Elderly
- Well-tolerated without any vaccine-related serious adverse events
- Adjuvant enhanced response seen in all dose levels
- Anti-F IgG antibodies to the F protein in serum rose 3.0-5.7 fold across all dose levels
- Palivizumab-like antibodies rose from undetectable levels to those previously associated with decreased hospitalization
- Increased RSV A and B neutralizing antibody responses seen in all vaccinated groups
- Data paves the way for ongoing development of an RSV-influenza combination vaccine
The study examined the immunogenicity and safety of
Highlights of the interim immunogenicity results of the RSV F vaccine in elderly adults include:
The overall immune responses, in terms of both frequency and amplitude of antibody rises, were greater in the groups receiving the 90μg dose of RSV F vaccine compared to the groups dosed with 60µg. Significantly greater immune responses were observed in the groups receiving adjuvanted vaccine compared to those receiving unadjuvanted formulations.
Increases in anti-F IgG were observed in all actively-vaccinated groups by Day 7 post-immunization. Antibody levels continued to rise through Day 28 among recipients of unadjuvanted vaccines, then plateaued. In contrast, anti-F IgG levels continued to rise through Day 56 in recipients of adjuvanted vaccine. The greatest response was observed in the 90µg RSV F adjuvanted vaccine group, with a 5.6 fold rise in anti-F IgG and a sero-response rate of 79% at Day 56.
Antibodies competing with palivizumab, a monoclonal antibody known to be efficacious in the prevention of severe RSV disease, were essentially undetectable in these elderly subjects at Day 0, but showed significant increases in 80 to 97% of active vaccine recipients by Day 28. In subjects receiving the adjuvanted vaccines, significant responses were sustained in 97% through Day 56. In the subjects receiving the 90µg RSV F vaccine with adjuvant, levels of competitive antibodies equivalent to 186µg/mL of palivizumab were achieved.
Levels of antibodies specific for the antigenic site II peptide, representing the neutralizing epitope on the RSV F protein recognized by palivizumab, rose 5.6 to 12.5-fold, with best responses again in the 90µg RSV F adjuvanted vaccine group.
RSV A and B microneutralizing antibody levels increased in all vaccinated subject groups, with greatest responses seen in the 90µg RSV F adjuvanted vaccine group. Geometric mean-fold increases in microneutralizing antibody titers ranged from 1.4 to 1.7-fold.
- Hemagglutination-inhibiting (HAI) responses to the seasonal influenza vaccine were unaffected by co-administration with the RSV F vaccines; an important feature given that the two vaccines would likely be given to the elderly contemporaneously in clinical practice.
"These data provide further evidence that our RSV F nanoparticle vaccine is well-tolerated and immunogenic," said
"Protecting the elderly from respiratory ailments is an important part of both our RSV and our seasonal influenza vaccine development programs," noted
RSV is a major respiratory pathogen in infants, children, and adults. RSV infections in adults represent re-infections and are generally mild to moderate in severity, except in persons with high-risk conditions including the elderly and adults with underlying chronic cardiac or pulmonary disease. It is estimated that between 11-17,000 adults die of RSV infection annually in the U.S., with and up to 180,000 admitted to hospital with respiratory symptoms. Currently, there is no approved RSV prophylactic vaccine available.
About VLPs and
VLPs are self-assembling protein structures that resemble the external structure of viruses, elicit broad and strong antibody and cellular immune responses but lack the live genetic material that causes viral replication and infection. VLPs contain three of the major structural virus proteins that are important for fighting influenza: hemagglutinin and neuraminidase, both of which stimulate the body to produce antibodies that neutralize the influenza virus and prevent its spread through the cells in the respiratory tract, and matrix 1, which stimulates cytotoxic T lymphocytes to kill cells that may already be infected. VLPs can be designed quickly to match individual viral strains and be produced efficiently using portable recombinant cell-culture technology.
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Barclay PhillipsSVP, Chief Financial Officer and Treasurer Novavax, Inc.240-268-2000