Multiple RSV vaccines in late-stage development show promise in older adults
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WASHINGTON — Three late-breaking studies offered a promising glimpse of respiratory syncytial virus vaccines in the pipeline for older adults — including the RSVPreF3 OA vaccine, which showed an overall vaccine efficacy of about 83%.
The latest results from the RSVPreF3 OA vaccine were initially announced by GlaxoSmithKline (GSK) in a press release last week. The vaccine contains a recombinant subunit pre-fusion RSV antigen, combined with an adjuvant called AS01E.
Michael G. Ison, MD, MS, a professor of medicine at Northwestern Medicine, presented the findings at IDWeek.
“RSV causes significant morbidity and mortality, particularly in older adults,” Ison told Healio. “To date, there are no vaccines or therapies for RSV.”
The CDC estimates that RSV results in more than 177,000 hospitalizations and 14,000 deaths among older adults in the United States each year.
A randomized controlled study of approximately 25,000 adults aged 60 years or older showed that a single dose of RSVPreF3 OA was highly efficacious, demonstrating an overall vaccine efficacy (VE) of 82.6% (96.95% CI, 57.9%-94%) and a VE of 94.1% (95% CI, 62.4%-99.9%) against severe disease. Additionally, VE was consistently high against both RSV subtypes A and B.
The safety profile of RSVPreF3 OA was favorable, too, according to GSK, with most adverse events being characterized as mild or moderate and transient. These included injection site pain, fatigue, myalgia and headache.
Ison said during the presentation that the study was conducted over a single RSV season, and that analyses are ongoing. GSK said it plans to start the regulatory approval process for RSVPreF3 OA this year.
“The data presented today demonstrate that the GSK RSVPreF3 OA vaccine was safe and associated with significant reductions in the risk of RSV lower respiratory tract infections, with similar vaccine efficacy for RSV-A and RSV-B,” Ison told Healio. “This has the potential to reduce the risk of RSV in vulnerable elderly adults.”
Additional RSV vaccine candidates in the pipeline
Bavarian Nordic’s MVA-BN RSV, a vector-based vaccine developed to protect against RSV subtypes A and B, advanced to phase 3 studies in older adults in April, according to the company. Separately, researchers conducted a human challenge study in healthy adults, the results of which were presented at IDWeek by Elke Jordan, PhD, a clinical scientist at Bavarian Nordic.
In the challenge study, 61 adults were randomly vaccinated with MVA-BN RSV or placebo and then intranasally given a mild form of RSV 28 days later. Results “confirmed the broad humoral and cellular immune response” elicited by MVA-BN RSV, according to the researchers, and Jordan said the estimated VE among healthy adults was 79% to 88.5%.
A third late-breaking study was presented by Edward E. Walsh, MD, a professor of medicine at the University of Rochester, who discussed findings from Pfizer’s investigational candidate RSVpreF — a bivalent pre-fusion F subunit vaccine also meant to protect against RSV subtypes A and B. The study, which included approximately 40,000 adults aged 60 years or older, showed a VE of 85.7% (96.66% CI, 32%-98.7%). Healio reported on the phase 3 results in April.
According to the researchers, the Pfizer vaccine was well tolerated, with no safety concerns.
The company said it is seeking FDA approval this fall, and it has already received breakthrough therapy designation for the vaccine to prevent RSV in older adults and in infants, which is achieved through maternal immunization.
References:
- CDC. RSV in older adults and adults with chronic medical conditions. https://www.cdc.gov/rsv/high-risk/older-adults.html. Accessed Oct. 19, 2022.
- GSK’s older adult respiratory syncytial virus (RSV) vaccine candidate shows 94.1% reduction in severe RSV disease and overall vaccine efficacy of 82.6% in pivotal trial. https://www.gsk.com/en-gb/media/press-releases/gsk-s-older-adult-respiratory-syncytial-virus-rsv-vaccine-candidate/. Published Oct. 13, 2022. Accessed Oct. 29, 2022.
- Ison MG, et al. Abstract LB745. Presented at: IDWeek; Oct. 19-23, 2022; Washington (hybrid meeting).
- Jordan E, et al. Abstract LB747. Presented at: IDWeek; Oct. 19-23, 2022; Washington (hybrid meeting).
- MVA-BN RSV phase 3 ongoing. https://www.bavarian-nordic.com/what-we-do/pipeline/rsv.aspx. Accessed Oct. 19, 2022.
- Pfizer granted FDA breakthrough therapy designation for respiratory syncytial virus (RSV) vaccine candidate for the prevention of RSV in infants from birth up to six months of age by active immunization of pregnant women. https://www.pfizer.com/news/press-release/press-release-detail/pfizer-granted-fda-breakthrough-therapy-designation. Published March 2, 2022. Accessed October 19, 2022.
- Walsh EE, et al. Abstract LB748. Presented at: IDWeek; Oct. 19-23, 2022; Washington (hybrid meeting).
Perspective
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Robert H. Hopkins Jr. , MD, MACP, FAAP
RSV is widely known as a cause of respiratory tract infections in children. Its role as a pathogen causing severe respiratory disease in adults (especially older adults, immune compromise, heart and lung disease) is less well known to the public and to the medical community. At present, there are no available vaccines to prevent RSV infection.
Three late-breaking abstracts presented at IDWeek highlight promising developments in vaccines, which may prove useful in prevention of RSV. These abstracts describe phase 3 trials of two vaccine candidates and an RSV challenge trial of a third vaccine candidate for the prevention of RSV in older adults. Each of these suggest efficacy of the candidate vaccines studied.
The potential availability of a vaccine to prevent severe RSV infection in adults will be a major advance in our ongoing “war” against viral respiratory pathogens.
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Ison MG, et al. Abstract LB745. Presented at: IDWeek; Oct. 19-23, 2022; Washington (hybrid meeting).
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