GS-5806 is a novel, orally bioavailable RSV fusion inhibitor discovered following a lead optimization campaign on a screening hit. The oral absorption properties were optimized by converting to the pyrazolo[1,5-a]-pyrimidine heterocycle, while potency, metabolic, and physicochemical properties were optimized by introducing the para-chloro and aminopyrrolidine groups. A mean EC50 = 0.43 nM was found toward a panel of 75 RSV A and B clinical isolates and dose-dependent antiviral efficacy in the cotton rat model of RSV infection. Oral bioavailability in preclinical species ranged from 46 to 100%, with evidence of efficient penetration into lung tissue. In healthy human volunteers experimentally infected with RSV, a potent antiviral effect was observed with a mean 4.2 log10 reduction in peak viral load and a significant reduction in disease severity compared to placebo. In conclusion, a potent, once daily, oral RSV fusion inhibitor with the potential to treat RSV infection in infants and adults is reported.
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http://dx.doi.org/10.1021/jm5017768 | DOI Listing |
J Infect Dis
December 2024
Department of Pediatrics, School of Medicine, Fukushima Medical University, Fukushima City, Fukushima 960-1295, Japan.
Background: Amino acid (AA) substitutions in the fusion protein of respiratory syncytial virus (RSV) and their effects remain unclear. We aimed to analyze AA substitutions in main neutralizing epitopes of the fusion (F) protein.
Methods: We analyzed F protein genes of 236 RSV strains isolated from children hospitalized with RSV infection in Fukushima, Japan (June 2008-February 2023).
Ther Adv Vaccines Immunother
December 2024
Centre for Human Drug Research, Leiden, The Netherlands.
Respiratory syncytial virus (RSV) causes high worldwide infant mortality, as well as a high disease burden in the elderly. Efforts in vaccine development over the past 60 years have recently delivered three approved vaccines and two monoclonal antibodies (mAbs). Looking back at the eventful history of RSV vaccine development, several factors can be identified that have hampered the developmental pathway, including the occurrence of enhanced RSV disease (ERD) in the first vaccine attempt and the difficulty in characterizing and stabilizing the pre-fusion F protein as a vaccine target.
View Article and Find Full Text PDFExpert Rev Vaccines
December 2025
HTA Value & Evidence, Pfizer Inc, New York, NY, USA.
Introduction: Among older adults, lower respiratory tract infection (LRTI) caused by respiratory syncytial virus (RSV) is common. We evaluated the cost-effectiveness of bivalent RSV prefusion F protein-based vaccine (RSVpreF) for prevention of RSV-LRTI among older adults in Germany.
Research Design And Methods: A static cohort model was developed to estimate lifetime health and economic outcomes of RSV-LRTI among adults aged 60-99 years in Germany, with (vs.
Clin Infect Dis
December 2024
Translational Medicine, Vaccines & Immune Therapies, BioPharmaceuticals R&D, AstraZeneca, Gaithersburg, MD, USA.
Background: Nirsevimab is an extended half-life, highly potent neutralizing monoclonal antibody against the respiratory syncytial virus (RSV) fusion protein, with efficacy in preventing RSV-associated medically attended (MA) lower respiratory tract infection (LRTI) in infants and medically vulnerable children (aged ≤24 months). This post-hoc exploratory analysis examined the incidence of LRTI from RSV and other respiratory pathogens during a 2:1 randomized, double-blind, placebo-controlled, phase 3 study of nirsevimab, in healthy-term and late-preterm (i.e.
View Article and Find Full Text PDFMol Ther
December 2024
Viral Hemorrhagic Fevers Research Unit, Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, Shanghai, China, 201203; Virology Laboratory, Institut Pasteur du Laos, Vientiane, Lao PDR, 01030. Electronic address:
Respiratory Syncytial Virus (RSV) represents a significant threat, being a primary cause of critical lower respiratory tract infections and fatalities among infants and the elderly worldwide, and poses a challenge to global public health. This urgent public health challenge necessitates the swift development of safe and effective vaccines capable of eliciting robust immune responses at low doses. Addressing this need, our study investigated five self-amplifying RNA (sa-mRNA) candidate vaccines that encode the various pre-fusion conformations of the RSV fusion protein.
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