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IVX-A12 + MF59

Development stage: Unknown
Lead developer: Icosavax
Modality: Split/Subunit Vaccines → Inactivated Vaccines → Prophylactic Vaccines → Vaccines & Immunotherapeutics, Cancer Vaccines → Therapeutic Vaccines → Vaccines & Immunotherapeutics, Recombinant Protein Vaccines → Recombinant Vaccines → Prophylactic Vaccines → Vaccines & Immunotherapeutics
Administration: Intramuscular

Overview

IVX-A12 + MF59 is a combination, investigational, protein-based **virus-like particle (VLP) vaccine** formulated against **respiratory syncytial virus (RSV)** and **human metapneumovirus (hMPV)**, designed for use in older adults. IVX-A12 itself is composed of two recombinant VLPs: IVX-121 (RSV prefusion F protein VLP) and IVX-241 (hMPV F protein VLP), combined in equal proportions. **MF59** is an oil-in-water emulsion adjuvant (squalene-based) used to enhance immune responses. The combination is delivered as a single dose, currently under clinical investigation for safety and immunogenicity in adults aged 60 and older. Early phase 1 and 2 data demonstrate robust neutralizing antibody responses to both RSV and hMPV, and a favorable safety/tolerability profile. Mechanism of action: VLPs mimic viral surfaces to elicit humoral immune responses (production of neutralizing antibodies) against RSV and hMPV. MF59 acts as an adjuvant by promoting recruitment and differentiation of innate immune cells, enhancing antigen uptake/presentation, and stimulating both antibody and T-cell responses[1][3][5][7].

Other names: IVX-A12 + MF59

Targets

RSV F (Respiratory syncytial virus fusion protein)hMPV preF (Human metapneumovirus prefusion fusion glycoprotein)

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