Dear Editor , Cancer immunotherapy has revolutionized oncology by leveraging immune mechanisms to eliminate tumors. However, many cancers evade immune detection due to the absence of recognizable antigens, limiting the ef fi cacy of current therapies. 1 Redirecting pre-existing antiviral immunity toward tumors by introducing exogenous viral antigens offers a promising solution. Here, we present a novel clinically translatable approach that uses lipid nanoparticles (LNPs) to deliver mRNA encoding the measles virus hemagglutinin (H) protein directly into tumors (Fig. 1a). Prior approaches have largely relied on antibody-recruiting molecules or the delivery of de fi ned viral peptides, thereby engaging only limited immune pathways. 2 In contrast, inducing de novo expression of a full-length viral surface antigen on tumor cells enables activation of both humoral and cellular immunity through recruitment of pre-existing antibodies and presentation of multiple epitopes to CD8 ⁺ T cells. Compared with other viral antigens explored in mRNA – LNP-based strategies, such as the SARS-CoV-2 spike protein, 3,4 measles H provides a distinct translational advantage due to the high durability and near ubiquity of measles immunity, 5 supporting a robust and broadly applicable approach for redirecting antiviral immune memory toward cancer. Together, this work introduces a previously unexplored and clinically relevant framework that combines LNP-mediated mRNA delivery with a highly conserved viral antigen to broadly redirect antiviral immunity toward cancer. To validate this approach, LNPs encapsulating mRNA encoding the measles virus H protein (LNP H) and, as a control, LNPs encapsulating luciferase mRNA (LNP Luc) were prepared and characterized. Both formulations exhibited an average diameter of approximately 180 nm, a low polydispersity
Martínez-Latorre et al. (Mon,) studied this question.