Work

A dual-function XCL1-CD40L mRNA adjuvant potentiates cancer vaccines by coordinating DC recruitment and maturation

Year: 2026

Type: article

Abstract: Background Despite the significant promise of mRNA tumor vaccines in treating solid tumors, their clinical response rate is constrained by the low effectiveness of antigen presentation resulting from the immune-suppressive tumor microenvironment (TME). Conventional type 1 dendritic cells (cDC1) are pivotal in antigen cross-presentation; yet, they frequently exhibit insufficient immune-activating communication within solid malignancies. Methods This investigation comprehensively examined the functional attributes of cDC1 by TCGA cohorts and single-cell transcriptomic data. Guided by these bioinformatic insights, we engineered and synthesized a dual-functional mRNA adjuvant encoding the mXCL1-mCD40L fusion protein. We assessed the biological functions and anti-tumor efficacy of this adjuvant in combination with Glypican-3 (GPC3) and HPV-associated mRNA vaccines via protein expression, structure prediction, in vivo antigen uptake and presentation assays, antigen-presenting cell activation assays, antigen-specific T cell activation tests, and therapeutic studies in tumor-bearing mouse models. Results A high cDC1 signature score was associated with improved overall survival across LIHC and SKCM TCGA cohorts. Compared to normal sample, cDC1s in HCC and melanoma retained their antigen-presentation machinery but received reduced activating ligand inputs (XCL1-XCR1 signaling in HCC and CD40-CD40L signaling in melanoma). AlphaFold 3 showed that the mXCL1-mCD40L fusion protein can maintain structural integrity without spatial steric hindrance. The fusion protein was confirmed to be secreted and to retain both XCL1-dependent chemotactic activity and CD40-dependent dendritic-cell activation. mXCL1-mCD40L mRNA-LNP activated macrophages and dendritic cells in vitro , upregulating immune-related gene expression as confirmed by qPCR. In vivo , the dual-functional adjuvant significantly enhanced the anti-tumor effect of the GPC3 vaccine, outperformed co-delivery of separate mXCL1 and mCD40L mRNA-LNP, and induced stronger specific IFN-γ producing T cells. Meanwhile, this adjuvant also boosted the anti-tumor efficacy of HPV-associated mRNA vaccines. Mechanistically, this adjuvant increased tumor-antigen acquisition and cross-presentation by CD103 + DCs and promoted DC maturation in draining lymph nodes, accompanied by an increased proportion of peripheral CD8 + T cells. Conclusion By enhancing the recruitment and maturation of cDC1s, the dual-function mXCL1-mCD40L mRNA adjuvant boosts the efficacy of GPC3 and HPV-associated mRNA vaccines, supporting its potential as an antigen-flexible adjuvant platform against solid tumors.

Source: Frontiers in Immunology

DOI: 10.3389/fimmu.2026.1875603