Chemokine-Armed Oncolytic Viruses: Engineering Immune Cell Trafficking to Transform the Tumor Microenvironment.

Most patients with solid tumors do not respond to immune checkpoint blockade, and inadequate T cell infiltration of the tumor parenchyma is the dominant mechanism of primary resistance. Oncolytic viruses address this problem by a distinct route: they replicate selectively within tumor cells, produce immunogenic cell death, and convert infected cells into local sources of any encoded transgene. Most armed designs to date have carried cytokine or checkpoint-antibody payloads, and chemokines have attracted comparatively little attention despite bearing directly on the trafficking bottleneck. This review synthesizes the preclinical literature on chemokine-armed oncolytic viruses across three receptor axes: CXCR3 (CXCL9, CXCL10, CXCL11), CCR5 (CCL5/RANTES), and CCR7 (CCL19). The accumulated evidence indicates that therapeutic outcome depends less on the chemokine payload itself than on the interaction between payload and viral backbone. CXCL11 outperforms its sister CXCR3 ligands not through intrinsic potency but because it is non-redundant with the endogenous chemokines induced by vesicular stomatitis virus and vaccinia, and because it largely escapes proteolytic cleavage by dipeptidyl peptidase 4 (DPP4). CCL5 has shown the most consistent activity in dual-payload designs that pair chemotaxis with a T cell survival cytokine such as IL-15. CCL19, which addresses lymphoid organization rather than effector recruitment, rests on a single published construct. One evidence gap is central: no head-to-head comparison of chemokine payloads within a single viral platform has been published. We therefore propose a translational decision framework that aligns chemokine selection with the immune contexture of the target tumor.