Fucosylation in cancer and its role in anti-tumor immunity

Fucose-containing glycans are central regulators of cell-surface biology, influencing receptor signaling, cell adhesion, immune recognition, and tissue organization. Through its incorporation into N-glycans, O-glycans, glycolipids, and specialized protein domains, fucose shapes how cells communicate with each other and respond to their environment. In cancer, this same regulatory capacity can be used in opposing directions. Aberrant fucosylation can promote malignant progression by stabilizing oncogenic receptors, enhancing adhesion and invasion, supporting metastatic dissemination, and contributing to therapy resistance. At the same time, fucose-dependent mechanisms can also strengthen antitumor responses, for example, by promoting tumor-cell death, immune recognition, and sensitivity to immunotherapy. This dual role is evident across both tumor cells and the tumor microenvironment. In malignant cells, changes in core and terminal fucosylation alter growth factor receptor signaling, integrin function, death receptor activity, and interactions with endothelial cells. In immune and stromal compartments, fucosylation regulates leukocyte trafficking, checkpoint receptor stability, T-cell activation or exhaustion, fibroblast-driven tumor support, angiogenesis, and extracellular matrix remodeling. These effects do not follow a simple pro- or anti-tumor logic, but depend on the modified substrate, glycan linkage, affected cell type, disease stage, and therapeutic setting. Therapeutically, this duality creates both opportunities and challenges. Inhibition of fucosylation can reduce oncogenic signaling, tumor-cell migration, immune evasion, and resistance mechanisms, supporting the development of metabolic inhibitors, selective fucosyltransferase inhibitors, enzymatic defucosylation strategies, and lectin-based approaches. Conversely, increasing fucose availability has been shown in several preclinical models to suppress tumor growth, promote tumor-cell death, and enhance immune-mediated tumor control. In melanoma, L-fucose supplementation increases tumor-cell MHC-II expression, promotes T-cell-mediated antitumor immunity, and improves sensitivity to immune checkpoint blockade. Fucosylation can also be exploited through antibody glycoengineering, where reduced Fc fucosylation enhances antibody-dependent cellular cytotoxicity. In this review, we discuss how fucose metabolism and fucosylation are altered in cancer, how these changes influence tumor-intrinsic signaling, tumor-stroma interactions, and antitumor immunity, and how fucose-dependent mechanisms may be targeted or harnessed therapeutically. Together, current evidence identifies fucose not as a uniformly tumor-promoting modification, but as a central regulator of tumor progression, immune control, and therapeutic response.