E-selectin ligand engineering overcomes trafficking barriers to potentiate adoptive T-cell and BiTE therapies

Adoptive T-cell transfer has transformed the treatment landscape for hematological cancers, yet its efficacy against solid tumors remains limited-largely due to inadequate infiltration of vascularly administered T cells into tumor tissue. Since shear-resistant interaction between endothelial E-selectin and its cognate ligand expressed on leukocytes, sialyl Lewis X (sLe X ), is an essential prerequisite for extravasation of circulating leukocytes, enhancing this interaction may improve therapeutic delivery. Here, we demonstrate that enforced sLe X display on T cells via surface “exofucosylation” using alpha1-3-fucosyltransferase (FUT6) significantly boosts their E-selectin binding and homing to tumor microenvironment with detectable E-selectin expression. This enhanced homing translates into potent antitumor activity across diverse murine models of solid tumors and metastatic disease, and restores sensitivity of galectin-3-rich tumors that are otherwise refractory to PD-1 checkpoint blockade. Mechanistically, exofucosylation enables CAR-T cells to overcome anti-PD-1 resistance by preventing galectin-3-mediated disruption of PD-1 antibody engagement. Furthermore, combining adoptive transfer of exofucosylated peripheral CD8⁺ T cells with bispecific T cell engager (BiTE) molecules produces strong synergistic therapeutic effects. Together, these findings establish exofucosylation as a clinically actionable strategy to overcome trafficking bottlenecks and unlock the full potential of adoptive T-cell and BiTE immunotherapies against solid and metastatic cancers.