Galectin-9 (LGALS9)

Class

Monoclonal antibody (fully humanized IgG4)

Pathway

Blocks galectin-9's maintenance of leukemia-initiating cells and immune-suppressive signaling; direct anti-leukemic apoptosis/DNA damage plus restoration of anti-tumor immunity

Galectin-9 is a glycan-binding protein (a lectin) that recognizes sugar structures on the surface of immune cells and tumor cells. It participates in two distinct biological processes relevant to cancer: first, it engages inhibitory receptors on T lymphocytes, such as TIM-3, delivering signals that push these effector immune cells toward exhaustion or programmed cell death, thereby dampening anti-tumor immune responses. Second, in certain hematologic malignancies, galectin-9 signaling appears to help sustain a subpopulation of leukemia-initiating cells—the reservoir of malignant cells thought to drive disease persistence and relapse. A monoclonal antibody directed against galectin-9 is designed to interrupt both processes simultaneously: by blocking the protein's interaction with its immune receptors, it aims to restore T-cell-mediated surveillance of tumor cells, while independently promoting direct cytotoxic stress, including DNA damage and apoptosis, within galectin-9-dependent leukemic populations. This dual rationale—immune restoration paired with direct anti-leukemic activity—reflects a broader strategy in oncology of targeting molecules that operate at the intersection of tumor cell biology and the surrounding immune microenvironment. Such an approach is of interest across hematologic cancers where leukemic stem-like cells and immune evasion both contribute to treatment resistance and relapse, and potentially in solid tumors where galectin-9 is expressed within immunosuppressive tumor microenvironments.