A newly published study in Nature Biotechnology introduces a distinct class of immunotherapeutic molecules designed to overcome an underexplored mechanism of immune suppression driven by tumor-associated sugars.
The research explores “glyco-immune checkpoints,” which are interactions between glycans on cancer cell surfaces and lectin receptors on immune cells. These interactions function as molecular brakes, reducing immune activation and helping tumors avoid destruction. In the paper, the authors introduce a new modular platform—antibody-lectin chimeras, or AbLecs—that directly targets this immune regulation pathway.
“Despite the curative potential of checkpoint blockade immunotherapy, many patients remain unresponsive to existing treatments,” the authors from MIT and Stanford write. “Glyco-immune checkpoints, which involve interactions of cell-surface glycans with lectin, or glycan-binding immunoreceptors, have emerged as prominent mechanisms of immune evasion and therapeutic resistance in cancer.”
AbLecs are bispecific, antibody-like molecules composed of two functional domains: a conventional antibody arm that targets a specific cell-surface antigen, and a lectin-based “decoy receptor” that binds tumor-associated glycans. By occupying these glycans, AbLecs prevent them from engaging inhibitory lectin receptors on immune cells, thereby lifting a key form of immune suppression.
In laboratory experiments using human immune cells, AbLecs enhanced immune-mediated destruction of cancer cells. The researchers found that these chimeric molecules increased antibody-dependent phagocytosis and cytotoxicity, even against tumor cells expressing low levels of the targeted antigen. In a humanized, immunocompetent mouse model, AbLec treatment reduced tumor burden and outperformed most existing therapies and combinations tested.
Importantly, AbLecs act through a mechanism distinct from established checkpoint inhibitors such as PD-1, PD-L1, or CTLA-4. By focusing on glycan–lectin interactions, they intervene at a different regulatory layer of immune signaling. “By targeting a distinct axis of immunological regulation, AbLecs synergize with blockade of established immune checkpoints,” the authors write, pointing to the potential for combination strategies that broaden patient benefit.
A key insight from the study involves how AbLecs alter the organization of the immunological synapse—the interface between immune cells and their targets. The researchers found that specific AbLecs targeting Siglec receptors—immune cell surface proteins that recognize sialic acid on self-glycans—were more effective than antibodies designed solely to block those receptors. “We found that T7 and T9 AbLecs were more effective Siglec antagonists than Siglec-blocking antibodies and as effective as sialoside degradation,” the authors write.
Further investigation revealed that this enhanced activity stems from the physical exclusion of Siglec inhibitory receptors from the immunological synapse. This spatial reorganization appears to reverse immune suppression and restore inflammatory signaling. As the paper notes, “Our data suggest that targeted lectin blockade mediated by AbLecs is at least as effective as systemic glyco-immune checkpoint blockade with the potential for reduced toxicity.”
The implications extend beyond Siglecs alone. “Our work adds to a growing body of evidence that the recruitment of checkpoint receptors and/or tyrosine phosphatases to synapses restrains inflammatory signaling and immune cell activation,” they write. In contrast, therapies like AbLecs that prevent this recruitment may reinvigorate immune responses against cancer.
Tumor cells are known to extensively remodel their surface glycosylation, a feature increasingly recognized as a driver of immune evasion. “It is now clear that a key role for these remodeled glycans is to facilitate immune evasion and tumor progression by engaging multiple broad classes of lectin receptors,” they write, positioning AbLecs as a flexible and extensible immunotherapy platform.
