N-acetylneuraminic acid (N-linked) (Neu5Ac)

N-linked sialic acids are terminal nine-carbon monosaccharides found on the N-glycans of cell surface glycoproteins. They serve as critical recognition elements in various biological processes, including cell-cell adhesion, protein stability, and immune system regulation [1]. In the context of infectious diseases, sialic acids act as the primary attachment receptors for many pathogens, most notably the influenza virus, which utilizes hemagglutinin to bind these residues for entry into host cells [4]. In oncology, many tumors exhibit hypersialylation, a process where an overabundance of sialic acids on the cell surface creates a glyco-immune checkpoint. This hypersialylation allows cancer cells to engage Siglec (Sialic acid-binding immunoglobulin-type lectin) receptors on immune cells, leading to the suppression of the anti-tumor immune response [2]. Therapeutic interventions targeting this axis include neuraminidase inhibitors that block viral release and novel sialidase-fusion proteins designed to strip sialic acids from tumor surfaces to enhance immune detection [3].

Other names

Sialic acidNeu5AcN-acetylneuraminateSIAN-linked sialic acid

The primary mechanisms of action for drugs involving N-linked sialic acid include the inhibition of viral neuraminidase enzymes, which prevents the cleavage of sialic acid and the subsequent release of viral progeny from host cells [1, 4]. In cancer therapy, sialidase-fusion proteins like E-602 enzymatically remove terminal sialic acids from the tumor cell surface, thereby disrupting the glyco-immune checkpoint and preventing the activation of inhibitory Siglec receptors on immune cells [2, 3].