Polysialic acid (polySia) (polySia)

Polysialic acid (polySia) is a unique post-translational carbohydrate modification consisting of long chains of alpha-2,8-linked sialic acid residues, primarily attached to the Neural Cell Adhesion Molecule (NCAM/CD56) [1]. In the context of small cell lung cancer (SCLC), polySia is frequently overexpressed and serves as a critical mediator of tumor progression and metastasis [2]. Its bulky, negatively charged structure creates a physical barrier that reduces cell-cell adhesion, thereby facilitating the detachment of malignant cells from the primary tumor and their subsequent migration [3]. Because polySia expression is largely restricted to embryonic development and specific regions of the adult central nervous system, it represents a highly specific tumor-associated antigen for SCLC [4]. Therapeutic strategies targeting polySia include monoclonal antibodies, antibody-drug conjugates, and CAR-T cell therapies designed to exploit this glycan signature [5]. However, challenges remain regarding potential off-target effects in the brain and the technical difficulty of generating high-affinity antibodies against carbohydrate epitopes [6].

Other names

PSAalpha-2,8-linked polysialic acidNCAM-PSAColominic acid

Targeted cell lysis via antibody-dependent cellular cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC), or CAR-T cell recognition of the glycan epitope.