NCIt definition : A highly negative-charged carbohydrate composed of a linear polymer of alpha 2,8-linked
sialic acid residue with potential immunotherapeutic activity. Polysialic acid (PSA)
is mainly attached to the neural cell adhesion molecule (NCAM), a membrane-bound glycoprotein
overexpressed in certain types of cancers. In embryonic tissue PSA-NCAM is abundantly
expressed and PSA plays an important role in formation and remodeling of the neural
system through modulation of the adhesive properties of NCAM, thereby reducing cell-cell
interactions and promoting cellular mobility. In adult tissue however, the expression
of PSA-NCAM is associated with a variety of malignant tumors, signifying its potential
role in tumor metastasis. When administered in a vaccine formulation, PSA may stimulate
a cytotoxic T cell response against tumors expressing PSA, thereby resulting in a
reduction in tumor size.;