Active specific immunotherapy: PEM as a potential target molecule

An understanding of the mechanisms involved in a biological phenomenon increases its potential for clinical exploitation. Thus, the simultaneous identification of TAA and the molecular mechanisms involved in antigen presentation and recognition by the immune system make the use of ASI a real possibility. The polymorphic epithelial mucin is expressed on most carcinomas and is highly immunogenic. Furthermore, it has many characteristics that make it potentially an ideal target molecule for ASI: (a) not only is it expressed, but it is upregulated by most carcinomas; (b) it is aberrantly glycosylated by carcinomas, resulting in the exposure of cryptic epitopes; (c) its tandem repeat structure results in there being many epitopes per molecule; (d) its extended structure at the surface means it is one of the first molecules the cells of the immune system encounter; and (e) its apparent ability to elicit HLA unrestricted killing already demonstrated in cancer patients makes it applicable to all individuals.