NCAM AND LUNG-CANCER

The presence of the neural cell adhesion molecule, NCAM, is indicative for a poor prognosis in lung-cancer patients. Using MAb 735, we have investigated the expression of polysialic acid, PSA, on NCAM in a spec trum of neuro-endocrine lung tumors, ranging from the slowly growing t ypical carcinoids via the atypical carcinoids with clinically unpredic table behavior to the highly aggressive small-cell lung carcinomas. Ou r immunohistochemical findings indicate a significant association betw een the presence of PSA on the tumor cells and an aggressive and immat ure sub-type of the tumor. This might be related to impairment of cell -cell and cell-matrix interactions by the presence of PSA, as we demon strated in vitro, since detachment is one of the first steps in the me tastatic process. The NCAM-MAb 123C3 used in these studies appeared ex tremely useful in immunoscintigraphy and immunotherapy of SCLC xenogra fts in nude mice, and for immunoscintigraphy of a SCLC patient. This m ay be explained by internalization of the 123C3 antibody, which we dem onstrated in vitro. 123C3 is the only Cluster-1 SCLC Mab studied thus fat that becomes internalized. (C) 1994 Wiley-Liss, Inc.