Monoclonal antibodies for diagnosis and potential therapy of small cell lung cancer--the ganglioside antigen fucosyl-GM1

Abstract

Lung carcinomas represent a highly heterogenous group of tumors, which includes small cell lung cancer (SCLC). The ganglioside fucosyl-GM1 (FucGM1) was originally identified as a highly selective marker for SCLC. A number of monoclonal antibodies against FucGM1 have been produced against the purified ganglioside, and their specificity validated. With monoclonal antibodies, FucGM1 has been detected in tissues as well as in serum samples from SCLC patients. A sensitive, quantitative assay method for FucGM1 was developed based on scintillation proximity immunoassay (SPA): A specific monoclonal antibody against FucGM1 is bound to immunosorbent particles that contain a fluor. When radiolabelled FucGM1 binds to these particles, the fluor is excited, and the photons emitted can be measured directly in a beta-counter. This sensitive assay for FucGM1 has several potential diagnostic applications: differential diagnosis of SCLC, development of serum assays for diagnosis and monitoring of disease progression, and monitoring of patient response to therapy. The expression of FucGM1 in SCLC cells is heterogeneous, and may depend on the differentiated state of tumor cells. However, monoclonal antibodies specific for FucGM1 may have important future applications for radioimmunoimaging as well as in immunotherapy for SCLC.