Expression of epithelial-cell adhesion molecule (Ep-CAM) in small cell lung cancer as defined by monoclonal antibodies 17-1A and BerEP4.

Small cell lung cancer (SCLC) comprises 15-20% of all lung cancer. Despite high initial response to chemotherapy chemoresistance at relapse leads to a less than 5% five-year survival rate. Adjuvant treatment with monoclonal antibodies (Mabs) against SCLC antigens may offer a therapeutic option. Mab 17-1A directed against the epithelial-cell adhesion molecule (Ep-CAM) has been extensively tested for therapy in patients with colorectal carcinoma. Expression of Ep-CAM in SCLC has been earlier described. However, reactivity of Mab 17-1A and another Ep-CAM-binding Mab BerEP4 has not yet been described for SCLC. Using immunohistology first with BerEP4 and confirmatory with 17-1A a homogenous and strong expression of Ep-CAM was seen in all SCLC specimens tested (n = 10). For comparison, heterogenous expression was seen in the non-SCLC tumors tested (n = 15). These findings strongly suggest that Mab 17-1A can be useful for adjuvant immunotherapy in patients with SCLC. For detection of Ep-CAM in tumor tissue in patients that might be considered for immunotherapy with Mab 17-1A, Mab BerEP4 appears to be preferred.