Detection of the Circulating Lung Cancer Marker Lcap with a New Monoclonal Antibody Trd-L1

Abstract

Lung Cancer Associated Protein (LCAP) is a high molecular weight glycoprotein defined by the monoclonal antibody (MAb) DF-L1 prepared against a primary adenocarcinoma of the lung. Previous studies have demonstrated that LCAP circulates at elevated levels in patients with lung cancer. However, a suitable assay for monitoring LCAP levels has not been available. The present work describes the development of a double-determinant LCAP assay using MAb TRD-L1 as the capture antibody and MAb DF-L1 as the tracer. In 60 normal subjects, the mean LCAP level was 4.8 U/ml with 2 (3.3%) subjects having values >12 U/ml (mean + 2SDS). By contrast, 37 of 67 (55.2%) patients with lung cancer had LCAP levels >12 U/ml. Moreover, only 14 of 203 (6.9%) patients with benign lung disease had elevated levels. LCAP levels were most commonly elevated (62.7%) in patients with adenocarcinoma of the lung and with advanced disease. These results indicate that LCAP as detected by MAb TRD-L1 is a potentially useful marker for the evaluation of patients with lung cancer.