A novel tumour marker related to the c-myc oncogene product.

We have studied the utility of the c-myc oncogene product as tumour marker using a set of monoclonal antibodies raised against synthetic peptides constructed from sequence data of the human c-myc oncoprotein. One antibody, Myc1-9E10, raised against the C-terminal 32 amino acids, has been shown to detect specifically the 62 kDa c-myc gene product in tumour cells. Immunoblotting of sera and urine with this antibody consistently revealed a single 40 kDa band (p40). Quantitative analysis using dilution dot immunoblotting demonstrated a considerable increase in the titre of p40 in the sera of 51 patients with a wide range of advanced solid tumours when compared with 17 healthy controls and 50 patients with non-malignant diseases. Serial measurement of the p40 titre in 12 patients with resected colorectal carcinoma shows a gradual return to normal with a half-life of 7 days. Our data suggests that p40 may be a useful new marker for monitoring tumour activity.