Metastatic Uveal Melanoma: An Ocular Melanoma Associated Antigen in the Serum of Patients with Metastatic Disease

Abstract

Two monoclonal antibodies, MAb8-1H and ME491, which bind to different determinants of the same highly glycosylated melanoma-associated antigen, were used to determine melanoma-associated antigen levels in serum samples from patients treated for primary choroidal or ciliary body melanoma and who subsequently developed systemic metastasis. An immunoassay was developed in which ME491 was absorbed to polystyrene beads in order to bind the melanoma-associated antigen present in serum. ¹²⁵I-MAb8-1H was used to detect the bound antigen. This double-determinant immunoassay is both sensitive and reproducible. Supernatant fluids of tissue cultured melanoma cell lines served as positive standards for the calculation of melanoma-associated antigen units. The mean serum levels of melanoma-associated antigen were 7.7 units for patients with benign ocular conditions, 9.51 units for patients with choroidal melanoma without documented metastatic disease, and 48.3 units for patients with choroidal melanoma and documented systemic metastasis. The clinical implications of using this test as a screening method for the detection of metastatic disease is discussed.