Quantification of cathepsin D in plasma of patients with malignant melanoma

The high mortality rate of melanoma patients who develop metastases prompte d us to seek for a prognostic soluble marker to identify high-risk and non- risk patients at the stage of the primary tumour. Therefore, we developed a new ELISA for quantifying plasma concentrations of the proteolytic enzyme cathepsin D (CD) inpatients with primary tumours (MM-P) and with metastases (MM-M), resepectively, compared to a control group. Whereas healthy proban ds (n=56) and MM-P (n=168) showed similar mean values of CD (0.73 +/- 0.45 ng/ml and 0.82 +/- 0.80 ng/ml), MM-M (n=40) yielded significantly reduced p lasma levels (0.43 +/- 0.53 ng/ml) revealing a high significant discriminat ion both between controls and MM-M, and MM-P and MM-M (p<0.0001). From the beginning of the study (1990) to the present II of 68 MM-P developed metast ases. In order to test the prognostic efficiency of this enzyme to determin e those patients at high-risk and non-risk for developing metastases, the r eceiver operating characteristic analysis was used showing that CD plasma l evels cannot supply reliable prognostic values (W=0.53, p=0.66).