sIL-2R- an Immuno-biomarker for Prediction of Metastases in Uveal Melanoma

Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. High serum levels of soluble IL-2 receptor (sIL-2R) have been reported in acute inflammations and metastatic cancers. This study evaluated the potential of high/increasing sIL-2R levels in predicting metastases.

The study included a total of 1,546 sera samples of subjects from three groups: 119 healthy controls (73 subjects), 566 UM 10 year (10y) disease-free (DF) (220 patients), 861 metastatic UM (268 patients). Patients were followed-up biannually with liver ultrasound and liver function tests for the presence of metastases (Mets). Blood samples to measure the levels of sIL-2R were obtained at the time of primary diagnosis, soon after initial treatment (enucleation, brachytherapy), every 6 months, 10 years from diagnosis, at Mets confirmation by CT, and after additional treatments.

Significantly higher sIL-2R levels were detected in the Mets patients compared to healthy controls and 10y DF patients. Compared to the upper limit of the normal levels of sIL-2R, 1,000 U/ml, its levels in metastatic UM were 61%, 25% in 10y DF UM, and 6.25% in the controls. High levels of sIL-2R in metastatic patients, decreased significantly post treatments. Individual kinetics of markers, indicated similar trends of sIL-2R compared to osteopontin and S-Protein 100, predicting metastases, which were confirmed on liver imaging.

Significantly higher sIL-2R levels were evident in all UM patients with Mets. Significant increases in sIL-2R levels on serial evaluations indicated and predicted UM Mets, enabling earlier treatment of Mets, to improve survival.