Predicting metastasis with novel prognostic liquid biopsy for uveal melanoma

Dr Christina Herrspiegel and colleagues from the Karolinska Institutet and St. Erik Eye Hospital, Stockholm, Sweden, reported that they have developed a prognostic test, referred to as serUM, that they believe is a strong predictor of metastasis of uveal melanoma.

The test is based on serum obtained from peripheral blood samples at the time of diagnosis of uveal melanoma in 83 patients (52% women; mean age at diagnosed, 65 years) from 1996 to 2000 at St. Erik Eye Hospital, they explained. All patients were diagnosed with primary melanoma in the choroid or ciliary body.

The investigators performed both proteome profiling of 84 different cancer-related proteins to screen for potential biomarkers and an enzyme-linked immunosorbent assay to evaluate the serum levels of the best protein candidates. Receiver operating characteristics were used to define thresholds for metastatic risk, they explained.

The prognostic test, serUM, was developed in a training cohort and tested in a validation cohort.

In the study patients, the mean tumour diameter and thickness were, respectively, 9.8 mm and 4.9 mm.

The proteome profiling evaluated 5 proteins, Leptin, Osteopontin, Progranulin, Tenascin C, and DLL-1, for further analysis. The prognostic test was based on the Leptin and Osteopontin concentrations developed in the training cohort (n = 17) and then tested in a validation cohort (n = 62) after exclusion of three patients with unreliable total protein fractions, the authors reported.

The results showed that with each increasing metastatic risk category, the patients had gradually shorter cumulative metastasis-free survival (log rank p for trend = 0.01).

Multivariate Cox regression analysis indicated that serUM was an independent predictor of metastasis when entering all of the following as covariates, the tumor diameter, tumour thickness, and patient age at diagnosis (hazard ratio 2.4, 95% confidence interval, 1.0-5.3).

Dr Herrspiegel and coauthors concluded, “serUM, a prognostic test based on serum obtained from a peripheral blood sample at diagnosis of uveal melanoma, is a strong predictor of metastasis.” They emphasized the need for future prospective studies to validate the findings of the current study.