Figure 1.

The level of CD73 enzymatic activity in serum discriminates patients with metastatic melanoma from healthy donors. A, AMPase activity in serum samples from patients with melanoma (MP, n=546) and healthy donors (HD; n=96), measured with malachite green assay kit. B, The AMP hydrolysis in samples of MPs is significantly reduced in presence of the selective CD73 inhibitor, APCP (100 µM) (n=71). C, Percentage of hydrolysis of ¹⁵N AMP by multiple reaction monitoring mass spectrometry in samples of MPs (n=13) in presence of APCP (100 µM) or anti-human CD73 monoclonal antibody (clone 7G2) (5 µg/mL) or vehicle (Ctrl). D, ELISA of CD73 in serum of MPs (n=83) and HD (n=38). E, Receiving operating characteristic curve analysis for CD73 protein expression and CD73 enzymatic activity in MPs compared with healthy donors. Mean±SD is shown. P values are from two-sided Mann-Whitney test (A, B, D) or one-way analysis of variance test (C). APCP, 5’-α,β-methylene diphosphate; AUC, area under the curve; Pi, inorganic phosphate.