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Table 1 Biochemical potency of CB-1158 against arginase and NOS activity

From: Inhibition of arginase by CB-1158 blocks myeloid cell-mediated immune suppression in the tumor microenvironment

  CB-1158, IC50 (nM)
Purified enzyme assay
 Recombinant human Arg1 86 (±25)
 Recombinant human Arg2 296 (±5)
 Recombinant bovine endothelial NOS N/A
 Rat cerebellar neuronal NOS N/A
 Recombinant murine inducible NOS N/A
Cell lysate assay
 Human granulocyte lysate 178 (±28)
 Human erythrocyte lysate 116
 Human hepatocyte lysate 158 (±23)
 Cancer patient plasma 122 (±32)
  1. Mean IC50 values in nanomolar for CB-1158 inhibition of purified recombinant arginases or native arginases in cell lysates or cancer patient plasma. Standard deviations are indicated in parentheses. Recombinant Arg1 assays (N = 3) were performed in duplicate wells in the presence of 160 μM L-arginine. Recombinant Arg2 assays (N = 2) were performed in triplicate wells with 20 mM L-arginine. Arginase activity assays using human granulocyte lysate (N = 3), human erythrocyte lysate (N = 1), human hepatocyte lysate (N = 4), and cancer patient plasma (N = 5) were performed in duplicate wells with 160 μM L-arginine. Purified NOS enzyme activity was assayed in the presence 50 μM CB-1158, which showed no inhibitory activity against the three NOS isoforms
  2. N/A not applicable