TNFSF13 and lung adenocarcinoma: However, APRIL CSF levels elevated above the threshold of 6.59 ng/ml (as calculated by ROC analysis, Fig. 2) were found in three patients with metastatic brain tumors (two with lung adenocarcinoma (10.36 and 17.01 ng/ml) and one with malignant melanoma (8.04 ng/ml)).