NETest liquid biopsy is diagnostic of small intestine and pancreatic neuroendocrine tumors and correlates with imaging

Introduction: Current monoanalyte biomarkers are ineffective in gastroenteropancreatic neuroendocrine tumors (GEP-NETs). NETest, a novel multianalyte signature, provides molecular information relevant to disease biology. Aim(s): Independently validate NETest to diagnose GEP-NETs and identify progression in a tertiary referral center. Materials and methods: Cohorts are 67 pancreatic NETs (PNETs), 44 small intestine NETs (SINETs) and 63 controls. Well-differentiated (WD) PNETs, n = 62, SINETs, all (n = 44). Disease extent assessment at blood draw: anatomical (n = 110) CT (n = 106), MRI (n = 7) and/or functional Ga-68-SSA-PET/CT (n = 69) or F-18-FDG-PET/CT (n = 8). Image-positive disease (IPD) was defined as either CT/MRI or Ga-68-SSA-PET/CT/F-18-FDG-PET/CT-positive. Both CT/MRI and Ga-68-SSA-PET/CT negative diagnosis in WD-NETs was considered image-negative disease (IND). NETest (normal: 20): PCR (spotted plate s). Data: mean +/- SD. Results: Diagnosis: NETest was significantly increased in NETs (n = 111; 26 +/- 21) vs controls (8 +/- 4, p < 0.0001). Seventy-five (42 PNET, 33 SINET) were image positive. Eleven (8 PNET, 3 SINET; all WD) were IND. In IPD, NETest was significantly high er (36 +/- 22) vs IND (8 +/- 7, P < 0.0001). NETest accuracy, sensitivity and specificity are 97, 99 and 95%, respectively. Concordance with imaging: NETest was 92% (101/110) concordant with anatomical imaging, 94% (65/69) with Ga-68-SSA-PET/CT and 96% (65/68) dual modality (CT/MRI and Ga-68-SSA-PET/CT). In 70 CT/MRI positive, NETest was elevated in all (37 +/- 22). In 40 CT/MRI negative, NETest was normal (11 +/- 10) in 31. In 56 Ga-68-SSA-PET/CT positive, NETest was elevated (36 +/- 22) in 55. In 13 Ga-68-SSA-PET/CT negative, NETest was normal (9 +/- 8) in ten. Disease status: NETest was significantly higher in progressive (61 +/- 26; n = 11) vs stable disease (29 +/- 14; n = 64; P < 0.0001) (RECIST 1.1). Conclusion: NETest is an effective diagnostic for PNETs and SINETs. Elevated NETest is as effective as imaging in diagnosis and accurately identifies progression.