The NETest liquid biopsy is diagnostic for gastric neuroendocrine tumors: observations on the blood-based identification of microscopic and macroscopic residual disease

Abstract

Background NETest, a novel multi-gene liquid biopsy has utility in neuroendocrine tumor (NET) diagnosis and identification of residual disease. We independently assessed utility of the NETest to diagnose gastric neuroendocrine neoplasms (GNENs) and identify micro- and macroscopic residual disease. Methods Cohorts comprised histologically confirmed GNENs at biopsy, n = 46; GNETs Type 1: 42 (32 NET G1, 10 NET G2), a GNET Type 3: 1 well-differentiated NET G3, neuroendocrine carcinomas (NECs) ( n = 3), and controls ( n = 63). Disease status at sampling was assessed by gastroscopy, histology (resection margin [R] positivity of polypectomy or biopsy), EUS, CT or MRI, and/or 68 Ga-DOTA-TATE PET/CT. Groups included image- (gastroscopy, EUS, and anatomical and/or functional imaging) positive or image negative disease. NETest assay by PCR (spotted plates, normal cut-off: 20). Data: mean ± SD. Results Disease extent : Image-negative ( n = 30) (21 R0, 9 R1); Image-positive, n = 16. Diagnosis: NETest was increased in GNETs (23 ± 11) vs. controls (7 ± 4, p < 0.0001). In histology-positive, the NETest accuracy was 100% (25/25). Microscopic disease: In image-negative but R1, NETest was elevated in 100% (9/9; 28 ± 9). Levels were elevated vs. controls (7 ± 4, p < 0.0001), or R0 (16 ± 11, p = 0.02). Eight of 21 R0, exhibited positive NETest. Macroscopic disease: Gastric lesions were multiple: 38%, single: 62%, submucosal: 13%, or ulcerated: 13%. Lesions size was ≤5 mm (50%), > 5–9.9 mm (17%), 10–19.9 mm (17%), ≥20 mm (17%) [≥10 mm: 34%). The NETest accuracy was 100% (16/16). Levels (28 ± 7) were higher than controls (7 ± 4, p < 0.0001) or R0 (16 ± 11, p = 0.002) but not to R1 (28 ± 9, p = 0.5). Conclusions NETest is diagnostic for gastric NETs. Elevated levels identify both microscopic and macroscopic residual disease. In histology/image-negative disease, elevated NETest may reflect early evidence of increased neuroendocrine gene expression of hypergastrinemia-induced neoplastic transformation of enterochromaffin-like (ECL) cells to tumor status. A sensitive liquid biopsy has utility in the management and surveillance of gastric NET disease.

Update of the diagnostic and therapeutic guidelines for gastro-entero-pancreatic neuroendocrine neoplasms (recommended by the Polish Network of Neuroendocrine Tumours) [Aktualizacja zaleceń ogólnych dotyczących postępowania diagnostyczno-terapeutycznego w nowotworach neuroendokrynnych układu pokarmowego (rekomendowane przez Polską Sieć Guzów Neuroendokrynnych)]

“…Studies on the clinical use of NETest in the Polish population have confirmed the earlier reports regarding its usefulness in the diagnosis of NENs of the gastrointestinal tract [33,43], respiratory system [44][45][46], pheochromocytoma and paraganglioma [29,30,47], as well as correlations with imaging tests [43] and disease activity (progression) [13,43,46,48]. A comparison of the clinical utility of NETest and circulating chromogranin A demonstrated a significant advantage of the molecular biomarker in the diagnosis and monitoring of NENs [48][49][50][51].…”

“…A negative test result (< 20%) excludes NEN or indicates a history of radical removal of the tumour; a positive test result (≥ 20%) correlates with the diagnosis of neuroendocrine neoplasm without identifying the primary tumour site [29,30]. Clinical use of NETest also includes the identification of microscopic disease [33,34], assessment of the radicality of surgical treatment [15,35], somatostatin analogues [13], radioisotope [36], and disease progression [37]. A test score between 20 and 40% indicates disease stabilisation, while a score between 41 and 100% indicates disease progression [38,39].…”

NETest: A Systematic Review Focusing on the Prognostic and Predictive Role

“…Despite all patients were disease free at endoscopical, radiological, and functional imaging, the NETest score was elevated in 6 patients, suggesting that these patients could have minimal residual disease. According to this hypothesis, the same study demonstrated that in case of microscopical residual disease evidenced at histological examinations (5 patients with positive polypectomy margin and 4 patients with random biopsies diagnostic for microscopic tumor), NETest was elevated (28 ± 9%), demonstrating the accuracy of this diagnostic instrument in detecting minimal residual disease before morpho-functional imaging [51].…”

Update on Epidemiology, Diagnosis, and Biomarkers in Gastroenteropancreatic Neuroendocrine Neoplasms

“…NETest can detect disease progression 5–24 months before imaging changes. Identification of MRD that cannot be detected by imaging studies should lead to earlier therapeutic intervention in GEP-NENs [ 76 , 78 ]. Follow-up of GEP-NENs requires frequent endoscopy with biopsy and/or CT scanning, which causes physical pain and radiation exposure, and is costly.…”