Insights into gastric neuroendocrine tumors burden

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

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 ⁶⁸Ga-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.

Effects of tumor types on treatment strategy formulation and prognostic evaluation of gastric neuroendocrine tumors

Aim: The effects of different types of gastric neuroendocrine tumors (G-NETs) on treatment strategy formulation and prognostic evaluation still remain controversial due to their rarity. Methods: 187 patients diagnosed with G-NETs were subdivided into four types based on the pathophysiology, etiology and presentation. Results: Type I, II G-NETs >1.0 cm and type III, IV G-NETs >2.0 cm are proved with aggressive behavior (p < 0.05). Type III G-NETs with higher Ki-67 index and tumor stage showed more invasive potential than type I and II G-NETs (p < 0.05). Endoscopic resection is the primary treatment for type I, II G-NETs, while surgical combined with chemotherapy is associated with favorable outcomes for type IV G-NETs. Conclusion: The clinical classifications of G-NETs are of great significance for the choice of treatment and the evaluation of prognosis.

Genomic dissection of gastrointestinal and lung neuroendocrine neoplasm

Objective

Neuroendocrine neoplasms (NENs) are relatively rare and heterogeneous malignancies with two major subtypes: low-grade neuroendocrine tumor (NET) and high-grade neuroendocrine carcinoma (NEC). Comprehensive molecular characterization of NENs is needed to refine our understanding of the biological underpinnings of different NEN subtypes and to predict disease progression more accurately.

Methods

We performed whole-exome sequencing (WES) of NEN samples from 49 patients (25 NETs and 24 NECs) arising from the stomach, intestines or lung. Clinicopathologic features were assessed and associated with molecular events.

Results

NENs generally harbor a low mutation burden, with TP53 being the top mutated gene found in 31% of patients. Consistent with other studies, p53 signaling pathway dysfunction is significantly enriched in NECs compared to NETs (P<0.01). Other thanTP53, tissue type-specific mutation profiles of NENs were observed in our cohort compared to those reported in pancreatic NETs. Importantly, we observed significant genomic instability, with increased copy number alterations observed across the NEN genome, which was more profound in NECs and independently correlated with poor overall survival (OS) (P<0.001). NECs could be further stratified into two molecular subtypes based on OS (P<0.001) and the chromosomal instability score (CIS). Interestingly, we discovered that the gain of whole chromosome 5 occurred at the early stage of NEN development, followed by the loss of 5q exclusively in NECs (P<0.001).

Conclusions

These findings provide novel insights into the molecular characteristics of NENs and highlight the association of genomic stability with clinical outcomes.