Supplementary Material for: <b><i>DAXX</i></b>, <b><i>ATRX</i></b>, and MSI in PanNET and Their Metastases: Correlation with Histopathological Data and Prognosis

<b><i>Introduction:</i></b> Studies on pancreatic neuroendocrine tumors (PanNETs) regarding loss of <i>ATRX</i>, <i>DAXX</i>, or frequency of microsatellite instability (MSI) show inconclusive results. So far, data on corresponding metastaseshave not been published. <b><i>Methods:</i></b> We performed immunohistochemistry (IHC) of <i>ATRX</i>, <i>DAXX</i>, <i>MSH2</i>, <i>MSH6</i>, <i>MLH1</i>, and <i>PMS2</i> on 74 PanNETs and 19 metastases. <i>ATRX-</i> and <i>DAXX</i>-negative PanNETs were further sequenced for mutations. We used polymerase chain reaction for MSI on cases with IHC loss of <i>MSH2</i>, <i>MSH6</i>, <i>MLH1</i>, and <i>PMS2</i>. <b><i>Results:</i></b> Immunohistochemical loss of <i>DAXX</i> and <i>ATRX</i> was observed in 8/74 (11%) and 6/74 (8%) PanNETs. Loss of <i>DAXX</i> immunoreactivity was statistically associated with higher tumor grade and showed a tendency toward a decreased overall survival. Sequencing of <i>DAXX-</i> (7/11 [64%]) and <i>ATRX-</i>negative (5/11 [45%]) PanNETs revealed a mutation in 6/7 (86%) and 2/5 (40%). The specificity of immunohistochemical loss of <i>DAXX</i> and <i>ATRX</i> for mutation was 80% and 67%, respectively. The expression status of <i>DAXX</i> compared to primary tumor differs in 2/12 (17%) lymph node metastases. We further identified 3/74 (4%) tumors as MSI, associated with a poor prognosis. <b><i>Discussion/Conclusion:</i></b> Our study supports the hypothesis that a loss of <i>DAXX</i> immunoreactivity can identify a more aggressive subtype of PanNET with high confidence, while <i>ATRX</i> loss is a weaker indicator. Our results also strengthen the role of <i>DAXX</i> immunolabeling as a prognostic marker. We could show that <i>ATRX</i> might be less suitable as a surrogate for sequencing. Our results indicate that IHC of <i>DAXX</i> and <i>ATRX</i> may identify PanNET subtypes as targets for more aggressive therapy.

**引言：** 现有针对胰腺神经内分泌肿瘤（pancreatic neuroendocrine tumors, PanNETs）中ATRX、DAXX缺失情况，或微卫星不稳定性（microsatellite instability, MSI）发生频率的相关研究，结论均未达成一致。截至目前，尚未有关于对应转移灶的相关研究数据发表。
**方法：** 本研究对74例胰腺神经内分泌肿瘤组织及19例转移灶组织进行了ATRX、DAXX、MSH2、MSH6、MLH1及PMS2的免疫组织化学（immunohistochemistry, IHC）检测。对ATRX及DAXX表达缺失的胰腺神经内分泌肿瘤标本，进一步开展基因突变测序分析。针对MSH2、MSH6、MLH1及PMS2免疫组化结果呈缺失的病例，采用聚合酶链式反应进行微卫星不稳定性检测。
**结果：** 免疫组化结果显示，74例胰腺神经内分泌肿瘤中分别有11%（8/74）及8%（6/74）存在DAXX及ATRX的表达缺失。DAXX免疫反应性缺失与肿瘤高级别分级具有统计学相关性，且呈现出总生存期缩短的趋势。对DAXX表达缺失的11例标本中7例（64%）、ATRX表达缺失的11例标本中5例（45%）进行测序后发现，分别有86%（6/7）及40%（2/5）存在基因突变。DAXX与ATRX免疫组化缺失对基因突变检测的特异性分别为80%与67%。在12例淋巴结转移灶中，有17%（2/12）的DAXX表达状态与原发肿瘤存在差异。本研究还发现，3/74（4%）的肿瘤为微卫星不稳定性表型，该表型与不良预后相关。
**讨论/结论：** 本研究支持以下假说：DAXX免疫反应性缺失可高置信度地识别出侵袭性更强的胰腺神经内分泌肿瘤亚型，而ATRX缺失作为该类亚型的识别指标则效力较弱。本研究结果进一步证实了DAXX免疫标记作为预后标志物的价值。本研究同时表明，ATRX或许并不适合作为基因突变测序的替代检测指标。本研究结果提示，针对DAXX与ATRX的免疫组化检测，可用于区分胰腺神经内分泌肿瘤亚型，从而为更具针对性的强化治疗提供靶点。

搜集汇总

背景与挑战

背景概述

该数据集是2022年发布的胰腺神经内分泌肿瘤（PanNET）研究补充材料，聚焦于DAXX、ATRX基因免疫组化损失和微卫星不稳定性（MSI）的分析。研究基于74个PanNETs和19个转移瘤样本，通过免疫组化和测序方法，发现DAXX损失与更高肿瘤分级及较差预后显著相关，而ATRX损失作为预后指标较弱，同时识别出MSI与不良预后关联，旨在为PanNET亚型分类和更激进治疗提供靶点。