Background/Objectives: Tumor-infiltrating B cells (TIBs) and tissue-resident memory T cells (TRMs) play significant roles in antitumor immunity. However, their prognostic relevance in brain metastases (BMs) derived from gastrointestinal (GI) cancers remains unclear. This study aimed to investigate the prognostic significance of TIBs and TRMs in GI cancer-derived BMs (GIBMs). Methods: Retrospective histopathological analyses were performed on surgically resected GIBM tissues from 13 patients. The densities of tumor-infiltrating lymphocytes (TIL) subsets (TIBs, CD4+T cells, CD8+CD103+TRMs, and CD8+CD103-non-TRMs) were quantified and correlated with clinical parameters and overall survival (OS) including the Graded Prognostic Assessment (GPA). Results: TIBs and CD4+T cells were predominantly accumulated in the tumor stroma, particularly around blood vessels, where they formed lymphocyte clusters without characteristics of tertiary lymphoid structures (TLSs). In contrast, TRMs more deeply infiltrated into the tumor epithelium than their counterpart non-TRMs. Positive correlations were found between TIB density and both the prognostic prediction of GPA and overall survival (OS) after BM diagnosis or surgery. Furthermore, increased densities of TIBs and TRMs were associated with enhanced survival after BM diagnosis. Conclusions: TIB and TRM densities in BM tissues could serve as reliable prognostic indicators for survival in patients with GIBMs. This study provides crucial insights for the development of novel immunotherapeutic strategies against this lethal disease.
**背景/目的：** 肿瘤浸润B细胞和组织驻留记忆T细胞在抗肿瘤免疫中发挥重要作用。然而，它们在源自胃肠道癌的脑转移中的预后相关性尚不明确。本研究旨在探讨TIBs和TRMs在胃肠道癌来源的脑转移中的预后意义。 **方法：** 对13例患者手术切除的GIBM组织进行回顾性组织病理学分析。量化了肿瘤浸润淋巴细胞亚群的密度，并将其与临床参数和总生存期相关联。 **结果：** TIBs和CD4+T细胞主要积聚在肿瘤间质中，尤其是在血管周围，形成不具有三级淋巴结构特征的淋巴细胞簇。相比之下，TRMs比其对应的非TRMs更深入地浸润到肿瘤上皮中。研究发现，TIB密度与GPA的预后预测以及BM诊断或手术后的总生存期均呈正相关。此外，TIBs和TRMs密度的增加与BM诊断后生存期的延长相关。 **结论：** BM组织中TIB和TRM的密度可作为GIBM患者生存的可靠预后指标。本研究为开发针对这一致命疾病的新型免疫治疗策略提供了重要见解。
肿瘤(癌症)患者之家