BCG treatment is the gold-standard therapy for high-grade intermediate-risk and high-risk non-muscle-invasive bladder cancer (NMIBC). However, ~30−40% of patients who receive BCG experience treatment failure, and the mechanisms by which it acts are not well understood. Thus, the role of the tumour microbiome in bladder cancer treatment response has gained increasing interest. Now, new data have provided insight into differences in microbiome species richness and diversity between BCG responders and BCG non-responders and enabled identification of possible mechanistic pathways.

In this study, both retrospectively collected and prospectively collected samples were analysed. In the retrospective analysis, 47 archival formalin-fixed paraffin-embedded (FFPE) tissue samples from transurethral resection of the bladder tumour (TURBT) and 14 paired radical cystectomy specimens collected between 2012 and 2018 were identified and compared for BCG response. All patients had received at least induction and six instillations of BCG. Responders were defined as having no evidence of disease for at least 2 years after one course of induction with or without maintenance therapy — 23 were identified in total. Non-responders were defined as experiencing progression to muscle-invasive bladder cancer, having persistent high-grade T1 disease or progressing to high-grade T1 disease within 3 months of completing induction BCG, or having persistent high-grade TA disease or carcinoma in situ despite two cycles of induction BCG, based on the AUA–SUO guidelines — 24 were identified in total, 14 of whom had paired radical cystectomy samples.

BCG 治疗是高级别、中危和高危非肌层浸润性膀胱癌 (NMIBC) 的金标准治疗。然而，约 30−40% 接受 BCG 的患者经历治疗失败，其作用机制尚不清楚。因此，肿瘤微生物组在膀胱癌治疗反应中的作用引起了越来越多的关注。现在，新数据让我们深入了解卡介苗应答者和卡介苗非应答者之间微生物组物种丰富度和多样性的差异，并能够识别可能的机制途径。

在这项研究中，对回顾性收集和前瞻性收集的样本进行了分析。在回顾性分析中，对 2012 年至 2018 年间收集的 47 份经尿道膀胱肿瘤切除术 (TURBT) 档案福尔马林固定石蜡包埋 (FFPE) 组织样本和 14 份配对根治性膀胱切除术样本进行了鉴定，并比较了 BCG 反应。所有患者均至少接受过诱导和六次 BCG 滴注。有反应者被定义为在一个疗程的诱导后至少 2 年内没有任何疾病证据，无论有或没有维持治疗——总共确定了 23 名。无反应者被定义为进展为肌层浸润性膀胱癌、患有持续性高级别 T1 疾病或在完成诱导 BCG 后 3 个月内进展为高级别 T1 疾病、或患有持续性高级别 TA 疾病或原位癌尽管根据 AUA-SUO 指南进行了两个周期的 BCG 诱导，但总共鉴定出 24 例，其中 14 例具有配对的根治性膀胱切除术样本。