BCG therapy downregulates HLA-I on malignant cells to subvert antitumor immune responses in bladder cancer [NanoString_IMM]. BCG therapy downregulates HLA-I on malignant cells to subvert antitumor immune responses in bladder cancer [NanoString_IMM]

Patients with high-risk non-muscle-invasive bladder cancer (NMIBC) frequently relapse after standard intravesical BCG therapy and may have a dismal outcome. Resistance mechanisms to such immunotherapy remain misunderstood. Here, using cancer cell lines, freshly resected human bladder tumors and cohorts of bladder cancer patients pre- and post-BCG therapy, we demonstrate two distinct patterns of immune subversion upon BCG relapse. In the first pattern, intracellular BCG infection of cancer cells induced a post-transcriptional downregulation of HLA-I membrane expression via an inhibition of the autophagy flux. Patients with HLA-I deficient cancer cells post-BCG therapy displayed a myeloid immunosuppressive tumor microenvironment with epithelial-to-mesenchymal transition (EMT) characteristics and dismal outcomes. Conversely, patients with HLA-I proficient cancer cells post-BCG therapy presented with CD8+ T cell tumor infiltrates, upregulation of inflammatory cytokines and inhibitory immune checkpoint molecules. Those patients had a very favorable outcome. We surmise that HLA-I expression in bladder cancers at relapse post-BCG does not result from immunoediting but rather from an immune subversion process directly induced by BCG on cancer cells, which predicts dismal prognosis. Cancer cells HLA-I scoring by immunohistochemistry (IHC) staining can be easily implemented by pathologists in routine practice to stratify future urothelial cancer patient treatment strategies. Overall design: NanoString Pan-Cancer Immune Panel on paired T1 human bladder tumors pre-BCG therapy and ≥T2 bladder tumors post-BCG therapy.

高风险非肌层浸润性膀胱癌（non-muscle-invasive bladder cancer, NMIBC）患者在接受标准膀胱内卡介苗（BCG）治疗后常出现复发，且预后不佳。此类免疫治疗的耐药机制目前仍未明确。本研究利用癌细胞系、新鲜切除的人膀胱肿瘤组织，以及卡介苗治疗前后的膀胱癌患者队列，揭示了卡介苗治疗复发后存在两种截然不同的免疫逃逸模式。在第一种模式中，癌细胞内的卡介苗感染通过抑制自噬流，诱导了人类白细胞抗原I类（HLA-I）膜表面表达的转录后下调。卡介苗治疗后癌细胞呈HLA-I缺陷状态的患者，其肿瘤微环境呈现髓系免疫抑制性特征，伴随上皮间质转化（epithelial-to-mesenchymal transition, EMT）表型，且预后不良。反之，卡介苗治疗后癌细胞保留HLA-I功能的患者，则表现出CD8+ T细胞肿瘤浸润、炎症细胞因子上调以及免疫检查点抑制分子表达升高，此类患者的预后极佳。我们推测，卡介苗治疗复发后膀胱癌组织的HLA-I表达并非源于免疫编辑，而是由卡介苗直接诱导癌细胞产生的免疫逃逸过程所致，这一特征可用于预测不良预后。病理医师可在日常临床工作中通过免疫组织化学（immunohistochemistry, IHC）染色对癌细胞的HLA-I表达进行评分，以此对未来的尿路上皮癌患者进行治疗策略分层。研究整体设计：对卡介苗治疗前的配对T1期人膀胱肿瘤组织，以及卡介苗治疗后的≥T2期膀胱肿瘤组织，采用NanoString泛癌免疫基因检测面板进行检测。