Tumor Escape Phenotype in Bladder Cancer Is Associated with Loss of HLA Class I Expression, T-Cell Exclusion and Stromal Changes

Cancer eradication and clinical outcome of immunotherapy depend on tumor cell immunogenicity, including HLA class I (HLA-I) and PD-L1 expression on malignant cells, and on the characteristics of the tumor microenvironment, such as tumor immune infiltration and stromal reaction. Loss of tumor HLA-I is a common mechanism of immune escape from cytotoxic T lymphocytes and is linked to cancer progression and resistance to immunotherapy with the inhibitors of PD-L1/PD-1 signaling. Here we observed that HLA-I loss in bladder tumors is associated with T cell exclusion and tumor encapsulation with stromal elements rich in FAP-positive cells. In addition, PD-L1 upregulation in HLA-I negative tumors demonstrated a correlation with high tumor grade and worse overall- and cancer-specific survival of the patients. These changes define common immuno-morphological signatures compatible with cancer immune escape and acquired resistance to therapeutic interventions across different types of malignancy. They also may contribute to the search of new targets for cancer treatment, such as FAP-expressing cancer-associated fibroblasts, in refractory bladder tumors.

Automated summary

The loss of HLA-I in bladder tumors is associated with T cell exclusion and encapsulation by stromal elements rich in FAP-positive cells. Additionally, upregulation of PD-L1 in HLA-I negative tumors is correlated with high tumor grade and worse overall- and cancer-specific survival of patients. These changes represent common immuno-morphological signatures for cancer immune escape and resistance to therapeutic interventions, and may lead to the identification of new targets for cancer treatment, such as FAP-expressing cancer-associated fibroblasts in refractory bladder tumors.