Evaluation of Therapeutic Targets in Histological Subtypes of Bladder Cancer.

Histologically, bladder cancer is a heterogeneous group comprising urothelial carcinoma (UC), squamous cell carcinoma, adenocarcinomas (ACs), urachal carcinomas (UrCs), and small cell neuroendocrine carcinomas (SCCs). However, all bladder cancers have been treated so far uniformly, and targeted therapy options are still limited. Thus, we aimed to determine the protein expression/molecular status of commonly used cancer targets (programmed cell death 1 ligand 1 (PD-L1), mismatch repair (MMR), androgen and estrogen receptors (AR/ER), Nectin-4, tumor-associated calcium signal transducer 2 (Tacstd2, Trop-2), epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (HER2), and fibroblast growth factor receptor 3 (FGFR3)) to give first insights into whether patients with SCC, AC/UrCs, and squamous-differentiated carcinomas (Sq-BLCA) of the bladder could be eligible for targeted therapies. In addition, for MMR-deficient tumors, microsatellite instability was analyzed. We completed our own data with molecular data from The Cancer Genome Atlas (TCGA). We present ratios for each drug and cumulative ratios for multiple therapeutic options for each nonurothelial subtype. For example, 58.9% of SCC patients, 33.5% of AC/UrCs patients, and 79.3% of Sq-BLCA patients would be eligible for at least one of the analyzed targets. In conclusion, our findings hold promise for targeted therapeutic approaches in selected patients in the future, as various drugs could be applied according to the biomarker status.

Therapeutic implications of PD-L1 expression in bladder cancer with squamous differentiation.

BACKGROUND: Immune checkpoint inhibitors (ICI) are an integral part of bladder cancer therapy, however, the relevance of ICI treatment for mixed and pure squamous cell carcinoma of the bladder remains poorly studied. Therefore, we analysed the expression of programmed death-ligand 1 (PD-L1) in urothelial carcinomas with squamous differentiation (UC/SCC) and pure squamous cell carcinoma (SCC) of the bladder and studied a UC/SCC patient with ICI therapy. METHODS: Tissue microarrays of 45 UC/SCC and 63 SCC samples were immunohistochemically stained with four anti-PD-L1 antibodies (28-8, 22C3, SP142 and SP263). PD-L1 expression was determined for tumour cells (TP-Score), immune cells (IC-Score) and combined (CPS, combined positive score). In addition, we present clinical and histological data of an UC/SCC patient with nivolumab therapy. RESULTS: Overall, positive PD-L1 staining ranged between 4.8 and 61.9% for IC and 0 and 51.2% for TC depending on the used antibody. There were no significant differences between UC/SCC and SCC. According to current FDA guidelines for example for first line therapy of urothelial cancer with pembrolizumab (CPS ≥ 10), a subset of SCC patients up to 20% would be eligible. Finally, our UC/SCC index patient revealed excellent therapy response regarding his lung metastasis. CONCLUSIONS: Our data reveal a PD-L1 expression in squamous differentiated carcinomas comparable with current data shown for urothelial tumours. In accordance with the encouraging clinical data of the index patient we suggest ICI treatment also for mixed and pure SCC of the urinary bladder.

Expression of programmed death ligand (PD-L1) in different tumors. Comparison of several current available antibody clones and antibody profiling.

PD-L1 is a surface molecule which is expressed on different types of cells, including antigen presenting cells, vascular endothelial cells and other cells of human tissues. Expression of PD-L1 is also found on human tumor cells. PD-L1 as the ligand to PD1 receptor molecule of CD8+ T cells inhibits its cytotoxic effect on the tumor cell. The modern target therapy uses this interaction to inhibit the PD-1 molecule of T cells to stimulate tumor necrosis. To compare expression differences, twelve frequent types of malignant tumors with ten patients per group were selected. Immunohistochemical stains with different antibodies for PD-L1 (DAKO, Spring Bioscience, Ventana, Cell Signaling, Biocare Medical, Abcam, Zeta Corporation) were performed, analyzed and compared. To summarize, we detected variable expression pattern of PD-L1 with general higher mean value of expression of tumor cells with clone SP263 in most tumor groups. In the comparison of selected cases of lung cancer, therapy relevant differences of PD-L1 expression on tumor cells with different antibodies were observed. Additionally, the profiling study of several PD-L1-antibody clones (28-8 Abcam and 28-8 DAKO, SP142, SP263) with Signal-to-Amino Acid Residue Plots was performed with interesting findings of cross-activity of SP142 with two peptides from PD-1, which can explain why clone SP142 stains immune cells more intensively, as previously published.