Complete response to pembrolizumab in recurrent nested variant of urothelial carcinoma

Large, Nested Variant of Urothelial Carcinoma Is Enriched with Activating Mutations in Fibroblast Growth Factor Receptor-3 among Other Targetable Mutations

The large, nested variant of urothelial carcinoma (LNVUC) is characterized by bland histomorphology mimicking that of benign von Brunn nests. In the current study, we aimed to investigate the Fibroblast Growth Factor Receptor-3 (FGFR-3) activation and missense mutation in 38 cases, including 6 cases diagnosed with LNVUC and 32 with metastatic invasive urothelial carcinoma (UC). Initially, six formalin-fixed paraffin-embedded (FFPE) tissue samples of the LNVUC were subjected to whole-exome sequencing (WES), and then we performed targeted sequencing on 32 cases of metastatic invasive UC of various morphological subtypes, which were interrogated for the FGFR3. Our results revealed 3/6 (50%) LNVUC cases evaluated by WES in our study showed an activating mutation in FGFR-3, 33% showed an activating mutation in PIK3CA, and 17% showed activating mutation in GNAS or MRE11. Additionally, 33% of cases showed a truncating mutation in CDKN1B. All LNVUC in our study that harbored the FGFR-3 mutation showed additional activating or truncating mutations in other genes. Overall, 6/32 (18.75%) cases of random metastatic invasive UC showed missense mutations of the FGFR-3 gene. The LNVUC variant showed the higher incidence of FGFR-3 mutations compared to other types of mutations. Additionally, all LNVUC cases show additional activating or truncating mutations in other genes, thus being amenable to novel targeted therapy.

Isolated Renal Calyceal Urothelial Carcinoma Effectively Treated With PD-1 Inhibitor Alone: A Case Report And Literature Review

The discovery of immune checkpoint inhibitors (ICIs) represents a significant step forward in the battle against malignant tumors. In a number of advanced malignancies, ICIs, such as antibodies to programmed cell death protein-1 inhibitor (PD-1) and its ligand, programmed death-ligand 1 (PD-L1), have shown good therapeutic benefits. A 71-year-old male patient was diagnosed with solitary renal calyceal urothelial cancer. The space-occupying lesion in the upper calyx of the left kidney dramatically decreased after 13 treatments with a PD-1 inhibitor (tislelizumab) alone, and the tumor reached partial remission. This case suggests that a PD-1 inhibitor (tislelizumab) alone may be an effective treatment strategy for solitary renal calyceal urothelial carcinoma.