The advances in targeted therapies, immunotherapy, and the recent emergence of antibody-drug conjugates (ADCs) herald a potential paradigm shift in treating patients with metastatic urothelial cancer. Yet, there are inherent challenges in utilizing these therapies, including the management of treatment-related toxicities. In this special Urologic Oncology: Seminars and Original Investigations issue, we review the latest developments and discuss insights into future research needs.

Alterations of fibroblast growth factor receptors (FGFRs) are common in bladder and other cancers and result in disrupted signalling via several pathways. Therapeutics that target FGFRs have now entered the clinic, but, in common with many cancer therapies, resistance develops in most cases. To model this, we derived resistant sublines of two FGFR-driven bladder cancer cell lines by long-term culture with the FGFR inhibitor PD173074 and explored mechanisms using expression profiling and whole-exome sequencing. We identified several resistance-associated molecular profiles. These included HRAS mutation in one case and reversible mechanisms resembling a drug-tolerant persister phenotype in others. Upregulated IGF1R expression in one resistant derivative was associated with sensitivity to linsitinib and a profile with upregulation of a YAP/TAZ signature to sensitivity to the YAP inhibitor CA3 in another. However, upregulation of other potential therapeutic targets was not indicative of sensitivity. Overall, the heterogeneity in resistance mechanisms and commonality of the persister state present a considerable challenge for personalised therapy. Nevertheless, the reversibility of resistance may indicate a benefit from treatment interruptions or retreatment following disease relapse in some patients. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Bladder carcinoma (BC) is the ninth most common cause of cancer worldwide. Surgical resection and conventional chemotherapy and radiotherapy will ultimately fail due to tumor recurrence and resistance. Thus, the development of novel treatment is urgently needed. Fibroblast growth factor receptor 3 (FGFR3) is an important and well-established target for BC treatment. In this study, we utilized the free and open-source protein-ligand docking software idock to prospectively identify potential inhibitors of FGFR3 from 3,167 worldwide approved small-molecule drugs using a repositioning strategy. Six high-scoring compounds were purchased and tested in vitro. Among them, the acaricide drug fluazuron exhibited the highest antiproliferative effect in human BC cell lines RT112 and RT4. We further demonstrated that fluazuron treatment significantly increased the percentage of apoptosis cells, and decreased the phosphorylation level of FGFR3 and its downstream proteins FRS2-α, AKT, and ERK. We also investigated the anticancer effect of fluazuron in vivo in BALB/C nude mice subcutaneously xenografted with RT112 cells. Our results showed that oral treatment with fluazuron (80 mg/kg) significantly inhibited tumor growth. These results suggested for the first time that fluazuron is a potential inhibitor of FGFR3 and a candidate anticancer drug for the treatment of BC.