Spectrum of genomic alterations in FGFR3: current appraisal of the potential role of FGFR3 in advanced urothelial carcinoma

Molecular analysis has identified subsets of urothelial carcinoma (UC) expressing distinct genetic signatures. Genomic alterations in the oncogenic fibroblast growth factor receptor 3 (FGFR3) pathway are among the most well described in UC and have led to extensive and ongoing investigation of FGFR3‐targeted therapies in this disease, although no new drugs have yet been approved. Given the unmet need for effective treatments in advanced and metastatic UC, a better understanding of the known molecular alterations of FGFR3 and of the previous and ongoing clinical investigations of this promising target in UC deserves attention. The objective of the present review is to describe the landscape of alterations and biology of FGFR3 in UC, comprehensively summarize the current state of UC clinical trials of FGFR3 inhibitors, and discuss future therapeutic applications. Using the Pubmed and Clinicaltrials.gov databases, articles describing the spectrum and biological activity of FGFR3 genomic alterations and trials of FGFR3 inhibitors in UC were identified. Search terms included ‘FGFR3 genomic alterations’ and ‘urothelial cancer’ or ‘bladder cancer’. Genomic alterations, including translocations and activating mutations, are increasingly described in advanced and metastatic UC. The majority of clinical trials have been performed in unselected populations; however, recent studies have reported encouraging preliminary data. We argue that routine use of molecular genomic tumour analysis in UC may inform selection of patients for appropriate trials and we further investigate the potential of FGFR3 as a meaningful clinical target for this difficult disease.     

Targeted therapies in the treatment of urothelial cancers

Progress has been slow in systemic management of locally advanced and metastatic bladder cancer over the past 20 years. However, the recent approval of immunotherapy with atezolizumab and nivolumab for second-line salvage therapy may usher in an era of more rapid improvement. Systemic treatment is suboptimal and is an area of substantial unmet medical need. The recent findings from The Cancer Genome Atlas project revealed promising pathways that may be amenable to targeted therapies. Promising results with treatment using vascular endothelial growth factor inhibitors such as ramucirumab, sunitinib or bevacizumab, and human epidermal growth factor receptor 2 targeted therapies, epidermal growth factor receptor inhibitors, and fibroblast growth factor receptor inhibitors, are undergoing clinical trials and are discussed later.     

Combination therapies involving checkpoint-inhibitors for treatment of urothelial carcinoma: a narrative review

The implementation of immune checkpoint-inhibitors (CPI) has significantly improved the prognosis of a subgroup of patients with urothelial bladder cancer (BC). Still, the majority of patients will progress or experience a recurrence on CPI monotherapy. The next generation of clinical trials is now testing combination therapy with CPI and other agents that target different oncogenic mechanisms in an effort to improve efficacy. The beneficial toxicity profile of CPI but also the approval of CPI combinations in other cancer sites justifies their investigation also in BC. Here we report on clinical trials in muscle-invasive, locally advanced and metastatic BC combining CPI with other therapies, with a focus on the latest results presented at ASCO GU 2020, ASCO 2020 and ESMO 2019 as well as Phase-III trials currently ongoing. Multiple phase I-III clinical trials are investigating the combination of a CPI with a second CPI, with chemotherapy, or with targeted therapies like fibroblast growth factor receptor (FGFR) inhibitors or Nectin-4 inhibitors in different disease states. The results of more than 10 phase-III trials in advanced BC are eagerly awaited. Preliminary data are contradictory, as some trials released promising interim results, while others reported failure to achieve the primary endpoints. Taken together, combining CPI with other therapies is a logical and potentially promising approach, but it is too early to draw conclusions on specific combinations. As combinatorial therapies markedly increase the level of complexity, bedside-to-bench studies are warranted to gain deeper insight of underlying biological mechanisms which can be used to optimize future trials.     

Targeted therapies in cancer

Cytotoxic chemotherapy has traditionally provided the backbone of medical care for cancer. While chemotherapy remains the treatment of choice for many types of cancer, so-called ‘targeted therapies’ are now increasingly available within the clinic across a broad range of tumour types. Targeted therapies can inhibit specific molecular targets implicated in cancer or single oncogenic drivers, rather than affecting cell division or DNA synthesis. While often better tolerated, they can be associated with adverse events, which require specialist multidisciplinary management. Targeted therapies have changed cancer care, with tailoring to an individual patients' tumour, new approaches to dosing and disease assessment, but with an increasing burden on health economics. Rather than a disease-specific approach, these novel therapies may be of benefit in multiple cancer types. There are three main categories of targeted therapies: small molecule inhibitors, monoclonal antibodies and immunotherapies, which will be considered in this article.     

Targeted therapies in cancer

Cytotoxic chemotherapy has traditionally provided the backbone of medical care for cancer. While chemotherapy remains the treatment of choice for many types of cancer, so called ‘targeted therapies’ are now increasingly available within the clinic across a broad range of tumour types. Targeted therapies can inhibit specific molecular targets implicated in cancer or single oncogenic drivers, preventing cell growth and tumorigenesis. While often better tolerated, they can be associated with adverse events that require specialist multidisciplinary management. Targeted therapies have changed cancer care, tailoring treatment to an individual patient's tumour characteristics and improving outcome. However, associated with this has come an increasing burden on health economics. Rather than a disease-specific approach, targeted therapies may be of benefit in multiple cancer types. There are three main categories of targeted therapies: small molecule inhibitors, monoclonal antibodies and immunotherapies, which will be considered in this article.     

The role of WNT signalling in urothelial cell carcinoma

Urothelial cell carcinoma (UCC) of the bladder is one of the most common malignancies, causing considerable morbidity and mortality worldwide. It is unique among the epithelial carcinomas as two distinct pathways to tumourigenesis appear to exist: low grade, recurring papillary tumours usually contain oncogenic mutations in FGFR3 or HRAS whereas high grade, muscle invasive tumours with metastatic potential generally have defects in the pathways controlled by the tumour suppressors p53 and retinoblastoma. Over the last two decades, a number of transgenic mouse models of UCC, containing deletions or mutations of key tumour suppressor genes or oncogenes, have helped us understand the mechanisms behind tumour development. In this summary, I present my work investigating the role of the WNT signalling cascade in UCC.     

Plasmacytoid and micropapillary urothelial carcinoma: rare forms of urothelial carcinoma

Plasmacytoid urothelial carcinomas (PUC) along with micropapillary urothelial carcinoma (MPC), small cell cancer, and nested-typed tumors are among the rare variations of urothelial carcinomas. The molecular characterization of PUC and MPC is currently the focus of our research on bladder cancer which we are conducting in cooperation with the Institute of Pathology in Erlangen. PUCs account for approximately 0.9% of all urothelial carcinomas. The diagnosis of these rare variants has acquired increasing importance since this may have prognostic and possibly therapeutic consequences for the patients. By analysis of 32 PUCs we were able to demonstrate the most comprehensive results available to date on the underlying molecular and clinical characteristics of these variants. Micropapillary cancers have already been described in multiple organs. Micropapillary breast cancer represent an individual entity with characteristic genomic aberrations and corresponding clinical and pathological features     

Rictor-dependent AKT activation and inhibition of urothelial carcinoma by rapamycin

ObjectiveWe previously reported a very high cumulative incidence of urothelial carcinoma in Taiwanese kidney transplant recipients. Rapamycin, the inhibitor of mTOR Complex 1, provides alternative immunosuppressive therapy after kidney transplantation with less neoplastic potential. We examined the in vivo and in vitro effects of rapamycin on urothelial carcinoma.Materials and methodsThe rat model of urothelial carcinoma was induced by 0.05% N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) in Fischer F344 rats. The anti-tumor effect of rapamycin was assessed grossly, microscopically, and by Western blot analysis. The mechanism of rapamycin's attenuation of urothelial carcinoma was also evaluated by T24 cells.ResultsRapamycin significantly reduced urinary bladder tumor growth in the rat model of 0.05% BBN-induced urothelial carcinoma (P < 0.001). The blood trough levels of rapamycin were correlated with the occurrence of urothelial carcinoma. In vitro, rapamycin also inhibited the cell proliferation, migration, and invasion, as well as the protein expression of vascular endothelial growth factor-A of T24 urothelial carcinoma cells, whereas rapamycin did not induce significant apoptosis in T24 cells. Rapamycin decreased the expression of phospho-mTOR, phospho-S6K, cyclin D1, and VEGF-A. Rapamycin also activated AKT in T24 cells in the rat model of urothelial carcinoma. The rapamycin-associated activation of AKT was inhibited by rictor siRNA, but not raptor siRNA.ConclusionsThis study provides in vitro and in vivo evidence that rapamycin may inhibit the development of urothelial carcinoma. The present findings also suggest rictor-dependent AKT activation as a consequence of mTORC1 inhibition.     

The emerging role of lymphadenectomy in upper tract urothelial carcinoma

Within the last decade, there has been an increased focus on lymphadenectomy or lymph node dissection (LND) in patients with upper tract urothelial carcinoma (UTUC). Although the data with regards to LND in UTUC are sparse, investigators are beginning to evaluate the role and define the anatomy to understand how LND may affect outcomes in patients with UTUC. This article reviews the history of LND for UTUC, outlines the relative anatomy, and evaluates the arguments and evidence for, and against, LND in patients with UTUC.     

Targeted therapies in diabetic nephropathy: an update

Diabetic nephropathy is the most common cause of end-stage renal disease worldwide. Various pathways in addition to the renin-angiotensinogen system have been implicated in the pathogenesis of diabetic nephropathy. Strategies to interrupt these pathophysiological pathways are a key to the development of new targeted therapies to prevent progression of diabetic nephropathy and are on the horizon. The various pharmacological drugs tried include aliskiren, a direct renin inhibitor blocking the first step in the renin pathway, and pentoxifylline and mammalian target of rapamycin inhibitors, which have antiinflammatory properties and have shown some promising results in management of diabetic nephropathy. Others include endothelin antagonists and vitamin D analogs which have been shown to decrease urinary albumin excretion. Inhibitors of advanced glycation and oxidative stress and plasminogen activator inhibitor-1 have proved useful in animal models of diabetic nephropathy. Others include ruboxistaurin, which blocks protein kinase C overexpression. Such targeted therapies would halt and might even reverse progression of diabetic nephropathy.     

Targeted therapies for the treatment of cancer

BACKGROUND: In contrast to conventional cytotoxic chemotherapy and radiation therapy, a new method of targeted cancer therapeutics is being directed towards molecular pathways that underlie the malignant phenotype. These therapies target specific tumor cell receptors or signaling events that are critical to tumor progression while reducing toxicity to normal cells. DATA SOURCES: The purpose of this review is to highlight several examples of novel targeted therapeutics that are currently approved by the FDA for treatment of patients with cancer. Rituxan is a humanized monoclonal antibody that binds to the CD20 antigen present on B cell lymphomas and is currently approved for the treatment of patients with relapsed or refractory low-grade CD20 positive follicular lymphoma. The humanized anti-HER-2/neu herceptin is approved for use in patients with metastatic breast cancer that demonstrates overexpression of HER-2/neu. Finally, Gleevec is a tyrosine kinase inhibitor that inhibits abl-specific phosphorylation and is approved for use in select patients with chronic myelogenous leukemia that is refractory to interferon therapy. CONCLUSIONS: The lessons learned from the use of these therapeutics will add to the growing knowledge of mechanistic approaches to the treatment of patients with cancer based upon targeted therapies, and herald a bright future that will improve the lives of patients with cancer.     

Topical chemotherapy in human urothelial carcinoma explants: a novel translational tool for preclinical evaluation of experimental intravesical therapies

Background

Urothelial carcinoma (UC) is associated with a high local recurrence rate despite intravesical therapy. There is a lack of representative preclinical models for standardized testing of novel experimental therapies.

Objective

To develop an ex vivo model for human UC and to evaluate its ability to generate reproducible and reliable results when testing cytotoxic agents.

Design, setting, and participants

Normal human urothelium (NHU) and bladder UC explants were collected from patients treated at our institution. A total of 195 surgical explants were cultured on a gelatine matrix. Tissue viability was regularly assessed using nicotinamide adenine dinucleotide (NADH) diaphorase enzymehistochemistry. Topical paclitaxel (PTX) or mitomycin C (MMC) chemotherapy was performed in a subset of 45 UC specimens.

Intervention

All patients underwent radical cystectomy (RC) or primary transurethral resection (TUR) of a bladder UC.

Measurements

Triple immunofluorescence (pan-cytokeratin [pan-CK]; 4′,6-diamidin-2′-phenylindol-dihydrochloride [DAPI]; terminal deoxynucleotidyl transferase biotin-dUTP nick-end labelling [TUNEL]) and caspase-3 staining of paraffin sections was performed. Proliferation rates were assessed using Ki-67 labelling indices. Apoptosis (percent) was quantified in representative tissue areas to characterize culture stability and to assess antineoplastic effects.

Results and limitations

No signs of necrosis and no significant changes in apoptosis were observed during the first 12 d of culture. Of all explants, 88.5% were vital after 20 d. In a highly reproducible fashion, topical chemotherapy resulted in significantly increased apoptosis (37.4% [19.0–75.0%] for PTX and 36.2% [18.8–46.7%] for MMC) compared with controls (7.5% [3.0–26.8%]; p < 0.001]). No statistically significant difference was observed regarding the effects of the two chemotherapeutic agents (p = 0.119).

Conclusions

The presented human ex vivo model takes UC heterogeneity into account and serves as a valuable translational tool. It offers an attractive alternative to preclinical cell line experiments or animal models and may even be used for prospective toxicity and drug efficacy tests in individual patients.     

Symposium report on urothelial dysfunction: pathophysiology and novel therapies

PURPOSE: The basic premise of this symposium (Workshop 7) at the 2004 International Continence Society meeting in Paris was to elucidate different mechanisms of urothelial cell pathology, explore their impact on bladder function and discuss novel therapeutic interventions. RESULTS: The topics included 1) urothelial structure and function, 2) the role of adenosine triphosphate in urothelial signaling and cystitis, 3) lamina propria myofibroblasts and purinergic receptors, 4) antiproliferative factor involvement in interstitial cystitis, 5) the urothelium as a reservoir for bacterial infections, 6) radiation cystitis, nitric oxide and gene therapy, and 7) intravesical treatments. DISCUSSION: It was agreed that the urothelium can no longer be regarded merely as a passive barrier separating urine from the underlying tissues. The epithelial cells of the urothelium form part of an integrated network that also includes afferent and possibly efferent nerves, and suburothelial myofibroblasts. It has a central role in several functions, including bladder wall sensation, local blood flow modulation, pathogen removal and active barrier provision. These functions are achieved through several autocrine and paracrine pathways that involve transmitter release from the urothelium and its ability to integrate incoming signals through its battery of membrane receptors. Several pathological processes were discussed using this knowledge, including the role of small glycoproteins released during interstitial cystitis, the molecular basis of radiation induced urothelial damage, the origin of recurrent urinary tract infections and the mode of action of potential intravesical treatments for overactive bladder. CONCLUSIONS: Overall it was concluded that the urothelium has a key role in regulating lower urinary tract physiology and pathology.     

Targeted therapies in metastatic renal cancer in 2009

The development of targeted molecules in renal carcinogenesis changed the therapeutic approaches of treatment for metastatic clear cell renal cell carcinoma. Four available drugs are currently available, i.e. bevacizumab, sunitinib, sorafenib and temsirolimus, but other molecules and combined therapy are under investigation. In this review we assess published reports of these targeted therapies and discuss the novel promising molecules targeting vascular endothelial growth factor and its receptors, the mammalian target of rapamycin and epithelial growth factor cascade.     

Radiochemotherapy of urothelial carcinoma

Radical cystectomy is the current standard therapy for muscle invasive or locally advanced transitional cell carcinoma of the bladder. Organ-preservingmonotherapeutic alternatives (e.g. transurethral resection, radiotherapy) do not lead to similar cure rates. In selected cases, a trimodal approach using transurethral resection and combined radio- and chemotherapy can be as efficient as cystectomy.     

FGFR3 mutations and a normal CK20 staining pattern define low-grade noninvasive urothelial bladder tumours

OBJECTIVES: Molecular markers superior to conventional clinicopathologic parameters are needed to predict disease courses in bladder cancer patients. In this study, we investigated four markers (Ki-67, TP53, CK20, FGFR3) in primary urothelial bladder tumours and compared them with traditional pathologic features. METHODS: Tissue microarrays were used to analyse CK20, TP53, and Ki-67 expression immunohistochemically in 255 unselected patients. FGFR3 mutations were detected by SNaPshot analysis. RESULTS: Abnormal CK20 expression was strongly associated with higher tumour grades and stages (p < 0.001); however, 65% of pTa tumours revealed an abnormal CK20 pattern. In the group of pTaG1 tumours, 59% presented with an abnormal CK20 pattern, whereas 82% carried the FGFR3 mutation. In the group of bladder tumours with normal CK20 pattern, the FGFR3 gene was mutated in 89%, whereas a mutated FGFR3 gene was found in only 37% of cases with abnormal CK20 expression (p < 0.001). All markers proved to be strong predictors of disease-specific survival in univariate studies. However, in multivariate analyses they were not independent from classical pathologic parameters. None of the molecular markers was significantly associated with tumour recurrence. CONCLUSIONS: Dysregulation of CK20 expression is an early event in the carcinogenesis of papillary noninvasive bladder cancer, but occurs later than FGFR3 mutations. The group of low-grade noninvasive papillary tumours is defined by the presence of an FGFR3 mutation and a normal CK20 expression pattern.     

Epidemiology of urothelial carcinoma

The epithelium lining is defined as the mucosal surfaces of the renal collecting tubules, calyces and pelvis, as well as the ureter, bladder and urethra. The term “urothelium” is used to refer to these surfaces. Upper tract urothelial carcinoma is a rare subset of urothelial cancers with a poor prognosis. Urinary bladder cancer is the most common malignancy involving the urinary system. Upper tract urothelial carcinoma is more common in men than in women, with a male‐to‐female ratio of 2:1. The incidence of urinary bladder cancer is also higher in men. Cigarette smoking and occupational exposure are the main upper tract urothelial carcinoma and urinary bladder cancer risk factors, while other factors are more specific to the carcinogenesis of upper tract urothelial carcinoma (i.e. Balkan endemic nephropathy, Chinese herb nephropathy). In Egypt until recent years, urinary bladder cancer was the most frequently diagnosed cancer due to Schistosoma haematobium. Substantial knowledge exists regarding the causes of upper tract urothelial carcinoma and urinary bladder cancer, and epidemiological studies have identified various chemical carcinogens that are believed to be responsible for most cases of urothelial carcinoma. In the era of precision medicine, genetic effects might play a direct role in the initiation and progression of urothelial carcinoma.