Role of Targeted Therapies in Management of Metastatic Urothelial Cancer in the Era of Immunotherapy

Tumor expression of Nectin-1-4 and its clinical implication in muscle invasive bladder cancer: An intra-patient variability of Nectin-4 expression

There is limited evidence regarding the tumor expression of nectins and their clinical implications in muscle invasive bladder cancer. Herein, we evaluated expression of Nectins 1-4 in 64 patients with muscle invasive bladder cancer who underwent radical cystectomy using a histochemical scoring method (H-score; immunohistochemical staining intensity multiplied by the percentage of positive-staining cells). The cutoff values were defined based on the median H-scores. Of the 64 patients, 45 (70%) had residual tumors in radical cystectomy specimens, while 13 (20%) had lymph node metastasis. The median (interquartile range) H-scores of Nectin-1, - 2, - 3, and - 4 expression were 0 (0-10), 80 (30-180), 5 (0-30), and 100 (33-160), respectively. The Nectin-4 H-score of the neuroendocrine variant was significantly lower than that of pure urothelial carcinoma (P = 0.015). Post-neoadjuvant chemotherapy pathological response (<ypT2N0 residual disease and pN-negative) was achieved in 18 (49%) of the 37 patients who received neoadjuvant chemotherapy. Clinical stage II, not Nectin expression, was an independent factor associated with pathological response (P = 0.019, adjusted odds ratio 6.9, vs stage III/IV). There was no correlation in Nectin-4 tumor expression between transurethral resection and matched radical cystectomy specimens and between radical cystectomy specimens and matched lymph node metastatic lesions. However, there was a significant decrease in Nectin-4 expression in post-neoadjuvant chemotherapy radical cystectomy specimens compared to pre-neoadjuvant chemotherapy transurethral resection specimens (P = 0.008). Given the downregulation of Nectin-4 by chemotherapy and the significant discrepancy between radical cystectomy and matched lymph node metastasis specimens, baseline primary tumors may not be a suitable material for evaluating Nectin-4 expression and its potential as a predictive biomarker for enfortumab vedotin treatment.

Expressions of PD-L1 and Nectin-4 in urothelial cancer patients treated with pembrolizumab

OBJECTIVES

Recently, the standard of care for advanced urothelial cancer (UC) has been changed by developing immune-checkpoint inhibitors (ICIs). However, its response rate is limited to 20-30%. The identification of biomarkers to predict the therapeutic effects of ICIs is urgently needed. The present study explored the association between immunohistochemical biomarkers and clinical outcomes in UC patients treated with pembrolizumab.

PATIENTS AND METHODS

A total of 85 patients with UC who received pembrolizumab after chemotherapy from January 2018 to May 2020 were retrospectively reviewed. Tumor tissues were obtained for immunohistochemical study from 47 out of 85 patients. The protein expressions of PD-L1, WT1, Nectin-4, CD4, CD8, Foxp3, and CD68 in tumor cells and/or tumor infiltrating lymphocytes were immunohistochemically examined. The associations between protein expressions and overall survival (OS), progression-free survival (PFS), and disease control rate (DCR) were statistically analyzed.

RESULTS

Patients with positive PD-L1 in tumor cells showed significantly worse OS (Log-rank test: HR 5.146, p = 0.001, Cox regression analysis: HR 4.331, p = 0.014) and PFS (Log-rank test: HR 3.31. p = 0.022), along with significantly lower DCR (14.3%) compared to the PD-L1 negative patients (67.5%). In addition, patients with strong expression of Nectin-4 in tumor cells showed significantly higher DCR (100%) than the other patients (50%).

CONCLUSION

PD-L1 expression in tumor cells was associated with poor prognosis (OS and PFS) and low DCR. Interestingly, the strong expression of Nectin-4 was correlated with high DCR. PD-L1 and Nectin-4 expression in tumor cells could be prognostic biomarkers useful for pembrolizumab in patients with advanced UC.

Mutually exclusive mutation profiles define functionally related genes in muscle invasive bladder cancer

Muscle Invasive bladder cancer is known to have an abundance of mutations, particularly in DNA damage response and chromatin modification genes. The role of these mutations in the development and progression of the disease is not well understood. However, a mutually exclusive mutation pattern between gene pairs could suggest gene mutations of significance. For example, a mutually exclusive mutation pattern could suggest an epistatic relationship where the outcome of a mutation in one gene would have the same outcome as a mutation in a different gene. The significance of a mutually exclusive relationship was determined by establishing a normal distribution of the conditional probabilities for having a mutation in one gene and not the other as well as the reverse relationship for each gene pairing. Then these distributions were used to determine the sigma–magnitude of standard deviation by which the observed value differed from the expected, a value that can also be interpreted as the ‘p-value’. This approach led to the identification of mutually exclusive mutation patterns in KDM6A and KMT2D as well as KDM6A and RB1 that suggested the observed mutation pattern did not happen by chance. Upon further investigation of these genes and their interactions, a potential similar outcome was identified that supports the concept of epistasis. Knowledge of these mutational interactions provides a better understanding of the mechanisms underlying muscle invasive bladder cancer development, and may direct therapeutic development exploiting genotoxic chemotherapy and synthetic lethality in these pathways.

Prognostic Role of FGFR Alterations and FGFR mRNA Expression in Metastatic Urothelial Cancer Undergoing Checkpoint Inhibitor Therapy

OBJECTIVE

To examine the disease-specific survival(DSS) after checkpoint inhibitor(CPI) therapy based on FGFR alterations and FGFR mRNA expression levels in patients with metastatic urothelial cancer(mUCa) within a multi-center cohort.

METHODS

Within a cohort of 72 patients with mUCa from five academic centers in Germany FGFR alterations, as well as FGFR1-4 mRNA expression levels in tumor samples from the primary tumor or metastatic sites. Spearman rank correlations, logistic regression, as well as Kaplan-Meier survival analyses and univariate Cox proportional hazards regression models were employed to examine the impact of different FGFR patterns on the DSS after CPI treatment.

RESULTS

FGFR3 mutations or gene fusions (gene alterations) were detected in 16.9% of all samples. Patients with or without FGFR3 gene alterations did not show different oncological outcomes undergoing CPI treatment. Low expression of FGFR2 mRNA alone, as well as the combination of either low FGFR2mRNA expression and FGFR3 gene alteration or high FGFR3mRNA expression (P = 0.027), identified a subgroup of patients with unfavorable outcomes, comprising 40% of the total cohort. This trend was also observed in univariate Cox proportional hazards regression analysis(FGFR3 gene alteration: Hazard ratio(HR) 5.33, 95%Confidence interval(CI)1.76-15.0, P = 0.004; FGFR3mRNA expression:HR 3.04, 95%CI 1.40-7.13, P = 0.005).

CONCLUSION

Assessment of FGFR mRNA expression identified a high-risk subgroup of patients with mUCa. These patients showing overexpression of FGFR3 mRNA were found to have unfavorable DSS after CPI treatment. Using this approach may be suitable for identifying a patient population with poor response to CPI treatment, which may benefit from early FGFR inhibition.

An adaptive, biomarker-directed platform study of durvalumab in combination with targeted therapies in advanced urothelial cancer

Durvalumab is a programmed death-ligand 1 (PD-L1) inhibitor with clinical activity in advanced urothelial cancer (AUC)¹. AUC is characterized by several recurrent targetable genomic alterations^2-5. This study ( NCT02546661 , BISCAY) combined durvalumab with relevant targeted therapies in biomarker-selected chemotherapy-refractory AUC populations including: (1) fibroblast growth factor receptor (FGFR) inhibitors in tumors with FGFR DNA alterations (FGFRm); (2) pharmacological inhibitor of the enzyme poly-ADP ribose polymerase (PARP) in tumors with and without DNA homologous recombination repair deficiency (HRRm); and (3) TORC1/2 inhibitors in tumors with DNA alteration to the mTOR/PI3K pathway^3-5.This trial adopted a new, biomarker-driven, multiarm adaptive design. Safety, efficacy and relevant biomarkers were evaluated. Overall, 391 patients were screened of whom 135 were allocated to one of six study arms. Response rates (RRs) ranged 9-36% across the study arms, which did not meet efficacy criteria for further development. Overall survival (OS) and progression-free survival (PFS) were similar in the combination arms and durvalumab monotherapy arm. Biomarker analysis showed a correlation between circulating plasma-based DNA (ctDNA) and tissue for FGFRm. Sequential circulating tumor DNA analysis showed that changes to FGFRm correlated with clinical outcome. Our data support the clinical activity of FGFR inhibition and durvalumab monotherapy but do not show increased activity for any of the combinations. These findings question the targeted/immune therapy approach in AUC.

2b or Not 2b: How Opposing FGF Receptor Splice Variants Are Blocking Progress in Precision Oncology

More than ten thousand peer-reviewed studies have assessed the role of fibroblast growth factors (FGFs) and their receptors (FGFRs) in cancer, but few patients have yet benefited from drugs targeting this molecular family. Strategizing how best to use FGFR-targeted drugs is complicated by multiple variables, including RNA splicing events that alter the affinity of ligands for FGFRs and hence change the outcomes of stromal-epithelial interactions. The effects of splicing are most relevant to FGFR2; expression of the FGFR2b splice isoform can restore apoptotic sensitivity to cancer cells, whereas switching to FGFR2c may drive tumor progression by triggering epithelial-mesenchymal transition. The differentiating and regulatory actions of wild-type FGFR2b contrast with the proliferative actions of FGFR1 and FGFR3, and may be converted to mitogenicity either by splice switching or by silencing of tumor suppressor genes such as CDH1 or PTEN. Exclusive use of small-molecule pan-FGFR inhibitors may thus cause nonselective blockade of FGFR2 isoforms with opposing actions, undermining the rationale of FGFR2 drug targeting. This splice-dependent ability of FGFR2 to switch between tumor-suppressing and -driving functions highlights an unmet oncologic need for isoform-specific drug targeting, e.g., by antibody inhibition of ligand-FGFR2c binding, as well as for more nuanced molecular pathology prediction of FGFR2 actions in different stromal-tumor contexts.

16-Hydroxycleroda-3,13-dien-15,16-olide Induces Apoptosis in Human Bladder Cancer Cells through Cell Cycle Arrest, Mitochondria ROS Overproduction, and Inactivation of EGFR-Related Signalling Pathways

A clerodane diterpene compound 16-hydroxycleroda-3,13-dien-15,16-olide (CD) is considered a therapeutic agent with pharmacological activities. The present study investigated the mechanisms of CD-induced apoptosis in T24 human bladder cancer cells. CD inhibited cell proliferation in a concentration and time-dependent manner. CD-induced overproduction of reactive oxygen species and reduced mitochondrial membrane potential, associated with reduced expression of Bcl-2 and increased levels of cytosolic cytochrome c, cleaved PARP-1 and caspase-3. In addition, CD treatment led to cell cycle arrest at the G0/G1 phase and inhibited expression of cyclin D1 and cyclin-dependent kinases 2 and 4 and led to increased levels of p21, p27Kip1 and p53. All of these events were accompanied with a reduction of pEGFR, pMEK1/2, pERK1/2, pAkt, pmTOR, pP70S6K1, HIF-1α, c-Myc and VEGF. RNAseq-based analysis revealed that CD-induced cell death was characterised by an increased expression of stress and apoptotic-related genes as well as inhibition of the cell cycle-related genes. In summary, CD induces apoptosis in T24 bladder cancer cells through targeting multiple intracellular signaling pathways as a result of oxidative stress and cell cycle arrest.

Combination of cyclin-dependent kinase and immune checkpoint inhibitors for the treatment of bladder cancer

BACKGROUND

Perturbation of the CDK4/6 pathway is frequently observed in advanced bladder cancer. We investigated the potential of targeting this pathway alone or in combination with chemotherapy or immunotherapy as a therapeutic approach for the treatment of bladder cancer METHODS: The genetic alterations of the CDK4/6 pathway in bladder cancer were first analyzed with The Cancer Genome Atlas database and validated in our bladder cancer patient-derived tumor xenografts (PDXs). Bladder cancer cell lines and mice carrying PDXs with the CDK4/6 pathway perturbations were treated with a CDK4/6 inhibitor palbociclib to determine its anticancer activity and the underlying mechanisms. The combination index method was performed to assess palbociclib and gemcitabine drug-drug interactions. Syngeneic mouse bladder cancer model BBN963 was used to assess whether palbociclib could potentiate anti-PD1 immunotherapy.

RESULTS

Of the 413 bladder cancer specimens, 79.2% harbored pertubations along the CDK4/6 pathway. Palbociclib induced G0/G1 cell cycle arrest but with minimal apoptosis in vitro. In mice carrying PDXs, palbociclib treatment reduced tumor growth and prolonged survival from 14 to 32 days compared to vehicle only controls (p = 0.0001). Palbociclib treatment was associated with a decrease in Rb phosphorylation in both cell lines and PDXs. Palbociclib and gemcitabine exhibited antagonistic cytotoxicity in vitro (CI > 3) and in vivo, but palbociclib significantly enhanced the treatment efficacy of anti-PD1 immunotherapy and induced CD8+ T lymphocyte infiltration in syngeneic mouse models.

CONCLUSIONS

The CDK4/6 pathway is feasible as a potential target for the treatment of bladder cancer, especially in combination with immunotherapy. A CDK4/6 inhibitor should not be combined with gemcitabine.

Emerging biomarkers in urothelial carcinoma: Challenges and opportunities

Advanced urothelial carcinoma (UC) is a very important cause of cancer-related morbidity and mortality with, until recently, only a few available therapeutic options. The treatment landscape has dramatically changed in recent years with the introduction of immune checkpoint inhibitors and the development of novel targeted agents, such as erdafitinib, and antibody-drug conjugates, such as enfortumab vedotin. Cost-effective utilization of this rapidly expanding therapeutic armamentarium can be further optimized via the identification and validation of reliable prognostic and predictive biomarkers that inform prognostication and patient selection. In this review, we aim to summarize examples of recent developments in the rapidly expanding field of emerging biomarkers in UC, outlining challenges and opportunities.

Targets for Therapy of Bladder Cancer

In 2018 bladder cancer (urothelial carcinoma) was ranked twelfth concerning worldwide diagnosis of malignancies. At the time point of diagnosis of bladder cancer, approximately 75% of patients present with a nonmuscle-invasive disease (NMIBC), while the remaining 25% show invasion of tumor cells in the muscle layer of the bladder wall (MIBC). Among NMIBC tumors, flat, high-grade carcinoma in situ (CIS) is a therapeutic challenge. CIS shows a tendency to invade the muscle tissue of the bladder wall and thus become a MIBC. Standard therapy of NMIBC (including CIS) is done via intravesical instillation of BCG (bacillus Calmette Guerin) inducing a local immune reaction that finally promotes elimination of bladder cancer cells. However, BCG treatment of NMIBC proves to be ineffective in approximately 40% of patients. Therefore, new therapeutic approaches for the treatment of bladder cancer are urgently needed. Among promising new treatment options that are currently being investigated are the use of immune checkpoint inhibitors, and targeted approaches attacking (among others) long noncoding RNAs, micro RNAs, cancer stem cells, PARP1, and receptor signaling pathways. Moreover, the use of antibody-drug-conjugates (ADCs) is investigated also in bladder cancer therapy. Another approach that has been successfully established in preclinical studies uses the cytotoxic power of the alpha-emitter Bi-213 coupled to an antibody targeting EGFR. Overexpression of EGFR has been demonstrated in the majority of patients suffering from CIS. Feasibility, safety, toxicity and therapeutic efficacy of intravesical instillation of Bi-213-anti-EGFR have been evaluated in a pilot study. Since the results of the pilot study proved to be promising, a further optimization of alpha-emitter immunotherapy in bladder cancer seems mandatory.

STAT3/5 Inhibitors Suppress Proliferation in Bladder Cancer and Enhance Oncolytic Adenovirus Therapy

The JAK-STAT signalling pathway regulates cellular processes like cell division, cell death and immune regulation. Dysregulation has been identified in solid tumours and STAT3 activation is a marker for poor outcome. The aim of this study was to explore potential therapeutic strategies by targeting this pathway in bladder cancer (BC). High STAT3 expression was detected in 51.3% from 149 patient specimens with invasive bladder cancer by immunohistochemistry. Protein expression of JAK, STAT and downstream targets were confirmed in 10 cell lines. Effects of the JAK inhibitors Ruxolitinib and BSK-805, and STAT3/5 inhibitors Stattic, Nifuroxazide and SH-4-54 were analysed by cell viability assays, immunoblotting, apoptosis and cell cycle progression. Treatment with STAT3/5 but not JAK1/2 inhibitors reduced survival, levels of phosphorylated STAT3 and Cyclin-D1 and increased apoptosis. Tumour xenografts, using the chicken chorioallantoic membrane (CAM) model responded to Stattic monotherapy. Combination of Stattic with Cisplatin, Docetaxel, Gemcitabine, Paclitaxel and CDK4/6 inhibitors showed additive effects. The combination of Stattic with the oncolytic adenovirus XVir-N-31 increased viral replication and cell lysis. Our results provide evidence that inhibitors against STAT3/5 are promising as novel mono- and combination therapy in bladder cancer.

Targeting FGFR in bladder cancer: ready for clinical practice?

Objective: To give a brief literature overview of current knowledge regarding FGFR inhibition in bladder cancer.Background: The deeper molecular understanding of bladder urothelial carcinoma (UC) has reshaped the diagnostic and therapeutic landscape of this malignancy. Rapid technological development, including the frequent use of next-generation sequencing (NGS) in clinical practice, has boosted identification and development of potential biomarkers and targeted therapies. Genetic aberrations in the fibroblast growth factor receptor (FGFR)-pathway may drive tumorigenesis and are considered as attractive drug targets in advanced and/or metastatic UC. Several clinical trials have been performed or are ongoing to assess the safety and efficacy of (non-)selective FGFR inhibitors in patients with advanced or metatastic UC.Results: While non-selective FGFR inhibitors have shown limited clinical response with unacceptable toxicity, selective 'pan'-FGFR inhibitors had favourable response rates with manageable toxicity. To predict response, patients were screened for FGFR aberrations using NGS after DNA/RNA extraction of UC tissue specimen or collection of ctDNA or cfDNA.Conclusion: Early clinical trials have shown promising results for targeting FGFR in advanced or metastatic UC, though these findings need to be validated in phase III trials. It seems that FGFR aberrations can be detected in ctDNA and cfDNA as efficiently as in tumour tissue, showing their potential as predictive, non-invasive liquid biomarkers.