Bladder cancer: novel molecular characteristics, diagnostic, and therapeutic implications

Diagnostic value of a comprehensive, urothelial carcinoma-specific next-generation sequencing panel in urine cytology and bladder tumor specimens

BACKGROUND

Urine cytology can reliably diagnose high-grade urothelial carcinoma (HGUC) but not low-grade urothelial carcinoma (LGUC), and a more sensitive test is needed. Previously, a pilot study highlighted the possible diagnostic utility of next-generation sequencing (NGS) in identifying both LGUC and HGUC in urine cytology specimens.

METHODS

Twenty-eight urine ThinPrep cytology specimens and preceding or subsequent bladder tumor biopsy/resection specimens obtained within 3 months were included in the study (LGUC, n = 15; HGUC, n = 13). A customized, bladder-specific NGS panel was performed; it covered 69 frequently mutated or altered genes in urothelial carcinoma (UC) that were reported by The Cancer Genome Atlas and the Catalogue of Somatic Mutations in Cancer.

RESULTS

The sequencing results were compared between the urine cytology specimens and the corresponding bladder tumor biopsies/resections. TP53 was the most frequently identified mutation in HGUC cases (11 of 13 [85%]). PIK3CA and KDM6A were the most frequently identified mutations in LGUC: they occurred in 7 of 15 cases (47%) and in 6 of 15 cases (40%), respectively. Additional frequent mutations identified in the panel included ARID1A (n = 5), EP300 (n = 4), LRP1B (n = 3), ERBB2 (n = 2), STAG2 (n = 2), FGFR3 (n = 3), MLL (n = 2), MLL3 (n = 2), CREBBP1 (n = 1), RB1 (n = 1), and FAT4 (n = 1). Overall, the concordance between the cytology and surgical specimens was 75%. The sensitivity and specificity for identifying mutations in urine cytology specimens were 84% and 100%, respectively.

CONCLUSIONS

A bladder-specific NGS panel increases the sensitivity and specificity of urine cytology's diagnostic utility in both low- and high-grade tumors and may serve as a noninvasive surveillance method in the follow-up of patients with UC harboring known mutations.

The genetic difference between Western and Chinese urothelial cell carcinomas: infrequent FGFR3 mutation in Han Chinese patients

Urothelial cell carcinoma (UCC) includes urothelial bladder carcinoma (UBC), renal pelvic carcinoma (RPC) and ureter carcinoma (UC), and its incidence varies dependent on geographical areas and tumor locations, which indicates different oncogenic mechanisms and/or different genetic susceptibility/environment exposure. The activating mutations of the fibroblast growth factor receptor 3 (FGFR3) gene and telomerase reverse transcriptase (TERT) promoter are the most frequent genetic events in UCCs. These mutations have clinical utilities in UCC initial diagnostics, prognosis, recurrence monitoring and management. However, the vast majority of the results are obtained from studies of UCC patients in Western countries, and little has been known about these in Han Chinese patients. In the present study, we screened the FGFR3 gene and TERT promoter for mutations in 116 UBC, 91 RPC and 115 UC tumors from Han Chinese patients by using Sanger Sequencing. TERT promoter mutations occurred at a high frequency in these UCC patients, comparable with that seen in Western patients, however, the FGFR3 mutation was surprisingly lower, only 9.4% for UBCs, 8.8% for RPCs and 2.6% for UCs, respectively. Taken together, the FGFR3 gene is an infrequent target in the pathogenesis of Han Chinese UCCs, and its mutation detection and targeted therapy have limited clinical utility in these patients. Our results underscore the need for extensive characterization of cancer genomes from diverse patient populations, thereby contributing to precision medicine for cancer treatment and prevention.

It's in your blood: spectral biomarker candidates for urinary bladder cancer from automated FTIR spectroscopy

Blood samples of urinary bladder cancer (UBC) patients and patients with urinary tract infection were analysed with advanced automated high throughput Fourier transform infrared (HT-FTIR)-spectroscopy. Thin dried film samples were robotically prepared on multi-well titer plates (MTP) for absorbance measurements in transmission mode. Within the absorbance, 1st and 2nd derivative spectra of serum and two plasma preparations, discriminative patterns were identified and validated using bioinformatic tools. The optimal spectral resolution for data acquisition was determined. An accurate discrimination of the patient groups was achieved with three different independent spectral variable sets. The HT-FTIR blood test may support future clinical diagnostics.

A 3-plex methylation assay combined with the FGFR3 mutation assay sensitively detects recurrent bladder cancer in voided urine

PURPOSE

DNA methylation is associated with bladder cancer and these modifications could serve as useful biomarkers. FGFR3 mutations are present in 60% to 70% of non-muscle invasive bladder cancer (NMIBC). Low-grade bladder cancer recurs in more than 50% of patients. The aim of this study is to determine the sensitivity and specificity of a urine assay for the diagnosis of recurrences in patients with a previous primary NMIBC G1/G2 by using cystoscopy as the reference standard.

EXPERIMENTAL DESIGN

We selected eight CpG islands (CGI) methylated in bladder cancer from our earlier genome-wide study. Sensitivity of the CGIs for recurrences detection was investigated on a test set of 101 preTUR urines. Specificity was determined on 70 urines from healthy males aged more than 50 years. A 3-plex assay for the best combination was developed and validated on an independent set of 95 preTUR, recurrence free, and nonmalignant urines (n=130).

RESULTS

The 3-plex assay identified recurrent bladder cancer in voided urine with a sensitivity of 74% in the validation set. In combination with the FGFR3 mutation assay, a sensitivity of 79% was reached (specificity of 77%). Sensitivity of FGFR3 and cytology was 52% and 57%, respectively.

CONCLUSION

The combination of methylation and FGFR3 assays efficiently detects recurrent bladder cancer without the need for stratification of patients regarding methylation/mutation status of the primary tumor. We conclude that the sensitivity of this combination is in the same range as cystoscopy and paves the way for a subsequent study that investigates a modified surveillance protocol consisting of the urine test followed by cystoscopy only when the urine test is positive.

Comparative study and meta-analysis of meta-analysis studies for the correlation of genomic markers with early cancer detection

A large number of common disorders, including cancer, have complex genetic traits, with multiple genetic and environmental components contributing to susceptibility. A literature search revealed that even among several meta-analyses, there were ambiguous results and conclusions. In the current study, we conducted a thorough meta-analysis gathering the published meta-analysis studies previously reported to correlate any random effect or predictive value of genome variations in certain genes for various types of cancer. The overall analysis was initially aimed to result in associations (1) among genes which when mutated lead to different types of cancer (e.g. common metabolic pathways) and (2) between groups of genes and types of cancer. We have meta-analysed 150 meta-analysis articles which included 4,474 studies, 2,452,510 cases and 3,091,626 controls (5,544,136 individuals in total) including various racial groups and other population groups (native Americans, Latinos, Aborigines, etc.). Our results were not only consistent with previously published literature but also depicted novel correlations of genes with new cancer types. Our analysis revealed a total of 17 gene-disease pairs that are affected and generated gene/disease clusters, many of which proved to be independent of the criteria used, which suggests that these clusters are biologically meaningful.

FTIR spectroscopy of biofluids revisited: an automated approach to spectral biomarker identification

The extraction of disease specific information from Fourier transform infrared (FTIR) spectra of human body fluids demands the highest standards of accuracy and reproducibility of measurements because the expected spectral differences between healthy and diseased subjects are very small in relation to a large background absorbance of the whole sample. Here, we demonstrate that with the increased sensitivity of modern FTIR spectrometers, automatisation of sample preparation and modern bioinformatics, it is possible to identify and validate spectral biomarker candidates for distinguishing between urinary bladder cancer (UBC) and inflammation in suspected bladder cancer patients. The current dataset contains spectra of blood serum and plasma samples of 135 patients. All patients underwent cytology and pathological biopsy characterization to distinguish between patients without UBC (46) and confirmed UBC cases (89). A minimally invasive blood test could spare control patients a repeated cystoscopy including a transurethral biopsy, and three-day stationary hospitalisation. Blood serum, EDTA and citrate plasma were collected from each patient and processed following predefined strict standard operating procedures. Highly reproducible dry films were obtained by spotting sub-nanoliter biofluid droplets in defined patterns, which were compared and optimized. Particular attention was paid to the automatisation of sample preparation and spectral preprocessing to exclude errors by manual handling. Spectral biomarker candidates were identified from absorbance spectra and their 1(st) and 2(nd) derivative spectra using an advanced Random Forest (RF) approach. It turned out that the 2(nd) derivative spectra were most useful for classification. Repeat validation on 21% of the dataset not included in predictor training with Linear Discriminant Analysis (LDA) classifiers and Random Forests (RFs) yielded a sensitivity of 93 ± 10% and a specificity of 46 ± 18% for bladder cancer. The low specificity can be most likely attributed to the unbalanced and small number of control samples. Using this approach, spectral biomarker candidates in blood-derived biofluids were identified, which allow us to distinguish between cancer and inflammation, but the observed differences were tiny. Obviously, a much larger sample number has to be investigated to reliably validate such candidates.

Single-cell sequencing analysis characterizes common and cell-lineage-specific mutations in a muscle-invasive bladder cancer

BACKGROUND

Cancers arise through an evolutionary process in which cell populations are subjected to selection; however, to date, the process of bladder cancer, which is one of the most common cancers in the world, remains unknown at a single-cell level.

RESULTS

We carried out single-cell exome sequencing of 66 individual tumor cells from a muscle-invasive bladder transitional cell carcinoma (TCC). Analyses of the somatic mutant allele frequency spectrum and clonal structure revealed that the tumor cells were derived from a single ancestral cell, but that subsequent evolution occurred, leading to two distinct tumor cell subpopulations. By analyzing recurrently mutant genes in an additional cohort of 99 TCC tumors, we identified genes that might play roles in the maintenance of the ancestral clone and in the muscle-invasive capability of subclones of this bladder cancer, respectively.

CONCLUSIONS

This work provides a new approach of investigating the genetic details of bladder tumoral changes at the single-cell level and a new method for assessing bladder cancer evolution at a cell-population level.

Genome-wide analysis of CpG island methylation in bladder cancer identified TBX2, TBX3, GATA2, and ZIC4 as pTa-specific prognostic markers

BACKGROUND

DNA methylation markers could serve as useful biomarkers, both as markers for progression and for urine-based diagnostic assays.

OBJECTIVE

Identify bladder cancer (BCa)-specific methylated DNA sequences for predicting pTa-specific progression and detecting BCa in voided urine.

DESIGN, SETTING, AND PARTICIPANTS

Genome-wide methylation analysis was performed on 44 bladder tumours using the Agilent 244K Human CpG Island Microarray (Agilent Technologies, Santa Clara, CA, USA). Validation was done using a custom Illumina 384-plex assay (Illumina, San Diego, CA, USA) in a retrospective group of 77 independent tumours. Markers for progression were identified in pTa (n = 24) tumours and validated retrospectively in an independent series of 41 pTa tumours by the SNaPshot method (Applied Biosystems, Foster City, CA, USA).

MEASUREMENTS

The percentage of methylation in tumour and urine samples was used to identify markers for detection and related to the end point of progression to muscle-invasive disease with Kaplan-Meier models and multivariate analysis.

RESULTS AND LIMITATIONS

In the validation set, methylation of the T-box 2 (TBX2), T-box 3 (TBX3), GATA binding protein 2 (GATA2), and Zic family member 4 (ZIC4) genes was associated with progression to muscle-invasive disease in pTa tumours (p = 0.003). Methylation of TBX2 alone showed a sensitivity of 100%, a specificity of 80%, a positive predictive value of 78%, and a negative predictive value of 100%, with an area under the curve of 0.96 (p<0.0001) for predicting progression. Multivariate analysis showed that methylation of TBX3 and GATA2 are independent predictors of progression when compared to clinicopathologic variables (p = 0.04 and p = 0.03, respectively). The predictive accuracy improved by 23% by adding methylation of TBX2, TBX3, and GATA2 to the European Organisation for Research and Treatment of Cancer risk scores. We further identified and validated 110 CpG islands (CGIs) that are differentially methylated between tumour cells and control urine. The limitation of this study is the small number of patients analysed for testing and validating the prognostic markers.

CONCLUSIONS

We have identified four methylation markers that predict progression in pTa tumours, thereby allowing stratification of patients for personalised follow-up. In addition, we identified CGIs that will enable detection of bladder tumours in voided urine.