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Mutational patterns in chemotherapy resistant muscle-invasive bladder cancer.

ABSTRACT: Despite continued widespread use, the genomic effects of cisplatin-based chemotherapy and implications for subsequent treatment are incompletely characterized. Here, we analyze whole exome sequencing of matched pre- and post-neoadjuvant cisplatin-based chemotherapy primary bladder tumor samples from 30 muscle-invasive bladder cancer patients. We observe no overall increase in tumor mutational burden post-chemotherapy, though a significant proportion of subclonal mutations are unique to the matched pre- or post-treatment tumor, suggesting chemotherapy-induced and/or spatial heterogeneity. We subsequently identify and validate a novel mutational signature in post-treatment tumors consistent with known characteristics of cisplatin damage and repair. We find that post-treatment tumor heterogeneity predicts worse overall survival, and further observe alterations in cell-cycle and immune checkpoint regulation genes in post-treatment tumors. These results provide insight into the clinical and genomic dynamics of tumor evolution with cisplatin-based chemotherapy, suggest mechanisms of clinical resistance, and inform development of clinically relevant biomarkers and trials of combination therapies.

SUBMITTER: Liu D

PROVIDER: S-EPMC5736752 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature

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Project description:BackgroundNeoadjuvant chemotherapy is underutilized in bladder cancer patients who undergo radical cystectomy. However, the quality of regimens used in this setting remains largely unknown.ObjectiveTo determine utilization treatment patterns and survival outcomes according to regimens administered.Design, setting, and patientsWe used the Surveillance, Epidemiology and End Results (SEER)-Medicare linked database to identify patients diagnosed with clinical stage TII-IV bladder cancer from January 1, 2001 to December 31, 2011.Outcome measurements and statistical analysisTemporal trends were assessed using the Cochran-Armitage test. Multivariable logistic regression models were used to identify predictors for neoadjuvant chemotherapy use. Cox proportional hazards models were used to compare overall survival according to regimens administered.Results and limitationsOf 2738 patients treated with radical cystectomy, 344 (12.6%) received neoadjuvant chemotherapy. The agents most commonly used were gemcitabine (72.3%), cisplatin (55.2%), and carboplatin (31.1%). The regimens most commonly used were gemcitabine-cisplatin (45.3%), gemcitabine-carboplatin (24.1%), and methotrexate, vinblastine, doxorubicin, and cisplatin (M-VAC; 6.7%). Use of neoadjuvant chemotherapy more than tripled during the study period, from 5.7% in 2001 to 17.3% in 2011 (p<0.001). The quality of the regimen administered impacted survival outcomes, as M-VAC use was significantly associated with better overall survival among patients diagnosed with stage II bladder cancer (hazard ratio 0.24, 95% confidence interval 0.07-0.86; p=0.030]. Limitations include the limited ability of retrospective analysis to control for selection bias.ConclusionsNeoadjuvant chemotherapy was underused, and the quality of neoadjuvant chemotherapy regimens administered for bladder cancer was inconsistent with guideline recommendations. These findings are important when interpreting population-based data on the use of chemotherapy and extrapolating survival outcomes.Patient summaryIn a large population-based study, 12.6% of patients undergoing radical cystectomy for bladder cancer received neoadjuvant chemotherapy, half of whom received guideline-recommended regimens. The quality of the regimen impacted survival outcomes, as use of cisplatin-based chemotherapy was significantly associated with better overall survival among patients diagnosed with stage II bladder cancer. However, <1% of radical cystectomy patients received this regimen.

Project description:BackgroundBladder cancer is one of the most lethal malignancy in urological system, and 20-25% of bladder cancer patients are muscle invasive with unfavorable prognosis. However, the role of alternative splicing (AS) in muscle-invasive bladder cancer (MIBC) remains to be elucidated.MethodsPercent spliced in (PSI) data obtained from the Cancer Genome Atlas (TCGA) SpliceSeq database (n = 394) were utilized to evaluate the AS events in MIBC. Prognosis-associated AS events were screened out by univariate Cox regression. LASSO Cox regression was used to identify reliable prognostic patterns in a training set and further validated in a test set. Splicing regulatory networks were constructed by correlations between PSI of AS events and RNA expression of splicing factors.ResultsAs a result, a total of 2589 prognosis-related AS events in MIBC were identified. Pathways of spliceosomal complex (FDR = 0.017), DNA-directed RNA polymerase II, core complex (FDR = 0.032), and base excision repair (FDR = 0.038) were observed to be significantly enriched. Additionally, we noticed that most of the prognosis-related AS events were favorable factors. According to the LASSO and multivariate Cox regression analyses, 15-AS-based signature was established with the area under curve (AUC) of 0.709, 0.823, and 0.857 at 1-, 3-, and 5- years, respectively. The MIBC patients were further divided into high- and low-risk groups based on median risk sores. Interestingly, we observed that the prevalence of FGFR3 with mutations and focal amplification was significantly higher in low-risk group. Functional and immune infiltration analysis suggested potential signaling pathways and distinct immune states between these two groups. Moreover, splicing correlation network displayed a regulatory mode of prognostic splicing factors (SF) in MIBC patients.ConclusionsThis study not only provided novel insights into deciphering the possible mechanism of tumorgenesis and pathogenesis but also help refine risk stratification systems and potential treatment of decision-making for MIBC.

Project description:BackgroundBladder-sparing chemoradiation therapy is a definitive first-line treatment option for muscle-invasive bladder cancer. Randomized trials have demonstrated that the addition of neoadjuvant chemotherapy to radical cystectomy or radiation monotherapy results in a survival benefit. Whether neoadjuvant chemotherapy improves outcomes when used with definitive chemoradiation is unknown.Patients and methodsWe identified 2566 patients in the National Cancer Data Base with cT2-4N0M0 urothelial cell carcinoma of the bladder treated with definitive intent concurrent chemoradiation from 2004 to 2015. The exposure of interest was receipt of neoadjuvant chemotherapy versus those without neoadjuvant chemotherapy. The primary outcome was overall survival defined from the time of diagnosis. Kaplan-Meier and multivariable Cox proportional hazard analyses were used to compare survival between groups. Sensitivity analyses tested (1) an interaction term for clinical T stage and (2) defining survival from start of radiation (as opposed to time of diagnosis) to address potential leading time bias.ResultsWe identified 462 patients treated with neoadjuvant chemotherapy followed by chemoradiation and 2104 patients treated with chemoradiation alone. With a median follow-up of 6.2 years, we found no difference in survival between groups: 5-year or 10-year overall survival of 30.6% (95% confidence interval [CI], 28.4%-32.9%) in the neoadjuvant group versus 31.8% (95% CI, 27.0%-36.8%) in the standard chemoradiation therapy group and 13.3% (95% CI, 11.2%-15.5%) in the neoadjuvant group versus 13.0% (95% CI, 8.4%-18.7%) in the standard chemoradiation therapy group, respectively (log-rank P = .19). On multivariable analysis we found no association between receipt of neoadjuvant chemotherapy and overall survival (hazard ratio, 1.01; 95% CI, 0.88-1.15; P = .921). The sensitivity analyses did not identify any differential effect by clinical T stage nor by defining survival from start of radiation.ConclusionThese results do not support the routine addition of neoadjuvant chemotherapy to definitive chemoradiation for bladder cancer, and optimizing the chemotherapy sequencing and regimens for bladder-preserving approaches to muscle invasive bladder cancer should continue to be studied under prospective clinical trials.

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Mutational patterns in chemotherapy resistant muscle-invasive bladder cancer.

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