Bladder cancer is a heterogeneous disease. Treatment decisions are mostly decided based on disease stage (non-muscle invasive or muscle invasive). Patients with muscle-invasive disease will be offered a radical treatment combined with systemic therapy, while in those with non-muscle-invasive disease, an attempt to resect the tumor endoscopically will usually be followed by different intravesical instillations. The goal of intravesical therapy is to decrease the recurrence and/or progression of the tumor. In the current landscape of bladder cancer treatment, BCG is given intravesically to induce an inflammatory response and recruit immune cells to attack the malignant cells and induce immune memory. While the response to BCG treatment has changed the course of bladder cancer management and spared many “bladders”, some patients may develop BCG-unresponsive disease, leaving radical surgery as the best choice of curative treatment. As a result, a lot of effort has been put into identifying novel therapies like systemic pembrolizumab and Nadofaragene-Firadenovac to continue sparing bladders if BCG is ineffective. Moreover, recent logistic issues with BCG production caused a worldwide BCG shortage, re-sparking interest in alternative BCG treatments including mitomycin C, sequential gemcitabine with docetaxel, and others. This review encompasses both the historic and current role of BCG in the treatment of non-muscle-invasive bladder cancer, revisiting BCG alternative therapies and reviewing the novel therapeutics that were approved for the BCG-unresponsive stage or are under active investigation.

Acquired therapeutic resistance remains a major challenge in cancer management and associates with poor oncological outcomes in most solid tumor types. A major contributor is tumor heterogeneity (TH) which can be influenced by the stromal; immune and epithelial tumor compartments. We hypothesize that heterogeneity in tumor epithelial subpopulations—whether de novo or newly acquired—closely regulate the clinical course of bladder cancer. Changes in these subpopulations impact the tumor microenvironment including the extent of immune cell infiltration and response to immunotherapeutics. Mechanisms driving epithelial tumor heterogeneity (EpTH) can be broadly categorized as mutational and non-mutational. Mechanisms regulating lineage plasticity; acquired cellular mutations and changes in lineage-defined subpopulations regulate stress responses to clinical therapies. If tumor heterogeneity is a dynamic process; an increased understanding of how EpTH is regulated is critical in order for clinical therapies to be more sustained and durable. In this review and analysis, we assess the importance and regulatory mechanisms governing EpTH in bladder cancer and the impact on treatment response.

Despite curative-intent radical cystectomy (RC), patients with muscle-invasive bladder cancer (MIBC) are at high risk of recurrence. Biomarkers are urgently needed to refine prognostication and selection of appropriate perioperative systemic therapies. Our aim was to evaluate the prognostic and predictive value of tumor-informed circulating tumor DNA (ctDNA) results in a multicenter cohort of patients with bladder cancer who underwent RC. We performed a retrospective analysis of real-world data for a commercial ctDNA test (Signatera; Natera, Austin, TX, USA) performed in 167 patients (852 plasma samples) before RC and during molecular residual disease (MRD; adjuvant decision) and surveillance windows. We assessed the correlation between recurrence and ctDNA status before and after RC using Cox regression analysis. During study-defined postoperative MRD and surveillance windows, detectable ctDNA was associated with shorter disease-free survival (DFS) when compared to undetectable ctDNA (MRD: hazard ratio 6.93; p < 0.001; surveillance: hazard ratio 23.02; p < 0.001). Of note, patients with undetectable ctDNA did not appear to benefit from adjuvant therapy (p = 0.34). Detectable ctDNA in the pre-RC (p = 0.045), MRD (p = 0.002), and surveillance (p < 0.001) windows was the only risk factor independently associated with shorter DFS. Limitations include the retrospective and nonrandomized nature of the study. ctDNA testing in patients with bladder cancer undergoing RC was prognostic and potentially predictive. Identification of patients at high risk of recurrence may aid in patient counseling and decision-making. We found that outcomes for patients with muscle-invasive bladder cancer are strongly linked to detection of tumor DNA in blood samples. The results show the value of tumor-informed testing for tumor DNA in blood for decisions on the best treatment for each individual patient.