Immune checkpoint inhibitors for BCG-resistant NMIBC: the dawn of a new era

Theories behind Bacillus Calmette-Guérin failure in high-risk non-muscle-invasive bladder cancer and update on current management

Bladder cancer encapsulates a wide spectrum of disease severities, with non-muscle invasive bladder cancer (NMIBC) representing an entirely different entity from muscle-invasive disease. Bacillus Calmette-Guérin (BCG) is one of the most successful intravesical treatment methods for patients diagnosed. However, a considerable proportion of patients fail to respond to BCG treatment. Given the propensity for recurrence in patients with high-risk bladder cancer, these patients present with surgical dilemmas. There is currently no gold standard for salvage treatment post-BCG failure or unified definition as to what that means. In this review, we discuss the mechanisms of action and pathophysiology of BCG, potential theories behind BCG failure, and the scope of novel treatments for this surgical conundrum.

Time to progression is the main predictor of survival in patients with high-risk nonmuscle invasive bladder cancer: Results from a machine learning-based analysis of a large multi-institutional database

BACKGROUND

In patients affected by high-risk nonmuscle invasive bladder cancer (HR-NMIBC) progression to muscle invasive status is considered as the main indicator of local treatment failure. We aimed to investigate the effect of progression and time to progression on overall survival (OS) and to investigate their validity as surrogate endpoints.

METHODS

A total of 1,510 patients from 18 different institutions treated for T1 high grade NMIBC, followed by a secondary transurethral resection and BCG intravesical instillation. We relied on random survival forest (RSF) to rank covariates based on OS prediction. Cox's regression models were used to quantify the effect of covariates on mortality.

RESULTS

During a median follow-up of 49.0 months, 485 (32.1%) patients progressed to MIBC, while 163 (10.8%) patients died. The median time to progression was 82 (95%CI: 78.0-93.0) months. In RSF time-to-progression and age were the most predictive covariates of OS. The survival tree defined 5 groups of risk. In multivariable Cox's regression models accounting for progression status as time-dependent covariate, shorter time to progression (as continuous covariate) was associated with longer OS (HR: 9.0, 95%CI: 3.0-6.7; P < 0.001). Virtually same results after time to progression stratification (time to progression ≥10.5 months as reference).

CONCLUSION

Time to progression is the main predictor of OS in patients with high risk NMIBC treated with BCG and might be considered a coprimary endpoint. In addition, models including time to progression could be considered for patients' stratification in clinical practice and at the time of clinical trials design.

Cancer cell-intrinsic PD-1: Its role in malignant progression and immunotherapy

Programmed cell death protein-1 (PD-1), also called CD279, is coded by the PDCD1 gene and is constitutively expressed on the surface of immune cells. As a receptor and immune checkpoint, PD-1 can bind to programmed death ligand-1/programmed death ligand-2 (PD-L1/PD-L2) in tumor cells, leading to tumor immune evasion. Anti-PD-1 and anti-PD-L1 are important components in tumor immune therapy. PD-1 is also expressed as an intrinsic variant (iPD-1) in cancer cells where it plays important roles in malignant progression as proposed by recent studies. However, iPD-1 has received much less attention compared to PD-1 expressed on immune cells although there is an unmet medical need for fully elucidating the mechanisms of actions to achieve the best response in tumor immunotherapy. iPD-1 suppresses tumorigenesis in non-small cell lung cancer (NSCLC) and colon cancer, whereas it promotes tumorigenesis in melanoma, hepatocellular carcinoma (HCC), pancreatic ductal adenocarcinoma (PDAC), thyroid cancer (TC), glioblastoma (GBM), and triple-negative breast cancer (TNBC). In this review, we focus on the role of iPD-1 in tumorigenesis and development and its molecular mechanisms. We also deeply discuss nivolumab-based combined therapy in common tumor therapy. iPD-1 may explain the different therapeutic effects of anti-PD-1 treatment and provide critical information for use in combined anti-tumor approaches.

Endothelial cells are a key target of IFN-g during response to combined PD-1/CTLA-4 ICB treatment in a mouse model of bladder cancer

To explore mechanisms of response to combined PD-1/CTLA-4 immune checkpoint blockade (ICB) treatment in individual cell types, we generated scRNA-seq using a mouse model of invasive urothelial carcinoma with three conditions: untreated tumor, treated tumor, and tumor treated after CD4+ T cell depletion. After classifying tumor cells based on detection of somatic variants and assigning non-tumor cell types using SingleR, we performed differential expression analysis, overrepresentation analysis, and gene set enrichment analysis (GSEA) within each cell type. GSEA revealed that endothelial cells were enriched for upregulated IFN-g response genes when comparing treated cells to both untreated cells and cells treated after CD4+ T cell depletion. Functional analysis showed that knocking out IFNgR1 in endothelial cells inhibited treatment response. Together, these results indicated that IFN-g signaling in endothelial cells is a key mediator of ICB induced anti-tumor activity.

Advanced Bladder Cancer: Changing the Treatment Landscape

Bladder cancer is the 10th most common cancer type in the world. There were more than 573,000 new cases of bladder cancer in 2020. It is the 13th most common cause of cancer death with an estimated more than 212,000 deaths worldwide. Low-grade non-muscle-invasive bladder cancer (NMIBC) is usually successfully managed with transurethral resection (TUR) and overall survival for NMIBC reaches 90% according to some reports. However, long-term survival for muscle-invasive bladder cancer (MIBC) and metastatic bladder cancer remains low. Treatment options for bladder cancer have undergone a rapid change in recent years. Immune checkpoint inhibitors (ICI), targeted therapies, and antibody-drug conjugates are available now. As bladder cancer is genetically heterogeneous, the optimization of patient selection to identify those most likely to benefit from a specific therapy is an urgent issue in the treatment of patients with bladder cancer.