Eligibility and Radiologic Assessment in Adjuvant Clinical Trials in Bladder Cancer

Definitions, End Points, and Clinical Trial Designs for Bladder Cancer: Recommendations From the Society for Immunotherapy of Cancer and the International Bladder Cancer Group

PURPOSE

There is a significant unmet need for new and efficacious therapies in urothelial cancer (UC). To provide recommendations on appropriate clinical trial designs across disease settings in UC, the Society for Immunotherapy of Cancer (SITC) and the International Bladder Cancer Group (IBCG) convened a multidisciplinary, international consensus panel.

METHODS

Through open communication and scientific debate in small- and whole-group settings, surveying, and responses to clinical questionnaires, the consensus panel developed recommendations on optimal definitions of the disease state, end points, trial design, evaluations, sample size calculations, and pathology considerations for definitive studies in low- and intermediate-risk nonmuscle-invasive bladder cancer (NMIBC), high-risk NMIBC, muscle-invasive bladder cancer in the neoadjuvant and adjuvant settings, and metastatic UC. The expert panel also solicited input on the recommendations through presentations and public discussion during an open session at the 2021 Bladder Cancer Advocacy Network (BCAN) Think Tank (held virtually).

RESULTS

The consensus panel developed a set of stage-specific bladder cancer clinical trial design recommendations, which are summarized in the table that accompanies this text.

CONCLUSION

These recommendations developed by the SITC-IBCG Bladder Cancer Clinical Trial Design consensus panel will encourage uniformity among studies and facilitate drug development in this disease.

Adjuvant immunotherapy in patients with high-risk muscle-invasive urothelial carcinoma: The potential impact of informative censoring

BACKGROUND

The results of 2 studies exploring adjuvant immune checkpoint inhibition (aCPI) in high-risk muscle-invasive urothelial cancer have yielded conflicting results. A trial employing placebo as the control arm demonstrated a significant prolongation in disease-free survival (DFS) whereas a trial employing observation as the control arm (IMvigor010) demonstrated no prolongation in DFS with CPI. Here, the authors aimed to estimate the aCPI benefit and to model the potential impact of informative censoring on trial results.

METHODS

Survival data from 1518 patients was reconstructed from Kaplan-Meier curves. A network meta-analysis approach was used to estimate aCPI benefit through the restricted mean disease-free survival time (RMDFST). To estimate the potential impact of informative censoring on IMvigor010, a simulation was performed. The minimum proportion of informative censoring on the observation arm that could account for the lack of observed improvement in DFS was estimated. Random variability from the time of censoring to progression was modeled using the exponential distribution.

RESULTS

Patients receiving aCPI had better DFS: ΔRMDFST at 36 months of 2.2 (95% CI, 0.6-3.7, P = .006) months relative to observation/placebo. In IMvigor010, in the observation arm, 20.5% of patients were censored due to consent withdrawal, protocol violation and/or noncompliance, or lost to follow-up versus 8.2% in the treatment arm. On simulation, it was found that the lack of observed improvement in DFS could have resulted from as few as 14% of the censored patients on observation arm not being censored at random (simulated DFS with 14% informative censoring hazard ratio, 0.83; 95% CI, 0.69-0.99; P = .049).

CONCLUSIONS

Phase 3 trials comparing adjuvant therapies to observation are at risk for informative censoring that could potentially impact interpretation of study results.

Evolving Role of Adjuvant Systemic Therapy for Kidney and Urothelial Cancers

The role of adjuvant therapy in renal cell carcinoma and urothelial carcinoma is rapidly evolving. To date, the U.S. Food and Drug Administration has approved sunitinib and pembrolizumab in the adjuvant setting for renal cell carcinoma and nivolumab for urothelial carcinoma based on disease-free survival benefit. The U.S. Food and Drug Administration held a joint workshop with the National Cancer Institute and the Society of Urologic Oncology in 2017 to harmonize design elements, including eligibility and radiologic assessments across adjuvant trials in renal cell carcinoma and urothelial carcinoma. Considerations from the discussion at these workshops led the U.S. Food and Drug Administration to draft guidances to help inform subsequent adjuvant trial design for renal cell carcinoma and urothelial carcinoma. Patient-centered decision-making is crucial when determining therapeutic choices in the adjuvant setting; utility functions can be used to help quantify each patient's goals, values, and risk/benefit trade-offs to ensure that the decision regarding adjuvant therapy is informed by their preferences and the evolving outcomes data.

Refining neoadjuvant therapy clinical trial design for muscle-invasive bladder cancer before cystectomy: a joint US Food and Drug Administration and Bladder Cancer Advocacy Network workshop

The success of the use of novel therapies in the treatment of advanced urothelial carcinoma has contributed to growing interest in evaluating these therapies at earlier stages of the disease. However, trials evaluating these therapies in the neoadjuvant setting must have clearly defined study elements and appropriately selected end points to ensure the applicability of the trial and enable interpretation of the study results. To advance the development of rational trial design, a public workshop jointly sponsored by the US Food and Drug Administration and the Bladder Cancer Advocacy Network convened in August 2019. Clinicians, clinical trialists, radiologists, biostatisticians, patients, advocates and other stakeholders discussed key elements and end points when designing trials of neoadjuvant therapy for muscle-invasive bladder cancer (MIBC), identifying opportunities to refine eligibility, design and end points for neoadjuvant trials in MIBC. Although pathological complete response (pCR) is already being used as a co-primary end point, both individual-level and trial-level surrogacy for time-to-event end points, such as event-free survival or overall survival, remain incompletely characterized in MIBC. Additionally, use of pCR is limited by heterogeneity in pathological evaluation and the fact that the magnitude of pCR improvement that might translate into a meaningful clinical benefit remains unclear. Given existing knowledge gaps, capture of highly granular patient-related, tumour-related and treatment-related characteristics in the current generation of neoadjuvant MIBC trials will be critical to informing the design of future trials.

Prognostic Value of Programmed Death Ligand-1 Expression on Tumor-Infiltrating Immune Cells in Patients Treated with Cisplatin-Based Combination Adjuvant Chemotherapy Following Radical Cystectomy for Muscle-Invasive Bladder Cancer: A Retrospective Cohort Study

Purpose

To investigate the prognostic value of programmed death ligand-1 (PD-L1) expression in tumor-infiltrating immune cells (ICs) in men treated with adjuvant chemotherapy (AC) following radical cystectomy (RC) for muscle-invasive bladder cancer (MIBC).

Materials and Methods

We retrospectively reviewed 219 “high-risk” (≥pT3a and/or pN+) patients who underwent RC and received cisplatin-based AC for MIBC between March 2015 and September 2019. PD-L1 expression was measured using the VENTANA (SP-142) immunohistochemistry assay and categorized into the three groups according to the percentage of the tumor area covered by PD-L1 expression on ICs: IC0 (<1%), IC1 (≥1% and <5%), and IC2/3 (≥5%). Positive PD-L1 expression was defined as IC2/3 (≥5%). Kaplan–Meier survival analysis was used to assess recurrence-free survival (RFS), and Cox proportional hazard models were applied to identify factors predicting tumor recurrence.

Results

In the entire cohort, the overall prevalence of PD-L1 IC0, IC1, and IC2/3 was 13.2%, 27.4%, and 59.4%, respectively. During the mean follow-up of 32.5 months, tumor recurrence was detected in 115 (52.5%) patients. On multivariable analysis, tumor stage (≥pT3; P=0.032), positive lymph nodes (P=0.001), and positive PD-L1 on ICs (P=0.005) were independent predictors of tumor recurrence. The 3 year RFS was 54.7% in patients with negative PD-L1 and 31.7% in patients with positive PD-L1.

Conclusion

PD-L1 is widely expressed in ICs. Positive PD-L1 on ICs was significantly associated with shorter RFS in patients treated with cisplatin-based AC following RC. The present results support the use of adjuvant immunotherapy in “high-risk” patients with PD-L1-expressing ICs.

MiR-582-5p Inhibits Bladder Cancer-Genesis by Suppressing TTK Expression

BACKGROUND

Bladder cancer (BC) refers to the malignant growth found in the cells and tissues of the urinary bladder. While many studies have researched the progression of BC, scientists are yet to fully understand the mechanism of BC. This research aimed to explore the role of miR-582-5p and its target gene TTK in BC pathogenesis.

METHODS

The evaluation of miR-582-5p and TTK mRNA expression in BC tissues or cells was performed using qRT-PCR. TargetScan was then used to predict the binding site of miR-582-5p on TTK mRNA. Subsequently, dual-luciferase reporter and RNA pull-down assays were employed to validate the binding relationship between miR-582-5p and TTK mRNA. CCK-8, BrdU, flow cytometry, and caspase-3 activity assays were later conducted to evaluate the viability, proliferation, cell cycle, and apoptosis of BC cells.

RESULTS

Investigations revealed that miR-582-5p was downregulated in BC tissues and cells. Meanwhile, miR-582-5p inhibited the viability and proliferation of BC cells while stimulating the apoptosis and cycle arrest of the cells. TTK, the target gene of miR-582-5p, was later found to be over-expressed in BC tissues and cells. TTK, however, was observed to exhibit an opposite effect on miR-582-5p. Simply put, it stimulated BC cell malignant phenotypes, and this stimulation could be directly reversed by miR-582-5p.

CONCLUSION

This research confirmed that miR-582-5p could restrain bladder carcinogenesis by inhibiting TTK expression.

Histologic Variants of Urothelial Carcinoma: Morphology, Molecular Features and Clinical Implications

Bladder cancer is a heterogeneous disease including conventional urothelial carcinoma (UC) and its histologic variants, and non-urothelial carcinoma, including squamous and glandular neoplasms. Urothelial carcinoma accounts for the majority of bladder cancer cases, but morphologic variants are common and include nested, microcystic, micropapillary, lymphoepithelioma-like, plasmacytoid, sarcomatoid, giant cell, undifferentiated, clear cell and lipoid. Certain variants of UC tend to be associated with a poor prognosis and have diagnostic and potential treatment implications that make the identification of variant histology crucial to clinical decision making. While there is still uncertainty regarding the prognostic implications of many of these variants, identifying and reporting variant histology is important to develop our understanding of their biology. Unique molecular features accompany many of these morphologic variants and to better understand these tumors, we review the molecular and clinical implications of histologic variants of bladder cancer. Major efforts are underway to include variant histology and divergent differentiation of UC in clinical trials to develop evidence based approaches to treatment. The purpose of this article is to review the current literature on variant histology of urothelial cancer and to highlight molecular findings and the clinical relevance of these tumors.

Eligibility and Radiologic Assessment for Adjuvant Clinical Trials in Kidney Cancer

Purpose

To harmonize the eligibility criteria and radiologic disease assessment definitions in clinical trials of adjuvant therapy for renal cell carcinoma (RCC).

Method

On November 28, 2017, US-based experts in RCC clinical trials, including medical oncologists, urologic oncologists, regulators, biostatisticians, radiologists, and patient advocates, convened at a public workshop to discuss eligibility for trial entry and radiologic criteria for assessing disease recurrence in adjuvant trials in RCC. Multiple virtual meetings were conducted to address the issues identified at the workshop.

Results

The key workshop conclusions for adjuvant RCC therapy clinical trials were as follows. First, patients with non-clear cell RCC could be routinely included, preferably in an independent cohort. Second, patients with T3-4, N+M0, and microscopic R1 RCC tumors may gain the greatest advantages from adjuvant therapy. Third, trials of agents not excreted by the kidney should not exclude patients with severe renal insufficiency. Fourth, therapy can begin 4 to 16 weeks after the surgical procedure. Fifth, patients undergoing radical or partial nephrectomy should be equally eligible. Sixth, patients with microscopically positive soft tissue or vascular margins without gross residual or radiologic disease may be included in trials. Seventh, all suspicious regional lymph nodes should be fully resected. Eighth, computed tomography should be performed within 4 weeks before trial enrollment; for patients with renal insufficiency who cannot undergo computed tomography with contrast, noncontrast chest computed tomography and magnetic resonance imaging of the abdomen and pelvis with gadolinium should be performed. Ninth, when feasible, biopsy should be undertaken to identify any malignant disease. Tenth, when biopsy is not feasible, a uniform approach should be used to evaluate indeterminate radiologic findings to identify what constitutes no evidence of disease at trial entry and what constitutes radiologic evidence of disease. Eleventh, a uniform approach for establishing the date of recurrence should be included in any trial design. Twelfth, patient perspectives on the use of placebo, conditions for unblinding, and research biopsies should be considered carefully during the conduct of an adjuvant trial.

Conclusions and Relevance

The discussions suggested that a uniform approach to eligibility criteria and radiologic disease assessment will lead to more consistently interpretable trial results in the adjuvant RCC therapy setting.