Abstract
Purpose: Precision oncology requires biomarker testing from tumor tissue for clinical decision-making and selection of targeted therapies. We systematically evaluated the role of tissue biomarker testing within interventional clinical trials for locally advanced and metastatic urothelial carcinoma (UC). Methods: A systematic search within the publicly available ClinicalTrials.gov database was performed for the period 1995 to January 2020. We searched for all interventional studies on systemic treatments for advanced UC. Two investigators independently screened the records and extracted the data for statistical analyses. Results: We included 356 studies out of 827 initial records in the final analysis. The overall number of interventional trials in UC patients significantly increased during the past 25 years. Forty-three studies (12.1%) required specific biomarker testing as a prerequisite for inclusion. Of the remaining 313 trials, explorative biomarkers of interest were studied in 83 studies (23.3%). In trials with obligate biomarker testing as a precondition for study inclusion, only 3 studies (7%) required an actual fresh pretreatment biopsy, while the majority of studies did not state any tissue requirements (55.8%) or accepted archival tissue samples (37.3%). Among studies without biomarker prerequisites, freshly obtained tissue samples were required in 16.3% of studies evaluating immune checkpoint inhibition and 5.7% evaluating targeted therapy. The collection of archival tissue was allowed in 67.4% and 20% of studies evaluating immune checkpoint inhibitors and targeted therapies, respectively. Conclusion: There has been an increase in the number of studies using biomarker-guided interventions for the treatment of advanced UC over the past 25 years. Studies investigating druggable targets in actual UC biopsies immediately before treatment are still rare. Standardized criteria for tissue-based biomarker testing may further accelerate personalized treatment of patients with advanced UC.