Evaluating worldwide disparities in bladder cancer clinical trial availability.
Authors: Shah Koral , Castro Daniela V. , Li Xiaochen , Zugman Miguel , Patel Jalen , Paul Teebro , Goud Jaya , Dickter Samuel , Dickter Lea , Bhatnagar Ishaan , Jaime-Casas Salvador , Ebrahimi Hedyeh , Mercier Benjamin , Hsu Joann , Dizman Nazli , Chehrazi-Raffle Alex , Tripathi Abhishek , Barragan-Carrillo Regina , Pal Sumanta Kumar 
Published: February 2025

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Background:
Bladder cancer (BC) poses a disproportionate burden on low- and middle-income countries (BJUI, 2017), yet BC clinical trials have historically been centralized in North America and Europe. Despite efforts to broaden global participation in cancer trials (ASCO Policy Statement, 2024), data on the impact of these initiatives, especially for BC, remain scarce. We aim to assess the current global availability of BC clinical trials.
Methods:
Through ClinicalTrials.gov, we indexed all protocols enrolling adults with BC from 6/1/2019 to 6/1/2024. We excluded non-interventional studies and those with non-oncologic interventions. We identified countries with at least one active trial site. Countries were classified based on income using the World Bank Ranking (WBR): high-income countries (HICs), upper middle-income countries (UMICs), lower middle-income countries (LMICs), and low-income countries (LICs). We also recorded data on BC type, sponsor, phase, cancer stage, enrollment, and endpoints. Descriptive statistics were used to summarize trial characteristics, and the Kruskal-Wallis test was used to assess the association between BC trial availability and WBR. Poisson regression analysis was employed to evaluate the association between clinical trial availability and incidence, mortality, WBR, health expenditure, and gross national income.
Results:
A total of 576 BC trials were identified, of which 539 trials met eligibility criteria with active sites across 63 countries. Many (64.6%) countries in the initial query were not represented in the trials, and 60.9% of these were LICs or LMICs. Of the 539 trials, most were exclusively available in HICs (79.4%), with the USA having hosted 321 trials, and none were available in LICs. Most trials were phase I or II (60.9%) and conducted in a single country (78.3%). Most were sponsored by academic institutions (54%), followed by pharma (36.7%). We observed a significantly lower availability of trials in UMICs (OR 0.30, p=0.01), LMICs (OR 0.076, p<0.001), and LICs (0.010, p=0.001). Moreover, we found that early-phase trials were more likely to be conducted exclusively in HICs compared to late-phase trials (p<0.001). Trials in non-HICs were often sponsored by academia (67.6% vs. 50.5%), had larger mean enrollment (238 vs. 154), and were less frequently funded by pharma (67.6% vs. 55.4%). Poisson regression analysis revealed that WBR and annual health expenditure were significantly associated with a country’s clinical trial availability.
Conclusions:
BC trials, particularly those in the early phase of clinical development, are disproportionately concentrated in HICs, with their availability directly correlating to country WBR and health expenditures. This creates a gap in safety and efficacy testing for diverse populations. Expanding early-phase and pharma-funded studies beyond HICs would amplify equitable care for patients with bladder cancer.