The ClinicalTrials.gov Landscape of Multiple Myeloma Clinical Trials: A 20-Year Analysis of Geographic Distribution and Growth Patterns: USMIRC Analysis

Background: Multiple myeloma (MM) has experienced rapid therapeutic innovation over the past two decades, leading to a substantial increase in clinical trial activity. However, the geographic distribution of these trials and the representation of different economic regions remain poorly characterized. We evaluated the global distribution, growth patterns, and phase-specific trends of MM clinical trials and trial sites across different economic settings. Methods: We conducted a retrospective registry-based analysis interventional MM clinical trials registered on ClinicalTrials.gov between January 2006 and January 2026. Trials were categorized based on the economic classification of participating countries using World Bank income groups and Economic Co-operation and Development (OECD) status. Trial characteristics including phase, geographic distribution, number of participating sites, and site-years were analyzed. Population-adjusted trial density and compound annual growth rates (CAGR) were calculated to assess temporal trends and geographic representation. Results: A total of 845 interventional MM clinical trials were identified during the study period. Trial activity was highest in the United States (337 trials, 39.9%), followed by international trials (271, 32.1%), high-income-OECD countries (129, 15.3%), and upper-middle-income countries (103, 12.2%), while high-income non-OECD countries contributed only a small fraction of trials. Trial activity increased substantially over time across all regions with the highest growth observed in upper-middle-income countries (CAGR 18.5%). The US demonstrated the highest population-adjusted trial density (0.99 per million population) and accounted for the largest number of trial sites and site-years. Phase-specific analyses revealed distinct geographic patterns. Phase 1 trials were predominantly conducted in the US and in international collaborative trials. Phase 3 trials were largely international, although the majority of participating sites remained located in the US and High-income countries that are members of the OECD (HIC-OECD). Conclusions: Over the past two decades, MM clinical trial activity has expanded globally but remains highly concentrated in the United States and high income-OECD countries, particularly with respect to trial sites and population-adjusted trial density. Although upper-middle-income countries have shown the fastest growth in trial activity expanding clinical trial infrastructure and strengthening international collaboration will be essential to promote a more equitable global distribution of MM research.