Geographic disparities in access to immunotherapy clinical trials for metastatic melanoma

Survival outcomes for metastatic melanoma have drastically improved with the advent of immunotherapy. Access to ongoing immunotherapy clinical trials has become increasingly important to patients with advanced disease. We sought to quantify geographic disparities in access to these trials by U.S. division, region, urban/rural status, and median income. We searched ClinicalTrials.gov for interventional immunotherapy trials for metastatic melanoma from 2015 to 2021 and identified U.S. zip codes for each participating trial site. ArcGIS was used to calculate the one-way driving time from each zip code to the nearest treatment center. Melanoma burden in each zip code outside a 60 min driving radius was calculated by multiplying population by the corresponding state's cancer-specific mortality rate. χ² tests were used to test for significance between census regions, divisions, and urban vs. rural zip codes, while logistic regression was used to quantify risk of poor access with median income. Across 148 trials, 4844 treatment centers were located in 1102 unique zip codes. 9010 zip codes were located greater than one-hour driving time from the nearest clinical trial. Southern regions were most likely to have poor access of all regions (p < 0.001), and rural status also significantly correlated with poor access (p < 0.001). For every $10,000 increase in median income, the likelihood of a zip code being within 60 min from a trial increased by 1.315. While immunotherapy continue to improve survival outcomes for metastatic melanoma, geographic access to clinical trials investigating these therapies remains a challenge for a significant proportion of the U.S. population.