Geographic disparities in the availability of renal cell carcinoma (RCC) clinical trials in the United States (US).

Abstract

431 Background: Clinical trials for cancer tend to be less available in regions of the US corresponding to high socioeconomic vulnerability (Kirkwood et. al., JCO Oncol Pract 2025); however, specific patterns for RCC have yet to be reported. We aimed to evaluate the current county-level distribution of RCC clinical trials in the US. Methods: Using ClinicalTrials.gov, we identified all interventional trials between 6/1/2019 and 6/1/2025 enrolling adult patients with RCC. Using US Postal Service data, we recorded every unique county for Zip code listed for each trial. Trial characteristics were summarized descriptively. We used the Centers for Disease Control and Prevention (CDC) Social Vulnerability Index (SVI) designations to reflect county demographics and socioeconomic status. Age-adjusted renal cancer incidence and mortality rates were obtained from the National Cancer Institute (NCI). To account for overdispersion of trial availability and high proportion of counties with no trials, we used a zero-inflated negative binomial (ZINB) regression model to assess the association between number of RCC trials per county and corresponding incidence, mortality, and SVI. To account for county size, we adjusted trial rates by number of households. Analyses were performed in R (v.4.4.3) using the “pscl” package. Results: Of 289 eligible trials, 127 (43.9%) enrolled patients with only clear cell RCC and 34 (11.8%) with only non-clear cell RCC. Pharmaceutical companies sponsored the greatest proportion of trials (46.0%), followed closely by academia (43.6%). Most trials (76.1%) enrolled patients with advanced or metastatic disease. Only 672 (21.4%) of all US counties had at least one clinical trial location. Compared with high-SVI counties (most socially vulnerable), those in the medium-high, low-medium, and low-SVI counties had 1.8-fold (95% CI: 1.38-2.36), 2.0-fold (95% CI: 1.50-2.58), and 3.1-fold (95% CI: 2.29-4.13) higher trial incidence rates, respectively (all p < 0.001). Of the 5,028 US trial sites analyzed, 1,681 (33.4%) were in counties with the lowest renal cancer incidence quintile, while only 254 (5.1%) were in counties with the highest incidence quintile. This pattern held for counties with the lowest and highest mortality quintiles, with 1508 (30.0%) and 183 (3.6%) trials, respectively. Conclusions: Most US counties lacked RCC clinical trial representation. Counties with higher social vulnerability had markedly lower RCC clinical trial availability. Social vulnerability reflects census-derived variables such as socioeconomic status, household composition, disability, minority status, English proficiency, transportation, etc. These findings highlight geographic and structural disparities in access to novel RCC therapies within the US, and emphasize the need for trial design and site selection that account for regional vulnerability.