Racial, Ethnic, and Sex Enrollment Disparity in Clinical Trials Leading to FDA Approval for Neoadjuvant Immunotherapy...

Racial demographics of clinical trials often do not mirror their distribution in the general population. This study analyzed enrollment rates by race, ethnicity, and sex in trials leading to FDA approval of neoadjuvant immunotherapy for colorectal cancer (CRC).

This cross-sectional study evaluated trials registered at ClinicalTrials.gov that resulted in new CRC neoadjuvant immunotherapy approvals by the FDA from 2010 to 2025. Exclusion criteria were international trials or lack of race data. Enrollment proportions and odds ratios (ORs) with 95% CIs were calculated to compare minority enrollment rates to non-Hispanic (NH) White and male reference patient groups for race and ethnicity, and sex, respectively.

Nine clinical trials, including 4 phase I, I/II, or II and 5 phase III trials, met study inclusion criteria. Six trials reported race and sex whereas 3 also reported ethnicity. Compared with NH-White patients, NH-Black patients were significantly underrepresented with the lowest ORs of any racial group (race only: OR 0.19, 95% CI 0.15 to 0.24). Hispanic patients were also significantly underrepresented compared with their NH-White and Asian/Pacific Islander counterparts (race and ethnicity: OR 0.37, 95% CI 0.29 to 0.49). Enrollment rates of female and male patients were comparable.

Our data indicate that NH-Black patients were represented approximately 5 times less and Hispanic patients were represented 2.7 times less when compared with NH-White patients. The underenrollment of NH-Black and Hispanic patients within these trials does not appropriately represent the population of patients with CRC in the US. Increasing minority enrollment in future trials can result in more reflective and equitable study samples.