Eligibility criteria and study phase limit racial/ethnic enrollment in oncology clinical trials

Racial/ethnic minority enrollment in oncological therapeutic clinical trials (TCT) remains low. Thus, we explored whether TCTs’ restrictiveness enrollment criteria and phase were associated with racial/ethnic minority enrollment. We analyzed cross-sectional (2016–2023) enrollment data and protocols from oncology TCTs completed at a large urban medical research institution. Two reviewers assessed eligibility restrictiveness using ASCO and Friends of Cancer Research recommendations. Trials received a score (0–8) based on criteria related to brain metastases, infectious diseases (HIV, hepatitis B/C), organ dysfunction (cardiac, liver, kidney), and prior or concurrent malignancies; those with scores above the 75th percentile were classified as restrictive (score > 4). Trial phase was categorized as early (I/II) or late (III/IV). Participants (n = 876) from 144 TCTs were classified as minority (Hispanic, Black, American Indian/Alaska Native, Native Hawaiian/Pacific Islander) or non-minority per NIH definitions. Multivariable Poisson GEE models, adjusting for age, sex, trial timing relative to ASCO/Friends recommendations, and sponsor type, explore these associations. Completed TCTs were most restrictive in excluding patients with a prior or concurrent malignancy(73%), HIV(59%), and/or liver dysfunction(53%). Of the 876 trial participants, 32% were racial/ethnic minorities, and only 17% were enrolled in restrictive TCTs. Restrictive TCTs had 45%(RR = 0.55, 95%CI = 0.3–0.98) and early-phase TCTs had 52%(RR = 0.48, 95%CI = 0.30–0.77) lower risk of enrolling racial/ethnic minority participants compared to standard and later-phase TCTs, respectively. TCT studies with restrictive enrollment eligibility criteria and early-phase studies were less likely to enroll racial/ethnic minority participants. Underscoring that enrollment eligibility criteria is a barrier that may hinder minority enrollment.