Abstract A165: Restrictive eligibility criteria impacts racial/ethnic enrollment in oncology therapeutic clinical trials: Findings from a large urban California institute

Background: To increase the number of people eligible for oncology clinical trials (CT) and improve their generalizability, ASCO and Friends of Cancer Research published recommendations in 2017 to broaden the CT eligibility criteria. NCI used these recommendations as the basis for the Experimental Therapeutics Clinical Trial Network protocols. The broadened CT criteria includes people with stable brain metastases, infectious disease (HIV and hepatitis B & C), organ dysfunction (cardiac, liver, and kidney function), and prior and concurrent malignancies. Given the persistently low racial/ethnic minority enrollment in clinical trials, we aimed to explore whether broadening the restiveness in CT enrollment criteria was associated with an increased likelihood of ethnic minority enrollment. Methods: We analyzed cross-sectional enrollment data from oncology CTs at the University of Southern California/Norris Comprehensive Cancer Center clinical sites completed between 2016-2023. Two reviewers independently assessed the full CT eligibility protocols for each completed CT to identify the restrictiveness based on the broadened CT criteria in the ASCO and Friends recommendations. We created a restiveness score ranging from 0 (least) – 8 (most) that operationalized as restrictive (>75th percentile) vs. standard (≤75th) CTs. Using the NIH underrepresented minority population, we classified our outcome as minority (Hispanic/Black/American Indian/Alaska Native/Native Hawaiian/Pacific Islander) vs non-minority. We used multivariable mixed-effects logistic regression adjusting for sex, age, trial completed pre- vs. post-ASCO & Friends recommendation, CT sponsor type, and early (I/II) vs late (III/IV) phase CT. Results: We analyzed 144 completed CTs. There was a higher proportion of industry-sponsored CTs and early-phase clinical trials. CTs were most restrictive in excluding individuals from the following categories: prior and concurrent malignancies (73%), HIV (59%), and liver dysfunction (53%). The restrictiveness scores ranged from 0-7, of which 20% were categorized as restrictive CTs (restrictive score 5-7). Of the 876 cancer patients enrolled in these CTs, 32% were racial/ethnic minorities, and 83% enrolled in standard CTs. Additionally, a higher proportion of racial/ethnic minorities were female (44% vs. non-minority 39%), younger (57 years vs. 63), and enrolled in non-industry CTs (31% vs. 19%). Restrictive CTs had 45% (OR=0.55, 95%CI=0.3-0.98) lower odds of enrolling racial/ethnic minorities compared to standard CTs, even after controlling for all covariates. Conclusion: Our findings highlight that racial/ethnic patients are less likely to be included in CT studies with restrictive enrollment eligibility criteria and broadening the CT enrollment criteria is likely to increase minority participation. Broadening the enrollment eligibility criteria for CTs could potentially decrease the racial/ethnic disparities while improving the generalizability for the innovative cancer treatments. Citation Format: Angel Arizpe, Jorge Nieva, Trevor A. Pickering, Lauren Scampavia, Jenny Ferrin, Albert J. Farias. Restrictive eligibility criteria impacts racial/ethnic enrollment in oncology therapeutic clinical trials: Findings from a large urban California institute [abstract]. In: Proceedings of the 18th AACR Conference on the Science of Cancer Health Disparities; 2025 Sep 18-21; Baltimore, MD. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2025;34(9 Suppl):Abstract nr A165.