Abstract PR-05: Worsening disparities of racial minority participation in phase 1 early drug development trials in the United States, 2001-2018

Purpose: The National Institute of Health has advocated for broad representation of racial and ethnic groups in drug development trials after the introduction of the Revitalization Act in 1993. However, no studies to date have specifically examined demographic disparities among participants in Phase 1 drug development trials. Herein we sought to assess the distribution of and changes in enrollment of racial and ethnic minorities in United States Phase 1 early drug trials for metastatic cancer treatment from 2001 to 2018. Patients and Methods: We queried the ClinicalTrials.gov website to identify completed Phase 1 drug trials in the U.S. from 2001 to 2018 with published results and participants > 18 years of age with metastatic cancer. We reviewed publications from each study to identify racial and ethnic compositions of participants. We compared the proportions of each racial/ethnic group of trial participants to those of corresponding annual incidence data from Surveillance, Epidemiology, and End Results (SEER); for each racial/ethnic group, the difference between trial and SEER proportions was examined using a two-sample test for equality of proportions with continuity correction. Results: We identified a cohort of 236 trials; 72% were industry-sponsored, 19% focused on metastatic breast cancer, 14.8% focused on metastatic colorectal cancer, and 28.3% were basket trials targeting specific genetic pathways with mixed histologies. Of the 9,273 total participants, 81.5% were White, 5.7% Black, 9.4% Asian/Pacific Islander (API), 0.26% American Indian/Alaska Native, and 4.4% Hispanic/Latinx. Comparing the racial/ethnic distributions of trial participants to the corresponding SEER data revealed an excess of White and API representation (1.2% (p<0.005) and 2.3% (p<0.001), respectively), and a 6.2% deficit of Black participants (p<0.001). White patients were overrepresented in clinical trials beginning in 2001-2011 (+4.5% p<0.001)), but not in trials beginning in 2012-2018 (-0.05% p>0.05)). Underrepresentation in trial enrollment worsened in this time period for Black patients (-4.2% to -7.4%, respectively) and Hispanic/Latinx patients (-0.07% to -3.5%). API patients shifted from underrepresentation in 2001-2011 (-2.5%) to overrepresentation in 2012-2018 (+5.52%). Disparities in Black patient enrollment in trials conducted at academic institutions worsened from -4.36% in 2001-2011 to -7.64% in 2012-2018 (p<0.0001). Conclusions: There are persistent and worsening disparities in accrual of racial and ethnic minorities in phase 1 drug trials. These include decreases in enrollment of Black and Hispanic/Latinx patients in clinical trials overall, and in enrollment of Black and AI/AN patients in trials conducted at academic institutions. These findings may represent widening inequalities in access to trial sites, as well as potential systemic biases. Current efforts to diversify clinical trials should expand their reach from phases 2 and 3 to include phase 1, in order to improve equity in access to new treatments at every stage. Citation Format: Hayley M. Dunlop, Evelyn Fitzpatrick, Kevin Kurti, Stephanie Deeb, Erin Gillespie, Fumiko L. Chino, Laura Dover, Cherry Estilo, C. Jillian Tsai. Worsening disparities of racial minority participation in phase 1 early drug development trials in the United States, 2001-2018 [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PR-05.