Abstract PR012: Underrepresentation and underreporting of minoritized racial and ethnic groups in clinical trials on immune checkpoint inhibitors
Authors: Chua Alfredo V. , Delmerico Jennifer , Sheng Haiyang , Gandhi Shipra , Puzanov Igor , Sakoda Lori C. , Morrow Gary R. , Ambrosone Christine B. , Kamen Charles , Yao Song 
Published: December 2023

Background: In the last decade, a fast-growing number of clinical trials on immune checkpoint inhibitors (ICIs) have led to their wide approval and clinical use with substantial improvement in patient outcomes across multiple cancer types. Historically, minoritized racial and ethnic groups have been underrepresented in clinical trials. Such disparities may be exacerbated in trials of new therapies such as ICIs. Our study aimed to examine the representation and reporting of the racial and ethnic composition of participants in clinical trials involving ICIs. Methods: Clinical trials published in full text in English from 2007 to 2022, with ICI as an active intervention for any malignancy, were reviewed. Information on trial characteristics and racial and ethnic composition of participants were extracted from published papers or ClinicalTrials.gov. Differences in participation in terms of year of publication, trial phase, ICI agent, and cancer type were analyzed. Enrollment-incidence ratio (EIR) was calculated using the proportion of minoritized racial/ethnic group patients among trial participants versus the age-adjusted cancer incidence by race and ethnicity for each cancer type and year from the National Cancer Institute Surveillance, Epidemiology, and End Result (SEER) database. An EIR greater than 1 signifies overrepresentation while less than 1 signifies underrepresentation. Results: A total of 471 clinical trials were identified and included in the analysis, with the majority published between 2019 and 2022 (68%) and conducted in Phase 2 (41%) or Phase 3 (26%). The most investigated ICI was pembrolizumab (28%), and lung cancer was the most studied malignancy (22%). Racial composition was unreported in 31% of the trials, while 59% did not report Hispanic/Latinx ethnic composition. Only 6.4% of the trials reported race/ethnicity-specific results. Overall, Hispanics/Latinx were the most underrepresented (EIR 0.30, 95% CI 0, 1.45), followed by Blacks/African Americans (EIR 0.40, 95% CI 0, 1.95), and American Indians/Alaska Natives (EIR 0.92, 95% CI 0, 8.98), while Whites (EIR 1.13, 95% CI 0.63, 1.43) and Asians (EIR 1.88, 95% CI 0, 8.11) were overrepresented. Subgroup analyses revealed consistent overrepresentation of only Whites across the years of publication (EIR 1.11-1.23), trial phases (EIR 1.07-1.22), ICIs agents (EIR 1.03-1.21), and cancer types (EIR 1.02-1.30), while Hispanics/Latinx and Blacks/African Americans were consistently underrepresented across these categories. Excluding phase 1 trials (31.9%) in the analyses did not significantly alter these findings. Conclusions: Disparities in the representation and reporting of minoritized racial and ethnic groups persist in recent trials on ICIs. Whites and Asians were overrepresented; Hispanics/Latinx, Blacks, and Native Americans were underrepresented. Concerted efforts from the clinical, research, patient, and advocate communities are warranted to improve diversity in trial representation and reporting and ensure safe and beneficial treatment with ICIs for all patients.

Citation Format: Alfredo V. Chua Jr., Jennifer Delmerico, Haiyang Sheng, Shipra Gandhi, Igor Puzanov, Lori C. Sakoda, Gary R. Morrow, Christine B. Ambrosone, Charles Kamen, Song Yao. Underrepresentation and underreporting of minoritized racial and ethnic groups in clinical trials on immune checkpoint inhibitors [abstract]. In: Proceedings of the 16th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2023 Sep 29-Oct 2;Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2023;32(12 Suppl):Abstract nr PR012.