Under-Representation and Under-Reporting of Minoritized Racial and Ethnic Groups in Clinical Trials on Immune Checkpoint Inhibitors.

Purpose: Minoritized racial/ethnic groups are historically under-represented in cancer clinical trials, which may be exacerbated in recent trials on immune checkpoint inhibitors (ICIs). We examined the representation and reporting of the racial/ethnic composition of participants in clinical trials on ICIs.

Methods: We examined English full-text trials on ICIs published from 2007 to 2022. Information on trial characteristics and racial/ethnic composition of participants was extracted from published papers or ClinicalTrials.gov. Differences in participation by publication year, ICI agent, and cancer site were analyzed. Enrollment-incidence ratio (EIR) was calculated to compare the proportion of minoritized racial/ethnic group patients in US-based trials against age-adjusted cancer incidence data available for the US population. An EIR > 1 signified over-representation, whereas an EIR <1 signified under-representation.

Results: Of the 471 trials examined, racial composition was unreported in 146 (31%), whereas Hispanic/Latinx ethnicity was unreported in 278 (59%). Only 30 (6%) trials reported race/ethnicity-specific results. In US-only trials (n = 174), White patients were over-represented (EIR, 1.20 [95% CI, 1.17 to 1.22]), whereas Hispanic/Latinx patients were the most under-represented (EIR, 0.35 [95% CI, 0.24 to 0.48]), followed by Black/African American patients (EIR, 0.66 [95% CI, 0.54 to 0.79]). Subgroup analyses consistently indicated over-representation of White patients across publication years (EIR, 1.19-1.24), ICI classes (EIR, 1.16-1.23), and cancer sites (EIR, 1.11-1.31), whereas Hispanic/Latinx patients were consistently under-represented. An upward trend of trial representation and reporting was observed for all minoritized racial/ethnic groups over time (trend values ≤.05).

Conclusion: Disparities in the representation and reporting of minoritized racial/ethnic groups persist in recent trials on ICIs, necessitating collaborative efforts for improved diversity and equitable cancer treatment access.