Disparities in Representation of Women, Older Adults, and Racial/Ethnic Minorities in Immune Checkpoint Inhibitor Trials

We aim to describe reporting and representation of minority patient populations in immune checkpoint inhibitor (ICI) clinical trials and assess predictors of enrollment disparity. Trial-level data were acquired from eligible phase II and III trials. Population-based estimates were acquired from the SEER 18 and Global Burden of Disease incidence databases. Trials reporting race, age, and sex were summarized using descriptive statistics. Enrollment-incidence ratio (EIR) was used to assess representation of subgroups. Average annual percentage change (AAPC) in EIR was calculated using Joinpoint Regression Analysis. Trial-level characteristics associated with EIR were assessed using multivariable linear regression. A total of 107 trials with 48,095 patients were identified. Participation of Black, White, Asian, Native American, Pacific Islander, and Hispanic participants was reported in 65 (61%), 77 (72%), 68 (64%), 40 (37%,) and 24 trials (22%), respectively. Subgroup analyses of clinical outcomes by race, age, and sex were reported in 17 (22%), 62 (78%), and 57 (57%) trials, respectively. Women (trial proportion [TP]: 32%; EIR: 0.90 [95% confidence interval [CI]: 0.84-0.96]), patients aged ≥65 years (TP: 42%; EIR: 0.78 [95% CI: 0.72-0.84]), Black participants (TP: 1.9%; EIR: 0.17 [95% CI: 0.13-0.22]) and Hispanics (TP: 5.9%; EIR: 0.67 [95% CI: 0.53-0.82]) were underrepresented. Representation of Black patients decreased significantly from 2009 to 2020 (AAPC: −23.13). Black participants were significantly underrepresented in phase III trials (P < .001). The reporting of participation by racial or ethnic subgroup categories is inadequate. Women, older adults, as well as Black and Hispanic participants are significantly underrepresented in ICI clinical trials.