Purpose:

We aim to describe reporting and representation of minority patient populations in immune checkpoint inhibitor (ICI) clinical trials and assess predictors of enrollment disparity.

Methods:

Trial-level data were acquired from eligible phase II/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.

Results:

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% 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 2009-2020 (APC: -23.13). Black participants were significantly underrepresented in phase III trials (p<0.001).

Conclusion:

The reporting of participation by racial/ethnic subgroup categories is inadequate and women, older adults, and racial/ethnic minorities are significantly underrepresented in ICI clinical trials.