Reporting and enrollment disparities in hematologic malignancy trials between 2000-2023.

Despite initiatives to enhance diversity in clinical trials (CTs), disparities persist in hematologic malignancy (HM) studies. We reviewed 1,230 US-based phase II-III HM CTs (2000-2023) including 149,434 participants and compared enrollment to SEER benchmarks. Race was reported in 59% of trials and ethnicity in 40%, with significant improvement over time. Trials initiated in 2016 or later were more likely to report race (OR 36.3) and ethnicity (OR 8.0) than those before 2008. Compared with NIH-sponsored studies, institutional (OR 0.34) and industry trials (OR 0.52) had lower odds of reporting demographics. Black and Hispanic individuals were consistently underrepresented, most notably in multiple myeloma (7.0% vs. 20.0% expected) and acute lymphoblastic leukemia (21.5% vs. 36.9% expected). NIH-funded trials enrolled more Black participants than other sponsor types. These findings emphasize the need for enforceable mandates on race and ethnicity reporting, as well as representation targets, to ensure equitable access and generalizability.