Enrollment of Black Americans in Pivotal Chimeric Antigen Receptor-T Cell Clinical Trials

Black Americans were severely under-represented in clinical trials that supported FDA approvals of chimeric antigen receptor (CAR)-T cell therapies in patients with multiple myeloma (MM), acute lymphoblastic leukemia (ALL), diffuse large B cell lymphoma (DLBCL), mantle cell lymphoma (MCL) and follicular lymphoma (FL), according to research presented at the 2021 ASH Annual Meeting and Exposition.

Lead author Samer Al Hadidi, MD, MSc, of the Winthrop P. Rockefeller Cancer Institute at the University of Arkansas for Medical Sciences in Little Rock, and collaborators examined the enrollment of Black Americans in these trials through a retrospective analysis. The seven pivotal trials included in the study evaluated the following drugs and malignancies: tisagenlecleucel for ALL (approved in 2017), axicabtagene ciloleucel for DLBCL (approved in 2017), tisagenlecleucel for DLBCL in (approved in 2018), brexucabtagene autoleucel for MCL (approved in 2020), lisocabtagene maraleucel for DLBCL in (approved in 2020), axicabtagene ciloleucel for FL in (approved in 2021), and idecabtagene vicleucel for MM (approved in 2021).

Prevalence-corrected estimates for enrollment of Blacks were calculated via the participation to prevalence ratio (PPR), defined as the percentage of Blacks among the clinical trial participants divided by the percentage of Blacks in the disease population. The report states that PPR between 0.8 and 1.2 indicates a similar representation of Black Americans between the trial and the disease populations.

Efficacy data were available for 782 of 1,051 patients enrolled in the CAR T-cell therapy trials. Black patients represented only 28 of the 782 treated patients (3.6%). Additionally, Black patients were particularly under-represented in MM studies.

Most treated patients had DLBCL (58%) or MM (16%). By specific disease, Black patients constituted only 4% of patients with DLBCL, 6% of patients with MM, and 1% of patients with other indications. The poorest PPR was in MM (0.17), a disease which the article notes is more common in Black Americans. The best PPR was in DLBCL (0.6), but still indicated suboptimal enrollment.

Dr. Hadidi concluded that “efforts should be made to enroll more Blacks in clinical trials that include novel, potentially beneficial CAR T-cell products.”