Examining the Diversity of Pivotal CAR T-Cell Clinical Trial Enrollment

Take-aways:

• Researchers examined the enrollment of Black Americans in seven pivotal trials of chimeric antigen receptor (CAR) T-cell therapies.
• Black patients represented only 28 of the 782 treated patients (3.6%), and Black patients were particularly under-represented in myeloma studies.
• The highest proportion of Black patients enrolled in trials was in diffuse large B-cell lymphoma, but still indicated suboptimal enrollment.

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Pivotal trials that supported U.S. Food and Drug Administration (FDA) approval of chimeric antigen receptor (CAR) T-cell therapies had low proportions of Black patients enrolled, according to research presented at the 2021 American Society of Hematology Annual Meeting.

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 7 pivotal trials included in the study evaluated the following drugs and malignancies:

• tisagenlecleucel for acute lymphoblastic leukemia (ALL; approved in 2017)
• axicabtagene ciloleucel for diffuse large B-cell lymphoma (DLBCL; approved in 2017)
• tisagenlecleucel for DLBCL in (approved in 2018)
• brexucabtagene autoleucel for mantle cell lymphoma (MCL; approved in 2020)
• lisocabtagene maraleucel for DLBCL in (approved in 2020)
• axicabtagene ciloleucel for follicular lymphoma (FL; approved in 2021)
• idecabtagene vicleucel for multiple myeloma (MM; approved in 2021)

Prevalence-corrected estimates for enrollment of Black patients were calculated via the participation to prevalence ratio (PPR), defined as the percentage of Black people among the clinical trial participants divided by the percentage of Black people 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 researchers noted 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.”

Disclosures: The study authors reported no relevant conflicts of interest.

Reference

Al Hadidi S, Schinke C, Thanendrarajan S, et al. Enrollment of Black Americans in pivotal clinical trials supporting Food and Drug Administration (FDA) chimeric antigen receptor (CAR)-T cell therapy approval in hematological malignancies. Abstract #566. Presented at the 2021 American Society of Hematology Annual Meeting, December 12, 2021.