Blacks, Hispanics, and Females Enroll Less in CLL Trials

Authored by Brian Koffman, MDCM (retired), MSEd

Bottom Line:

Despite improvement in outcomes in CLL and other blood cancers, disparities persist, with Blacks, Hispanics, and females underrepresented in clinical trials.

Who Performed the Research and Where Was it Presented:

Inna Y Gong, MD, PhD from Princess Margaret Cancer Centre in Toronto, ON, Canada, and colleagues presented the results in a poster session at the American Society for Hematology (ASH) Annual Meeting 2024.

Background:

New therapies have revolutionized the management of chronic lymphocytic leukemia (CLL) and many other blood cancers, but there are persistent disparities in the benefits realized based on age, gender, race, and ethnicity. This research looks at one aspect of those disparities, namely the imbalances seen in those enrolled in all clinical trials (CT) for hematologic malignancies, though we will focus on CLL. These disparities can result in several problems:

1. Often, the best care is through a CT, and it is sometimes the only pathway to life-extending novel therapies. Access to the best care is not being optimized for too many.
2. When the trial participants don’t represent the community being treated, results can be biased, and important variations between different groups can be missed. The heterogeneity of responses and adverse events based on age, gender, race, and ethnicity cannot be well assessed.
3. Accrual to trials is slowed, so drug development is slow.

Methods:

• All phase II and III blood cancer CTs registered in ClinicalTrials.gov based in the USA from January 1, 2000, to December 31, 2023, that had fully accrued were reviewed.
• The data studied included:
  • Trial characteristics, including funding sources
  • Demographic information (age, sex, race, and ethnicity).
• The demographic data in the trials were compared to age-adjusted population-based Surveillance, Epidemiology, and End Results (SEER) data for hematologic malignancies. SEER is the gold-standard source for the incidence of any disease in the USA.
• SEER data provided the demographic subgroup proportions for sex, race (White, Black, Asian, or Pacific Islander [A/PI], Native American/Alaska Native [NA/AN]), and ethnicity (Hispanic and non-Hispanic).

Results:

Trial Details:

• 1,286 blood cancer CTs were discovered on Clinicaltrials.gov
• 583 CTs were for lymphoma (Hodgkin lymphoma [HL], non-Hodgkin lymphoma [NHL], chronic lymphocytic leukemia [CLL])
• 87% were phase II CTs
• 29% received NIH funding
• 34% of trials involved novel therapies

Participants:

• There were 153,074 participants.
• Race was reported in 57% of trials, and ethnicity in only 39%. When it was reported, the breakdown was:
  • 85.4% were White.
  • 7.7% A/PI.
  • 6.3% Black.
  • 0.3% NA/AN.
  • 87.9% identified as non-Hispanic.

SEERS vs CT enrollment:

• Black patients made up 10.3% of those with hematologic malignancies, but they represented only 6.3% of those recorded as participants across all the clinical trials that had data on race.
• 6.9% of all CLL patients are Black, but they only made up 3.8% of those in the trials.
• The difference in multiple myeloma (MM), the most common blood cancer in Blacks who have a higher incidence of MM and worse outcomes compared to Whites, was even more dramatic. 20% of those diagnosed with MM are Black, but they represented only 7% of trial participants.
• Hispanic CLL patients were underrepresented, with only 4.0% in CT compared to the 5.6% they represent of those diagnosed with CLL.
• In contrast, A/PIs participated more actively in the NHL, MM, and acute myeloid leukemia (AML) trials than those with the diagnoses.
•  Females were underrepresented across most blood cancer trials compared to SEER data. In the case of CLL they made up 35.1% of trial participants but a full 40.2% of those with the disease.
• All these differences in SEER vs. trial percentages were statistically significant.

Conclusions:

Only a little more than half of the trials reported the participants’ race, and even fewer recorded their ethnicity. This is a significant missed opportunity to fill gaps in our knowledge about drugs in different populations. We have reported before on the underrepresentation of people of color in clinical trials, so that is no surprise. The FDA recognized these disparities and now demands that the population in studies must accurately reflect the population that will ultimately be treated.

This research is weakened by its broad reach. It covers 23 years, and other research on diversity in clinical trials tells us that there has been significant progress for Black CLL patients over the past decade in their representation in trials. The abstract would be strengthened if demographic trends in trial participation were included.

Despite this, this research presents strong evidence of historical inequities that almost certainly persist and that must be remedied.

Links and Resources:

Listen to Dr. Koffman’s monologue below.

There are many more details in the ASH 2024 abstract:  Disparities in Phase II and III Clinical Trial Enrollment for Hematologic Malignancies. The same author, Dr. Gong, also presented more data in this related ASH 2024 abstract: Disparities in Clinical Trial Participation Among Medicare Beneficiaries with Hematologic Malignancies from 2006 to 2019: A SEER-Medicare Analysis.