Oldest Patients Underrepresented in Hematologic Cancer Trials

A new study has found that there are significant gaps in participation among people aged 75 and older in clinical trials of hematologic malignancies when considered against the incidence of these malignancies in this age group. In contrast, adults aged younger than 65 were overrepresented in these trials despite the fact that a majority of blood cancers occur in people older than 65.

“Until now, there has been very little information about the enrollment of adults with hematologic cancers. Based on our findings, the occurrence of cancer is much higher in adults over 75 years of age compared with the proportion of patients in this age group who enroll in clinical trials,” said lead study author Bindu Kanapuru, MD, medical officer in the Division of Hematology Products, Office of Hematology and Oncology Products in the US Food and Drug Administration’s (FDA) Center for Drug Evaluation and Research, who presented the results at the 59th American Society of Hematology (ASH) Annual Meeting and Exposition, held December 9–12 in Atlanta.

“With so few patients aged 75 or older enrolled in clinical trials, critical information on the safety and effectiveness of new therapies in this age group is greatly lacking,” she said.

In the study, the researchers identified 44,144 patients enrolled in clinical trials evaluating hematologic malignancies submitted to the FDA in support of approval of new or supplemental indications from 2005 to 2015. The researchers grouped patients into disease categories based on diagnosis and analyzed the data according to age distributions.

About one-half (45%) of patients were enrolled in lymphoma trials, one-quarter (24%) in chronic myeloid leukemia (CML) trials or multiple myeloma trials (22%), and 2% of patients were enrolled in trials of acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). Less than 1% of patients were enrolled in trials of acute lymphoblastic leukemia (ALL).

More than half of patients, with the exception of those enrolled in CLL and AML/MDS trials, were younger than age 65, and more than 85% of patients enrolled in ALL trials were younger than 65. Compared with the United States cancer populations, trials of lymphoma, CLL, CML, and myeloma enrolled a disproportionately higher percentage of patients younger than 65 years.

In contrast, patients aged 75 and older accounted for approximately 29% of CML diagnoses, yet this age group made up less than 4% of those enrolled in clinical trials to evaluate new treatments for the disease. These patients were significantly underrepresented in trials of new treatments for lymphoma, CLL, and myeloma compared with the incidence of these diseases in that age group.

“We weren’t surprised to see that, overall, adults aged 75 years and older were underrepresented in clinical trials, as this is common across cancer trials,” Kanapuru said in a press release. “But we were surprised by the magnitude of the gap for this age group, particularly for CML trials.”

However, the data did show that among patients aged 65 to 74, the proportion enrolled in lymphoma and CML trials mirrored the reported incidence of hematologic malignancies in this age group. In myeloma and CLL trials, the proportion of people aged 65 to 74 was higher than the reported incidence.