Enrollment of older adults in clinical trials for oncology indications, 2010-2020: An evaluation by the FDA.

Abstract

e23029 Background: Underrepresentation of older adults (≥65 years) in clinical trials may limit important evidence for regulatory and clinical decision-making. Prior FDA analysis1 demonstrated underrepresentation of older adults in oncology clinical trials. With recent efforts to encourage inclusion of older adults, we evaluated representation in clinical trials using updated data. Methods: This analysis used patient-level data from pivotal trials supporting approvals of new drugs and biologics, and expanded indications from 2010-2020 for cancers with high incidence in the U.S. population and older adults: breast (BC), colorectal (CRC), non-small cell lung (NSCLC), prostate (PC), chronic myeloid leukemia (CML), and multiple myeloma (MM). Age distribution of trial participants compared to incident cases from the NCI SEER Program was analyzed using the Enrollment to Incidence Ratio (EIR). For each cancer-age group, EIR is the percentage of trial participants divided by percentage of incident cases. Previously established EIR categories of < 0.8, 0.80-1.20, and > 1.2 indicate under-, adequate, and over-representation, respectively. Results: The analysis included 86000 participants in 152 trials. Adults >65 yrs were underrepresented in BC trials. Adults >75 yrs were underrepresented in BC, CRC, NSCLC, CML, and MM trials (Table 1). Conclusions: Despite slight variation across cancers, adults >75 yrs appeared to be underrepresented in clinical trials, excepting PC. Given heterogeneity in the natural history by cancer site, incidence may not best represent age distribution of the intended use population for all trials. Further evaluation using prevalence as a comparator may provide additional insights. Additionally, results may be affected by clinical factors such as stage; however, comparison is limited by SEER data element availability. Planned sensitivity analyses such as stratification by drug class and line of therapy may further elucidate enrollment patterns.