Racial and ethnic differences in plasma p-tau217 ratio biomarker eligibility rates in a preclinical AD trial with lecanemab.

Introduction: Consistent predictive performance across racial and ethnic groups is essential to the use of plasma biomarkers as screening tools in preclinical Alzheimer's disease trials.

Methods: Logistic regression examined racial and ethnic group differences in plasma eligibility using an algorithm that included Phosphorylated tau217 to non-phosphorylated tau217 ratio, amyloid beta 42/40, age, and apolipoprotein E to predict > 18 Centiloids on amyloid imaging in cognitively unimpaired individuals.

Results: Among 6437 participants screened, with non-Hispanic (NH) White as the reference group, odds ratios of plasma ineligibility were 2.88 (95% confidence interval [CI]: 1.40-6.96) for Hispanic Black, 1.60 (95% CI: 1.33-1.92) for Hispanic White, 2.10 (95% CI: 1.37-3.38) for NH Asian, and 1.59 (95% CI: 1.27-2.0) for NH Black participants. Positron emission tomography (PET) eligibility rates did not differ among those who were plasma eligible.

Discussion: Differential rates of plasma eligibility, but consistent PET eligibility among plasma-eligible participants, were observed, supporting the use of universal biomarker cutpoints across race and ethnic groups. Underrepresented racial and ethnic groups had lower rates of plasma eligibility compared to non-Hispanic White individuals based on a plasma screening algorithm that included the phosphorylated tau 217 ratio.Among plasma-eligible participants, amyloid positron emission tomography eligibility rates did not differ by racial and ethnic group.Plasma biomarker tests may provide equivalent effectiveness for identifying imaging biomarker eligible, cognitively unimpaired individuals across racial and ethnic groups.