Biomarkers in Alzheimer's disease clinical trials: 2025

Biomarkers play an important role in Alzheimer's disease (AD) clinical trials in several contexts of use, including defining trial eligibility and serving as outcome measures. Utilizing clinicaltrials.gov, a registry of clinical trials, we assessed biomarker usage across all active AD disease-targeted therapeutic (DTT) trials. Biomarkers are widely used in AD DTT trials, with 84% including a fluid, imaging, and/or digital biomarker, either as an inclusion criterion or as an outcome measure. In DTT trials, biomarkers were included in 83% of Phase 3 trials, 91% of Phase 2 trials, and 72% of Phase 1 trials. Biomarkers were used for trial inclusion in 58% of DTT trials and as a primary outcome measure in 36%. Characterization of biomarker usage in AD clinical trials offer valuable insights across the drug development spectrum, with the goal of increasing trial efficiency and interpretation, while reducing time for new therapies to become available.