Background Biomarkers are an integral component in the drug development paradigm. According to the US Food and Drug Administration (FDA), a biomarker is "a defined characteristic that is measured as an indicator of normal biological processes, pathogenic processes, or biological responses to an exposure or intervention, including therapeutic intervention" (FDA-NIH Biomarker Working Group. BEST (Biomarkers, EndpointS, and other Tools) Resource [Internet]. Silver Spring (MD): Food and Drug Administration (US); 2016-. Glossary. 2016 [Updated 2021 Nov 29, cited 2024 Apr 14]. Available from: https:// www.ncbi.nlm.nih.gov/books/ NBK338448/ Co-published by National Institutes of Health (US), Bethesda (MD)). The European Medicines Agency (EMA) defines a biomarker as "an objective and quantifiable measure of a physiological process, pathological process or response to a treatment (excluding measurements of how an individual feels or functions" European Medicines Agency (EMA). Biomaker. 2020a. Available from: https://www.ema.europa.eu/en/glossary-terms/ biomarker#:similar to:text=Biomarker-,Biomarker,an%20individual%20feels%20or%20functions. Several clinical biomarkers are well-documented and have been used routinely for decades in health care settings and have long been accepted as valid endpoints for drug approval (for example, blood pressure measurement as a biomarker for cardiovascular health) (European Medicines Agency (EMA). Assessment report, TAGRISSO. 2016. Available from: https://www.ema.europa.eu/en/docum ents/assessment-report/tagrisso-epar-public-assessment-report_en.pdf. Accessed 15 Apr 2024). Recently, novel biomarkers have been identified and validated to accelerate developing innovative therapies indicated for serious human diseases, for example targeted/immune therapies of cancer (Chen in Med Drug Discov 21:100174, 2024). As indicators of the efficacy of new pharmacological treatments or therapeutic interventions, biomarkers can improve clinical trial efficacy and reduce uncertainty in regulatory decision making (Bakker et al. in Clin Pharmacol Ther 112:69-80, 2022; Califf in Exp Biol Med 243:213-221, 2018; Parker et al. in Cancer Med 10:1955-1963, 2021). Methodology This article describes case studies of recent drug approvals that successfully leveraged validated and nonvalidated biomarkers (i.e., tofersen for the neurodegenerative disease amyotrophic lateral sclerosis (ALS) in adults; and osimertinib for treatment of patients with metastatic epidermal growth factor receptor (EGFR) T790M mutation- positive non-small cell lung cancer (NSCLC)). Conclusions Best practices for biomarker selection and strategies for health authority biomarker qualification programs are presented along with an overview of current limitations and challenges to optimizing biomarker applications along the drug development continuum from regulatory, translational, and operational perspectives.
