Translational Pharmacology Should Treat Biomarkers as Decision Tools Rather Than Decorative Correlates

Biomarkers are often presented as evidence of biological relevance even when the development decision they are meant to change is unspecified. This creates a recurrent translational error: a statistically associated or mechanistically plausible measurement is treated as though it already has decision utility. Biomarker usefulness instead depends on context of use, analytical fitness, biological proximity to the pharmacological question, timing, population, treatment, dose, and the consequences of an incorrect result. This Perspective argues that biomarker interpretation should be organized around the decision a measurement is intended to change. Target engagement, pharmacodynamic response, patient stratification, and dose selection are distinct functions, and evidence supporting one role should not be silently transferred to another. Examples from circulating tumor DNA, imaging, target-engagement studies, biosimilar pharmacodynamic programs, and model-informed dose selection show that useful biomarker evidence is conditional. We propose that translational pharmacology distinguish measurement validity, biological relevance, action threshold, consequence, and transferability as separate evidentiary questions. This decision-utility view clarifies when biomarkers are descriptive, when they support pharmacological inference, and when they are sufficiently qualified to alter development or treatment choices.