A Nature Reviews Clinical Oncology review proposed a modular biomarker framework for antibody–drug conjugates that goes beyond semi-quantitative immunohistochemistry. The paper emphasizes integrating antigen biology, intracellular processing, payload susceptibility, and toxicity prediction to better match patients to ADC mechanisms. The framework is intended to sharpen clinical decision-making across heterogeneous tumors by addressing multiple failure points that occur after antibody binding. For biopharma, it reinforces the trend toward multi-dimensional companion diagnostics tailored to ADC-specific biology.