FAQ - CDx : Discovery & Feasibility 
 

When should a biomarker be evaluated for CDx development?

A biomarker should be evaluated for CDx potential as early as possible during therapeutic development. Early evaluation helps determine whether the biomarker is biologically relevant, clinically actionable, and feasible to measure in a clinical setting. Waiting until late-phase trials can lead to insufficient sample collection or misaligned evidence generation.

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How do companies decide whether a diagnostic should be companion, complementary, or exploratory?

The diagnostic role is determined by how the biomarker affects treatment decisions. If the test result is required for safe and effective use of the therapy, it is considered a companion diagnostic. Complementary diagnostics provide additional clinical insight but are not mandatory for prescribing decisions. Early definition of the diagnostic role helps align regulatory strategy and clinical evidence generation.

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What makes biomarker-positive populations difficult to study in CDx programs?

Many biomarkers occur in small or heterogeneous patient populations. This limits available samples and can reduce statistical power in clinical studies. Companies must design trials carefully to ensure sufficient representation of biomarker-positive patients while maintaining clinically meaningful endpoints.