Table 4.

Simplified overview of drug/diagnostic co‐development.

Drug phase	Drug/biomarker interaction	Predictive biomarker/diagnostic activities
Pre‐clinical	Link to drug sensitivity for biomarker discovery and strength of hypothesis.
Phase 1	No meaningful data usually available.	Biomarker validation on relevant clinical samples: evaluability and prevalence.
Phase 2 trial against comparator in biomarker +ve and −ve patients	Indication of clinical utility of biomarker. Role of predictive biomarker in Phase 3 trial design and case for co‐development.	Biomarker status of trial participants by research use only (RUO) assay
Preparation for commercial launch		Conversion of RUO assay to final format.
Phase 3	Confirmation of clinical utility of biomarker.	Biomarker status of trial participants by diagnostic assay