No Biomarker, No Trial?
The vast majority of experimental cancer drugs fail during the later stages of clinical development – after considerable time and expense has already been invested. The right biomarkers could help us weed out unsuitable candidates early on, and focus our efforts on therapies with real potential.
James Ritchie, Sidath Katugampola, Paul Jones |
The way we have developed cancer drugs to date is far from optimal and, in most instances, results in failure (1). The stark truth is that the majority of drug discovery and development activity yields little benefit to patients, while exposing them to potentially toxic drugs and wasting billions of dollars in the process. With the majority of experimental cancer drugs falling down at the costly mid-to-late stages of clinical development (Phase II or III clinical trials), we’ve reached a stage where something has to give. We need to bring critical decision points forward, ideally into the initial stages of clinical development (Phase I), before costs, timelines and patient numbers escalate. The shrewd application of biomarkers in early-phase clinical development can help us to make these critical go/no-go decisions in time.
Biomarkers come in many flavors
A biomarker is defined by the FDA as “a characteristic that is objectively measured and evaluated as an indicator of normal biologic processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention.” Under the umbrella term of “biomarkers”, there are many different flavors. One of the most commonly adopted biomarker classification systems is that suggested by Bradley (2), which categorizes biomarkers (with some minor modifications) as follows:
- Proof of mechanism (PoM)
- Proof of principle (PoP)
- Proof of concept (PoC)
- Predictive biomarkers (sometimes known as patient stratification, selection or enrichment biomarkers)
- Safety biomarkers
These biomarker categories are explained in more detail below.
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