Challenges

From Companiondiagnostics

A disease status can be described by the constellation of multiple biomolecules abundances and/or activities. Examples are profiles of RNA expression or protein abundances. To date it is even possible to measure the activity of multiple proteins in a tumor lysate, like those of kinases.

These biomolecules' characteristics are referred to as biomarkers. Biomarkers are the basis of test development.
By linking biomolecules' abundance or activity profiles to a disease status allows the identification of biomarkers for diagnostic test development. When such biomarkers are correlated to for example disease progression, they can be used for prognostic test development. Finally, when linked to drug responses and treatment efficacy such markers are called predictive markers and are the basis of companion diagnostic test development. Thus a companion diagnostic test is aimed to predict the success of drug treatment.

In summary:
- diagnostic markers identify a disease (status)
- prognostic markers predict development of the disease
- predictive markers predict the effect of (drug) treatment

The challenge in development of companion diagnostics is in the identification and validation of predictive biomarkers by correlating biomolecules' abundance or activity profiles to clinical data of drug treatment efficacy (e.g. drug response).