The ability to identify specific groups of patients and/or stages of disease progression for which a new drug will be effective generates substantial potential cost savings by reducing the use of therapeutics that are either ineffective or cause adverse reactions: for the UK healthcare system alone this could result in possible savings of between 23% and 54% and may equate to saved costs in excess of £2.4bn and £5.6bn per annum

Regulators, such as the FDA, are increasingly looking for improvements in the demonstrated effectiveness of a drug before approval is given and are consequently recognising the need for and, in certain instances, requiring that diagnostic tests be available before a drug can be marketed - so-called companion diagnostics. This then generates a need for the industry to

• Find ways to identify those patients most likely to respond positively in the clinical trials, increasing likelihood of drug approval

• Develop simple diagnostics tests that can be used to pre-select patients who will respond positively to the therapy.

Biomarkers, almost by definition, can be used as a diagnostic for a given disease and in many instances are now being developed as a prognostic of the likely disease progression.