In order to foster flexible yet rigorous biomarker method validation, the fit-for-purpose approach has recently been developed.This minireview focuses on many of the basic issues surrounding validation of biomarker assays utilised in clinical trials.Guidance for Industry: Pharmacogenomic Data Submissions The use of "companion diagnostics" to drive molecularly targeted drug development also requires that the "diagnostic" be clinically validated through the FDA's PMA or 510(K) process.

Clinical development of new anticancer drugs can be compromised by a lack of qualified biomarkers.

An indispensable component to successful biomarker qualification is assay validation, which is also a regulatory requirement.

IDDI has experience in the challenging statistical issues that characterize the identification and validation of biomarkers of diagnostic utility, prognostic and/or predictive ability, and those that can potentially be used as surrogate endpoints in clinical trials.

Biomarker classification depends on its context of use, which in turn defines the extent to which the biomarker must be "validated." In terms of requirements for validation, the "holy grail" of biomarker application is one that can serve as a surrogate endpoint in a clinical trial.

TRUS-biopsy can cause side-effects including bleeding, pain, and infection.

Multi-parametric magnetic resonance imaging (MP-MRI) used as a triage test might allow men to avoid unnecessary TRUS-biopsy and improve diagnostic accuracy.

They may be utilised as discovery tools, as pharmacodynamic (PD) markers of drug mechanism or efficacy both preclinically and in early phase trials, and as predictive indices of patient response in late phase trials (Lee et al, 2005; Sarker and Workman, 2007).

Thus, incorporation of biomarkers into clinical trials has the potential to guide and accelerate the pace of development of new anticancer drugs (Mc Shane et al, 2009).

Increasingly, tumor biomarker tests are being used to drive patient management, either by identifying patients who do not require any, or any further, treatment, or by identifying patients whose tumors are so unlikely to respond to a given type of treatment that it will cause more harm than good.

A tumor biomarker assay should only be used to guide management if it has analytical validity, meaning that it is accurate, reproducible, and reliable, and if it has been shown to have clinical utility.

In most instances, clinical validation is necessary for reimbursement.