Biomarkers for tuberculosis disease activity, cure, and relapse.

New drugs, vaccines, and other therapies will be required to realise the goal of global tuberculosis elimination or control. This Review covers the important role biomarkers can have in accelerating drug development by providing validated surrogate endpoints that can bring enhanced statistical power to small short studies. Candidate biomarkers should differentiate people with active tuberculosis from healthy individuals, normalise with therapy, and reproducibly predict clinical outcomes in diverse patient populations. Although a large number of promising candidate biomarkers have been examined to date, few patients in these studies have reached clinically meaningful outcomes, and few of the studies have been conducted to international research standards. These markers must be further studied in tuberculosis treatment trials to evaluate the kinetics of the responses and their relation to long-term clinical outcomes. These studies will benefit from multidisciplinary collaborations including microbiologists, immunologists, clinicians, tuberculosis control personnel, and the pharmaceutical and biotechnology industry.