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Published on: November 5, 2019
Tumour mutational burden: an overview for pathologists
Kenneth D Doig1, Andrew Fellowes2, Prudence Scott3
1Department of Pathology, Peter MacCallum Cancer Centre, Parkville, Vic, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Vic, Australia.
Abstract:
Cancer immunotherapy holds great promise and has shown durable responses in many patients; however, these responses are not uniform in all patients or all tumour streams. There is an ongoing clinical need for objective diagnostic biomarkers to identify patients that will respond to immunotherapies. Tumour mutational burden (TMB) is a diagnostic biomarker that can stratify cancer patients for response to immune checkpoint inhibitor therapies. It is commonly defined as the average number of somatic mutations per megabase in a tumour exome. Here we describe the TMB biomarker, how it is determined, its underlying molecular basis, the relationship to neoantigens and the issues around its clinical use. This overview is directed toward practising pathologists wishing to be informed of this predictive biomarker.
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