Tumor Mutational Burden (TMB) 

What is TMB? Tumor mutational burden is a measurement of mutations carried by tumor cells and is a predictive biomarker being studied to evaluate its association with response to Immuno-Oncology (I-O) therapy.1, 2

How is TMB measured? DNA sequencing, such as Whole Exome Sequencing (WES) is typically used to determine the number of acquired mutations in the tumor.1, 2

Why is TMB important? 
Tumor cells with high TMB may have more neoantigens, with an associated increase in cancer-fighting T cells in the tumor microenvironment and periphery. These neoantigens can be recognized by T cells, inciting an anti-tumor response.

References
1. Alexandrov LB et al. Nature. 2013; 500: 415-421.
2. Yuan J et al. J lmmunother Cancer. 2016; 4:3.
3. Schumacher TN, Schreiber RD. Science. 2015;348(6230):69-74.
4. Gibney GT et al. Lancet Oncol. 2016; 6;17: e542-e551.