Aligning tumor mutational burden (TMB) quantification across diagnostic platforms: phase II of the Friends of Cancer Research TMB Harmonization Project

•Estimation of TMB varies across different panels, with panel size, gene content and bioinformatics pipelines contributing to empirical variability.•Panel sizes greater than 667Kb are necessary to maintain adequate PPA and NPA for calling TMB high versus TMB low across the range of cutoffs used in practice.•Statistical calibration can achieve more consistent results across panels and allows for comparison of TMB values across various panel assays.