Viewpoint: The Current Advances and Future Optimization of Blood-based Tumor Mutation Burden as a Biomarker for Cancer Immunotherapy

Instead of tissue-based detection, blood-based tumor mutation burden (bTMB) is becoming an alternative promising alternate to predict the response of immune checkpoint inhibitor in cancers, especially non-small-cell lung cancer. Although bTMB is more convenient and less invasive, many evidences identified its limited predictive ability and less accurate discrimination of candidates to receive immunotherapy. Several ways of adjustments have been applied to improve the clinical usefulness of bTMB, such as setting restriction for threshold of allele frequency to exclude some unwanted mutations. But many questions remained to be explored such as the number and the type of mutations that should be incorporated into the bTMB estimation. This viewpoint summarized the current attempts to modify bTMB and provided granular aspects that have implications for further enhancement of bTMB’s predictive capability.