Wednesday, August 14, 2024 Plasma versus tissue tumor mutational burden as Biomarkers of Durvalumab plus Tremelimumab response in patients with metastatic colorectal cancer in the CO26 trial. Jonathan M. Loree, Emma Titmuss, James T. Topham, Hagen F. Kennecke, Harriet Feilotter, Shakeel Virk, Young S. Lee, Kimberly Banks, Katie Quinn, Aly Karsan, Derek J. Jonker, Dongsheng Tu, Chris J. O’Callaghan, Eric X. Chen AACR Journal Volume 30, Issue 15 1 August 2024Purpose: Tissue-derived tumor mutation burden (TMB) of ≥10 mutations/Mb is a histology-agnostic biomarker for the immune checkpoint inhibitor (ICI) pembrolizumab. However, the dataset in which this was validated lacked colorectal cancers (CRC), and there is limited evidence for immunotherapy benefits in CRC using this threshold. Conclusions: pTMB derived from either clonal or subclonal mutations may identify a group likely to benefit from immunotherapy, although validation is required. Tissue TMB provided no predictive utility for immunotherapy in this trial.
