Real-world application of tumor mutational burden-high (TMB-high) and microsatellite instability (MSI) confirms their utility as immunotherapy biomarkers

•This retrospective study examined the real-world use of immune checkpoint inhibitors (ICIs) in TMB/MSI-high patients with a diverse set of cancer types.•TMB is an emerging tumor-agnostic biomarker for response to treatment with ICIs that may expand personalized cancer care.•ICIs remain underutilized as a first-line therapy for TMB/MSI-H patients without specific histologic approval for ICIs.•The PFS2 to PFS1 ratio was 4.7, favoring immunotherapy over chemotherapy even as a second-line therapy.•Our study reinforces the real-world evidence that TMB is a valid surrogate marker for MSI and can predict response to ICIs.