Tissue-agnostic biomarkers in solid tumors: current approvals and emerging candidates.

The landscape of cancer treatment has shifted from histology-specific to tissue-agnostic approaches, targeting molecular alterations regardless of tumor origin. Currently, six pan-cancer biomarkers-NTRK, BRAF V600E, RET, HER2-positive, MSI-high, and TMB-high-along with nine molecularly targeted therapies have expanded treatment options across diverse malignancies. This review examines each biomarker's molecular basis, prevalence across tumor types, and corresponding FDA-approved therapies. Additionally, emerging candidates-including FGFR, ALK, MET, ROS1, NRG1, PIK3CA, AKT, KRAS G12C, HER2 mutations, HER2-low/ultralow, B7-H3, and tumor-infiltrating lymphocytes (TILs)-are explored. While these biomarkers represent a paradigm shift in oncology, their integration into clinical practice requires overcoming challenges related to tumor heterogeneity and lineage-specific molecular dependencies. Future research should focus on identifying novel biomarkers, optimizing treatment strategies through multiomic analyses, and leveraging innovative clinical trial designs to advance precision oncology. In particular, further investigation into TILs as a predictive biomarker for immunotherapy is warranted, given their distinct immunophenotypic features and prognostic significance in shaping treatment responses across cancer types.