Precision oncology — matching cancer treatment to the molecular characteristics of individual tumors rather than tissue of origin alone — has fundamentally transformed cancer care across multiple tumor types. As of 2025, the FDA has approved over 90 biomarker-driven cancer therapies, and comprehensive genomic profiling (CGP) has become the standard of care for many advanced cancers. The clinical challenge is no longer "do we test?" but "how do we interpret and act on the results?"
Key Biomarkers and Their Clinical Significance
Microsatellite instability-high/mismatch repair deficient (MSI-H/dMMR): the first tumor-agnostic FDA approval (pembrolizumab, 2017). Found in 3–5% of solid tumors overall — highest prevalence in endometrial (30%), colorectal (15%), and gastric cancers. Pembrolizumab produces 40–45% objective response rate and durable responses in MSI-H tumors. Universal IHC MSI testing is now recommended for all newly diagnosed CRC. PD-L1 expression: predictive for immune checkpoint inhibitor (ICI) response in NSCLC (pembrolizumab monotherapy approved for TPS ≥50%), urothelial carcinoma, cervical cancer, and others. Not a binary predictive biomarker — response occurs across PD-L1 expression levels. Tumor mutational burden (TMB): ≥10 mutations/megabase defines TMB-H (tumor-agnostic FDA approval for pembrolizumab 2020). Enriches for ICI response but overlaps with MSI-H — clinical utility varies by tumor type. EGFR, ALK, ROS1, RET, NTRK, MET, KRAS G12C, HER2: actionable driver mutations in NSCLC and other cancers with matched targeted therapies. For oncology facilities performing molecular testing, our laboratory supplies section includes biopsy collection kits, tissue collection supplies, and specimen management products.
