GEN eBook - From Sample to Insight | Precision Oncology

From Sample to Insight: Technologies Driving the Future of Precision Oncology Assays

Understanding Cancer Biomarkers: Classification, Function, and Clinical Impact Oncology biomarkers are measurable biological indicators that offer critical insights into cancer development, progression, and response to treatment. Found in tumor tissue, blood, or other body fluids, these markers can guide clinical decision-making at nearly every stage of the cancer care continuum—from early detection and diagnosis to treatment selection, monitoring, and prognosits. 4

Biomarkers are commonly classified by their clinical purpose: Biomarker Type Function Diagnostic

Confirms the presence or type of cancer (e.g., PSA, CA-125)

Prognostic Predictive

Predicts disease course or aggressiveness (e.g., Ki-67 proliferation index) Indicates likely response to specific therapy (e.g., EGFR mutations) Reflects biological response to a therapy (e.g., BCR-ABL levels) Tracks disease status or recurrence (e.g., ctDNA for MRD testing)

Pharmacodynamic

Monitoring

Biomarkers can also be categorized by their molecular origin or mechanism: Molecular Class Examples Genetic Alterations Mutations, amplifications, translocations Protein-Based Markers

Enzymes, receptors, hormones, tumor-associated antigens

Epigenetic Changes

DNA methylation, histone modification RNA expression profiles, protein isoforms

Transcriptomic/Proteomic Immune-Related Markers

PD-L1 expression, tumor mutational burden (TMB)

Leukemia : Detection of the Philadelphia chromo- some in acute lymphoblastic leukemia (ALL) and chronic myelogenous leukemia (CML) supports treatment with tyrosine kinase inhibitors such as imatinib (Gleevec) or dasatinib (Sprycel), or later nilotinib (Tasigna). Colorectal cancer : RAS mutation testing helps identify patients likely to benefit from EGFR-tar- geted therapies like cetuximab (Erbitux) or panitu- mumab (Vectibix).

The first biomarker tests—such as those assessing estrogen receptor status in breast cancer—were intro- duced over 30 years ago to determine eligibility for targeted treatments. As a result of these early advances, routine biomarker testing has become a standard part of care for several common tumor types: 5 Breast cancer : Testing for estrogen and proges- terone receptors, as well as HER2 overexpression, guides the use of targeted therapies like trastu- zumab (Herceptin) or lapatinib (Tykerb).

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