Biomarker Discovery

Multiple functions, including amplification of a gene’s mutations, aberrant cell division, and growth, induce secretion or release in the human body of specific solid tumor markers commonly found in malignancy. Therefore, biomarkers can be measured or quantified through non-invasive means in different biological fluids [whole blood (serum or plasma) and urine] or through invasive methods requiring biopsy of the malignant solid tumor tissue or cells. A particular biomarker type is the genomic biomarker. DNA collection is required for studying this type of cancer marker, as well as quantification in cancerous tissue or whole blood.

Biomarkers from solid tumor-derived malignancies, such as breast, colon, lung, brain, melanoma, or prostate, can assist in the molecular classification of cancers. Biomarkers must have a high-level of specificity and sensitivity in differentiating a benign or aggressive cancer from an inconsequential one. These primary characteristics of biomarkers are crucial for evaluating and establishing the optimal limits of cutoff values describing the accuracy and ability of biomarkers to distinguish between healthy and unhealthy subjects.

Biomarkers and cutoff values

• Sensitivity and specificity, the main characteristics of biomarkers, are inversely proportional to each other
• Highly specific, but low-sensitivity biomarker: increase of cutoff points leads to an increase of specificity of the assay or a false negative response and decrease of false-positive reactions
• Highly sensitive, but low-specificity biomarker: decrease of cutoff points leads to lower percentage of false negatives, but more false positives
• Increasing specificity of threshold cutoff limit implies a sensitivity of approximately 100% for the cutoff value

Biomarkers should preferentially exhibit these main characteristics:

• Non-invasive and reproducible detection methods (serum, whole blood, urine, or accessible tissue samples)
• Low cost of performing, interpreting, and verifying methods
• Superior specificity (~100% negative control detection, actual negative control subjects) and sensitivity (~100% valid positive rate or TPR, detection in all cancer samples)
• Function as negative controls—detectable at low levels in healthy and benign-specific samples
• Organ and tissue-derived specific biomolecules
• Directly proportional to the tumor volume or cancer evolution

Characterization or classification of human solid tumor-derived malignancies are in a constant need of development for future therapies. These building blocks represent the basics in the field of personalized medicine or multi-omics approaches. The human genome is responsible for expressing almost 30,000 genes, and so it can offer molecular insights for scientists to design and manufacture drugs targeting specific molecules. Additionally, biomarkers are being used to achieve these outcomes by unveiling genetic oscillations.

The idea of isolated biomarker discovery was replaced recently by the idea of multi-biomarker discovery. This refers to a panel of genes or proteins and the checking of whether a heterogeneous and multifactorial cancer may have a single fingerprint or not.

Overcoming future challenges of biomarker research requires a broad understanding of the abnormal genetic mutations’ mechanisms at the cellular and molecular levels. Once achieved, researchers may be able to convert the biomarkers’ mechanism to a clinical diagnosis in the future.