Surely you have been told more than once to undergo a blood test in order to see how your biomarkers are. If you are a male over 45 years of age, surely in your annual analyses you can see the result of the PSA biomarker of prostate cancer, but have you ever considered what a biomarker is? or why they are measured?
A biomarker is a molecule, usually proteins, but not exclusively, that changes its concentration or its original state when a pathology is developed. By having the «normal» values described, the changes in the concentration or morphology of these molecules act as warning signs of the possible development of a certain pathology. In more professional terms, the U.S. Food and Drug Administration (FDA) defines a valid biomarker as «a defined characteristic that is measured as an indicator of normal biological processes, pathogenic processes, or responses to an exposure or intervention, including therapeutic interventions»1. According to this definition it is possible to find three types of genetic markers useful in clinical2.
- Diagnosis biomarkers. They are those markers that let you carry out an early detection of a disease. The ideal diagnostic marker would be one whose detection is non-invasive, cheap and effective to identify early diseases still asymptomatic or with few symptoms. In cancer they would also be useful to discern the type of tumor in question.
- Prognostic markers. They are those that predict the natural history of the disease and can be used to address patients’ expectations. Their presence/absence is associated with a better or worse prognosis and, therefore, can be a tool that helps the patient to know the severity of his/her disease.
- Predictive markers. They are the most informative at the clinical level since this type of markers directly influence the patient’s response to a certain treatment. Predictive markers let you focus each treatment in a personalized way.
Although numerous biomarkers have been described for several diseases, the discovery of tumor biomarkers has, undoubtedly, improved diagnostic and treatment strategies.
There are many tumors that do not manifest symptoms until they are in an advanced stage. In these cases, discovering molecules that with a simple blood test can give the alarm signal is priceless or incalculable.
In cancer, however, markers serve another important function: they help classify tumors into subtypes and can determine their treatment. What several years ago was breast cancer, later turned into hormonal or non-hormonal breast cancer thanks to the discovery of the presence of hormone receptors in tumor biopsies. This discovery allowed breast cancer patients to be divided into two subgroups with different treatment and prognosis. Every year millions of dollars are invested in analyzing tumor biopsies with increasingly sophisticated methods in order to find new biomarkers that contribute to a more accurate stratification and the discovery of new treatments. In fact, today, within hormonal or non-hormonal breast cancer we can find several subtypes with different treatments.
How are biomarkers measured?
When you have a biopsy to determine if a lesion is malignant, the extracted tissue is sent to the pathology laboratory where pathologists examine it thoroughly under a microscope and measure the presence or absence of tumor markers by immunohistochemistry methods. That is, they use methods that let you detect the number of biomarkers in a given area of the biopsy.
Based on various studies, the World Health Organization and other medical organizations determine a threshold value from which a biomarker is considered positive or negative and, based on that, a treatment pattern is established. Depending on the marker and always based on the results of scientific studies, this threshold value can be higher or lower.
In recent years it has become clear that this strategy is sometimes not entirely accurate. This is the case of immunotherapy. The threshold value from which immunotherapy treatment is scheduled is low so that many patients can benefit from this treatment. However, it has been observed that not all patients respond equally to treatments. In addition, people with low values (even below the threshold value) can show a good response to immunotherapy. This fact highlights the need to continue advancing in the study of biomarkers.
QF-Pro diagnostic strategy from Fastbase Solutions can determine how many of these biomarkers are active or inactive. The results obtained to date indicate that this approach is much more accurate in determining treatment response. In other words, it has been observed that there are patients with very low values of a certain marker that is very active. In these patients, treatments directed against this biomarker work well. In contrast, there are other patients with a high presence of an inactive biomarker. In this case the treatment is not as effective. The QF-Pro tool measures the activity of biomarkers and can be a key element in determining tumor treatment and diagnosis3.
1. US Food & Drug Administration website
2. Winter JM, Yeo CJ, Brody JR (2013). Diagnostic, prognostic, and predictive biomarkers in pancreatic cancer. J Surg Oncol. 107(1):15-22.
3. Sánchez-Magraner L et al. High PD-1/PD-L1 Checkpoint Interaction Infers Tumor Selection and Therapeutic Sensitivity to Anti-PD-1/PD-L1 Treatment. Cancer Res. 2020 Oct 1;80(19):4244-4257.