Liquid biopsy determines efficacy of early cancer treatment

Enriqueta Felip, president of SEOM; and Luis Paz-Ares, president of Aseica.

The liquid biopsy is a test that can help find a early stage cancer. It is like performing an analysis, although in this case what is sought is tumor cells or products thereof such as circulating DNA fragments. The applications of this technique currently cover both the obtaining of information on the molecular alterations of the tumors as the minimally invasive follow-up of patients throughout their treatment.

To inform the population and patients of this diagnostic tool, the Spanish Association for Cancer Research (Aseica) and the Spanish Society of Medical Oncology (SEOM) have jointly produced an informative video that they present this Thursday on the occasion of the celebration of the World Innovation Day.

as comment Enriqueta Felipepresident of SEOM: “The liquid biopsy is an important element in current research in oncologyand numerous studies have shown its role in determining the efficacy of treatments early and in identifying mutations involved in resistance to target drugs”.

For its part, Luis Paz-Arespresident of Aseica, explains that: “Among the advantages of this technique we find that it is a minimally invasive procedure, without the complications that conventional biopsies usually entail. In addition, it allows to follow the evolution of the treatment of the patients in real time, as well as to plan a more personalized treatment both before and during treatment.

The alternative in the diagnosis of liquid biopsy

In recent years, Oncology has experienced a real revolution at the hands of Precision Medicinethanks to an ever deeper knowledge of the Molecular biology. This knowledge, together with the iidentification of biomarkershas made it possible to subdivide and classify tumors, better understand their evolution and develop more specific treatments against certain types of cancer. Although these biomarkers are commonly identified using conventional biopsies of the patient samples, liquid biopsy represents an alternative that complements and, in many cases, improves the diagnosis of patients.

It is also important to follow the evolution of the disease in patients, something that conventional biopsies and other less decisive techniques can hardly do efficiently. The identification of biomarkers in blood This is possible because tumors continuously release cells, DNA fragments, and other molecules into the bloodstream, all of which can be detected by liquid biopsy.

The capacity of detect tumor DNA The circulating blood depends on multiple clinical factors, including the type of tumor and the stage: the more voluminous the tumors or the greater the number of metastases, the greater the probability of detecting cells or molecules derived from the tumor in the bloodstream. However, if small tumors are present or the metastatic locations are exclusively at the level of the central nervous system, the possibility of detecting them decreases. circulating tumor DNAleading to false negative results of the liquid biopsy. In the latter case, liquid biopsies can be performed in the cerebrospinal fluid instead of in the bloodstream, as Spanish researchers belonging to Aseica have successfully shown.

There are different techniques of liquid biopsy according to its objectives and complexity. Thus, some versions focus on the detection of alterations in very specific targets that allow determining what therapies can be used. However, other techniques are based on the massive sequencing of the material obtained, which allows, for example, to have a very precise image of the molecular heterogeneity of the patient’s tumor. All of them have a significant impact on patient care protocols today.

Difference between tissue biopsy and liquid biopsy

The tissue biopsy It gives information about the genomic alterations that exist in a specific point of the tumor. For his part, affirms Paz-Ares, “the liquid biopsy allows obtaining more extensive information, since it includes the possible alterations that exist in different tumor locations, giving more information on the possible heterogeneity of the genomic profile between the primary tumor and its metastatic sites.

Philip points out that “capture this heterogeneity It is essential, since this information can have an impact on the type of treatment chosen. Furthermore, being a minimally invasive technique it allows it to be repeated during the course of the disease, thus providing real-time dynamic information on the genomic profile of the tumor at all times and seeing how it evolves at the genomic level depending on the treatments administered to the patient”.

Today there are a number of practical recommendations for the use of liquid biopsy, although not all of them are approved for routine clinical practice. One of the most prominent and accepted applications of liquid biopsy is determination of biomarkers to predict advanced cancer and deliver targeted therapies. Paz-Ares and Felip coincide in emphasizing the predictive role of liquid biopsythat is, the efficacy of targeted treatments is the same regardless of whether the identification of the known therapeutic target has been carried out in liquid biopsy or tissue biopsy.

This allows that, when these predictive biomarkers are detected in liquid biopsies, the targeted treatment without the need for confirmation in a tissue biopsy. In patients treated with targeted therapies at the time of disease progression, massive sequencing in liquid biopsy it is a useful diagnostic tool for determining resistance mechanisms and evaluating sequential targeted therapies.

Prognostic role of tumor DNA determination

Recently, it has been assessed forecast paper of the determination of circulating tumor DNA in different tumor types, especially in advanced or metastatic disease. Cancer patients who are detected circulating tumor DNA before starting treatment they have a worse prognosis than those patients without detection of circulating tumor DNA.

This observation is probably related to the fact that patients with positive circulating tumor DNA have a increased tumor burden and/or increased aggressiveness. And it has made it possible to assess the behavior of this basal circulating tumor DNA over time once treatment has begun, either with chemotherapy, immunotherapy either targeted therapy.

In different types of cancers, regardless of treatment, it has been observed that a reduction in circulating tumor DNA at two months of having started the administration of the medication is related to a greater benefit for the patients. This dynamic information will allow, in the future, to select patients who are not benefiting from a certain treatment and to assess whether they may be candidates for more intensive treatments: that is, to select patients for an escalation in therapeutic strategy.

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