Liquid Biopsy: A Useful Tool for Cancer

Highlights:

Early diagnosis of disease leads to better treatment and increased quality of life
Liquid biopsy is a laboratory test done on a sample of blood, urine, or other body fluids to look for cancer cells from a tumor or small pieces of DNA, RNA, or other molecules released by tumor cells into a person's body fluids
Liquid biopsies can help detect various cancers and Alzheimer's disease

Cancer is the leading cause of death globally. Early detection of cancer is almost always associated with better treatment outcomes. When cancer care is delayed or inaccessible, there is a lower chance of survival, greater problems associated with treatment, and higher costs of care ().

Liquid biopsies are becoming an increasingly imperative tool in the early detection, prognosis, and monitoring of treatment outcomes in cancer. This diagnostic tool holds the promise of transforming the management of other diseases in the future.

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‘Early diagnosis leads to better treatment outcomes, and liquid biopsies might be the key to that.’

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Liquid Biopsies and Their Use in Different Cancers

With advancing technology, liquid biopsies are able to deliver personalized medicine, especially for cancer diagnosis and management. Many of these tests for cancer have so far been approved by the US Food and Drug Administration (FDA) for use in patients – and they will without a doubt continue to become an increasingly important tool for tumor profiling.

Breast and Prostate Cancer

The CellSearch® system was the first liquid biopsy test to be approved for clinical use in predicting outcomes for advanced breast cancer patients in 2004 ().

It has also been approved for monitoring patients with advanced colorectal or prostate cancer. The test detects the presence of circulating tumor cells (CTC) in a blood sample –patients with higher numbers of these rare cells are predicted to have poorer outcomes compared to those with fewer CTCs in their bloodstream.

Companion diagnostics, which provide robust genotyping results, are an important part of personalized cancer treatment. The number of FDA-approved liquid biopsies based on the mutational profiling of circulating free DNA (cfDNA) from a blood sample is steadily increasing.

The therascreen® PIK3CA RGQ PCR Kit CDx test is a companion diagnostic for the PI3K inhibitor alpelisib, detecting specific mutations in the PIK3CA gene in breast cancer patients.

Lung Cancer

In the year 2013, the cobas® EGFR mutation Test v2 liquid biopsy test for non-small cell lung cancer (NSCLC) was the first test of this type to receive approval. It detects mutations in the epidermal growth factor receptor (EGFR) gene – and is used for identifying patients with advanced NSCLC who are eligible for treatment with an approved EGFR inhibitor ().

The Guardant360® CDx and FoundationOne® Liquid CDx are two other cfDNA-based liquid biopsy assays approved as companion diagnostics for several targeted therapies, as well as for more comprehensive tumor profiling (). Such pan-cancer liquid biopsies that use next-generation sequencing to examine several cancer-related genes offer the potential to revolutionize cancer treatment – enabling doctors to identify cancer patients who may benefit from being prescribed targeted therapies off-label or are eligible to participate in certain clinical trials.

Colorectal Cancer

One liquid biopsy test has received FDA approval for the early detection of cancer to date. Epi proColon® is a blood-based screening test that can help identify the presence of colorectal cancer by detecting the methylation of the SEPT9 gene in people aged 50 or older who are unwilling or unable to undergo a colonoscopy ().

Liquid Biopsies Effective To Detect Mutations In Advanced Lung Cancer
Liquid biopsies offer the advantage of testing without discomfort to the patient and possible risks associated with invasive biopsies.

Impact of Liquid Biopsies in Neurodegenerative Diseases

Creating liquid biopsy tests to diagnose and track the evolution of neurodegenerative disorders is still a massive challenge. Liquid biopsies offer the promise of improving the early detection of Alzheimer's disease (AD) through a minimally-invasive screening test – and have been studied in cerebrospinal fluid, blood, ocular, oral, and olfactory fluids (). Many of these studies have looked to detect abnormal brain proteins linked with the disease, but advances in next-generation sequencing-based methods have led to increasing interest in cell-free RNAs and DNAs as potential biomarkers. The feasibility of using blood extracellular vesicles (EVs), such as exosomes, as a way to diagnose AD and other neurodegenerative diseases has also been investigated.

Urine Liquid Biopsies Could Help Monitor Bladder Cancer Treatment: Study
The immune cells in the urine of bladder cancer patients accurately reflect those in the tumour environment, stated study.

Other Clinical Applications of Liquid Biopsy

In the near future, further advances in liquid biopsy technologies will ultimately lead to improvements in the management and outcomes of a myriad of different illnesses. This includes the diagnosis of infectious diseases, precision dosing for heart diseases, and the detection of biomarkers associated with certain psychiatric behaviors ().

References:

Promoting cancer early diagnosis - (https://www.who.int/activities/promoting-cancer-early-diagnosis)
Circulating tumor cells, disease progression, and survival in metastatic breast cancer - (https://pubmed.ncbi.nlm.nih.gov/15317891/)
Profile of the Roche cobas® EGFR mutation test v2 for non-small cell lung cancer - (https://pubmed.ncbi.nlm.nih.gov/28129709/)
FDA Approval Summary: Sotorasib for KRAS G12C-Mutated Metastatic NSCLC - (https://aacrjournals.org/clincancerres/article-abstract/28/8/1482/694149/FDA-Approval-Summary-Sotorasib-for-KRAS-G12C)
Epi proColon® for Colorectal Cancer Screening: A Profile of Its Use in the USA - (https://pubmed.ncbi.nlm.nih.gov/32557236/)
Nucleic acid liquid biopsies in Alzheimer's disease: current state, challenges, and opportunities - (https://www.cell.com/heliyon/fulltext/S2405-8440(22)00527-8)
Biomarkers for suicidal behavior: miRNAs and their potential for diagnostics through liquid biopsy - a systematic review - (https://pubmed.ncbi.nlm.nih.gov/33350851/)

Source-Medindia

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