Pros: Can tissue biopsy be replaced by liquid biopsy?

ALK Status Assessment with Liquid Biopsies of Lung Cancer Patients

Patients with advanced stage non-small cell lung carcinoma (NSCLC) harboring an anaplastic lymphoma kinase ALK gene rearrangement, detected from a tissue sample, can benefit from targeted ALK inhibitor treatment. However, while treatment is initially effective in most cases, relapse or progression occurs due to different resistance mechanisms including mutations in the tyrosine kinase domain of echinoderm microtubule-associated protein-like 4 (EML44)-ALK. The liquid biopsy concept has recently radically changed the clinical care of NSCLC patients, in particular for those harboring an epidermal growth factor receptor (EGFR) gene mutation. Therefore, liquid biopsy is an alternative or complementary method to tissue biopsy for the detection of some resistance mutations in EGFR arising during tyrosine kinase inhibitor treatment. Moreover, in some frail patients, or if the tumor lesion is not accessible to a tissue biopsy, a liquid biopsy can also detect some activating mutations in EGFR on initial assessment. Recent studies have evaluated the possibility of also using a liquid biopsy approach to detect an ALK rearrangement and/or the emergence during inhibitor treatment of some resistance mutations in ALK. These assessments can be performed by studying circulating tumor cells by fluorescent in situ hybridization and by immunocytochemistry and/or after the isolation of RNA from plasma samples, free or associated with platelets. Thus, the liquid biopsy may be a complementary or sometimes alternative method for the assessment of the ALK status in certain NSCLC patients, as well as a non-invasive approach for early detection of ALK mutations. In this review, we highlight the current data concerning the role of the liquid biopsy for the ALK status assessment for NSCLC patients, and we compare the different approaches for this evaluation from blood samples.

Liquid biopsy for early detection of lung cancer

PURPOSE OF REVIEW

The possibility of complete recovery for a lung cancer patient depends on very early diagnosis, as it allows total surgical resection. Screening for this cancer in a high-risk population can be performed using a radiological approach, but this holds a certain number of limitations. Liquid biopsy could become an alternative and complementary screening approach to chest imaging for early diagnosis of lung cancer.

RECENT FINDINGS

Several circulating biomarkers indicative of lung cancer can be investigated in blood, such as circulating tumor cells, circulating free nucleic acids (RNA and DNA) and proteins. However, none of these biomarkers have yet been adopted in routine clinical practice and studies are ongoing to confirm or not the usefulness and practical interest in routine early diagnosis and screening for lung cancers.

SUMMARY

Several potential circulating biomarkers for the early detection of lung cancer exist. When coupled to thoracic imaging, these biomarkers must give diagnosis of a totally resectable lung cancer and potentially provide new recommendations for surveillance by imagery of high-risk populations without a detectable nodule. Optimization of the specificity and sensitivity of the detection methods as well as standardization of the techniques is essential before considering for daily practice a liquid biopsy as an early diagnostic tool, or possibly as a predictive test, of lung cancer.

EGFR T790M ctDNA testing platforms and their role as companion diagnostics: Correlation with clinical outcomes to EGFR-TKIs

Somatic mutation in the epidermal growth factor receptor (EGFR) predict clinical response to EGFR tyrosine kinase inhibitors in non-small cell lung cancer (NSCLC) and is a promising target for personalised medicine. EGFR mutations have prognostic value. Initially patients respond well to tyrosine kinase inhibitors but finally they would develop resistance and about 50% of this resistance can be attributed to the emergence of EGFR resistant mutation, T790M. This necessitates the need for genetic testing for clinical management of patients. Molecular testing has become the standard of care in patients with NSCLCs based on the recommendations of standard guidelines. Though there are several platforms for EGFR mutation detection, highly sensitive platforms for clinical applicability as companion diagnostics for ctDNA based testing are emerging. Due to the dynamic changes in the T790M mutation during tyrosine kinase inhibitor (TKI) treatment, real-time monitoring of these genetic alterations is mandate for planning treatment strategies. With the advent of third generation TKIs that potentially target T790M, improvement in clinical outcome is documented in patients with NSCLCs. Managing these outcomes with appropriate companion diagnostics using ctDNA in early detection of these genetic alterations will improve patient care.

Liquid biopsies come of age: towards implementation of circulating tumour DNA

Improvements in genomic and molecular methods are expanding the range of potential applications for circulating tumour DNA (ctDNA), both in a research setting and as a 'liquid biopsy' for cancer management. Proof-of-principle studies have demonstrated the translational potential of ctDNA for prognostication, molecular profiling and monitoring. The field is now in an exciting transitional period in which ctDNA analysis is beginning to be applied clinically, although there is still much to learn about the biology of cell-free DNA. This is an opportune time to appraise potential approaches to ctDNA analysis, and to consider their applications in personalized oncology and in cancer research.