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| LETTER TO EDITOR |
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| Year : 2020 | Volume
: 3
| Issue : 4 | Page : 863-864 |
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Expanding opportunities in precision oncology
T Raja
Department of Medical Oncology, Apollo Hospitals, Chennai, Tamil Nadu, India
| Date of Submission | 28-Oct-2020 |
| Date of Decision | 09-Dec-2020 |
| Date of Acceptance | 09-Dec-2020 |
| Date of Web Publication | 25-Dec-2020 |
Correspondence Address:
T Raja
Apollo Hospitals, Chennai, Tamil Nadu
India
 Source of Support: None, Conflict of Interest: None
DOI: 10.4103/crst.crst_340_20
How to cite this article:
Raja T. Expanding opportunities in precision oncology. Cancer Res Stat Treat 2020;3:863-4 |
Liquid biopsy is a minimally invasive procedure that can circumvent the challenges of surgical and core biopsies. It plays a supportive role in situations that require serial monitoring, especially when a tissue biopsy is not possible. The liquid biopsy also offers us the unique advantage of the ease of collection and analysis of different types of bodily fluids. Tumors such as non-small-cell lung cancer (NSCLC) are generally heterogeneous and comprise various subclones. Some subclones outgrow the others due to therapeutic stress caused, especially by the targeted drugs, which can cause changes in the tumor microenvironment leading to disease progression/metastasis. These changes can dynamically modify the genomic landscape of the tumor. One of the advantages of liquid biopsies is that it better represents the genomic heterogeneity of the tumors.[1],[2],[3],[4]
However, the liquid biopsy also has certain limitations. The detection of circulating tumor DNA (ctDNA) requires highly sensitive techniques as traditional techniques such as Sanger sequencing and pyrosequencing cannot be used because of the low fraction and high fragmentation rates of ctDNA. The lack of availability of these highly sensitive tests in the laboratories poses a practical challenge. Further, liquid biopsy requires highly specialized and specific sample processing and handling and does not provide information about the tumor histology or morphological changes like small cell lung cancer transformation, which is one of the acquired epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor resistance mechanisms.[1],[5],[6],[7]
The usefulness of ctDNA mutation analysis translating into a noninvasive approach for the detection of targetable mutations causing resistance to therapy is a welcome advance. In a study of patients with lung cancer by Rijavec et al., the analysis of cell-free DNA (cfDNA) showed the appearance of the T790M EGFR mutation following gefitinib treatment, supporting the hypothesis of treatment-related selective pressure. Following this, Thress et al. analyzed the cfDNA from 15 patients harboring the EGFR T790M mutation and identified the C797S EGFR mutation as a novel acquired resistance mechanism to AZD9291.[8],[9],[10]
In the last issue of the Journal, through their commendable study, Chougule et al.[11],[12] have shown that the concordance for mutation detection of the formalin-fixed and paraffin-embedded tissue samples with plasma was 64% and that with the other bodily fluids was 100%. More hearteningly, it was possible to detect the exon 20 T790M resistance mutation in the plasma and other bodily fluids at progression. This highlights the increasing number of various applications of liquid biopsy in the diagnosis and treatment decision-making of patients with NSCLC. Moreover, the minimally invasive nature and the low cost of liquid biopsy allow for repeated testing, making it a very useful tool in clinical practice.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
| References | |  |
| 1. | Chang S, Hur JY, Choi YL, Lee CH, Kim WS. Current status and future perspectives of liquid biopsy in non-small cell lung cancer. J Pathol Transl Med 2020;54:204-12.  |
| 2. | Siravegna G, Marsoni S, Siena S, Bardelli A. Integrating liquid biopsies into the management of cancer. Nat Rev Clin Oncol 2017;14:531-48. |
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| 8. | Rijavec E, Coco S, Genova C, Rossi G, Longo L, Grossi F, et al. Liquid biopsy in non-small cell lung cancer: Highlights and challenges. Cancers (Basel) 2019;12:17. |
| 9. | Thress KS, Paweletz CP, Felip E, Cho BC, Stetson D, Dougherty B, et al. Acquired EGFR C797S mutation mediates resistance to AZD9291 in non-small cell lung cancer harboring EGFR T790M. Nat Med 2015;21:560-2. |
| 10. | Chabon JJ, Simmons AD, Lovejoy AF, Esfahani MS, Newman AM, Haringsma HJ, et al. Circulating tumour DNA profiling reveals heterogeneity of EGFR inhibitor resistance mechanisms in lung cancer patients. Nat Commun 2016;7:11815. |
| 11. | Chougule A, Pange P, Kale S, Jagtap V, Nambiar K, Nikam A, et al. Concordance of epidermal growth factor receptor mutation detection in bodily fluids other than blood with tissue biopsy: A retrospective analysis. Cancer Res Stat Treat 2020;3:475-80. [Full text] |
| 12. | Addeo A, Friedlaender A. Circulating tumor DNA in non-small-cell lung cancer: A step beyond blood. Cancer Res Stat Treat 2020;3:577-9. [Full text] |
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