With rising cases of lung cancer worldwide, liquid biopsies are becoming increasingly popular as clinically relevant potential non-invasive alternatives to tissue-based biopsies. The principle of partitioning utilized by the droplet digital polymerase chain reaction (ddPCR) makes it a highly sensitive technique for detecting rare tumor-derived mutations in blood. The presence of KRAS mutations is a negative prognostic marker for tyrosine kinase inhibitor (TKI) therapy in lung cancer; hence, profiling of major KRAS mutations before treatment is very crucial for the success of TKI therapy. This study was aimed at profiling three major KRAS mutations, namely G12D (GGT→GAT), G12V (GGT→GTT), and G13D (GGC→GAC) in lung cancer patients using ddPCR. ddPCR assays that rely on probe-based chemistry were standardized for KRAS G12D, KRAS G12V, and KRAS G13D mutations using cfDNA extracted from the patient’s blood. To determine the concordance, blood-derived cfDNA and tumor DNA were compared using ddPCR. A positivity rate of 81.67% for KRAS mutations was observed in the cohort analyzed. KRAS mutations in the cfDNA from blood were effectively detected by ddPCR even at low fractional abundance. Moreover, a comparison of blood-derived cfDNA and tumor-derived genomic DNA-based analysis revealed a concordance of 66.67%, suggesting tumor heterogeneity as the probable reason for the lack of total concordance between the data. This study highlights the usefulness of ddPCR as a prospective clinical tool in oncology and liquid biopsy using blood cfDNA. It can be considered a better alternative to tissue biopsies and mutation profiling of candidate genes, particularly those that are linked to therapeutic response to TKIs.
Kishore et al. (Wed,) studied this question.