Liquid biopsy for lung cancer: A cross section on the diagnostic routine experience of a referral Italian institution

Background: Lung cancer is the leading cause of cancer death worldwide. Over the last decade, molecular testing of a growing number of predictive biomarkers has become mandatory in the management of NSCLC patients. However, a major obstacle in routine clinical practice is the scant quantity of available tissue specimens obtainable from advanced stage of NSCLC patients. Thus, liquid biopsy, mostly involving blood sampling, has now been integrated in routine diagnostic practice. However, although liquid biopsies constitute a versatile, compliant, and dynamic source of nucleic acids, many of the current testing approaches pose few technical challenges. Here, to validate the feasibility of implementing NGS-based liquid biopsy approaches in routine diagnostic practice, we overviewed the NGS molecular data generated by our in-house narrow gene panel on plasma samples from real-world NSCLC patients. Methods: Our Institution received testing request on liquid biopsy samples from peripheral institutions not equipped to internally analyze liquid biopsy samples. Molecular data from NSCLC patients following oncological requested for clinically approved plasma-based biomarkers evaluated in a diagnostic routine setting from January 2020 to September 2022 were retrieved from our institutional archive. A customized NGS panel integrated with an optimized bioinformatic pipeline was adopted. Results: Overall, a total of n = 185 cases were retrieved. Of note, 103 (55.7 %) and 82 (44.3 %) patients were analyzed at basal setting and after resistance to first line TKI administration, respectively. Moreover, 31 out of 185 (16.7 %) cases reveled EGFR clinically relevant alterations. In particular, 6 out of 31 (19.3 %) and 25 out 31 (80.7 %) EGFR mutated patients were tested in basal setting and after first or second line TKIs progression. In addition, exon 20 p.T790 M mutation was also detected in 12 out of 25 (48.0 %) EGFR concomitant mutated cases. Moreover, KRAS hot spot mutations were found in 24 out of 185 (13.0 %) cases. Among them, exon 2 p.G12C clinically relevant mutations were observed in 8 out 24 cases (33.3 %). Conclusions: This review highlights the technical suitability of an NGS-based liquid biopsy system for the analysis of clinically relevant mutations in NSCLC patients.