Abstract
Lung cancer is the leading cause of cancer-related deaths. Surgery remains the best option to treat lung cancer when feasible. However, many cases are diagnosed beyond the initial stages. There has been tremendous progress in the treatment of lung cancer over the last few years. Studies have shown that biomarker-driven targeted therapies lead to better outcomes. Due to the technical difficulties and significant procedural risk associated with repeated tissue biopsies, analysis of tumor constituents circulating in the blood, such as circulating tumor DNA (ctDNA) and various proteins, is becoming more widely recognized as an alternative method of tumor sampling, i.e., liquid biopsy. Liquid biopsy is superior to tissue biopsy, as it is minimally invasive and easily repeatable. Given the recent data on changes in mutations as the disease progresses or responds to treatment, liquid biopsies can help monitor the changes and guide us in giving targeted drugs. Here we present a case of advanced NSCLC who was initially started on Alectinib based on positivity for ALK gene rearrangement found in the FISH study. At the time of progression, molecular profiling liquid biopsy was obtained, which revealed KRAS-p.G12C mutation. Thus, the patient's therapy was later on changed to sotorasib after the FDA approved a KRAS-p.G12C mutation inhibitor.