Diagnosis and treatment of patients with advanced non–small-cell lung cancer (NSCLC) requires obtaining biopsy samples to perform molecular profiling. Biopsy samples are often of insufficient quantities and involve invasive procedures to obtain. Liquid biopsy, during which cancer cells or fragments of DNA from tumors are obtained, can circumvent these issues along with reducing the time to tumor detection and improving resource efficiency. They can also be used to screen for more diseases than traditional biopsy.1 Detecting circulating tumor DNA (ctDNA) in plasma can also decrease some of the risks involved in obtaining traditional biopsy samples, including bleeding and the risk of tumor spread.1 Currently, the gold standard of cancer diagnosis is standard tissue biopsy with liquid biopsy performed as a research activity or to complement tissue biopsy.1
To determine if liquid biopsy can be used for molecular genotyping in the prediagnostic workup for lung cancer, Garcia and colleagues enrolled 20 patients who had a ≤15 pack-per-year smoking history and radiologic evidence of stage IV lung cancer in a rapid cancer diagnostic program. The study compared the results to turnaround time, actionable target identification, and time to treatment initiation between plasma and tissue testing. The study participants underwent plasma ctDNA testing using a DNA-based mutation panel. Along with the ctDNA testing, tissue profiling was performed, including a comprehensive next-generation sequencing panel.
Among the study participants, 12 had a lung adenocarcinoma diagnosis and 3 had a non–lung cancer diagnosis. Mutations were found in plasma or tissue samples in 7 patients: 4 of the 7 were concordant, 2 were found in the tissue sample, and 1 patient had a mutation found in the plasma only. EGFR mutations were found in 6 of the 7 and ERBB2 mutation was found in 1 sample. In 3 patients, fusions were found via immunohistochemistry. ALK fusion was found in 2 of the 3 patients and RET fusion was found in 1 patient. When median time to sampling was evaluated, plasma sampling was performed in 2 days and tissue biopsy was performed in a median of 9 days. Median turnaround time was 17 days for plasma samples and 22 days for tissue samples. Median referral to treatment initiation if plasma sampling identified an actionable alteration was 31 days with a range of 16 to 41 days. If no actionable alteration was identified in the plasma, the median referral to treatment initiation was 35 days, with a range of 20 to 58 days. An expansion study of 150 participants is ongoing.
Garcia M, Czarnecka K, Law J, et al. Accelerating lung cancer diagnosis and molecular profiling through liquid biopsy. Presented at: IASLC Targeted Therapies of Lung Cancer Meeting. February 22-26, 2022; Santa Monica, CA.
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