Genetic profiling of cell-free DNA from pleural effusion in advanced lung cancer as a surrogate for tumor tissue and revealed additional clinical actionable targets

Abstract Background : Pleural effusion(PE) has been one of the promising sources of liquid biopsy in advanced lung cancer patients. However, its clinical utility is not widely accepted due to the lack of full estimation of its potential versus routine clinical samples. Method : A total of 164 advanced lung cancer patients were enrolled with 164 matched tumor tissue and PE-cfDNA, 153 accompanied plasma and 63 PE-sDNA. Result : PE-cfDNA displayed significantly higher median mutant allele frequency and an overall mutation concordance rate of 65% to tissue, which was higher than PE-sDNA (43%) and plasma-cfDNA (43%). The discrepancies between PE-cfDNA and tumor tissue were high in several genes, including SMARCA4, PIK3CA, ERBB2, KM T2A, ALK and NF1. For clinically actionable mutations, the concordance rate between PE-cfDNA and tumor tissue is 87%. Eleven patients were identified with actionable mutations in PE-cfDNA and four patients benefited from PE-cfDNA-guided targeted. Meanwhile, PE-cfDNA recapitulated mutations of diverse tissue origins and provided more mutational information under the circumstance that tumor tissue or tumor tissue of different origins were unavailable. The combination of tumor tissue and PE-cfDNA profiling increased positive detection rates of patients compared to tumor tissue alone. Our finding highlighted the importance of PE-cfDNA in the optimal selection of patients for targeted therapy. Conclusion : The PE-cfDNA-based liquid biopsy displays better performance in the characterization of gene alterations than PE-sDNA and plasma-cfDNA. PE-cfDNA together with tumor tissue profiling optimizes comprehensively genomic profiling of lung cancer patients, which might be important for selecting patients for better treatment management.