Complementing Tissue Testing With Plasma Mutation Profiling Improves Therapeutic Decision-Making for Patients With Lung Cancer.

BACKGROUND

Tissue biopsy is an integral part of the diagnostic approach to lung cancer. It is however invasive and limited by heterogeneity. Liquid biopsies may complement tissue testing by providing additional molecular information and may be particularly helpful in patients from whom obtaining sufficient tissue for genomic profiling is challenging.

METHODS

Patients with suspected lung cancer ( = 71) were prospectively recruited. Blood and diagnostic tissue samples were collected within 48 h of each other. Plasma cell-free DNA (cfDNA) testing was done using an ultrasensitive amplicon-based next-generation sequencing (NGS) panel (plasma NGS testing). For cases diagnosed as non-small cell lung carcinoma (NSCLC) histology or cytology, targeted testing for epidermal growth factor receptor () mutations was performed using tissue biopsy samples (tissue testing), where available. Concordance of clinically actionable mutations between methods and sample types was assessed.

RESULTS

For confirmed NSCLC cases ( = 54), tissue test results were available only for 70.3% (38/54) due to sample inadequacies, compared to blood samples for 98.1% (53/54) cases. Tissue testing identified sensitizing (L858R or exon 19 deletion) mutation in 31.6% (12/38) of cases. Plasma NGS identified clinically actionable mutations in 37.7% (20/53) of cases, including mutations in two cases with no tissue results, and mutations in , and . The overall sensitivity of sensitizing mutation detection by plasma NGS was 75% (9/12), and specificity was 100% (25/25) in patients tested in both tissue and plasma NGS ( = 37). In this cohort of patients, tissue testing alone informed clinical decisions in 22.2% (12/54) of cases. Adding plasma NGS to tissue testing increased the detection rate of actionable mutations to 42.6% (23/54), representing a 1.9-fold increase in clinically relevant findings. The average turnaround time of plasma NGS was shorter than standard tissue testing (10 vs. 29.9 days, < 0.05).

CONCLUSIONS

In the first-line setting, plasma NGS was highly concordant with tissue testing. Plasma NGS increases the detection of actionable findings with a shorter time to results. This study outlines the clinical utility of complementary plasma mutation profiling in the routine management of lung cancer patients.