A retrospective analysis examining the use of tissue-based and blood-based NGS in patients (pts) with advanced non-small cell lung cancer (NSCLC).

Abstract

e21195 Background: Next generation sequencing (NGS) of tumor has become an integral part of cancer diagnostics and therapeutics today. While tissue-based (TB) NGS is still considered gold-standard, cell-free DNA NGS obtained from peripheral blood (blood-based or BB) offers many advantages because of its quicker turnaround time, minimally-invasive nature and ability to address tumor heterogeneity and track development of resistance mutations over time. It however does have its disadvantages, predominant of which is its lower sensitivity. Integration of BB and TB NGS can both optimize turnaround time and increase detection of targetable mutations. Methods: We conducted a single institution, IRB approved, retrospective study evaluating NGS testing patterns in patients with advanced NSCLC treated at our institution between 1/1/16 and 3/31/20. Our primary endpoint was to evaluate the number of patients who had BB NGS performed at any point during their clinical course in addition to TB NGS testing. Our secondary endpoint was to evaluate the number of patients for who BB NGS led to change in treatment plan. Exploratory points included the concordance rate between BB and TB NGS performed within 1 month of each other and the details of discordance if any. Results: There was a total of 437 eligible advanced NSCLC patients who were treated at our institution between January 2016 and March 2020. Out of these, 104 (23.8%) had BB NGS performed at some point in their disease course. The median number of BB NGS testing done for these patients was 2 and ranged from 1 to 4. 32/104 (30.8%) of patients had change in management because of BB NGS results. TB and BB NGS were performed within one month of each other in 52 patients. 11 of these (21.2%) had detection of identical actionable mutations (AM) on both BB and TB NGS assays. 5 of the patients (9.6%) had AM detected on TB NGS alone and 6 of the patients (11.5%) had AM detected on BB NGS alone. 30/52 patients (57.7%) had no AM identified on both BB and TB NGS. Conclusions: BB NGS has added tremendous value to diagnosis and treatment of NSCLC. It is increasingly used in practice, in tandem with TB NGS. Nearly a fourth of our patients had BB NGS performed at some point in their clinical course. Nearly 20% of simultaneously performed BB and TB NGS were discordant and an AM was identified in only one of the biopsies. Although further research is needed, our study supports simultaneous BB and TB testing at diagnosis and progression thereby maximizing therapeutic potential.