3PD Liquid biopsy in patients with adenocarcinoma of the lung and its correlation with their tumor tissue molecular profile

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Background: Adequate quantity of tumor tissue for molecular analysis is a major handicap to deliver personalized medicine. Reasons such as difficulty to perform tumor biopsy (TBX) either because of tumor location, patient’s co-morbid conditions or the fact we need to repeat the TBX are among the common factors for lack of molecular profiling results (MPR). Hence, liquid biopsy (LBX) has emerged as a potential alternative to detect these genomic alterations. Methods: We analyzed 59 patients with stage IV or recurrent adenocarcinoma of the lung (ADENO) using Guardant 360 test; sample collections were done at Lynn Cancer Institute and Memorial Cancer Institute. Alterations detected by this test include single nucleotide variations, amplifications, ALK, FGFR2, FGFR3, RET, ROS1, NTRK1 genes, and short insertions/duplications/deletions in exons 19 and 20 of the EGFR and ERBB2 genes as well as exon 14 skipping of the MET gene. We compared these results with their tumor tissue MPR in each individual, to assess their correlation. Results: 41/59 pts were females; median age 75 (range, 27–99). 44 pts (75%) had at least 1 genomic alteration by LBX (range, 1–10). Most common abnormalities found in LBX: EGFR (20 pts), TP53 (19 pts), and NF1 (11 pts). From this 44 pts with + LBX results, 29 pts (66%) had tumor tissue MPRs for comparison. Major reason for lack of tumor tissue MPRs: insufficient tumor (11/17; 65%). For comparison between the 2 modalities, we considered all pts with available results in both tests (n = 42 pts); 20 pts (48%) had at least 1 genomic abnormality or no abnormality identify in both type of “biopsies”. Most of the concordance was in EGFR mutations; LBX caught 12/17 (71%) EGFR mutations in TBX. Nonetheless, LBX caught 11 EGFR alterations not present or available by TBX MPR. Conclusions: Insufficient amount of tumor is the reason for lacking tumor MPRs. LBX offers an alternative/complementary way to identify genomic alterations in a much easy way. Our cohort had 48% concordance between LBX and TBX; however, for EGFR mutation, correlation was higher (71%). Discrepancies between both modalities could be explained by timing when samples were taken and tumor heterogeneity. Updated data with 90 pts will be presented at the meeting. Legal entity responsible for the study: Lynn Cancer Institute Research Department Funding: Lynn Cancer Institute Research Department Disclosure: L. Raez, B. Hunis: Research support: Liquid Genomics; Exosomes. All other authors have declared no conflicts of interest. 4P Co-amplifications of PD-L1/PD-L2 genes (9p24.1) and PD-L1 protein expression in NSCLC patients