The RAD18 E3 ligase requires SIVA1 as an accessory protein for binding to its substrate PCNA during translesion DNA synthesis.

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Background Pulmonary neuroendocrine tumors (pNETs) include typical carcinoid (TC), atypical carcinoid (AC), large cell neuroendocrine carcinoma (LCNEC), and small cell lung carcinoma (SCLC). The optimal treatment strategy for each subtype remains elusive, partly due to the lack of comprehensive understanding of their molecular features. We aimed to explore differential genomic signatures in pNET subtypes and identify potential prognostic and therapeutic biomarkers. Methods We investigated genomic profiles of 57 LCNECs, 49 SCLCs, 18 TCs, and 24 ACs by sequencing tumor tissues with a 520-gene panel and explored the associations between genomic features and prognosis. Results Both LCNEC and SCLC displayed higher mutation rates for TP53, PRKDC, SPTA1, NOTCH1, NOTCH2, and PTPRD than TC and AC. Small cell lung carcinoma harbored more frequent co-alterations in TP53-RB1, alterations in PIK3CA and SOX2, and mutations in HIF-1, VEGF and Notch pathways. Large cell neuroendocrine carcinoma (12.7 mutations/Mb) and SCLC (11.9 mutations/Mb) showed higher tumor mutational burdens than TC (2.4 mutations/Mb) and AC (7.1 mutations/Mb). 26.3% of LCNECs and 20.8% of ACs harbored alterations in classical non-small cell lung cancer driver genes. The presence of alterations in the homologous recombination pathway predicted longer progression-free survival in advanced LCNEC patients with systemic therapy (P = .005) and longer overall survival (OS) in SCLC patients with resection (P = .011). The presence of alterations in VEGF (P = .048) and estrogen (P = .018) signaling pathways both correlated with better OS in patients with resected SCLC. Conclusion We performed a comprehensive genomic investigation on 4 pNET subtypes in the Chinese population. Our data revealed distinctive genomic signatures in subtypes and provided new insights into the prognostic and therapeutic stratification of pNETs.

9043 Background: MET amplification is an important mechanism mediating acquired resistance to EGFR tyrosine kinase inhibitors (TKI). Until now, no consensus exists on the standard treatment strategy for this subset of patients due to the lack of clinical data from large cohort or controlled trials. In our clinical practice, three regimens were commonly administered to patients after MET amplification-mediated EGFR-TKI progression: EGFR-TKI and MET-TKI combination therapy, MET-TKI monotherapy, or chemotherapy. Our study aimed to compare the effectiveness of these three regimens. Methods: Seventy patients with EGFR-mutant advanced NSCLC who progressed from prior EGFR-TKI through the acquisition of MET amplification and received treatment between March 2015 and March 2020 were included in this study. Of them, 38 received EGFR-TKI plus crizotinib, 10 received crizotinib monotherapy, and 22 received platinum-based doublet chemotherapy. Somatic mutation profiling was performed on blood and tissue biopsy samples. Resistance mechanisms to the combination targeted therapy were also explored in 12 patients. Results: The objective response rate (ORR) and disease control rate (DCR) were 47.5% and 84.0% for EGFR-TKI+crizotinib group, 40.0% and 70.0% for crizotinib monotherapy group, and 18.2% and 50.0% for chemotherapy group, respectively. The EGFR-TKI+crizotinib group had significantly better ORR (P = 0.026) and DCR (P = 0.016) than the chemotherapy group but was not statistically different from the crizotinib monotherapy group (ORR, P = 0.73; DCR, P = 0.39). Progression-free survival (PFS) was significantly longer for the EGFR-TKI+crizotinib group than those who received crizotinib monotherapy (5.0 vs 2.3 months, P = 0.004) or chemotherapy (5.0 vs 2.9 months, P = 0.036), but overall survival was comparable (10.0 vs 4.1 vs 8.5 months, P = 0.088). TP53 mutation (58.5%) and EGFR amplifications (42.9%) were the two common concurrent mutations in the three cohorts. PFS was significantly longer for patients with either concurrent TP53 mutation (n = 17) (6.0 vs 2.3 vs 2.9 months, P = 0.009) or concurrent EGFR amplification (n = 13) (5.0 vs 1.2 vs 2.4 months, P = 0.016) who received EGFR-TKI+crizotinib. Potential molecular mechanisms of acquired resistance to EGFR-TKI+crizotinib therapy included EGFR T790M (n = 2), EGFR L718Q (n = 1), EGFR S645C (n = 1), MET D1228H (n = 1), BRAF V600E (n = 1), NRAS Q61H (n = 1), and amplifications in KRAS (n = 2), ERBB2 (n = 1), CDK4 (n = 1), and MYC (n = 2). Conclusions: Our study provides real-world clinical evidence, in the largest cohort to date, that simultaneous inhibition of EGFR and MET improves clinical outcomes of patients with EGFR-mutant NSCLC who acquired MET amplification from prior EGFR-TKI therapy, indicating that combinatorial regimen of EGFR-TKI and MET-TKI could be a more effective therapeutic strategy in this subset of patients.

Background: Comprehensive genomic profiling has become standard clinical practice in the management of advanced lung cancer. In addition to tissue and plasma, other body fluids are also being actively explored as alternative sources of tumor DNA. This study investigated the utility of induced sputum obtained from patients with non-small-cell lung cancer (NSCLC) for somatic variation profiling.Methods: Our study included 41 treatment-naïve patients diagnosed with locally advanced to advanced NSCLC between October 2018 and June 2019. Capture-based targeted sequencing was performed on matched tumor, plasma, and induced sputum samples of 41 patients using a 168-gene panel. We analyzed the somatic variations detected from each sample type and the concordance of variations detected between matched samples. The concordance rate was defined as the proportion of the total number of variations detected from one sample type relative to the reference sample type.Results: Comparative analysis on the somatic variation detection using matched tumor samples as a reference revealed detection rates of 76.9% for plasma, 72.4% for sputum-supernatant, and 65.7% for sputum-sediment samples. Plasma, sputum-supernatant, and sputum-sediment achieved positive predictive values of 73.3%, 80.4%, and 55.6% and sensitivities of 50.0%, 36.9%, 31.3%, respectively, relative to tumor samples for 168 genes. Sputum-supernatants had significantly higher concordance rates relative to matched tumor samples (69.2% vs. 37.8%; P=0.031) and maximum allelic fraction (P<0.001) than their matched sputum-sediments. Sputum-supernatants had comparable detection rates (71.4% vs. 67.9%; P=1.00) but with significantly higher maximum allelic fraction than their matched plasma samples (P=0.003). Furthermore, sputum-supernatant from smokers had a significantly higher maximum allelic fraction than sputumsupernatant from non-smokers (P=0.021).Conclusions: Our study demonstrated that supernatant fraction from induced sputum is a better sampling source than its sediment and performs comparably to plasma samples. Induced sputum from NSCLC patients could serve as an alternative media for next-generation sequencing (NGS)-based somatic variation profiling.