MET Copy Research Articles

Abstract 1103: MET gene amplification is a mechanism of resistance to entrectinib in ROS1+ NSCLC

Abstract ROS1 TKIs entrectinib and crizotinib have significantly improved outcomes for ROS1+ lung adenocarcinoma patients. However, drug resistance inevitably develops, leading to disease progression. Approximately 1/3 of patients resistant to ROS1 TKIs demonstrate ROS1 kinase domain (KD) mutations (Dziadziuszko et al. ESMO 2019), but the mechanism of resistance in most patients is unknown or poorly characterized. To model and characterize acquired resistance to ROS1 TKIs, we used patient-derived cell line CUTO28 (TPM3-ROS1) to generate an entrectinib-resistant derivative (CUTO28-ER) in vitro. We utilized several techniques to probe the mechanisms driving resistance: DNA and RNA sequencing (seq), fluorescence in-situ hybridization (FISH), cell proliferation assays, and western blotting. DNA seq of the ROS1 KD in CUTO28-ER failed to reveal mutations. CUTO28-ER cells displayed sensitivity to MET-selective TKIs in proliferation assays, and MAPK and AKT pathways were inhibited only with MET-selective TKI. RNA seq and western blot showed MET overexpression, and interphase FISH confirmed MET amplification compared to parental cells (MET:CEP7 ratio 4.2 vs 1.0). We substantiated in vitro findings in patient tissue, utilizing tumor samples at 2 different points of a single CD74-ROS1 NSCLC patient’s tumor progression. The first tumor sample did not display MET amplification while on ROS1 TKI (MET:CEP7 ratio 0.9, 3.4 copies of MET). However, the second tumor sample collected 5 months later displayed a MET:CEP7 ratio of 2.5 (9.5 copies of MET), indicating progression on ROS1 TKI was likely MET-driven. To determine prevalence of MET amplification in entrectinib-resistant ROS1+ NSCLC, we analyzed circulating tumor DNA (ctDNA) by FoundationOne Liquid CDx from patients with ROS1+ NSCLC in the STARTRK-2 entrectinib trial. Of 105 ROS1+ NSCLC patients with ctDNA analysis both at enrollment and progression, 2 (1.9%) displayed copy number amplification (CNA) of MET. Of these, 1 patient had no detectible CNA at study baseline but MET CNA gain by day 166 of entrectinib therapy and the other had detectable MET CNA gains both at baseline and at progression only 28 days later. Both received 3 lines of therapy prior to entrectinib, none of which targeted ROS1 or MET. In conclusion, we demonstrated MET gene amplification as a potential mechanism of resistance to ROS1 TKI entrectinib. The prevalence of MET amplification at resistance was 2 of 105, but may be greater than was detected in STARTRK-2 due to the sensitivity of ctDNA assays and challenges of measuring CNA in ctDNA. Utilization of the ROS1/MET TKI crizotinib or combination of entrectinib with capmatinib should be explored in patients with ROS1+ NSCLC that display MET CNA to overcome MET-driven resistance following entrectinib. Citation Format: Logan C. Tyler, Anh T. Le, Hala Nijmeh, Liming Bao, Timothy R. Wilson, Brian Simmons, David Chen, Robert C. Doebele. MET gene amplification is a mechanism of resistance to entrectinib in ROS1+ NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1103.

Abstract 5103: Characterization of the genomic landscape and actionable mutations in Taiwanese prostate cancer patients

Abstract Background: Prostate Cancer (PCa) is the second most common male cancer worldwide and the most common cancer in males over 65 years old. PCa is the sixth most common cancer in Taiwan, and its incidence rate has increased gradually over the past 30 years. PAPR inhibitors are the only type of targeted drug approved by the FDA to treat advanced castration-resistant prostate cancer (CRPC) that has grown after the hormone therapy drugs. This study aimed to characterize the genomic profile of Taiwanese PCa and explore whether there are potential treatment guidances derived. Methods: Formalin-fixed paraffin-embedded (FFPE) tumor tissues from 99 patients diagnosed with PCa and collected at Chi-Mei Medical Center (CMMC) were subject to next-generation sequencing using ACTOnco® CGP panel that cover coding regions of 440 cancer-related genes. Genomic alterations (GAs) and signatures, including single nucleotide variations (SNVs), short insertions and deletions (InDels), copy-number variations (CNVs), fusion genes, tumor mutations burden (TMB), and microsatellite instability (MSI) status were retrieved. The gene mutation prevalence was compared with the Western population using the TCGA prostate cancer dataset. Results: A total of 1558 variants was identified, including 215 SNVs, 22 InDels, 1178 CN gain and 135 homozygous deletions. Similar to the Western population, the most frequently mutated genes were SPOP (21.2%), KMT2C (10.1%), MUC16 (8.1%), TP53 (6.1%), ARID2 (5.1%), IDH1 (5.1%), PTGS2 (5.1%). Further analysis showed that 12 patients harbored deleterious/likely deleterious mutations in genes implicated in homologous recombination (HRR) DNA repair pathway, including three BRCA2, two CDK12, BRAD1 and ARID1A, respectively, and one ATR, ATM and PALB2, respectively. All BRCA2 mutations were predicted to be germline origin and only one-third of 12 HRR mutants had a biallelic gene loss. Median TMB calculated from NGS data is 0.6 muts/Mb (range 0 to 4.5) and all samples are microsatellite-stable (MSS). Therapeutically actionable gene and pathway analysis revealed that up to 24.2% of patients harbored at least one aberration against FDA-approved targeted drugs, such as MET copy number (CN) gain (11.1%), mTOR pathway aberration (6.1%), HRR gene biallelic loss (4%), BRAF activating mutation (4%), IDH1 activating mutations (4%), EGFR CN gain (3.0%), FGFR1 CN gain (2.0%), MET fusion (1.0%) and BRAF fusion (1%). Conclusion: This CGP study unraveled the genomic profile of Taiwanese prostate cancers, and the results showed that GAs identified could serve as a potential biomarker to guide personalized, targeted therapies in one-fourth of patients. Citation Format: Kien Thiam Tan, Chia-Ling Wu, Yen-Jung Lu, Ka-Po Tse, Chien-Feng L Li. Characterization of the genomic landscape and actionable mutations in Taiwanese prostate cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5103.

Abstract LB515A: A MET targeting biparatopic antibody-drug conjugates (ADC), REGN5093-M114, has an antitumor efficacy in NSCLC harboring MET gene alterations

Abstract Introduction: Aberrations in MET occurs frequently in non-small cell lung cancer (NSCLC), via MET amplification or MET exon 14 skipping (METex14) mutation. Small-molecule tyrosine kinase inhibitors (TKIs) targeting MET have been developed, but durable response is invariably limited by the emergence of acquired resistance. In this study, we examined the preclinical activity of a MET x MET biparatopic antibody to a novel maytansinoid payload, REGN5093-M114, in MET-driven patient-derived models. Experimental Design: We had previously established patient-derived models from EGFR-TKIs resistant patients with MET-amplified or -overexpressed EGFR-mutant NSCLC. Patient-derived organoids (PDOs), patient-derived cells (PDCs), or ATCC cell lines were used for cell viability, apoptosis assay and western blots to investigate the activity of REGN5093-M114. In order to explore the predictive biomarker correlates of REGN5093-M114 and MET status, we investigated whole MET expression, surface MET expression by flow cytometry, MET amplification by copy number analysis. We evaluated the antitumor activity of REGN5093-M114 in patient-derived tumor xenograft (PDX) models from EGFR-mutant NSCLC patients with acquired resistance to osimertinib plus savolitinib, including acquired MET p.Y1230C mutation. Finally, we determined whether REGN5093-M114 is able to overcome acquired resistance to the MET-TKI, tepotinib, using PDC from METex14 mutant NSCLC patients. Result: In acquired MET-amplified EGFR-TKI resistant PDCs, PDOs, ATCC cell lines and PDX models, REGN5093-M114 alone exhibited a significant antitumor efficacy compared to MET-TKI or the MET x MET biparatopic antibody (REGN5093), but had no effect on some models with same MET copy number as the sensitive models. On the other hand, regardless of MET CNV, MET-overexpressed TKI-naïve EGFR mutant NSCLC cells showed a sensitive response to REGN5093-M114. Thus, we calculated the area under the curve plot for REGN5093-M114 by quantifying whole MET expression, surface MET expression, and MET CNV values for each cell line. As a result, the surface MET expression had the most predictive power on determining the efficacy of the REGN5093-M114. Notably, REGN5093-M114 potently reduced tumor growth of EGFR mutant NSCLC with PTEN loss or MET Y1230C mutation after progression on prior TATTON study. Furthermore, we demonstrated that the combined treatment of MET-TKI and REGN5093-M114 shows synergistic antitumor efficacy with a marked reduction of MET downstream signals and increased apoptotic proteins in the METex14 mutant NSCLC. Altogether, REGN5093-M114 is a potent candidate to overcome the current challenges faced in targeting MET pathway. Conclusion: REGN5093-M114 has the potential to be a novel therapeutic option in NSCLC harboring MET genetic alterations, and further clinical application is highly warranted. Citation Format: Seung Yeon Oh, Sun Min Lim, You Won Lee, Eun Ji Lee, Jae Hwan Kim, Seong Gu Heo, Mi Ra Yu, Min Hee Hong, Hye Ryun Kim, John DaSilva, Christopher Daly, Mi Ran Yun, Byoung Chul Cho. A MET targeting biparatopic antibody-drug conjugates (ADC), REGN5093-M114, has an antitumor efficacy in NSCLC harboring MET gene alterations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB515A.

Analysis of molecular characterization: Pancreatic ductal adenocarcinoma with hepatic metastases.

4129 Background: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal solid tumors. Distant metastasis is the leading cause of cancer death. Approximately 50% of PDAC patients are discovered to have distant metastases, mainly in the liver. Chemotherapy is the main recommended treatment for metastatic PDACs, with a median survival time of only 4-6 months and the 5-year survival of 1%. Therefore, deciphering the molecular mechanisms of metastatic PDAC is urgently for exploring effective therapeutic targets. Methods: 93 normal-paired samples from patients with PDAC were analyzed using hybridization capture-based next generation sequencing. Somatic and germline mutations were identified including 500 genes associated with tumor development. Sequencing data were analyzed to call tumor specific single nucleotide variants (SNV), small insertions and deletions (InDels), copy number alterations (CNA) and gene fusions and rearrangements. Results: A total 93 patients with PDAC were analyzed, including hepatic metastases (15/93), lymph node metastases (1/93), colon metastases (1/93), pelvic metastases (1/93), and no distant metastasis (75/93). In PDAC patients without distant metastasis, the most frequent mutated gene was KRAS (72%), followed by TP53 (60%), CDKN2A (21%), SMAD4 (17%), ARID1A (11%), RNF43 (9%), and RBM10 (8%). In PDAC patients with hepatic metastases, we found that the most frequent one was KRAS (100%), followed by TP53 (87%), CDKN2A (40%), SMAD4 (40%), RNF43 (13%), and RBM10 (6%). Furthermore, four PDAC patients occurred KRAS copy number amplification, including 2 cases of hepatic metastases. And a hepatic metastases PDAC patient had ERBB2 and MET copy number amplification. We also found that seven no-metastasis patients carried pathogenic or likely pathogenic germline variants, including BRIP1, PALB2, RECQL, ATM, RAD50, FANCM and BRCA1. Conclusions: High frequency mutation genes in PDAC patients with hepatic metastases were highly consistent with those of no-metastasis patients. KRAS and TP53 gene co-mutations were extensively mutated in hepatic metastases patients. Our results revealed the molecular mechanisms driving PDAC hepatic metastases should be considered in further study.

Implementation of clinical sequencing for molecular profiling in patients with advanced cancer.

The advancement of cancer genomics has allowed for multiplex gene assays using next-generation sequencing (NGS) to be practically implemented, however, a clinical practice system remains to be established. We evaluated the feasibility of clinical sequencing using NGS-based multiplex gene assays between cooperating medical institutions in patients with advanced cancers. In this observational study, DNA and RNA samples prepared from existing tumor tissues were subjected to comprehensive genomic profiling using targeted sequencing. From January 2017 to March 2019, 36 samples from 33 patients were assessed. Of all patients, 27 (82%) had lung cancer, with the median age of 50 years (range 38-83). Multiplex gene panel tests were successfully carried out on 35/36 (97%) samples. Potentially actionable gene alterations were identified in 10/30 (33%) samples (3 HER2, 2 KRAS, 2 ALK, 1 PIK3CA, 1 RET, and 1 CDKN2A). In the 6 samples examined for resistant mechanisms, ALK I1171N mutation and MET copy number gain were detected in 2 patients with ALK rearrangement-positive lung cancer. Clinical sequencing using NGS-based multiplex gene assays between collaborating domestic medical institutions was feasible, with a success rate of > 97%. Overall, clinical sequencing benefits therapeutic decision-making in patients with advanced cancer.

The Activity of Crizotinib in Chemo-Refractory MET-Amplified Esophageal and Gastric Adenocarcinomas: Results from the AcSé-Crizotinib Program.

BackgroundThe AcSé-crizotinib program provides extensive screening of crizotinib-targeted genomic alteration in several malignancies. We here report the results in patients with esogastric MET-amplified adenocarcinomas.ObjectiveThe objective of the study was to evaluate the efficacy and tolerability of crizotinib in patients with pretreated esogastric MET-amplified adenocarcinoma who have no alternative treatment options.Patients and MethodsMET expression was evaluated by fluorescence in situ hybridization in tumor samples with immunohistochemistry scores ≥ 2+. Patients with chemo-refractory tumors showing ≥ 6 MET copies were eligible for crizotinib 250 mg twice daily. The primary efficacy outcome was the objective response rate after two cycles of crizotinib.ResultsMET was prospectively analyzed in 570 esogastric adenocarcinomas. Amplifications were found in 35/570 adenocarcinomas (29/523 gastric and 6/47 esophageal). Nine patients were treated with crizotinib. The objective response rate after two cycles was 33.3% (95% CI 7.5–70), the best overall response rate was 55.6% (95% CI 21.2–86.3), with median progression-free survival of 3.2 months (95% CI 1.0–5.4), and overall survival of 8.1 months (95% CI 1.7–24.6). Safety was consistent with that previously reported for crizotinib.ConclusionsLarge-scale screening for MET-amplified esogastric adenocarcinomas is feasible. MET amplification was observed in 5.5% of gastric and 12.8% of esophageal adenocarcinomas. Crizotinib shows encouraging results in selected patients. Thus, c-MET inhibition for MET-amplified tumors deserves further evaluation.Trial Registration NumberNCT02034981.Date of Registration14 January 2014.

The FAM3C locus that encodes interleukin-like EMT inducer (ILEI) is frequently co-amplified in MET-amplified cancers and contributes to invasiveness

BackgroundGene amplification of MET, which encodes for the receptor tyrosine kinase c-MET, occurs in a variety of human cancers. High c-MET levels often correlate with poor cancer prognosis. Interleukin-like EMT inducer (ILEI) is also overexpressed in many cancers and is associated with metastasis and poor survival. The gene for ILEI, FAM3C, is located close to MET on chromosome 7q31 in an amplification “hotspot”, but it is unclear whether FAMC3 amplification contributes to elevated ILEI expression in cancer. In this study we have investigated FAMC3 copy number gain in different cancers and its potential connection to MET amplifications.MethodsFAMC3 and MET copy numbers were investigated in various cancer samples and 200 cancer cell lines. Copy numbers of the two genes were correlated with mRNA levels, with relapse-free survival in lung cancer patient samples as well as with clinicopathological parameters in primary samples from 49 advanced stage colorectal cancer patients. ILEI knock-down and c-MET inhibition effects on proliferation and invasiveness of five cancer cell lines and growth of xenograft tumors in mice were then investigated.ResultsFAMC3 was amplified in strict association with MET amplification in several human cancers and cancer cell lines. Increased FAM3C and MET copy numbers were tightly linked and correlated with increased gene expression and poor survival in human lung cancer and with extramural invasion in colorectal carcinoma. Stable ILEI shRNA knock-down did not influence proliferation or sensitivity towards c-MET-inhibitor induced proliferation arrest in cancer cells, but impaired both c-MET-independent and -dependent cancer cell invasion. c-MET inhibition reduced ILEI secretion, and shRNA mediated ILEI knock-down prevented c-MET-signaling induced elevated expression and secretion of matrix metalloproteinase (MMP)-2 and MMP-9. Combination of ILEI knock-down and c-MET-inhibition significantly reduced the invasive outgrowth of NCI-H441 and NCI-H1993 lung tumor xenografts by inhibiting proliferation, MMP expression and E-cadherin membrane localization.ConclusionsThese novel findings suggest MET amplifications are often in reality MET-FAM3C co-amplifications with tight functional cooperation. Therefore, the clinical relevance of this frequent cancer amplification hotspot, so far dedicated purely to c-MET function, should be re-evaluated to include ILEI as a target in the therapy of c-MET-amplified human carcinomas.

Genomic and clinical characteristics of MET exon14 alterations in a large cohort of Chinese cancer patients revealed distinct features and a novel resistance mechanism for crizotinib

Background: Alterations in MET exon 14 (METex14) and its flanking intronic regions have been identified in a variety of cancers. Patients with METex14 alterations often benefit from MET inhibitors such as crizotinib. Given the unique mutation profiles of Chinese lung cancer patients, it is necessary to investigate the prevalence of METex14 alterations in a large cohort of cancer patients.Patients and methods: Cases carrying METex14 alterations were screened from 26,391 Chinese cancer patients by next-generation sequencing (NGS), and the clinicopathologic and molecular characteristics were reviewed.Results: Compared to Western population (~3%), the frequency of METex14 alterations is much lower in Chinese cancer patients (0.7%, n=184) and lung cancer patients (1.1%, n=175). Seventy-eight distinct METex14 alterations, including several novel alteration types were detected. Concurrent MET copy gain and non-exon14 MET mutations were also found. EGFR copy gain (11%) and mutations (8%), KRAS (5%) and PIK3CA (5%), appeared in a mutually exclusive pattern. Female patients contain much less TP53 mutations than male patients (65% vs. 24%, FDR = 0.01). Co-amplification of CDK4 and MDM2, CDK6 and EGFR were identified, which indicated cell cycle dysregulation and EGFR alteration are important co-occurring features in patients with METex 14 alteration. Of 9 tissue specimens having PD-L1 immunohistochemistry (IHC) results, 5 of them (55.5%) were found PD-L1 positive, which is comparable to other types of tumor. In 14 crizotinib-treated patients, the median progression free survival (mPFS) was 7 months. Upon resistance to crizotinib, two patients acquired secondary mutations in MET and one patient acquired BRAF p.K601E that can be a novel resistance mechanism.Conclusion: Chinese cancer patients have a relatively lower frequency of METex14 alterations compared to Western patients. Patients with METex14 alterations showed distinct molecular characteristics and the representative case study showed responses to MET tyrosine kinase inhibitor (TKI).

Abstract 1324: Genomic and clinical characteristics of MET exon14 alterations in 26,391 Chinese cancer patients

Abstract Background: Alterations in MET exon 14 (METex14) and its flanking intronic regions have been identified in a variety of cancers, and suggested to cause enhanced MET activity and oncogenesis. Clinical evidences suggested that patients with METex14 alterations often benefit from MET inhibitors such as crizotinib. Given the unique mutation profiles of Chinese lung cancer patients, it is necessary to investigate the prevalence of METex14 alterations in a large cohort of cancer patients. Patients and methods: Cases carrying METex14 alterations were screened from 26,391 Chinese cancer patients, and the clinicopathologic and molecular characteristics of the cohort were reviewed. PD-L1 immunohistochemistry and the treatment response to MET inhibitors were also analyzed for cases with such information available. Results: Compared to Western cancer population (3~7%), the frequency of METex14 alterations is much lower in Chinese cancer patients (0.7%, n=184) and in Chinese lung cancer patients (1.1%, n=175). Seventy-eight distinct METex14 alterations were detected, with majority of alterations are base substitutions at splice donor site (42%) and insertion/deletions (indels) in intron 13 (28%). Concurrent MET copy gain and non-exon14 MET mutations were found in 4% and 11% of cases, respectively. Other driver alterations, such as EGFR copy gain (11%) and mutations (8%), KRAS (5%) and PIK3CA (5%), appeared in a mutually exclusive pattern. In 71 patients sequenced by 425-gene panel, gene copy gains were prevalent in MDM2 (24%), CDK4 (14%), MCL1 (13%), TERT (13%), MYC (11%), CD274 (7%) and CDK6 (6%). Female patients contain much less TP53 mutations than male patients (65% vs. 24%, FDR = 0.01). Of 9 tissue specimens having PD-L1 immunohistochemistry (IHC) results, 5 of them (55.5%) were found PD-L1 positive, indicating the option for immunotherapy. In 14 patients who received crizotinib-treatment, the median progression free survival (mPFS) was 7 months with the longest PFS of 17 months. Upon resistance to crizotinib, two patients acquired secondary mutations in MET and one patient acquired BRAF p.K601E that can be a novel resistance mechanism to crizotinib treatment. Conclusion: Chinese cancer patients have a relatively lower frequency of METex14 alterations compared to Western patients, and these patients can be potentially treated by immunotherapy and crizotinib. Citation Format: Sisi Liu, Danni Song, Xiaoling Tong, Xue Wu, Xiaonan Wang, Yang Washington Shao. Genomic and clinical characteristics of MET exon14 alterations in 26,391 Chinese cancer patients [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1324.

Safety and preliminary clinical activity of the MET antibody mixture, Sym015 in advanced non-small cell lung cancer (NSCLC) patients with MET amplification/exon 14 deletion (METAmp/Ex14∆).

9510 Background: Sym015, a mixture of 2 humanized antibodies, triggers MET degradation by a unique mechanism with superior specificity compared to tyrosine kinase inhibitors (TKIs). The Sym015-01 phase (P)1a trial met, the primary objective of identifying the recommended P2 dose (RP2D) as 18 mg/kg on cycle 1 day 1 followed by 12 mg/kg Q2W. The P2a was expanded to enroll METAmp/Ex14∆ NSCLC patients (pts) based on preliminary efficacy findings. Here we present interim safety (n = 45) and efficacy (NSCLC cohort, n = 20) results from P2a. Methods: The expansion NSCLC Cohort enrolled pts with METEx14Δ (n = 12) or METAmp (n = 8 defined as > 5 MET copies by NGS or MET/CEP7 ratio > 2.2 updated to ≥3.0 by in situ hybridization; including 1 with METAmp+Ex14Δ). Tumor MET status was confirmed centrally and longitudinal ctDNA was analyzed by Guardant360. Results: By January 2020, 45 pts (median age 61.7 years) have been treated in P2a. Median duration of exposure (DoE) was 3.8 months (m) (n = 45; range 0.4+ to 22 m). Treatment emergent adverse events occurred in 93%, treatment related AEs (TRAE) in 42.2% and TRAE ≥G3 in 13.3% pts. No pts discontinued or died due to TRAE. The most common TRAE in ≥10% pts were fatigue (13.3%) and peripheral edema (11.1%). Of 20 NSCLC pts, 5 had confirmed PR (ORR 25%; 2/8 METAmp and 3/12 METEx14Δ); 11 had SD (DCR 80%; 6/8 METAmp and 5/12 METEx14Δ); 2 had PD (2/12 METEx14Δ); and 2 were not evaluable. 10 NSCLC pts were MET TKI naive (7 METAmp and 3 METEx14Δ) and had 50% ORR and 100% DCR (5 PR and 5 SD; DoR range 1 to 18.3 m; DoE 1.5 to 22 m); 10 NSCLC pts were prior MET TKI treated (9 METEx14Δ and 1 METAmp+Ex14Δ) with DCR 60%, (6 SD; DoE 0.4-9.6 m). Median PFS was 5.5 m overall (95% CI 3.5-9.7 m). Median PFS for MET TKI naive and MET TKI pre-treated NSCLC pts was 6.5 m (95% CI 3.4-21.9 m) and 5.4 m (95% CI 1.2-9.7 m) respectively. Median OS was not reached for overall or for prior MET TKI subgroups. 89% METEx14∆ tumor tissue to blood concordance (8/9 NSCLC pts) was observed. Conclusions: Sym015 was well-tolerated at the RP2D with a response rate similar to MET TKI in MET-treatment naïve METAmp/Ex14Δ NSCLC and seems to delay disease progression in MET TKI pretreated NSCLC pts. Combination with MET TKI to delay or prevent resistance should be further explored. Clinical trial information: NCT02648724 .

1490PD - A phase Ia/IIa trial of Sym015, a MET antibody mixture, in patients with advanced solid tumours

BackgroundMET gene amplification/mutation is implicated in oncogenesis of many tumor types. Sym015 is a recombinant antibody (Ab) mixture containing 2 humanized Abs binding non-overlapping epitopes on MET which has superior preclinical activity compared to other MET Abs. Here we present interim results from the First in Human study of Sym015. MethodsIn part 1 dose escalation, Sym015 was evaluated on every 2-week (q2w) schedule at 6/12/18/24mg/kg doses in late line advanced solid tumor patients (pts). Based on PK/PD assessment, 18mg/kg loading dose followed by 12mg/kg q2w was selected as RP2D. The on-going Part 2 Dose expansion enrolls pts with MET amplification (METAmp >5 MET copies by Next Generation Sequencing (NGS) or FISH MET/CEP7 ratio >2.2 updated to≥3.0) and/or MET exon 14 deletion (METEx14Δ) positive tumors. Central FISH confirmation of tumor MET status and longitudinal circulating tumor (ct)DNA profiling is performed. ResultsBy April 2019, 51 pts (median age 61 yrs) have been treated, 12 pts in Part 1 and 39 pts in Part 2, the majority are non small cell lung cancer (NSCLC; 14 pts; 6 METAmp,7 METEx14Δ, 1 both) and gastric cancer (GC; 12 METAmp pts). Treatment-related adverse events (TRAE) occurred overall in 41,2%; TRAE ≥ gr3 in 9,8% (edema, colitis, septic shock, hypoalbuminemia, hypophosphatemia, increased amylase). No pts discontinued or died due to TRAE. The most common TRAE of≥5% were fatigue 15.7%, peripheral edema 7,8%, nausea, decreased appetite, pruritus and abdominal pain reported by 5.9% of pts each. The table shows preliminary efficacy in NSCLC patients. Sym015PK was slightly non-linear, with a dose-dependent t½ of 7-10 days for the first dose. 83% METAmp concordance (10/12 samples) between tumor and blood was observed.Table1490PDTableNSCLC PtMET Status (Local Assessment)Best Response (Best % Change From Baseline)Previous MET TKI therapyDuration of Response (weeks)1METAmp NGS 6.8 CopiesPR (-53%)No802METAmp NGS >5 CopiesSD (-29%)No9, Ongoing3METAmp NGS >5 CopiesSD (+3%)No9, Ongoing4METEx14ΔSD (-28%)No7, Ongoing5METAmp FISH MET/ CEP7:4.9SD (+6%)No116METEx14ΔSD (-4%)Yes87METEx14ΔSD (-21%)Yes158METEx14ΔSD (-20%)Yes89METAmp SISH MET/ CEP7: 15.2PendingNoOngoing10METEx14ΔPendingYesOngoing11METEx14Δ + METAmpPendingPendingOngoing12METEx14ΔPendingNoOngoing13METEx14ΔPendingNoOngoing14METEx14ΔNot EvaluableYesNot Evaluable ConclusionsSym015 was well tolerated with early evidence of antitumor activity. Predictive biomarker analysis is underway. The study continues to enroll NSCLC patients with METAmp and/or METEx14Δ. MET screening in blood seems feasible and may be included in future trials. Clinical trial identificationNCT02648724. Legal entity responsible for the studySymphogen A/S. FundingSymphogen A/S. DisclosureD.R. Camidge: Advisory / Consultancy: 2019: Takeda, CBT Pharmaceuticals, Daiichi-Sankyo (ILD adjudication committee), G1 Therapeutics (DSMB), Bio-Thera (DSMB), Blueprint; Advisory / Consultancy: 2018: AstraZeneca, Takeda, Arrys/Kyn, Regeneron, Hengrui, G1 Therapeutics (DSMB), Daiichi Sankyo (ILD adjudication committee), Hansoh (SRC), Bio-Thera (DSMB), Ribon, BMS, Blueprint, Roche/Genentech, Inivata; Advisory / Consultancy: 2017: Genoptix, G1 Therapeutics (DSMB), Mersana Therapeutics, Roche/Genentech, Takeda, Ignyta, Daiichi Sankyo (ILD adjudication committee), Hansoh SRC, Bio-Thera DSMB, Lycera, Revolution Med; Research grant / Funding (self), Research grant / Funding (institution): 2017: Takeda Investigator-initiated Trial; Research grant / Funding (self), Research grant / Funding (institution), Company Sponsored Trials at Institution: 2018/9: AbbVie, AstraZeneca, BMS, Hansoh, Lycera, MedImmune, Merck, Pfizer, Phosplatin, Roche/Genentech, Seattle Genetics, Symphogen, Takeda. F. Janku: Research grant / Funding (self): Novartis, Genentech, BioMed Valley Discoveries, Astellas, Agios, Plexxikon, Deciphera, Piqur, Symphogen, Bristol-Myers Squibb, Asana, Upsher-Smith Laboratories; Advisory / Consultancy: Guardant Health, IFM Therapeutics, Synlogic, Deciphera; Advisory / Consultancy, Shareholder / Stockholder / Stock options: Trovagene; Advisory / Consultancy: Immunomet. D.V. Catenacci: Honoraria (self), Advisory / Consultancy: Merck, BMS, Lilly, Astellas, Gritstone, Taiho, Five Prime, Genentech Roche, Foundation Medicine, Guardant Health, Tempus. H.C. Chung: Honoraria (self): Merck-Serono, Lilly, Foundation Medicine; Advisory / Consultancy: Taiho, Celltrion, MSD, Lilly,Quintiles, BMS, Merck-Serono; Research grant / Funding (institution): Lilly, GSK, MSD, Merck-Serono, BMS-ONO, Taiho. A. Dowlati: Advisory / Consultancy: Seattle genetics, Takeda, AbbVie; Research grant / Funding (institution): Takeda, Taiho, Roche, EMD Serono, Bayer, Tesaro, Regeneron, Amgen, Mirati, BMS. K.S. Rohrberg: Research grant / Funding (institution), Travel / Accommodation / Expenses: Roche; Research grant / Funding (institution): Loxo Oncology, Orion Pharma, Pfizer, PUMA, Cantargia, Genmab, Novartis, Incyte, Bayer, AstraZeneca, Alligator, Merck, BMS; Travel / Accommodation / Expenses: Sanofi; Research grant / Funding (institution): Symphogen. T.T. Poulsen: Full / Part-time employment: Symphogen A/S. H. Rudbæk: Full / Part-time employment: Symphogen A/S. L. Alifrangis: Full / Part-time employment: Symphogen A/S. R.P. Dalal: Full / Part-time employment: Symphogen A/S. All other authors have declared no conflicts of interest.

Abstract 5119: Customizable all-in-one cancer panels to detect copy number variation, DNA rearrangement and mutations by targeted NGS

Abstract Background: The current standard of genomic profiling of cancer tissues relies upon multiple separate technologies to aid in tumor characterization. Here we describe a customizable NGS design and analysis workflow for cancer samples that can detect single nucleotide polymorphisms (SNPs), insertions and deletions (INDEL), somatic copy number alterations (SCNAs), and translocations (TLs) in a single assay. Methods: We have created a library of strategically placed target-enrichment probes to provide for specific detection of SNP/INDEL, SCNAs, and translocation in genes identified as important in several cancer subtypes. The probes are optimized with the SureSelect XTHS protocol, which enables extremely sensitive detection of rare exonic mutation events within a heterogeneous sample. SCNA detection is further enhanced with additional probes targeting high minor allele frequency SNPs within the target gene boundary. Translocation detection is enabled by targeting intronic regions of fusion gene candidates. The data analysis is performed by the software SureCall that calls SNPs across all regions covered by probes. SCNA detection utilizes either a matched normal or standard control DNA and aberrant regions are identified by jointly segmenting the read depth ratios and SNP allele frequencies. The clonal structure is discerned using two Bayesian cancer models in a hierarchical manner. Translocation are identified by analyzing split reads across putative fusion breakpoints that are supported by both high- and low-confidence reads that pass quality filters. Results: We demonstrate rare allele detection in cancer cells down to 1%. We also show detection of 3 copies of MET at 20% tumor fraction and 16 copies of ERBB2 at 2% tumor fraction. For translocations, DNA level gene fusions were detected for ALK and ROS fusion genes at <=3% tumor fraction. In 39 ERBB2 FISH-positive FFPE samples, ERBB2 CNV detected by AIO panel was 97.4% concordant with FISH (scored according to standard ASCO/CAP convention). Using FISH as the gold standard, the false negative rate was 2.6% and false positive rate was 2.4%. In 43 ALK FISH-positive FFPE samples, ALK fusion was detected using a small AIO lung panel which includes probes spanning introns 18/19 of the ALK gene and is 90.7% concordant with FISH (Agilent SureFISH ALK BA). Using FISH as the gold standard, the false negative rate was 9.3% and false positive rate was 2.3%. Conclusions: This work represents an important advancement in the development of a single assay to detect copy number variation, DNA rearrangement and mutations. Citation Format: Arjun Vadapalli, Ashutosh Ashutosh, Heather Tao, Linus Forsmark, Christian Le Cocq, Akansha Khare, Bahram Arezi, Gilbert Amparo, Michael Ruvolo, Carlos Pabon, Jayati Ghosh, Jimmy Jin, Tracy Liu, Douglas Roberts. Customizable all-in-one cancer panels to detect copy number variation, DNA rearrangement and mutations by targeted NGS [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5119.

Abstract 3032: Acquired resistance to osimertinib in patients with de novo EGFRT790M-positive non-small cell lung cancer (NSCLC)

Abstract Background: Epidermal growth factor receptor (EGFR) T790M mutation is well known as primary and acquired resistance mechanisms to the 1st and 2nd generation EGFR tyrosine kinase inhibitors (TKIs). However, a de novo and clonal EGFR T790M mutation is rarely observed in 0.8-2% of patients with EGFR-mutant NSCLC. The 3rd generation EGFR TKIs including osimertinib are expected to be effective against de novo, clonal EGFRT790M-positive NSCLC. However, the efficacy and resistance mechanisms of osimertinib have been limited in patients with de novo and clonal EGFRT790M-positive NSCLC. Methods: The seven (1%) of 690 patients with EGFR-mutant NSCLC were identified as having de novo and clonal EGFRT790M mutations between December 2002 and July 2014 in Seoul National University Hospital. Three with de novo EGFRL858R/T790M mutation received osimertinib at a dose of 80mg or 160mg once daily (NCT01802632) and two showed acquired resistance to osimertinib. Fresh tumor samples were obtained before and after treatment with osimertinib and analyzed by whole-exome and -transcriptome sequencings as well as droplet digital polymerase chain reaction (ddPCR). MET amplification was determined by fluorescence in situhybridization (FISH) in formalin-fixed paraffin-embedded tumor tissues. Results: Three patients with de novo EGFRL858R/T790M mutation received osimertinib and two (LC1 and LC2) showed acquired resistance to osimertinib at 16 and 30 months, respectively (Table 1). As of November 2018, the LC3 patient received osimertinib without disease progression. Novel MTOR L1433S mutation within FAT domain that was not seen at initial tumors (ploidy 2.3) was clonally acquired at osimertinib-resistant tumors (ploidy 2.4) in the LC1 patient. In addition, a novel and clonal MGA V124D mutation within T-box was found at osimertinib-resistant tumors (ploidy 5.9) of the LC2 patient. MET copy number was 14 with high fpkm level (721.9) at osimertinib-resistant tumors in the LC2 patient. Average MET gene copies per nucleus by FISH were 2.74 at initial tumors and 5.25 at osimertinib-resistant tumors in LC2 patient, resulting in MET amplification as a resistance mechanism. Subclonal MGA V124D mutation was found at initial tumors of the LC2 patient using ddPCR. The Ba/F3 systems confirmed that novel mutants were oncogenic. Conclusions: Novel MTOR and MGA mutations were functional and clonally acquired as resistance mechanisms to osimertinib in patients with de novo EGFRL858R/T790M-mutant NSCLC. In addition, MET amplification contributed to acquired resistance to osimertinib. Taken together, acquired resistance mechanisms of osimertinib might be mainly mediated by alternative pathway activation in de novo EGFRT790M-positive NSCLC. Citation Format: Ha-Ram Park, Yusoo Lee, Tae Min Kim, Soyeon Kim, Chan-Young Ock, Miso Kim, Bhumsuk Keam, Yoon Kyung Jeon, Dong-Wan Kim, Dae Seog Heo. Acquired resistance to osimertinib in patients with de novo EGFRT790M-positive non-small cell lung cancer (NSCLC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3032.

Abstract LB-105: Therapeutic efficacy of ABN401, highly selective c-MET inhibitor, in NSCLC with MET-amplified AND/OR EGFR mutation

Abstract c-MET, also known as a hepatocyte growth factor receptor encoded by the MET gene, plays role in normal physiology by regulating cellular physiology. In cancer, MET alterations containing gene amplification, mutation, overexpression have been strongly implicated in tumorigenic transformation, tumor growth, angiogenesis, invasion, and metastasis. These MET alterations are reported in a wide variety of cancers such as lung, gastric, colon, liver, and head and neck. Especially in NSCLC, MET amplification and mutations including exon 14 deletion are observed in 4% of patients. Also, in NSCLC, EGFR mutation is observed in about 15~35% of patients. Among those 15-35% of patients, approximately 5-11% of NSCLC patients, who were treated by EGFR TKi, experience acquire resistance mechanism induced by c-MET. Also, EGFR amplification and overexpression are acquired resistance mechanism for MET. The alterations and cross-reactivity between c-MET and EGFR induce cancer by bypassing mechanisms for each other. c-MET, which acts as a resistance mechanism after EGFR TKi treatment, makes c-MET as an attractive target for cancer therapy. In this study, we determined the efficacy of ABN401 and other tyrosine kinase targeting inhibitor by combination treatment based on genetic analysis using cell lines and PDX models for NSCLC. The cytotoxic effect of ABN401 and synergism was evaluated in five NSCLC cell lines. c-MET and its downstream signaling were also assessed. In vivo anti-tumor therapeutic efficacy of ABN401 was evaluated in one NSCLC cancer cell xenograft model and 4 PDX models. MET copy number, c-MET protein expression, and genetic aberration were also determined. Our results revealed that ABN401 shows over 60-90% cytotoxicity in five NSCLC cell lines (H596, H1993, EBC-1, H820, HCC827) between 10 nM to 10 uM and inhibits auto-phosphorylation of c-MET as well as its downstream signalling. H1993, H596, and EBC-1 showed cytotoxicity effect on several nM of single treatment of ABN401. Other cell lines which harbor EGFR mutations exhibited lower cytotoxicity effect single treatment of ABN401. Combination treatment of ABN401 and EGFR TKi showed about 80% of cytotoxic effect. The CI index, which is an indicator for synergism, appeared less than 1 in certain concentrations of combination therapy. In in vivo, single treatment of ABN401 showed tumor growth suppression on xenograft model with MET amplification and PDX model with MET amplification and Ex14del. PDX model with MET and EGFR amplification regardless of presence of EGFRm L858R, did not show tumor growth suppression by single treatment of ABN401. However, significant tumor growth suppression was observed when treated with both ABN401 and EGFRm TKi. Both in vivo and in vitro results suggest that single treatment of ABN401 has efficacious effects when MET is highly amplified regardless of MET Ex14del’s presence. Combination treatment of ABN401 and EGFRm TKi showed efficacious effect on both MET and EGFR amplification regardless of the presence of EGFR mutation. Based on this study, we concluded that ABN401 can be a potential drug candidate for NSCLC patients who has METamplification and/or Ex14del as a single agent as well as combination treatment for patients who show resistance to EGFR inhibitors and exhibit MET amplification. Citation Format: Joo Seok Kim, Kyeung Eui Park, Yeong Mun Kim, Kevin Sha, Min Ji Seo, Sungyoul Hong, Jun Young Choi, Young Kee Shin. Therapeutic efficacy of ABN401, highly selective c-MET inhibitor, in NSCLC with MET-amplified AND/OR EGFR mutation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-105.

Abstract PR13: MET copy number gain is associated with gefitinib resistance in leptomeningeal carcinomatosis of EGFR-mutant lung cancer

Abstract Leptomeningeal carcinomatosis occurs frequently in EGFR-mutant lung cancer, and develops acquired resistance to EGFR tyrosine kinase inhibitors (EGFR-TKIs). This study aimed to clarify the mechanism of EGFR-TKI resistance in leptomeningeal carcinomatosis and seek a novel therapeutic strategy. We examined EGFR mutations, including the T790M gatekeeper mutation, in 32 re-biopsy specimens from 12 leptomeningeal carcinomatosis and 20 extracranial lesions of EGFR-mutant lung cancer patients who became refractory to EGFR-TKI treatment. All 32 specimens had the same baseline EGFR mutations, but the T790M mutation was less frequent in leptomeningeal carcinomatosis specimens than in extracranial specimens (8% vs. 55%, P < 0.01). To study molecular mechanisms of acquired EGFR-TKI resistance in leptomeningeal carcinomatosis, we utilized our previously developed mouse model of leptomeningeal carcinomatosis with the EGFR-mutant lung cancer cell line PC-9/ffluc cells, in which acquired resistance to gefitinib was induced by continuous oral treatment. Compared with subcutaneously inoculated gefitinib-resistant tumors, the T790M mutation was less frequent in leptomeningeal carcinomatosis that acquired resistance to gefitinib. PC-9/LMC-GR cells were established from the gefitinib-resistant leptomeningeal carcinomatosis model, and they were found to be intermediately resistant to gefitinib and osimertinib (third-generation EGFR-TKI). Although EGFR-T790M was negative, gefitinib resistance of PC-9/LMC-GR cells was related to MET copy number gain with MET activation. Moreover, combined use of EGFR-TKI and crizotinib, a MET inhibitor, dramatically regressed leptomeningeal carcinomatosis with acquired resistance to gefitinib or osimertinib. These findings suggest that combination therapy with MET inhibitors may be promising for controlling leptomeningeal carcinomatosis that acquires resistance to EGFR-TKIs. This abstract is also being presented as Poster B29. Citation Format: Shigeki Nanjo, Sachiko Arai, Wei Wang, Akito Hata, Nobuyuki Katakami, Seiji Yano. MET copy number gain is associated with gefitinib resistance in leptomeningeal carcinomatosis of EGFR-mutant lung cancer [abstract]. In: Proceedings of the Fifth AACR-IASLC International Joint Conference: Lung Cancer Translational Science from the Bench to the Clinic; Jan 8-11, 2018; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(17_Suppl):Abstract nr PR13.

40. Genomic profiling of lung adenocarcinomas with increased MET copy numbers

40. Genomic profiling of lung adenocarcinomas with increased MET copy numbers

Abstract LB-194: Therapeutic efficacy of ABN401, a highly potent and selective c-MET inhibitor, on the basis of diagnostic test for biomarkers in MET-amplified cancers

Abstract The receptor tyrosine kinase c-MET regulates essential cellular processes in tissue remodeling and homeostasis, and mammalian development. Although c-MET is an important in normal physiology, the dysregulation of c-MET signaling has been strongly implicated in tumorigenic transformation, tumor growth, angiogenesis, invasiveness, and metastasis. The aberrant activation of c-MET, particularly in tumors with gene amplification and mutations, reported in a wide variety of cancers. In approximately 10% of gastric cancer, MET is amplified and is activated in the ligand-independent pathway. MET-amplified cancer cell lines are dependent on its signaling for survival and proliferation. That being so, c-MET is attractive target and a number of clinical trials are ongoing. However, some clinical trials were failed due to inappropriate patient selection criteria such as low cut-off. To select patients who respond to c-MET inhibitor, the selection criteria by using both IHC and FISH is necessary. In this study, we determined the efficacy of ABN401 based on histopathologic and genetic analysis using cell lines and patient-derived xenograft (PDX) models for gastric cancer and other c-MET related cancers as well. The cytotoxic effect of ABN401 was evaluated in six gastric cancer cell lines and one normal fibroblast cell as control by using cell viability assay. c-MET and its downstream signaling were assessed by western blot assay. In vivo anti-tumor therapeutic efficacy of ABN401 was evaluated in two gastric cancer cell xenograft models and eight PDX models. MET copy number, c-MET protein expression and genetic aberration were estimated by diagnostic test such as IHC and FISH, NGS, and array CGH in cell lines and PDX models. Our results revealed that ABN401 showed over 90% of cytotoxicity in five gastric cancer cell lines (SNU5, SNU620, SNU638, Hs746T, MKN45) and inhibited auto-phosphorylation of the c-MET as well as its downstream signal. Except for SNU638, the other four cell lines were MET copy number > 10, MET/CEP7 > 5, and c-MET expression (IHC 3+). Moreover, ABN401 significantly suppressed tumor growth in three of eight PDX models with MET copy number >5. MET/CEP7 > 5 and c-MET expression level (IHC 3+). However, ABN401 had no effect in gastric PDX model with MET copy number 5, MET/CEP7 ratio > 5, c-MET protein level IHC 2+ and esophagus PDX model with MET copy number 6, MET/CEP7 ratio = 2.2, IHC 1+. Both in vivo and in vitro experiment suggest that MET copy number and c-MET expression level affects effectiveness of c-MET inhibitor ABN401, which alert us the importance of cut-off. Based on this study, we conclude that it would be possible to make a conjecture in future clinical trials by establishing the characteristics of each sample and find the correlation with the efficacy of c-MET inhibitor. Citation Format: Jooseok Kim, Kyungsoo Jung, Kyungeui Park, Minji Seo, Yoonla Choi, Junyoung Choi, Sungyoul Hong, Youngkee Shin. Therapeutic efficacy of ABN401, a highly potent and selective c-MET inhibitor, on the basis of diagnostic test for biomarkers in MET-amplified cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-194.

Abstract P4-14-05: Genomic parameters affecting the outcome of patients with advanced breast cancer treated with trastuzumab

Abstract Background-Aim: There is an unmet need for de-selecting HER2-positive patients with advanced breast cancer (ABC), since only some of those patients benefit from the addition of anti-HER2 agents to chemotherapy. The aim of this study was to investigate candidate biomarkers, including MYC and MET, in parallel with an extended array of biomarkers previously associated with trastuzumab (T) resistance. Patients and Methods: Two hundred and twenty-nine ABC patients treated with T and chemotherapy over a period of 13 years were included in the study. Paraffin tumors were retrospectively centrally assessed with immunohistochemistry (IHC) for breast cancer subtypes; fluorescence in situ hybridization (FISH) for HER2, TOP2A and centromere (CEN) 17, MYC and CEN8, MET and CEN7; qPCR for MYC and MET copy number (CN); and, for PI3K activation (PIK3CA mutations, PTEN and phospho-mTOR IHC). Patterns of CEN CN aberrations corresponding to chromosome "polysomy" were also evaluated, with cut-offs based on normal tissue. Time to progression (TTP) and survival were evaluated from the initiation of T as first-line treatment. Results: Median follow-up was 70 months. Of the 229 patients treated with T as HER2-positive, central analysis identified 90 cases being HER2-negative, as per current guidelines (39.3% of the total cohort). HER2-positive patients showed a trend for survival benefit over HER2-negative patients (median 50.7 vs. 38.1 months, respectively, p=0.118). HER2-positive tumors were subtyped as Luminal-HER2 (n=77) and HER2-enriched (n=53); 156 patients presented with ABC and 65 with disease initially diagnosed at stage IV (de novo ABC). MET and MYC CN gains (≥2.5 copies) were found in 40 (25%) and 15 (9%) cases with qPCR, while MET and MYC amplification with FISH was present in 4 (2.5%) and 31 (18%) cases, respectively. Concordance between FISH and qPCR was low for MYC (kappa value 0.46) and absent for MET. Polysomy was collectively observed in 70 cases, in 54 of them (32% of all tumors) concerning any 1 of the 3 examined chromosomes. This condition, called restricted polysomy, interacted with ABC presentation, conferring decreased survival to patients with ABC (HR=2.32, 95% CI 1.43-3.76, Wald's p=0.001) but not to those with de novo ABC (interaction p=0.077). MYC CN gain was the only marker significantly associated with increased risk for progression (HR=3.22, 95% CI 1.66-6.24, p<0.001) and death (HR=5.45, 95% CI 2.89-10.28, p<0.001) at univariate analysis. Adjustment of all tested markers with standard clinicopathological parameters revealed that along with poor patient performance status that was associated with poor prognosis, MYC CN gain was an independent adverse prognosticator for both TTP and survival (all p-values <0.001). The HER2-enriched subtype was independently associated with T benefit for TTP (p=0.001) and survival (p=0.051). The interaction between restricted polysomy and disease presentation was also independently significant for survival (p=0.041). Conclusions: MYC CN gain is a strong unfavorable prognosticator in T-treated ABC patients. Distinguishing between HER2-positive subtypes seems important for identifing T benefit in ABC. Chromosomal polysomy may distinctly affect T benefit in patients with pre-treated and de novo ABC. Citation Format: Gogas H, Kotoula V, Alexopoulou Z, Christodoulou C, Kostopoulos I, Bobos M, Raptou G, Charalambous E, Tsolaki E, Xanthakis I, Pentheroudakis G, Koutras A, Bafaloukos D, Papakostas P, Aravantinos G, Psyrri A, Petraki K, Kalogeras KT, Fountzilas G, Pectasides D. Genomic parameters affecting the outcome of patients with advanced breast cancer treated with trastuzumab. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-14-05.

Abstract B187: Prevalence of MET copy number variation, MET expression and MET related genomic alterations in all solid tumors pre-screening program. VHIO experience

Abstract Background: Aberrant MET activation occurs in many types of malignancies and includes protein overexpression, increased gene copy number, amplifications, mutations and deletions. The frequency of genomic alterations in MET varies widely among solid tumors. The criteria for MET amplification and MET overexpression have not been established as well as the relationship between MET amplification, MET expression and additional genomic alterations known to be important in tumor biology. Previous and current phase 1 clinical trials have selected patients without matching MET criterion. Materials and Methods: From Dec/2012 to Dec/2014, 203 formalin fixed paraffin embedded tumor samples from 197 patients consented to undergo targeted MET analysis. Samples were 117 primary and 86 metastatic tumors. Tumor types included colorectal, gastric, lung, glioblastoma, and breast. Samples were analyzed by fluorescence in situ hybridization (FISH) for MET gene amplification (MET/CEN-7 FISH Zytolight SPEC assay Z-2087, Zytovision), and by immunohistochemistry (IHC) for MET protein expression [Met (D1C2) XP® Rabbit mAb #8198, Cell signaling]. Mutations in key oncogenes were determined using Sequenom (Mass Array) and Amplicon-Mi Seq (Illumina) Cancer Panel. Results: MET gene copy number variation (>5copies) was found in 11 of 203 samples (5%) and MET gene amplification (based on the definition of MET/CEN-7 ≥2.2) was found in 6 of 203 samples (3%). Eleven (5%) samples had ≥4 or ≤5 copies of MET gene. KRAS mutation was found in 28 of 167 samples (17%) and PIK3CA mutation in 6 of 167 samples (4%). Both mutations were observed in tumor samples with < 4 copies of MET gene. MET IHC positive (≥ 50% positive cells 3+) was found in 11 of 203 samples (5%). Seven of 203 samples (3%) had MET IHC positive (≥ 50% positive cells 3+ and 2+). MET protein expression showed statistical association with MET gene copy number (P<0.001). There was a statistically significant increased expression of MET in metastatic samples compared with primary tumor specimens (P = 0.001). Conclusion: MET expression is higher in metastatic than primary tumor samples. There is a significant association between MET expression and gene copy number. High MET copy number was more frequent in tumors without KRAS and PIK3CA mutation. Quantitative MET protein expression data will be presented. MET IHCMET FISH≥ 50% cells 3+≥ 50% cells 3+ and 2+< 50% cells 3+and 2+< 2 copies01 (0.7%)40 (28.2%)2- <4 copies4 (2.8%)3 (2.1%)79 (55.6%)4-5 copies1 (0.7%)1 (0.7%)4 (2.8%)>5 copies5 (3.5%)04 (2.8%) Citation Format: Analía Azaro, Guillem Argilés, María Alsina, Elena Elez, Teresa Macarulla, Cristina Cruz, Donatella Marino, Cinta Hierro, Susana Cedres, Alejandro Navarro, María Ochoa de Olza, Irene Braña, Juan Martín-Liberal, Marta Vilaró, Debora Moreno, Paola Martínez, María Díaz, Ana Vivancos, Jordi Rodón, Josep Tabernero, Ludmila Prudkin, Paolo Nuciforo. Prevalence of MET copy number variation, MET expression and MET related genomic alterations in all solid tumors pre-screening program. VHIO experience. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B187.

Heterogeneity of c-Met expression in Chinese gastric cancer patients

c-Met is an attractive target for gastric cancer (GC) therapy, and detection of c-Met expression is critical for diagnosis. The aims of this study were to quantify the heterogeneous expression of c-Met in GC and to explore its impact on diagnosis. The expression of c-Met in 199 tumor fragments derived from 47 GC patients was evaluated by immunohistochemistry. In parallel, copy numbers of MET were determined by fluorescence in situ hybridization. Expression of c-Met was observed in 22 patients, and 18 (81.8%) of 22 were heterogeneous; but the incidence rate of heterogeneity was not significantly different among patient subgroups with various degrees of c-Met expression. MET copies were increased in 4 patients. Two represented polysomy, and 2 were caused by amplification. Expression of c-Met in MET-amplified tumors was homogeneous. In conclusion, heterogeneity of c-Met expression was widely observed in GC but was not associated with the extent of expression.