MET-amplified Tumors Research Articles

MET gene alterations predict poor survival following chemotherapy in patients with advanced cancer.

Background: To aid in oncology drug development, we investigated MET proto-oncogene receptor tyrosine kinase gene aberrations in 2,239 oncology patients who underwent next-generation sequencing (NGS) in clinical practice. Materials and methods: From November 2019 to January 2021, 2,239 patientswith advanced solid tumors who visited oncology clinics underwent NGS. The NGS panel included >500 comprehensive NGS tests using archival tissue specimens. Programmed death-ligand 1(PD-L1) 22C3 assay results and clinical records regarding initial chemotherapy were available for 1,137 (50.8%) and 1,761 (78.7%) patients, respectively for overall survival (OS) analysis. Results: The 2,239 patients represented 37 types of cancer. The NGS panel included >500 genes, microsatellite instability status, tumor mutational burden, and fusions. The most common cancer types were colorectal (N = 702), gastric (N = 481), and sarcoma (N = 180). MET aberrations were detected in 212 patients. All MET-amplified tumors had microsatellite stable status, and 8 had a high tumor mutational burden. Of 46 patients with MET-amplified cancers, 8 had MET-positive protein expression by immunohistochemistry (2+ and 3+). MET fusion was detected in 10 patients. Partner genes of MET fusion included ST7, TFEC, LRRD1, CFTR, CAV1, PCM1, HLA-DRB1, and CAPZA2. In survival analysis, patients with amplification of MET gene fusion had shorter OS and progression-free survival (PFS) than those without. Thus, MET aberration was determined to be a factor of response to chemotherapy. Conclusion: Approximately 2.1% and 0.4% of patients with advanced solid tumors demonstrated MET gene amplification and fusion, respectively, and displayed a worse response to chemotherapy and significantly shorter OS and PFS than those without MET gene amplification or fusion.

Mutational Landscape and Expression of PD-L1 in Patients with Non-Small Cell Lung Cancer Harboring Genomic Alterations of the MET gene.

Mesenchymal-to-epithelial transition (MET) exon 14 skipping mutations and MET gene amplification occur in 3-5% of non-small cell lung cancer (NSCLC) patients. Tyrosine kinase inhibitors (TKIs) targeting MET alterations have shown promising results in these patients. The aim of this study was to describe the genomic profile, PD-L1 expression and clinicopathological features of MET dysregulated NSCLC. We identified 188 patients with advanced-stage NSCLC with data on MET expression by immunohistochemistry (IHC). IHC for PD-L1 expression was performed in 131 patient samples, and next-generation sequencing (NGS) analysis was performed in 109 patient samples. MET exon 14 skipping alterations were identified in 16 (14.7%) samples, MET amplifications with cut-off ≥4 copy number variations were identified in 11 (10.1%) samples, and an oncogenic MET mutation (MET p.D1228N) was identified in 1 (0.9%) sample. 12/15 tumors (80.0%) harboring MET exon 14 alterations and 7/11 (63.6%) MET-amplified tumors expressed PD-L1 in ≥1% of tumor cells. Tumors harboring MET exon 14 skipping alterations expressed PD-L1 more frequently than MET wild-type IHC-positive tumors (p=0.045). Twenty-five percent of MET exon 14-altered cases and 33% of MET-amplified cases harbored potentially targetable oncogenic co-mutations in KRAS, BRAF, and EGFR. The most frequent co-occurring mutations in all MET-altered tumors were TP53, KRAS, BRAF, and CDK4. We demonstrated that MET exon 14 skipping alterations and MET amplification are not mutually exclusive to other oncogenic co-mutations, and report the association of genomic MET alterations with PD-L1 expression. Since genomic MET alterations are emerging targets requiring upfront treatment, optimal understanding of the co-mutational landscape for this patient population is needed.

Prevalence of MET aberration using next generation sequencing in oncology clinic: A real-world experience.

e16099 Background: MET has been known as an important therapeutic target in various solid cancer types. With the establishment of next-generation sequencing (NGS) in the oncology clinics, understanding the incidence of MET aberration in patients with metastatic cancer is critical for oncology drug development and efficacy. We investigated MET gene aberration in 2,239 oncology patients who underwent NGS in clinical practice with real-world data. Methods: From Nov. 2019 to Jan. 2021, 2,239 metastatic solid tumor patients who visited oncology clinic were enrolled in the NGS analysis. The NGS panel (TruSight Oncology 500 Assay, Illumina) was over 500 comprehensive sequencing using archival tissue specimen. In addition, PD-L1 22C3 assay results were available in 1,137 patients (50.8%) and 1,761(78.7%) patients had clinical record about 1st chemotherapy for overall survival analysis. Results: 2,239 patients with metastatic solid tumor (37 cancer types) received NGS as part of the clinical practice with an aim to be guided to targeted agents or immunotherapy. The most common cancer types were CRC (N = 702, 31.4%), followed by GC (N = 481, 21.5%), and sarcoma (N = 180, 8.0%). Of 2,239 patients, any MET aberrations (CNVs, fusions, and SNV) were detected in 212 patients. Of the 46 patients with MET amplification, 14 (30.4%) were GC followed by CRC (N = 10, 21.7%), melanoma (N = 7, 15.2%), CCC (N = 6, 13.0%), sarcoma (N = 2, 4.3%), HCC (N = 2, 4.3%), NSCLC (N = 2, 4.3%), pancreatic cancer (N = 2, 4.3%), and gallbladder cancer (N = 1, 2.2%). All MET-amplified tumors had microsatellite stable (MSS) status and 17.4 % patients (N = 8) were TMB-high status. And, 8 of MET-amplified patients concurrently showed MET-positive protein expression by IHC (2+ and 3+). Of note, MET fusion was detected in 0.4% (10 of 2,239) of the patients. The partner gene included ST7, TFEC, LRRD1, CFTR, CAV1, PCM1, HLA-DRB1 and CAPZA2. In survival analysis, patients having MET amplification or fusion had shorter OS and PFS than the others, suggesting MET aberration was an important key factor that could determine final response results to current chemotherapy. Conclusions: Based on our comprehensive NGS survey focused on MET aberration, we identified approximately 2.1% MET amplification and 0.4% MET fusion in patients with metastatic solid tumors. They showed worse response after chemotherapy and shorter OS and PFS.

Phase 1b/2 study of capmatinib plus gefitinib in patients with EGFR-mutated, MET-dysregulated non-small cell lung cancer who received prior therapy: Final overall survival and safety.

9048 Background: Primary findings from the phase 1b/2 study (NCT01610336) demonstrated clinical activity of combination therapy with capmatinib, a potent and selective MET inhibitor, and gefitinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) in heavily pre-treated patients with EGFR-mutated and MET dysregulated non-small cell lung cancer (NSCLC). The objective response rate (ORR) was 27% in patients across phase 1b/2 of the study. At the recommended phase 2 dose (R2PD) of capmatinib 400 mg twice-daily (bid) and gefitinib 250 mg once-daily (qd), the ORR was 47% in patients with high MET-amplified tumors ( MET gene copy number ≥6). Here, we report the updated data on the efficacy and safety from the NCT01610336 study. Methods: Patients with locally advanced or metastatic NSCLC harboring EGFR exon 19 deletion or L858R mutation with a recorded clinical benefit on prior single-agent EGFR-TKI before progression and confirmed dysregulated MET pathway after progression on EGFR TKIs were included. Patients in phase 1b received capmatinib 100 to 800-mg capsules qd or 200 to 600-mg capsules or tablets bid, plus gefitinib 250 mg qd. Patients in phase 2 received the R2PD dose. Data on the overall survival (OS) and cumulative safety endpoints are reported in this final analysis. Results: Overall, 161 patients received the combination treatment in this study; phase 1b (n = 61) and phase 2 (n = 100). The median age of patients was 60.0 years, mostly Asian (67.1%) with an Eastern Cooperative Oncology Group performance status of 0/1: 18.0%/78.3%. At data cut-off on May 27, 2020, all patients had discontinued the study; 82 out of the 100 patients in phase 2 had died and 18 were censored (mostly lost to follow-up [n = 15]). One patient was still on treatment with a partial response and rolled over to another study. The median (range) follow-up time for OS was 12.2 (0.9-70.2) months. The median OS was 13.9 months (95% confidence interval, 11.6-15.7 months). The median (range) duration of exposure for capmatinib plus gefitinib was 16 weeks (0.4-209.7 weeks) during phase 1b and 18.5 weeks (0.4-268.0 weeks) during phase 2. Majority of the patients (98.8%) experienced ≥1 adverse event (AE); 87% of the patients had treatment-related AEs. Most common treatment-related AEs (reported in ≥20%) were nausea (28.0%), peripheral edema (23%), rash (21.7%), and decreased appetite (21.1%). Grade 3 or 4 treatment-related AEs occurred in 51 patients (31.7%) across both phases, of which, the most frequent (reported in ≥5%) were increased amylase and increased lipase (6.2% each) and peripheral edema (5%). Conclusions: Capmatinib 400 mg bid in combination with gefitinib 250 mg qd was well-tolerated and showed encouraging clinical activity in patients with EGFR-mutant and MET-dysregulated NSCLC. Clinical trial information: NCT01610336.

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.

Genetic Heterogeneity of MET-Aberrant NSCLC and Its Impact on the Outcome of Immunotherapy

IntroductionRobust data on the outcome of MET-aberrant NSCLC with nontargeted therapies are limited, especially in consideration of the heterogeneity of MET-amplified tumors (METamp). MethodsA total of 337 tumor specimens of patients with MET-altered Union for International Cancer Control stage IIIB/IV NSCLC were analyzed using next-generation sequencing, fluorescence in situ hybridization, and immunohistochemistry. The evaluation focused on the type of MET aberration, co-occurring mutations, programmed death-ligand 1 expression, and overall survival (OS). ResultsMETamp tumors (n = 278) had a high frequency of co-occurring mutations (>80% for all amplification levels), whereas 57.6% of the 59 patients with MET gene and exon 14 (METex14) tumors had no additional mutations. In the METamp tumors, with increasing gene copy number (GCN), the frequency of inactivating TP53 mutations increased (GCN < 4: 58.2%; GCN ≥ 10: 76.5%), whereas the frequency of KRAS mutations decreased (GCN < 4: 43.2%; GCN ≥ 10: 11.8%). A total of 10.1% of all the METamp tumors with a GCN ≥ 10 had a significant worse OS (4.0 mo; 95% CI: 1.9–6.0) compared with the tumors with GCN < 10 (12.0 mo; 95% confidence interval [CI]: 9.4–14.6). In the METamp NSCLC, OS with immune checkpoint inhibitor (ICI) therapy was significantly better compared with chemotherapy with 19.0 months (95% CI: 15.8–22.2) versus 8.0 months (95% CI: 5.8–10.2, p < 0.0001). No significant difference in median OS was found between ICI therapy and chemotherapy in the patients with METex14 (p = 0.147). ConclusionsMETex14, METamp GCN ≥ 10, and METamp GCN < 10 represent the subgroups of MET-dysregulated NSCLC with distinct molecular and clinical features. The patients with METex14 do not seem to benefit from immunotherapy in contrast to the patients with METamp, which is of particular relevance for the prognostically poor METamp GCN ≥ 10 subgroup.

Revisiting MET: Clinical Characteristics and Treatment Outcomes of Patients with Locally Advanced or Metastatic, MET-Amplified Esophagogastric Cancers.

Metastatic esophagogastric cancers (EGCs) have a poor prognosis with an approximately 5% 5-year survival. Additional treatment approaches are needed. c-MET gene-amplified tumors are an uncommon but potentially targetable subset of EGC. Clinical characteristics and outcomes were evaluated in patients with MET-amplified EGC and compared with those without MET amplification to facilitate identification of these patients and possible treatment approaches. Patients with locally advanced or metastatic MET-amplified EGC at Massachusetts General Hospital (MGH) were identified using fluorescent in situ hybridization analysis, with a gene-to-control ratio of ≥2.2 defined as positive. Non-MET-amplified patients identified during the same time period who had undergone tumor genotyping and treatment at MGH were evaluated as a comparison group. We identified 233 patients evaluated for MET amplification from 2002 to 2019. MET amplification was seen in 28 (12%) patients versus 205 (88%) patients without amplification. Most MET-amplified tumors occurred in either the distal esophagus (n = 9; 32%) or gastroesophageal junction (n = 10; 36%). Of MET-amplified patients, 16 (57%) had a TP53 mutation, 5(18%) had HER2 co-amplification, 2 (7.0%) had EGFR co-amplification, and 1 (3.5%) had FGFR2 co-amplification. MET-amplified tumors more frequently had poorly differentiated histology (19/28, 68.0% vs. 66/205, 32%; p = .02). Progression-free survival to initial treatment was substantially shorter for all MET-amplified patients (5.6 vs. 8.8 months, p = .026) and for those with metastatic disease at presentation (4.0 vs. 7.6 months, p = .01). Overall, patients with MET amplification had shorter overall survival (19.3 vs. 24.6 months, p = .049). No difference in survival was seen between low MET-amplified tumors (≥2.2 and <25 MET copy number) compared with highly amplified tumors (≥25 MET copy number). MET-amplified EGC represents a distinct clinical entity characterized by rapid progression and short survival. Ideally, the identification of these patients will provide opportunities to participate in clinical trials in an attempt to improve outcomes. This article describes 233 patients who received MET amplification testing and reports (a) a positivity rate of 12%, similar to the rate of HER2 positivity in this data set; (b) the clinical characteristics of poorly differentiated tumors and nodal metastases; and (c) markedly shorter progression-free survival and overall survival in MET-amplified tumors. Favorable outcomes are reported for patients treated with MET inhibitors. Given the lack of published data in MET-amplified esophagogastric cancers and the urgent clinical importance of identifying patients with MET amplification for MET-directed therapy, this large series is a valuable addition to the literature and will have an impact on future practice.

Phase I Dose-Escalation and -Expansion Study of Telisotuzumab (ABT-700), an Anti–c-Met Antibody, in Patients with Advanced Solid Tumors

This first-in-human phase I study evaluated the pharmacokinetics, safety, and preliminary efficacy of telisotuzumab, formerly called ABT-700, an antagonistic antibody directed against c-Met. For dose escalation (3+3 design), 3 to 6 patients with advanced solid tumors were enrolled into four dose cohorts (5-25 mg/kg). In the dose-expansion phase, a subset of patients was prospectively selected for MET amplification (FISH screening). Patients received telisotuzumab intravenously on day 1 every 21 days. For dose expansion, 15 mg/kg was chosen as the dose on the basis of safety, pharmacokinetics, and other data from the escalation cohorts. Forty-five patients were enrolled and received at least one dose of telisotuzumab (dose escalation, n = 15; dose expansion, n = 30). Telisotuzumab showed a linear pharmacokinetics profile; peak plasma concentration was proportional to dose level. There were no acute infusion reactions and no dose-limiting toxicities were observed. The most common treatment-related adverse events included hypoalbuminemia (n = 9, 20.0%) and fatigue (n = 5, 11.1%). By Response Evaluation Criteria In Solid Tumors (RECIST), 4 of 10 (40.0%) patients with MET-amplified tumors had confirmed partial response in target lesions (one ovarian, two gastric, and one esophageal), two (20.0%) had stable disease, three (30.0%) had progressive disease; one patient was unable to be evaluated. Among patients with nonamplified tumors (n = 35), no objective responses were observed; however, 11 patients had stable disease per RECIST criteria. In conclusion, telisotuzumab has an acceptable safety profile with clinical activity observed in patients with MET-amplified advanced solid tumors.

Mechanisms of Acquired Resistance to Savolitinib, a Selective MET Inhibitor in MET-Amplified Gastric Cancer.

PURPOSESome gastric cancers harbor MET gene amplifications that can be targeted by selective MET inhibitors to achieve tumor responses, but resistance eventually develops. Savolitinib, a selective MET inhibitor, is beneficial for treating patients with MET-driven gastric cancer. Understanding the resistance mechanisms is important for optimizing postfailure treatment options.PATIENTS AND METHODSHere, we identified the mechanisms of acquired resistance to savolitinib in 3 patients with gastric cancer and MET-amplified tumors who showed a clinical response and then cancer progression. Longitudinal circulating tumor DNA (ctDNA) is useful for monitoring resistance during treatment and progression when rebiopsy cannot be performed.RESULTSUsing a next-generation sequencing 100-gene panel, we identified the target mechanisms of resistance MET D1228V/N/H and Y1230C mutations or high copy number MET gene amplifications that emerge when resistance to savolitinib develops in patients with MET-amplified gastric cancer.CONCLUSIONWe demonstrated the utility of ctDNA in gastric cancer and confirmed this approach using baseline tumor tissue or rebiopsy.

Elucidation of the relationships of MET protein expression and gene copy number status with PD-L1 expression and the immune microenvironment in non-small cell lung cancer

ObjectivesAlterations in the MET gene, such as mutations and high-level amplification, are important drivers of non-small cell lung cancer (NSCLC). The efficacy of immune checkpoint inhibitors (ICIs) in lung cancer with MET abnormalities is unclear. We evaluate the potential relationship between MET alterations and the tumor immune microenvironment and PD-1/PD-L1 axis. Material and MethodsMET and phospho-MET protein expression were assessed in 622 resected NSCLC specimens. MET amplification was assessed by fluorescence in-situ hybridization in 272 tumors. PD-L1 expression was evaluated by immunohistochemistry. CD8+, Foxp3+, CD45RO, and PD-1+ tumor-infiltrating lymphocytes (TILs) in the tumor nest and surrounding stroma were profiled. Associations with MET alterations were explored. ResultsThe cohort comprised 425 male patients (68.3 %), 184 never-smokers (29.6 %), and 408 adenocarcinoma (ADC) patients (65.6 %). Median age was 68 years. MET alteration was observed mainly in ADCs (18.9 % MET-positive, 3.9 % phospho-MET-positive, and 15.1 % with MET amplification). PD-L1 expression was significantly increased in MET-altered ADCs (P < 0.001 for MET; P = 0.002 for phospho-MET; P = 0.019 for MET amplification). Most TIL subset numbers in the tumor nest were significantly increased in MET-altered tumors. Only MET amplification was independently associated with tumoral CD8 + TILs. Three of the six patients responded to ICI treatment; two of them showed MET overexpression and an increase in MET copy number. ConclusionMET-altered tumors showed significantly stronger PD-L1 expression and more abundant tumoral TILs than non-MET-altered tumors. Among the MET alterations assessed, MET amplification was particularly implicated in the inflamed microenvironment, suggesting that MET-amplified tumors might respond to ICIs.

Abstract 4817: Preclinical evaluation of a new, non-agonist ADC targeting MET-amplified tumors with a peptide-linked maytansinoid

Abstract With cancer among the leading causes of death worldwide, the search for better, personalized treatments is imperative. Novel techniques such as next generation sequencing have identified many assayable genetic biomarkers associated with cancer in patient samples. The tyrosine kinase receptor cMet is one such biomarker that is upregulated in various solid tumors and associated with poor prognosis, disease progression and metastasis. While most patients with elevated cMet show increased levels through protein upregulation, a small population harbors gene amplification. These patients face worse outcomes which could be improved with therapies specifically targeting MET-amplification. Antibody-drug conjugates (ADCs) are a modality designed to selectively deliver highly potent cytotoxic agents to tumors. cMet is an attractive target for ADCs which may address the unmet treatment need for patients with tumors harboring MET amplification. Since dimerization of cMet receptors by ligand HGF leads to agonistic proliferative events, a carefully selected antibody should be chosen to avoid triggering activation. As previously described, we identified and humanized an antibody with minimal agonism. Introducing an additional disulfide in the hinge region while maintaining the IgG1 isotype further reduced agonism as measured in vitro in both cell proliferation and phosphorylation signaling assays, while retaining high affinity to human and cynomolgus cMet, and acceptable expression and biophysical properties. To assess potential toxicity due to normal tissue expression, we measured binding of our antibody to normal hepatocytes from humans and cynos. Here we found very low expression and binding versus tumor cell lines. Next, we demonstrated that the cytotoxic activity of disulfide-cleavable maytansinoid ADCs prepared from the hinge-variant cMet antibody were equivalent to the parental form in in vivo models. In a MET-amplified xenograft model of gastric cancer, Hs746T, both parental and modified hucMet-sSPDB-DM4 ADCs demonstrated tumor eradication and comparable plasma clearance at 5 mg/kg. Similar results were found in the MET-amplified NSCLC model EBC-1 at 2.5 mg/kg. Conjugation to the newly-described dipeptide-linked maytansinoid DM21 further improved anti-tumor activity in both Hs746T and EBC-1 models, with a 2-fold decrease in minimally-efficacious dose. The activity of hucMet27Gv1.3Hinge-L-DM21 was durable, with a single dose yielding full regressions and tumor-free survivors in both models (EBC-1, 1.25 mg/kg dose, 6/6 TFS d49; Hs746T, 2.5 mg/kg dose, 8/8 TFS d55). Taken together, these data demonstrate compelling cMet-targeted activity of hucMet27Gv1.3Hinge-L-DM21 in MET-amplified models of NSCLC and gastric cancer with a wide margin of safety. These data merit further exploration of this ADC as a novel treatment option for patients with MET-amplified tumors. Citation Format: Katharine C. Lai, Min Li, Kathryn Selvitelli, Surina Sikka, Steven Boulé, L Cristina Gavrilescu, Stuart W. Hicks, Kerry Donahue. Preclinical evaluation of a new, non-agonist ADC targeting MET-amplified tumors with a peptide-linked maytansinoid [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 4817.

Phase I Study of AMG 337, a Highly Selective Small-molecule MET Inhibitor, in Patients with Advanced Solid Tumors.

This first-in-human, open-label phase I study evaluated AMG 337, an oral, highly selective small-molecule inhibitor of MET in advanced solid tumors.Patients and Methods: Patients enrolled into dose-escalation cohorts received AMG 337 up to 400 mg once daily or up to 250 mg twice daily, following a modified 3+3+3 design. Dose expansion was conducted in MET-amplified patients at the maximum tolerated dose (MTD). Primary endpoints included assessment of adverse events (AEs), establishment of the MTD, and pharmacokinetics; clinical response was a secondary endpoint. The safety analysis set included 111 patients who received ≥1 dose of AMG 337. Thirteen patients had ≥1 AE qualifying as dose-limiting toxicity. The MTD was determined to be 300 mg once daily; the MTD for twice-daily dosing was not reached. Most frequent treatment-related AEs were headache (63%) and nausea (31%). Grade ≥3 treatment-related AEs occurred in 23 patients (21%), most commonly headache (n = 6) and fatigue (n = 5). Maximum plasma concentration occurred at 3.0 hours following 300-mg once-daily dosing, indicating AMG 337 absorption soon after treatment. Objective response rate was 9.9% (11/111; 95% CI, 5.1%-17.0%) in all patients and 29.6% (8/27; 95% CI, 13.8%-50.2%) in MET-amplified patients; median (range) duration of response was 202 (51-1,430+) days in all patients and 197 (64-1,430+) days in MET-amplified patients. Oral AMG 337 was tolerated with manageable toxicities, with an MTD and recommended phase II dose of 300 mg once daily. The promising response rate observed in patients with heavily pretreated MET-amplified tumors warrants further investigation.See related commentary by Ma, p. 2375.

MET-amplification (MET-amp) in relation to aggressive biology in esophagogastric cancer (EGC): An analysis of clinical outcomes of MET-amp vs non-MET-amp EGC.

74 Background: c-MET gene amplified ( MET-amp) tumors have been identified as a rare but targetable subset of esophagogastric cancer (EGC). In a phase I study, patients with MET-amp EGC had a 50% response rate to the oral MET inhibitor AMG 337, with some responses exceeding a year (Kwak EL, GI ASCO 2015). We evaluate clinical characteristics and outcomes were evaluated in patients with MET amplified esophagogastric cancer to facilitate identification of patients and establishment of treatment paradigms. Methods: Patients with metastatic MET amplified EGC were identified. MET-amplification was identified by fluorescent in situ hybridization (FISH) on paraffin-embedded tissue, with a gene to control ratio of &gt; 2.2 defined as positive. Clinical characteristics, treatment factors, and survival were recorded. A group of metastatic non- MET amplified patients identified during the same time period who had undergone tumor genotyping and treatment at our institution was evaluated as a comparison group. Results: 21 patients were identified with metastatic MET amplified EGC and 65 patients with metastatic non- MET amplified EGC. The majority of MET amplified tumors occurred in the distal esophagus. 4 patients had co-amplification of HER2, 1 patient had PIK3CA mutation and 1 patient had a TP53 mutation. Compared to non- MET amplified tumors, MET-amplified tumors were more likely to have poorly differentiated tumors. There was no difference in initial sites of metastatic disease. Progression-free survival (PFS) for first line therapy was substantially shorter for patients with MET (6.5 mo vs 14.3 mo, p = 0.0033). MET amplified patients trended towards a shorter overall survival (OS) as well (12.3 mo vs. 20.1 mo, p = 0.0523). Conclusions: MET amplified EGC represents a distinct clinical entity characterized by rapid progression and short survival. Given the efficacy seen with MET inhibition, patients need to be tested and identified early and directed to appropriate MET-targeted clinical trials.

Genetic screening and molecular characterization of MET alterations in non-small cell lung cancer

Aberrant activation of MET as a result of exon 14-skipping (METex14) mutations or gene amplification is an oncogenic mechanism in non-small cell lung carcinoma (NSCLC) and a potential therapeutic target. The purpose of this study was to characterize MET alterations in a cohort of NSCLC patients treated with surgery. 157 NSCLCs of various histopathologies, including pulmonary sarcomatoid carcinomas (PSC), were tested for MET alterations. METex14 mutations, MET copy number alterations and the levels of MET protein were determined by Sanger sequencing, fluorescence in situ hybridization and immunohistochemistry, respectively. Concurrent alterations of other important cancer genes and immunostaining of the downstream effector, phopho-S6, were also determined. METex14 mutations and MET amplification were detected in seven tumors. MET genetic alterations were found predominantly in the lung adenocarcinoma (ADC) and PSC histopathologies. High levels of MET protein were found in most MET-amplified tumors, but not in all METex14-mutated tumors. Strong phopho-S6 staining was observed in about half of the MET-activated tumors. One tumor with METex14 exhibited concurrent ERBB2 amplification. MET activation, by either METex14 mutations or amplification, is characteristic of a subset of early stage NSCLCs and may coexist with ERBB2 amplification. This may have potential therapeutic implications. The presence of METex14 mutations was associated with low levels of MET protein, which may limit the use of total MET immunostaining as a marker for preselecting patients for MET-targeted therapies.

Sym015: A Highly Efficacious Antibody Mixture against MET-Amplified Tumors.

Purpose: Activation of the receptor tyrosine kinase MET is associated with poor clinical outcome in certain cancers. To target MET more effectively, we developed an antagonistic antibody mixture, Sym015, consisting of two humanized mAbs directed against nonoverlapping epitopes of MET.Experimental Design/Results: We screened a large panel of well-annotated human cancer cell lines and identified a subset with highly elevated MET expression. In particular, cell lines of lung cancer and gastric cancer origin demonstrated high MET expression and activation, and Sym015 triggered degradation of MET and significantly inhibited growth of these cell lines. Next, we tested Sym015 in patient- and cell line-derived xenograft models with high MET expression and/or MET exon 14 skipping alterations, and in models harboring MET amplification as a mechanism of resistance to EGFR-targeting agents. Sym015 effectively inhibited tumor growth in all these models and was superior to an analogue of emibetuzumab, a monoclonal IgG4 antibody against MET currently in clinical development. Sym015 also induced antibody-dependent cellular cytotoxicity (ADCC) in vitro, suggesting that secondary effector functions contribute to the efficacy of Sym015.Retrospectively, all responsive, high MET-expressing models were scored as highly MET-amplified by in situ hybridization, pointing to MET amplification as a predictive biomarker for efficacy. Preclinical toxicology studies in monkeys showed that Sym015 was well tolerated, with a pharmacokinetic profile supporting administration of Sym015 every second or third week in humans.Conclusions: The preclinical efficacy and safety data provide a clear rationale for the ongoing clinical studies of Sym015 in patients with MET-amplified tumors. Clin Cancer Res; 23(19); 5923-35. ©2017 AACR.

Phase I dose-escalation study of the c-Met tyrosine kinase inhibitor SAR125844 in Asian patients with advanced solid tumors, including patients with MET-amplified gastric cancer.

SAR125844 is a potent and selective inhibitor of the c-Met kinase receptor. This was an open-label, phase I, multicenter, dose-escalation, and dose-expansion trial of SAR125844 in Asian patients with solid tumors, a subgroup of whom had gastric cancer and MET amplification (NCT01657214). SAR125844 was administered by intravenous infusion (260–570 mg/m2) on days 1, 8, 15, and 22 of each 28-day cycle. Objectives were to determine the maximum tolerated dose (MTD) and to evaluate SAR125844 safety and pharmacokinetic profile. Antitumor activity was also assessed. Of 38 patients enrolled (median age 64.0 years), 22 had gastric cancer, including 14 with MET amplification. In the dose-escalation cohort (N = 19; unselected population, including three patients with MET-amplification [two with gastric cancer and one with lung cancer]), the MTD was not reached, and the recommended dose was established at 570 mg/m2. Most frequent treatment-emergent adverse events (AEs) were nausea (36.8%), vomiting (34.2%), decreased appetite (28.9%), and fatigue or asthenia, constipation, and abdominal pains (each 21.1%); none appeared to be dose-dependent. Grade ≥ 3 AEs were observed in 39.5% of patients and considered drug-related in 7.9%. SAR125844 exposure increased slightly more than expected by dose proportionality; dose had no significant effect on clearance. No objective responses were observed in the dose-escalation cohort, with seven patients (three gastric cancer, two colorectal cancer, one breast cancer, and one with cancer of unknown primary origin) having stable disease. Modest antitumor activity was observed at 570 mg/m2 in the dose-expansion cohort, comprising patients with MET-amplified tumors (N = 19). Two gastric cancer patients had partial responses, seven patients had stable disease (six gastric cancer and one kidney cancer), and 10 patients had progressive disease. Single-agent SAR125844 administered up to 570 mg/m2 has acceptable tolerability and modest antitumor activity in patients with MET-amplified gastric cancer.

MET tyrosine kinase receptor expression and amplification as prognostic biomarkers of survival in gastroesophageal adenocarcinoma.

BACKGROUND MET gene amplification and Met protein overexpression may be associated with a poor prognosis. The MET/Met status is typically determined with fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC), respectively. Targeted proteomics uses mass spectrometry–based selected reaction monitoring (SRM) to accurately quantitate Met expression. FISH, IHC, and SRM analyses were compared to characterize the prognostic value of MET/Met in gastroesophageal adenocarcinoma (GEC).METHODSSamples from 447 GEC patients were analyzed for MET gene amplification (FISH) and Met protein expression (IHC and SRM). Cox proportional hazards models and Kaplan‐Meier estimates were applied to explore relations between Met, overall survival (OS), and clinical/pathological characteristics. Spearman's rank coefficient was used to assess the correlation between parameters.RESULTSPatients with MET‐amplified tumors had worse OS when: the MET/centromere enumeration probe for chromosome 7 FISH ratio was ≥ 2 (hazard ratio [HR], 3.13; 95% confidence interval [CI], 1.84‐5.33), the MET gene copy number was ≥5 (HR, 2.51; 95% CI, 1.45‐4.34), or ≥ 10% of the cells had ≥15 copies (HR, 4.28; 95% CI, 2.18‐8.39). Similar observations were made with Met protein overexpression by IHC (≥1 + intensity in ≥ 25% of the tumor cell membrane: HR, 1.39; 95% CI, 1.04‐1.86) or SRM (≥400 amol/μg: HR, 1.76; 95% CI, 1.06‐2.90). A significant correlation was observed between MET FISH/Met IHC, MET FISH/Met SRM, and Met IHC/Met SRM; only MET FISH and Met SRM were independent negative prognostic biomarkers in multivariate analyses.CONCLUSIONS MET amplification and overexpression, assessed by multiple methods, were associated with a worse prognosis in univariate analyses. However, only MET amplification by FISH and Met expression by SRM were independent prognostic biomarkers. Compared with IHC, SRM may provide an added benefit for informed decisions about Met‐targeted therapy. Cancer 2017;123:1061–70. © 2016 American Cancer Society.

O.04: Profiling of MET-Amplified Non-Small Cell Lung Cancer (NSCLC), Correlation to cMET Protein Expression/MET Exon 14 Skipping

Recent genomic studies of molecular subtypes of NSCLC revealed a plethora of data surrounding its underlying biology. Knowledge of EGFR-driven NSCLC has changed the way one molecular subtype is being managed. While MET-driven NSCLC has been documented, a lot remains unknown about this molecular subtype of NSCLC, in contrast to EGFR- and KRAS-mutated molecular subtypes. The purpose of this study is to investigate the genomics of MET-amplified NSCLC to further understand its tumor biology, and to indicate potential for clinical trials. In total, 3,540 NSCLC specimens underwent multiplatform testing at a CAP/ISO/CLIA-certified laboratory (Caris Life Sciences). Analysis included protein expression by immunohistochemistry (IHC), gene amplification by in situ hybridization (ISH), fusions by ArcherDx FusionPlex assay, and copy number variance (CNV)/mutation by next generation sequencing (NGS). The laboratory validated CISH assay, utilized a gene copy number > 5 to assess gene amplification. In this cohort, 3.1% (109/3,540) patients were MET-amplified. In MET-amplified tumors (n=109), protein expression by IHC showed no ALK expression (0/36), positive EGFR at 47.5% (38/80), and positive PD-L1 at 56.0% (36/64, using 5% cut off value with SP142 antibody), with a sub-group showing a PD-L1 positive rate (50% cut off) of 68.8% (11/16) using the recently FDA approved companion diagnostics kit (22C3 antibody). For gene translocation by FISH, ALK was 2.5% (2/79) and ROS1 was 0.0% (0/97). For mutational analysis, BRAF mutations were 6.5% (6/92), EGFR was 23.1% (21/91), ERBB2 was 1.1% (1/92), and KRAS was 13.0% (12/92). ForMET-amplified NSCLC specimens, cMET protein expression was detected in 92.5% (74/80), MET amplification by CNV was 66.7% (4/6), MET mutation rates were 5.4% (5/92), and MET fusion was found in 20.0% (1/5). Evaluation of the 3,540 specimens revealed 17 MET exon 14 skipping mutations with only two showing amplification (11.8%, 2/17). Our analysis reveals potentially targetable aberrations in MET-driven NSCLC. High PD-L1 rates in this group indicate potential for targeting with PD-1blockade therapy and potential for combined immune blockade/MET inhibition therapy. Differences in cMET alterations indicate the need to analyze patient specimens for MET using different technologies and to find the optimal threshold for MET. Further studies of this molecular subtype of NSCLC are urgently needed to elucidate the optimal therapy for these patients.

Abstract A04: Combined anti–MET/EGFR treatment results in complete tumor regression and prevents resistance onset in a MET-amplified gastroesophageal xenopatient cohort

Abstract Gastric cancer is the world third leading cause of cancer mortality. In spite of the significant therapeutic advances, the overall clinical outcome for patients with advanced gastric cancer is poor, with 5-20% 5-year survival. The only targeted therapy approved so far are trastuzumab, and Ramucirumab which have given unsatisfactory results. Around 50% of gastric tumors bear genetic alterations affecting tyrosine kinase pathways (mainly EGFR, HER3, FGFR2 and MET pathways, besides HER2) but their clinical validation as tumor drivers is missing. The need for new therapeutic options and the possible presence of “druggable” targets prompted us to investigate potential targeted therapies for this disease. Our project aims at identifying and validating targeted therapeutic strategies in gastric cancer, through the generation of a platform of gastric tumor patient-derived xenografts (PDXs), animal models in which tumor surgical specimens are directly transferred into mice. Upon engraftment, the tumor is split and re-implanted in a cohort of mice, allowing the simultaneous testing of different drugs on the same tumor. Thanks to the establishment of a network of 15 Italian centers for samples collection, we generated around 80 gastric PDXs and successfully derived cell lines and organoids from engrafted tumors. Among the tumors collected so far, we found HER2, EGFR, FGFR2, MET and KRAS amplifications. This gastric PDX platform will be exploited for: 1) Validation of candidate oncogenes as relevant targets and identification of efficient therapeutic strategies 2) Identification of novel molecular targets; 3) identification of genetic predictors of response/resistance. In the PDX platform we identified one tumor bearing a high level of MET gene amplification (26 gene copies). We thus performed a preclinical study on a cohort of patient-derived xenografts generated from the MET-amplified gastroesophageal tumor. Despite the high amplification level, MET inhibitors induced only a partial response, while the combined anti-MET/EGFR treatment led to complete tumor regression. Most important, the combo treatment also prevented resistance onset. This data represent the proof of concept that a combined anti-MET/EGFR therapy can be more effective than anti-MET treatment alone in MET-amplified gastroesophageal tumors, in the absence of EGFR genetic lesions. Citation Format: Simona Corso, Maria Apicella, Silvia Menegon, Marilisa Cargnelutti, Maria Stella Scalzo, Rossella Reddavid, Paola Cassoni, Anna Sapino, Maurizio De Giuli, Silvia Giordano. Combined anti–MET/EGFR treatment results in complete tumor regression and prevents resistance onset in a MET-amplified gastroesophageal xenopatient cohort. [abstract]. In: Proceedings of the AACR Special Conference: Patient-Derived Cancer Models: Present and Future Applications from Basic Science to the Clinic; Feb 11-14, 2016; New Orleans, LA. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(16_Suppl):Abstract nr A04.

Abstract 396: Analysis of MET-amplified solid tumors using chromogenic in situ hybridization (CISH)

Abstract MET amplification has been implicated in signaling pathways that promote cell proliferation, invasion, and survival. It has been identified as an oncogenic driver in various malignancies and is currently being investigated as a potential therapeutic target. To date, MET exon 14 skipping by sequencing and MET amplification by FISH have been found to have potential clinical utility in predicting those patients who may derive benefit from MET-targeted therapy. However, little research has been conducted on alternative technologies to FISH such as CISH, which does not require a dark room and can be interpreted by a board-certified pathologist. The purpose of this study is to report our experience with MET amplification across solid tumors using CISH. A retrospective analysis was done on 26,619 specimens analyzed for MET amplification by CISH at a CLIA-certified lab (Caris Life Sciences). The validated CISH assay, previously validated against a FISH assay, utilized a gene copy number &amp;gt; 5 to assess amplification. Concordance and correlative studies were done in MET-amplified, non-small cell lung cancer (NSCLC) specimens analyzed using a cMET IHC (SP44, 2+ or 3+ staining intensity in 50% or more tumor cell membrane) analyzing protein expression. Correlative studies involving co-existing aberrations, including PD-L1 (SP142, any intensity in at least 50% of tumor cells), in this MET-amplified, NSCLC cohort were also performed. MET amplification utilizing CISH was 0.7% (188/26,619) overall. MET-amplified solid tumors included carcinomas such as NSCLC (3.1%, 87/2767), gastric adenocarcinoma (3.8%, 11/293), esophageal and esophagogastric junction adenocarcinoma (3.3%, 11/338), and endometrial carcinoma (0.4%, 9/2020) along with non-carcinomas, including glioblastoma multiforme (1.0%, 5/510), uterine sarcoma (1.3%, 5/400), melanoma (0.4%, 2/538), and rare tumors such as placental-site trophoblastic tumor (100%, 1/1) and prostatic neuroendocrine tumor (100%, 1/1). A sub-analysis of MET-amplified, NSCLC specimens demonstrated co-occurring protein overexpression in 92.6% (75/81) of cases. These same MET-amplified, NSCLC specimens were found to have EGFR pathogenic/presumed pathogenic mutations (19.7%, 15/76), ALK rearrangements (2.5%, 2/80), and PD-L1 overexpression (27.5%, 14/51). ROS1 rearrangements were not detected in this NSCLC cohort (0%, 0/76). Our data suggest MET amplification detection utilizing CISH is a viable option for identifying MET-driven cancers. The presence of MET across various solid tumors contrasts with biomarkers like HER2, which are exclusive to carcinomas. A sub-analysis of our NSCLC population shows MET-amplified tumors contains a similar molecular distribution to the general NSCLC population. Future studies should incorporate MET CISH in clinical trials utilizing MET-targeted agents to determine its potential as a predictive test for evaluating who may derive the most benefit. Citation Format: David Arguello, Zoran Gatalica, Semir Vranic, Sandeep Reddy, Ari VanderWalde. Analysis of MET-amplified solid tumors using chromogenic in situ hybridization (CISH). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 396.