c-MET Amplification Research Articles

Molecular Mechanisms of Tyrosine Kinase Inhibitor Resistance Induced by Membranous/Cytoplasmic/Nuclear Translocation of Epidermal Growth Factor Receptor

IntroductionThe molecular mechanism underlying the induction of resistance to tyrosine kinase inhibitors (TKIs) via the membranous/cytoplasmic/nuclear translocation of EGFR has not yet been reported. MethodsWe performed immunohistochemistry to detect the distribution of EGFR in lung adenocarcinoma specimens after TKI treatment and analyzed the relationship between different EGFR locations and patient survival duration. Mass spectrometry analysis and immunoprecipitation were performed to show the interaction of cytosolic EGFR with YY1 associated protein 1 (YAP) and salt inducible kinase 2 (SIK2). Dual-luciferase assays, immunoblotting, real-time polymerase chain reaction, and functional experiments were used to elucidate the role of EGFR cytoplasmic/nuclear translocation in Hippo pathway dysregulation. ResultsPatients with advanced lung adenocarcinoma with membranous mutant EGFR (19del or 21 L858R) showed significantly longer progression-free survival than those with cytoplasmic mutant EGFR after gefitinib treatment. The concentration that inhibits 50% in PC-9 with cytoplasmic EGFR was higher than that in hunman non-small cell lung cancer 827 with membranous EGFR. During first-generation TKI resistance induction, membrane EGFR translocated to the cytoplasm/nucleus, accompanied by the Hippo pathway inhibition. Cytoplasmic EGFR and SIK2 interaction inhibited large tumor suppressor kinase 1 (LATS1) and macrophage stimulating 1 (MST1) interaction, promoting YAP nuclear translocation. However, cells with osimertinib-induced resistance also showed EGFR translocation and lower phospho-EGF receptor but did not show Hippo pathway inhibition. Moreover, osimertinib and erlotinib could restore sensitivity to each other in resistant cells. ConclusionsPlasma/nuclear translocation of EGFR and inhibition of the Hippo pathway are some of the important mechanisms underlying the resistance induced by first-generation TKIs. Membrane/plasma translocation of EGFR induced by osimertinib may be another resistance phenomenon besides MNNG HOS transforming gene (c-MET) amplification, C797S mutation, and ERK pathway inhibition.

JNJ-61186372 (JNJ-372), an EGFR-cMet bispecific antibody, in EGFR-driven advanced non-small cell lung cancer (NSCLC).

9009 Background: JNJ-372 binds EGFR and cMet to block ligand binding, promote receptor degradation, and trigger antibody-dependent cellular cytotoxicity in models of EGFR-mutated (EGFRm) NSCLC. Here we describe the ongoing phase 1 safety, pharmacokinetics (PK), and activity of JNJ-372 in patients (pts) with NSCLC, including 3rd generation tyrosine kinase inhibitor (3GTKI)-relapsed EGFRm NSCLC and EGFR Exon20ins disease. Methods: Pts received JNJ-372 (140–1400 mg) IV weekly for the first 28-day cycle and biweekly thereafter. 1050–1400 mg doses are being explored in dose expansion. Blood samples were collected for PK analyses. Efficacy by investigator per RECIST v1.1 in pts with EGFRm NSCLC treated at ≥700 mg is presented. Tumors were characterized by next-generation sequencing of circulating tumor (ct)DNA and/or tumor tissue. Results: As of 17 Jan 2019, 116 enrolled pts with NSCLC were treated. Median age was 63 years, 38% were male, 77% were Asian, and 97% had EGFR mutations. Mean duration of treatment was 3.8 months, longest exposure was 20 cycles. The PK data set included pts from Korea (77%) and the US (23%). At the 1050 mg dose, 72% of pts achieved average concentrations above the EC90 based on preclinical models. Adverse events (AEs; ≥20%) were rash (59%), infusion related reaction (58%), paronychia (28%), and constipation (22%). Additional EGFR/cMet-related AEs include stomatitis (17%), pruritis (15%), peripheral edema (11%), and diarrhea (7%). Grade ≥3 AEs were reported in 34% (8% treatment-related) with dyspnea (6%) and pneumonia (3%) most frequently observed. Among response-evaluable pts, 25/88 (28%) achieved best timepoint response of partial response (PR). 10/47 pts with prior 3GTKI therapy had best timepoint response of PR (6 confirmed), including 4 with C797S, 1 with cMet amplification, and 5 without identifiable EGFR/cMet-dependent resistance. 6/20 pts with Exon20ins had best timepoint response of PR (3 confirmed). Conclusions: JNJ-372 has a manageable safety profile consistent with EGFR and cMet inhibition. Preliminary responses were achieved in 3GTKI-relapsed disease, including C797S and cMet amplification, and Exon20ins disease; enrollment in dose expansion is ongoing. Clinical trial information: NCT02609776.

Understanding biological driver mutations and mechanism of resistance to EGFR-tyrosine kinase inhibitors in lung cancer patients using a novel translational platform.

e20555 Background: Lung cancer causes ~1.69 million deaths globally and 5-year survival rate is < 20%. Surgery is preferred for patients with early stage NSCLC, however, in > 50% cases lung cancers are diagnosed at an advanced stage. EGFR-TKIs, erlotinib and gefitinib have shown benefit in patients harboring sensitizing EGFR mutations, although 20-30% of NSCLC patients do not show good clinical response to EGFR-TKIs despite having the mutations. Several factors have been identified for de novo and acquired resistance to first generation EGFR-TKIs, including secondary mutations such as T790M, aberrant activation of bypass pathways such as amplification of c-MET, or other abnormalities in downstream pathways including KRAS mutations or loss of PTEN among others. There exist significant inter-patient variations in response profiles and mechanisms of resistance, which often confounds treatment selection on a personalized level, especially if first-line therapy fails. Methods: We have developed a patient tumor derived ex vivo platform technology using multi-disciplinary systems biology-based approach that recreates a patient’s tumor microenvironment by preserving the tumor-stromal architecture and immune contexture. Fresh tumor biopsies and 10-ml blood were collected from patients with IRB approval and patient consent. Tumors obtained from 21 lung cancer patients were grown ex vivo on our platform in presence of PBMC and autologous sera. The tumors were treated with standard of care chemotherapies and EGFR inhibitors, and drug efficacy on tumors were measured. Results: Of 18 tumor samples treated with EGFR-TKIs, 4 were predicted responders to gefitinib and 14 were predicted non-responders to EGFR-TKIs (erlotinib or gefitinib). Of the 14 non-responders, 7 were predicted responders to carboplatin/pemetrexed and/or carboplatin/docetaxel. Patients were followed, and clinical data was captured. Whole genome sequencing and mutational analysis was done on the tumors. Hits were validated by immunohistochemical assays. Data from molecular signatures of the tumors with functional, phenotypic assays, were used to delineate mechanism of resistance in individual lung cancer patients to EGFR-TKIs. Conclusions: We have developed an ex vivo, personalized platform, which enables prediction of treatment response on an individual level, and also aids in capturing resistance mechanisms for identifying actionable targets.

Effect of tivantinib on VEGF signaling pathways and apoptosis of gastric cancer cells with c-MET or VEGFA amplification.

e14719 Background: VEGFA is the key mediator of angiogenesis in cancer and previous studies reported that VEGFA expression was significantly up-regulated in gastric cancer tissues compared with matched normal tissues. We showed that increased levels of VEGFA are significantly associated with expression of hepatocyte growth factor receptor (MET) (r = 0.6255, P < 0.0001). In addition, it is well known that c-MET is potentially a highly plausible target for cancer therapy in gastric cancer. In this study, cytotoxic activity of tivantinib were evaluated in gastric cancer cells with high c-MET expression or VEGFA amplification. Methods: In this study, Western blot and quantitative real-time PCR analysis were used to detect the expression of protein and genes after treatment of tivantinib. In addition, MTS, flow cytometry, and migration assay were used. Results: Tivantinib inhibited growths of a high c-MET-expressed or VEGFA-amplified cell lines. Furthermore, in migration and apoptosis analysis, tivantinib induced apoptosis of SNU620, MKN45 (carried VEGFB mutation), AGS, and MKN28 cells but not in KATO III (carried VEGFB and VEGFC mutation) cells. We also found that tivantinib inhibited the VEGF signaling pathway and MYC expression in VEGFA-amplified gastric cancer cell lines. Conclusions: The data indicate that tivantinib could be a potential therapeutic agent for the treatment of gastric cancer with high c-MET expression or VEGFA amplification.

Antitumor Activity of DFX117 by Dual Inhibition of c-Met and PI3Kα in Non-Small Cell Lung Cancer.

Aberrant activation of hepatocyte growth factor (HGF)/c-Met signaling pathway caused by gene amplification or mutation plays an important role in tumorigenesis. Therefore, c-Met is considered as an attractive target for cancer therapy and c-Met inhibitors have been developed with great interests. However, cancers treated with c-Met inhibitors inevitably develop resistance commonly caused by the activation of PI3K/Akt signal transduction pathway. Therefore, the combination of c-Met and PI3Kα inhibitors showed synergistic activities, especially, in c-Met hyperactivated and PIK3CA-mutated cells. In our previous study, we rationally designed and synthesized DFX117(6-(5-(2,4-difluorophenylsulfonamido)-6-methoxypyridin-3-yl)-N-(2-morpholinoethyl) imidazo[1,2-a]pyridine-3-carboxamide) as a novel PI3Kα selective inhibitor. Herein, the antitumor activity and underlying mechanisms of DFX117 against non-small cell lung cancer (NSCLC) cells were evaluated in both in vitro and in vivo animal models. Concurrent targeted c-Met and PI3Kα by DFX117 dose-dependent inhibited the cell growth of H1975 cells (PIK3CA mutation and c-Met amplification) and A549 cells (KRAS mutation). DFX117 subsequently induced G0/G1 cell cycle arrest and apoptosis. These data highlight the significant potential of DFX117 as a feasible and efficacious agent for the treatment of NSCLC patients.

133P - A study evaluating the different treatment modalities for EGFR mutation positive advanced NSCLC patients that acquire c-MET amplification after EGFR TKI therapy resistant

133P - A study evaluating the different treatment modalities for EGFR mutation positive advanced NSCLC patients that acquire c-MET amplification after EGFR TKI therapy resistant

Crizotinib with or without an EGFR-TKI in treating EGFR-mutant NSCLC patients with acquired MET amplification after failure of EGFR-TKI therapy: a multicenter retrospective study

BackgroundMET amplification is associated with acquired resistance to first-generation epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) in treating non-small-cell lung cancer (NSCLC); however, the therapeutic strategy in these patients is undefined. Herein we report the clinical outcomes of patients with c-MET amplification resistance to EGFR-TKIs treated with crizotinib.MethodsWe retrospectively analyzed advanced NSCLC patients from five sites who were diagnosed with EGFR-mutant NSCLC and received EGFR-TKI treatment. After disease progression, these patients were confirmed to have a MET-to-centromere ratio (MET:CEN) ≥ 1.8 based on fluorescence in situ hybridization (FISH) examination and without a T790M mutation. We assessed the efficacy and safety of crizotinib to overcome EGFR-TKI resistance in EGFR-activating mutations NSCLC with acquired MET amplification.ResultsAmplification of the acquired MET gene was identified in 18 patients with EGFR-mutant NSCLC. Fourteen patients received crizotinib treatment after acquired resistance to EGFR-TKIs. Among the 14 patients, 6 (42.9%) received crizotinib plus EGFR-TKI and 8 (57.1%) received crizotinib monotherapy. The overall objective response rate (ORR) and disease control rate (DCR) were 50.0% (7/14) and 85.7% (12/14), respectively. The median PFS (mPFS) of patients receiving crizotinib monotherapy and crizotinib plus EGFR-TKI was 6.0 and 12.6 months, respectively (P = 0.315). Notably, treatment efficacy was more pronounced in patients with crizotinib than patients with chemotherapy (24.0 months vs. 12.0 months, P = 0.046). The mOS for 8 of 14 patients receiving crizotinib monotherapy and 6 of 14 patients receiving crizotinib plus EGFR-TKI was 17.2 and 24.0 months, respectively (P = 0.862). Among the 14 patients, 1 who received crizotinib monotherapy (grade 3 nausea) and 2 who received crizotinib plus EGFR-TKI (grade 3 elevated liver aminotransferase levels) received reduced doses of crizotinib (200 mg twice daily) to better tolerate the dose.ConclusionsWe observed the clinical evidence of efficacy generated by combination of crizotinib and previous EGFR-TKIs after the resistance to first-generation EGFR-TKIs. These results might increase evidence of more effective therapeutic strategies for NSCLC treatment. Combination therapy did not increase the frequency of adverse reactions.

Oncogenic alterations detected by droplet digital PCR in patients with metastatic colorectal cancer resistant to cetuximab.

575 Background: Anti-EGFR therapy is the standard of care for metastatic colorectal cancer (mCRC) patients with RAS and BRAF genes wild type (wt). Secondary alterations of several genes have been identified as possibly resistant mechanisms to EGFR blockade, these including mutations of KRAS, NRAS, BRAF, MEK and EGFR ectodomain, as well as amplifications of HER2 and c-MET. In this study, we investigated alterations of these targeted genes for mCRC patients with acquired resistance to cetuximab treatment by using non-invasive droplet digital PCR (ddPCR) method within circulating DNA. Methods: We enrolled 38 RAS and BRAF wt patients, who progressed after failure of cetuximab contained regimens between Jul 2015 and Jan 2018. Plasma samples from all 38 patients were collected and detected for seven candidates (mutation of KRAS, NRAS, EGFR, BRAF, MEK, amplification of HER2, c-MET) by using ddPCR at the time of baseline, each evaluation by interval of 2 months and documented progression. All clinical parameters were collected simultaneously. Results: A total of 23 secondary alterations were found in 17 (17/38,44.7%) cetuximab resistant patients. The targeted gene alterations were detected as follows: 9 (9/23,39%) RAS mutations, 5 (22%) HER2 amplifications, 5 (22%) EGFR mutations, 2 (9%) c-MET amplifications, 1 (4%) BRAF and 1 MEK mutation. Among 17 patients, 6 patients had multiple alterations, including 2 patients with KRAS+EGFR mutations, 2 patients with HER2+c-MET co-amplifications and 2 patients with KRAS gene exon 2 and 3 multiple mutations. Primary sites were 15 left sides and 2 right sides, descending colon (12 cases) was the most common origins. Eleven patients were synchronous disease. Twelve patients received cetuximab as first line therapy, whereas 5 patients in the ≥ 2nd line setting. All of these 17 patients, plasma levels of oncogenic alterations detected by ddPCR were showed dynamic changing and good agreement with tumor responding status. Conclusions: Oncogenic alterations detected by ddPCR were found in almost half mCRC patients resistant to cetuximab. Dynamic changes of specific alteration may facilitate making decisions for selection of anti-EGFR mAb during the treatment course.

ROS-1 re-arrangements and c-MET amplifications in adenocarcinoma lung: A tertiary care center study from North India.

C-ros oncogene 1, receptor tyrosine kinase (ROS 1) proto-oncogene 1, receptor tyrosine kinase (ROS-1) fusions are potent oncogenic drivers and these re-arrangements promote signal transduction programs leading to uninhibited cell survival and proliferation identified in 1-2% of cases of nonsmall-cell lung cancer. Mesenchymal epithelial transition factor (MET) receptor tyrosine kinase and its ligand are predominantly involved in epithelial mesenchymal transition and tissue regeneration. The MET amplification and overexpression is oncogenic in 3-7% cases. The objectives of this study were to identify the frequency of ROS-1 and c-MET protein expression in adenocarcinoma lung and to correlate it with the clinicopathological parameters and to analyze the histomorphology of cases that harbor the characteristic mutations (c-MET and ROS-1). Study group comprised a prospective cases series of 90 cases of adenocarcinoma lung. ROS-1 protein expression was determined by immunohistochemistry using the D4D6 rabbit monoclonal antibody (Cell Signaling, Danvers, MA) and c-MET protein expressed was analyzed using the SP-44 clone (Ventana Medical Systems). c-MET protein expression was identified in 33.33% cases (n = 30/90) with statistically significant thyroid transcription factor-1 (TTF-1) positivity. ROS-1 protein expression was detected in 3.33% cases (n-3/90), in biopsies from the respiratory tree with TTF-1 expression. This is the first study from the Indian subcontinent to identify the frequency of ROS-1 re-arrangements and MET amplification in the Indian population. The availability of targeted therapy that has a significant impact on survival makes it essential to detect these less frequent mutations.

Morphological characterization and molecular profiling of malignant pericardial effusion in patients with pulmonary adenocarcinoma.

Malignant pericardial effusions (MPCEs) is a common complication observed in advanced pulmonary adenocarcinoma. In such cases, investigating molecular alterations can have significant therapeutic implication in determining anticancer drugs. The objective was to evaluate the significance of cell block technique in the diagnosis of MPCE and further investigate the morphological and molecular profiles of MPCE in patients with pulmonary adenocarcinoma. Cytopathological and molecular profiles of 19 MPCE cases in patients with pulmonary adenocarcinoma were retrospectively analyzed. The control group consisted of 14 malignant pleural effusion (MPE) cases in patients with pulmonary adenocarcinoma. Anaplastic lymphoma kinase (ALK) and tyrosine-protein kinase Met (C-MET) expression was evaluated by fluorescence in situ hybridization (FISH). Epithelial growth factor receptor (EGFR) and K-Ras (KRAS) mutations were detected by ARMS real-time polymerase chain reaction (RT-PCR). Associations between MPCE and MPE were analyzed using Fisher's exact test. MPCE was found to have micropapillary and solid pattern predominant with mucin secretion compared to acinar patterns, as seen in MPE. Seventeen MPCE cases (89.5%) and all MPE cases (100%) underwent molecular analysis. Mutations in EGFR and KRAS, ALK rearrangement, and C-MET amplification were observed in MPCE and MPE with statistical differences. Additionally, two MPCE cases demonstrated EGFR T790M mutation and multiple insertions at L858. MPCE shows micropapillary and solid cytological patterns predominant with mucin secretion. MPCE are suitable to analyze oncogenic mutations and to develop targeted therapy for patients with pulmonary adenocarcinoma. Further molecular investigations may reveal novel molecular alterations.

Gastric cancer patient with c-MET amplification treated with crizotinib after failed multi-line treatment: A case report and literature review

Gastric cancer is one of the most common gastrointestinal tumors. Most patients have been in advanced stage at diagnosis and lack effective treatment. Molecular targeted drugs have become new therapeutic strategies. MET is an important driving gene for the development of gastric cancer. MET gene amplification and protein over-expression are closely related to the invasion and metastasis, late stage and poor prognosis of gastric cancer. Crizotinib is a small molecule inhibitor against MET. There are few reports of crizotinib in gastric cancer patients with c-MET amplification. This article reports a case of c-MET gene amplification in advanced gastric cancer with liver metastases. After 2 months of treatment with crizotinib, liver lesions were completely relieved and progression-free survival lasted for up to 20 months.

Real-life efficacy of osimertinib in pretreated patients with advanced non-small cell lung cancer harboring EGFR T790M mutation

Objectives The efficacy of osimertinib in pretreated patients with advanced non-small cell lung cancer (NSCLC) harboring EGFR T790 M resistance mutation was demonstrated in clinical trials. However, data on efficacy of osimertinib in real world remain rare.Materials and methods This retrospective multicentric study analyzed T790M-positive advanced NSCLC patients enrolled in French early access program for osimertinib. Patients were pretreated with first- or second-generation EGFR tyrosine-kinase inhibitor and for a majority with chemotherapy. Primary endpoints were progression-free survival (PFS) and overall survival (OS) from osimertinib initiation.Results 205 patients (mean age, 69.5 years; female, 68.8%; adenocarcinoma, 97.5%, never-smokers, 71.5%) were analyzed. Osimertinib was used in second and third line in 18.0% and 82.0% of patients, respectively. Median PFS was 12.4 (95% CI, 10.1–15.1) months. In patients with and without cerebral metastasis, PFS was 9.7 (7.7–13.5) and 15.1 (12.0–17.1) months (p = 0.21), respectively. PFS in second and third line or more was 12.6 (6.7–17.5) and 12.4 (9.7–15.3) months, respectively. Median PFS in patients with EGFR exon 19 deletion and exon 21 mutation was 13.5 (10.1–16.0) and 9.7 (7.4–13.2) months, respectively (p = 0.049). Median OS since osimertinib initiation was 20.5 (16.9–24.3) months: 23.1 (18.6–27.8) and 18.0 (12.2–22.2) months in patients without and with cerebral metastasis (p = 0.11); 17.5 (11.6–27.8) and 21.7 (17.3–24.3) months as second or third line of treatment or more (p = 0.46), respectively. Median OS in patients with EGFR exon 19 deletion and exon 21 mutation was 23.1 (18.6–25.7) and 15.3 (11.6–21.7) months, respectively (p = 0.03).Osimertinib dosage was modified in 8.0% of patients and definitively discontinued for adverse events in 5.9%. Fifty patients benefited from rebiopsy (persistence of T790 M mutation, 44.7%; C797S mutation, 21.1%; cMET amplification, 8.0%).Conclusion In pretreated patients with T790M-mutated advanced NSCLC, the efficacy of osimertinib appears similar in real-world setting to that of clinical trials.

In silico guided development of imine-based inhibitors for resistance-deriving kinases

Two major mechanisms involved in resistant NSCLC (non-small cell lung cancer) include secondary acquired mutation in EGFR (epidermal growth factor receptor), that is, EGFR T790M and amplification of c-MET (hepatocyte growth factor receptor). Thus, already established pharmacophore models of EGFR T790M and c-MET were employed to filter-out an in-house database. Further fitness score led to the selection of imino-pyrimidine scaffold. Followed by sketching of imino-pyrimidine derivatives having varied aryl substitutions, which were then docked and subjected to molecular dynamic simulations, to study the orientations and conformations of the designed molecules in the catalytic domain. Molecules with hydrophobic interaction with mutant residue M790 were selected. Finally, MM-GBSA (Molecular Mechanics‐Generalized Born Surface Area) calculations were performed, to study the effect of substitutions on the binding affinity of the double mutant EGFR towards these small molecules. Finally, the designed compounds were synthesized and evaluated for their kinase inhibitory potential using in-vitro experiments. Two compounds were found to possess sub-micromolar range inhibitory potential against EGFR (T790M), while one of the compound showed significant selective inhibitory potential against c-MET. Additionally, one compound was found to possess significant dual inhibitory potential against these target kinases.Communicated by Ramaswamy H. Sarma

Re-evaluation of HER2 status in patients with HER2-positive advanced or recurrent gastric cancer refractory to trastuzumab (KSCC1604)

BackgroundAnti-HER2 therapy has not demonstrated a survival advantage in the second-line setting of patients with HER2-positive gastric cancer. We conducted this study to assess changes in HER2 status and to identify possible biomarkers for acquired resistance after the use of trastuzumab as the first-line therapy. Patients and methodsPatients with advanced or recurrent HER2-positive gastric adenocarcinoma who were diagnosed with progressive disease after the first-line trastuzumab-based therapy and developed pathologically confirmed adenocarcinoma within 3 months after completion of trastuzumab-based therapy were enrolled in this study. We collected re-biopsied samples from the HER2-positive patients who had developed resistance to trastuzumab and re-evaluated their HER2 status. Amplification of EGFR and c-met, as well as PIK3CA mutation, were comparatively analysed when samples were available. ResultsAmong 33 eligible patients, loss of HER2 was identified in 20 patients (60.6%) with refractory disease. Immunohistochemistry showed that the rate of HER2 overexpression was greatly reduced after therapy (pre-HER2 3+: 24 [72.7%] vs. post-HER2 3+: 13 [39.4%]). We found that the use of fixatives other than 10% neutral buffered formalin significantly reduced the HER2-positive rate. EGFR amplification, c-met amplification and PIK3CA mutation before and after trastuzumab-based therapy were observed in 10.3% and 3.8%, 17.9% and 4.2% and 4.0% and 4.2% of cases, respectively. ConclusionRe-evaluation of HER2 status is needed to determine the appropriate use of anti-HER2–targeted therapy after disease progression. Our results also highlight the importance of formalin fixation conditions for HER2 testing.

P1.15-15 Real-world Experience with Afatinib after Failure of First-Generation Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitor

Background: Afatinib, a second-generation epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI) is the recommended first-line treatment for patients with advanced non-small cell lung cancer harbouring sensitizing EGFR mutations. The role of afatinib after failure of first-generation EGFR-TKIs is controversial. Method: A retrospective observational study of patients with EGFR mutant advanced NSCLC receiving second-line afatinib after failure of firstgeneration EGFR-TKI in University Malaya Medical Center from 1st December 2014 to 30th April 2018. Result: The demographic and clinical characteristics of 27 patients treated with afatinib after failure of first-generation EGFR-TKI are shown in Table 1. Twenty-three patients received gefitinib and 4 patients received erlotinib as first-line treatment. The mPFS with first-line treatment was 11.9 months. Fifteen patients had progression of disease (PD) following second-line afatinib with mPFS of 4.2 months and median time-to-treatment failure of 5.7 months. The mPFS2 conferred by first-line first-generation EGFR-TKI and second-line afatinib was 18.4 months. The overall response rate to second-line afatinib was 18.5% (5/27) while the disease control rate as 70.3% (19/27). Two patients who had PD on first-generation EGFR-TKI due to T790M mutation received second-line afatinib while waiting for compassionate access to osimertinib. Nine of the 15 patients (69.2%) with PD on afatinib underwent investigations for resistance mechanisms. Three patients had T790M mutation, one of whom had concomitant small cell lung cancer transformation. c-MET amplification was detected in another 3 patients. One patient each had EML4-ALK rearrangement and epithelial mesenchymal transition. Conclusion: Afatinib conferred a modest mPFS benefit after failure of first-generation EGFR-TKI. The mPFS of sequential treatment with first-generation EGFR-TKI followed by afatinib seems longer than the mPFS of first-line afatinib in phase 3 randomised controlled trials. Apart from T790M mutation, the resistance mechanisms to second-line afatinib in our patients are more heterogenous.

P2.13-21 MET Addiction Can be Circumvented Through EGFR Inhibition Via AXL in MET-Amplified Primary Resistant EGFR-Mutant NSCLCX.

Primary resistance to EGFR-TKI is observed in approximately 10% of patients with activating EGFR mutations. In a patient harboring L858R mutation and high cMET amplification (MET copy number 7.3, CEP7 ratio 3.4) who progressed after just 4 weeks of erlotinib (ERL), significant tumor regression was achieved with MET inhibition alone (Crizotinib, CRZ). We confirmed this phenotype in the corresponding patient-derived cell line model (A482) and identified EGFR-AXL interaction as a mechanism that can circumvent clonal cMET addiction. We generated patient-derived cell lines from the patient’s baseline neck excision biopsy (A482) and evaluated the effect of mono and combination therapy (ERL, CRZ, ERL-CRZ) on A482, including viability (CellTiter-Glo Luminescent Assay, Promega), colony forming (Crystal Violet Assay), downstream signaling (Western blots) and adaptive pathways (Human Phosho-Receptor Tyrosine Kinase Array Kit, RandD systems). AXL was identified as a key mediator of resistance and subsequently subjected to further functional validation. Finally, we examined the prevalence of this clinical phenomenon in a retrospective series of MET amplified EGFR-mutant NSCLC. Cell viability assays confirmed the patient-derived cell line to be more sensitive to CRZ as compared to ERL alone or with combination CRZ-ERL. Upregulation of AXL, RET and FGFR3 expression were identified as adaptive changes 24 hours upon ERL exposure. A targeted pharmacologic screen revealed A482 to be exquisitely sensitive to combination EGFR and AXL inhibition. Immunoprecipitation revealed a direct interaction between EGFR and AXL, which upon treatment with ERL resulted in attenuation of cMET addiction. Co-existing cMET amplification with demonstrated suboptimal response to EGFR TKI was found in 3% of EGFR-mutant NSCLC in a retrospective series of patients. Targeting the EGFR-AXL axis through EGFR inhibition alone can lead to paradoxical MET pathway activation, while the combination of EGFR and AXL inhibition can circumvent downstream signaling in MET amplified EGFR-mutant NSCLC. AXL expression levels can potentially identify patients in whom combination or monotherapy with MET inhibitors may be most beneficial. Our data highlights the challenge in interpreting genomic alterations alone; and how cellular context can lead to differential sensitivities to EGFR and MET inhibitors alone and/or in combination in MET amplified EGFR-mutant NSCLC.

Crizotinib treatment for patients with EGFR mutation positive NSCLC that acquire cMET amplification after EGFR TKI therapy results in short-lived and heterogeneous responses

PurposeNext to secondary epidermal growth factor receptor (EGFR) mutations, cMET amplification plays an important role in mediating acquired resistance to EGFR tyrosine kinase inhibitors (TKI) treatment. Crizotinib, a dual ALK and cMET inhibitor, can induce responses in patients with EGFR mutation positive non-small cell lung cancer (NSCLC) that acquire cMET amplification after EGFR TKI treatment. However, little is known about the duration of response and post-progression resistance mechanisms. Here, we report on the clinical outcome of a series of patients with cMET-driven resistance to EGFR TKIs, treated with crizotinib. Materials and methodsEight patients with EGFR mutation positive NSCLC that acquired cMET amplification after EGFR TKI treatment were treated with crizotinib 250 mg twice daily, as monotherapy (n = 2) or in combination with an EGFR TKI (n = 6). ResultsFour out of eight patients (50%) showed a partial response (PR) according to RECIST 1.1. Median progression-free survival (PFS) was 1.4 (95% CI 1.2–5.0) months. Responses were short-lasting with a median PFS of 3.5 (95% CI 1.4–5.2) months in patients with a PR. Median overall survival was 5.9 (95% CI 1.3–6.0) months and not statistically different between responders and non-responders (p = 0.37). All but one patient tolerated crizotinib treatment well. Heterogeneous responses were seen in patients with progressive disease as best response with a marked size decrease of the biopsied (cMET amplification positive) lesion and progression of other lesions. cMET amplification was not always mutually exclusive with other EGFR TKI resistance mechanisms. Post-progression biopsies were negative for cMET amplification. ConclusionCrizotinib treatment for patients with EGFR mutation positive NSCLC that acquire cMET amplification after EGFR TKI treatment results in short-lived and often heterogeneous responses, possibly due to subclonality of cMET-driven resistance and co-occurrence of other EGFR TKI resistance mechanisms.

Does the primary site really matter? Profiling mucinous ovarian cancers of uncertain primary origin (MO-CUP) to personalise treatment and inform the design of clinical trials

ObjectiveAdvanced stage mucinous ovarian cancers are diagnostically and therapeutically challenging. Histotype specific trials have failed due to low recruitment after excluding non-ovarian primaries. Mucinous ovarian cancers are commonly metastatic from other sites however lack definitive diagnostic markers. We suggest a classification of mucinous ovarian cancers of uncertain primary origin ‘MO-CUPs’ in clinical trials. This study aims to identify drug targets to guide treatment and future trials. MethodsWe analyzed a large de-identified, multi-platform tumor profiling dataset of MO-CUPs enriched for advanced stage and recurrent cases submitted to Caris Life Sciences. Available data included a 45-gene next-generation sequencing (NGS) panel, gene amplification of HER2 and cMET and 18 immunohistochemical (IHC) markers of drug sensitivity/resistance. ResultsMucinous tumors from 333 patients were analyzed, including 38 borderline tumors and 295 invasive cancers. The most common mutations in a subset (n = 128) of invasive cancers were KRAS (60%), TP53 (38%), PIK3CA (13%) and PTEN (9%). Borderline tumors had higher rates of BRAF mutations, and PGP and TOP2A overexpression than invasive cases. KRAS mutant invasive cancers had lower expression of thymidylate synthase (p = 0.01) and higher expression of TUBB3 (p = 0.01) than KRAS wildtype tumors. ConclusionsTo our knowledge, this is the largest series profiling mucinous ovarian cancers and almost certainly includes cases of ovarian and non-ovarian origin. Given the difficulty recruiting patients to histotype-specific trials in rare subsets of ovarian cancer, it may be more important to focus on identifying potential treatment targets and to personalise treatment and design clinical trials in MO-CUPS agnostic of primary site to overcome these issues.

Abstract 4576: Combination of a label independent CTC enrichment platform with fluorescence in situ hybridization for the molecular characterization of CTCs in non-small cell lung cancer patients

Abstract Background: Patients with EGFRmt non-small cell lung cancer (NSCLC) develop resistance to first (erlotinib/ gefitinib) and second (afatinib) generation EGFR tyrosine kinase inhibitors (EGFR TKIs). Circulating tumor cells (CTCs) may be used as a potential biological material to monitor genetic alterations during the clinical course of the disease. We used the ParsortixTM (ANGLE) system, a label-independent microfluidic-based technology platform, to enrich CTCs from whole blood of NSCLC patients to evaluate the presence of HER-2 and c-MET amplification using fluorescence in situ hybridization (FISH). Materials and methods: Peripheral blood (PB) (15mL) from 42 patients with EGFRmt and resistant to 1st and 2nd generation EGFR TKIs NSCLC was obtained before, during and after treatment with osimertinib. CTCs were isolated using the ParsortixTM system and were further analyzed for HER-2 and c-MET amplification by FISH. Results: PB samples were obtained before (n=42), after one cycle (n=12) and at PD (n=7) during treatment with Osimertinib. One patient had HER-2 amplified CTCs whereas in total, 5 patients had marginally HER-2-positive CTCs; HER-2-positive CTCs were observed in 1/42 baseline sample but in none post-1st cycle and PD samples. Similarly, c-MET amplification was detected in 3/42 patients at baseline whereas in total 4 patients had marginally c-MET-positive CTCs. Treatment with Osimertinib resulted in a decrease of the number of c-MET amplified CTCs in these patients. In all c-MET and HER-2 amplified CTCs there was no HER-2 or c-MET amplification in the primary tumor. c-MET amplification in the primary tumor was detected only in one patient, however this patient had no detectable CTCs. Conclusions: Our preliminary results indicate that in selected patients with EGFRmt NSCLC, detection of HER-2 or c-MET amplified CTCs may be correlated with tumor resistance to EGFR TKIs. The ParsortixTM system can be successfully combined with downstream FISH analysis for the molecular characterization of CTCs in NSCLC patients. More samples are currently being analyzed in order to reveal the implication of HER-2 and c-MET amplification in resistance to therapy with first, second and third generation EGFR TKIs. Citation Format: Aliki Ntzifa, Martha Zavridou, Pavlos Pollakis, Georgia Bardi, Vasilis Georgoulias, Athanasios Kotsakis, Evi Lianidou. Combination of a label independent CTC enrichment platform with fluorescence in situ hybridization for the molecular characterization of CTCs in non-small cell lung cancer patients [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 4576.

Abstract 1816: Mechanism of resistance to single treatment with MET inhibitor in EGFR-mutant lung cancer cell secondarily acquiring c-MET amplification

Abstract Amplification in c-MET is the second most common mechanism of resistance to EGFR tyrosine kinase inhibitors (TKI) in lung cancer harboring activated EGFR mutations. An acquired resistance mechanism to single treatment with MET kinase inhibitor remains unknown. In this study, we modeled acquired resistance to experimental type I MET kinase inhibitor PHA66572 in MET-amplified HCC827 lung cancer cell line, which was established under chronic exposure to gefitinib in our lab. We found that reactivation of the EGFR pathway emerges as a resistance mechanism in MET secondarily amplified EGFR-mutant lung cancer cells after prolonged exposure to PHA66572. Any gene alteration influencing sensitivity to the drugs was not observed. Long treatment with only MET inhibitor resulted in partial resensitization to EGFR-TKI in these resistant lung cancer cells. Thus, the combination of gefitinib and PHA66572 could completely suppress the cell growth. Our findings support an intimate relationship between the EGFR and MET signaling pathways in HCC827 lung cancer cell line. Citation Format: Youngjoo Lee, Yu-Ra Choi. Mechanism of resistance to single treatment with MET inhibitor in EGFR-mutant lung cancer cell secondarily acquiring c-MET amplification [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 1816.