Isamu Okamoto

Kyushu University, Hukuoka, Fukuoka, Japan

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Publications (201)1142.26 Total impact

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    ABSTRACT: The standard diagnostic method for echinoderm microtubule-associated protein-like 4-anaplastic lymphoma receptor tyrosine kinase translocation is fluorescence in situ hybridization (FISH). Recently, immunohistochemistry (IHC) has been reported as a potential method in screening for anaplastic lymphoma kinase (ALK)-positive non-small-cell lung carcinomas (NSCLC), whereas several authors have reported a discordance between FISH and IHC results. We investigated the heterogeneity of ALK gene rearrangement in excision specimens by FISH and also examined whether the FISH score of ALK gene rearrangement corresponded in excision and biopsy samples from the same patient. Twenty ALK IHC-positive patients including six patients treated with crizotinib therapy were evaluated for the presence of ALK FISH. For evaluation of heterogeneity of ALK gene rearrangement in excision specimens, we defined six to 10 observation areas in each case, and the number of ALK FISH positive observation areas (≥15% rearrangement detected) was investigated. ALK FISH score in small biopsy samples was classified as positive (≥15% rearrangement detected), equivocal (5-14% rearrangement detected), or negative (<4% rearrangement detected). Of a total of 64 tumor observation areas from nine excision specimens, 50 areas were positive for ALK gene rearrangement (81.8%). In the comparison of excision and small biopsy samples, all excision specimens were ALK FISH-positive (100%; 6 of 6), whereas only three of the small biopsy samples in these patients were positive (50%; 3 of 6), two were equivocal (33%; 2 of 6), and one was negative (17%; 1 of 6). The two equivocal patients received crizotinib and showed a response. ALK gene rearrangement heterogeneity was observed in NSCLC specimens by FISH. Our findings suggested that IHC-positive/FISH-equivocal cases should not be considered true "false-negatives" when a small biopsy sample was used for ALK analysis.
    Journal of thoracic oncology: official publication of the International Association for the Study of Lung Cancer 05/2015; 10(5):800-5. DOI:10.1097/JTO.0000000000000507 · 5.80 Impact Factor
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    ABSTRACT: Crizotinib was the first clinically available inhibitor of the tyrosine kinase ALK, and next-generation ALK inhibitors, such as alectinib, are now under development. Although crizotinib is generally well tolerated, severe esophageal injury has been reported as a rare but serious adverse event of crizotinib therapy. We now describe the successful treatment with alectinib of a patient who developed crizotinib-induced esophageal ulceration. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
    Lung cancer (Amsterdam, Netherlands) 03/2015; DOI:10.1016/j.lungcan.2015.03.012 · 3.74 Impact Factor
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    ABSTRACT: The epidermal growth factor family (EGF) has been suggested to influence the sensitivity to anti-epidermal growth factor receptor therapy. We examined the correlation between circulating levels of the epidermal growth factors amphiregulin and transforming growth factor-α (TGF-α) and the MET ligand hepatocyte growth factor and sensitivity to the anti-epidermal growth factor receptor antibody in colorectal cancer (CRC) patients. Plasma levels of each ligand were measured by enzyme-linked immunosorbent assay in 51 patients with wild-type KRAS CRC. Patients with high hepatocyte growth factor (HGF) levels had a significantly lower disease control rate (DCR) and shorter median progression-free survival (PFS) and overall survival (OS) than those with low expression levels. Amphiregulin was correlated with objective response rate (ORR) but not with PFS or OS. Cetuximab response and survival were not associated with TGF-α. Circulating HGF may help identify CRC patients most likely to benefit from anti-epidermal growth factor receptor antibody therapy. Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.
    Anticancer research 03/2015; 35(3):1683-9. · 1.87 Impact Factor
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    ABSTRACT: Three epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) – afatinib, erlotinib, and gefitinib – are available for the treatment of patients with EGFR mutation-positive non-small cell lung cancer (NSCLC). Given the long-term exposure of such patients to EGFR-TKIs, the toxicological properties of these agents in these individuals may differ from those observed in unselected patients. We compared the frequencies of severe adverse events (AEs) among EGFR mutation-positive NSCLC patients treated with these three EGFR-TKIs.
    Lung Cancer 02/2015; DOI:10.1016/j.lungcan.2015.01.026 · 3.74 Impact Factor
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    ABSTRACT: Given our previously published study, α 1 nicotinic acetylcholine receptors (nAChR) plays an essential role in nicotine-induced cell signaling and nicotine-induced resistance to epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) in non-small cell lung cancer (NSCLC) PC9 cells. The aim of this study was to investigate the potential mechanism between nAChR and EGFR for nicotine-induced resistance to EGFR-TKI erlotinib in the NSCLC xenograft model.
    Lung Cancer 01/2015; 88(1). DOI:10.1016/j.lungcan.2015.01.017 · 3.74 Impact Factor
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    ABSTRACT: Nearly half of all cases of acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) for non–small-cell lung cancer (NSCLC) are due to the T790M mutation in EGFR exon 20. The T790M mutation is a C → T transition mutation at a CpG dinucleotide. DNA methylation of cytosine (5-methylcytosine; 5-mC) in CpG dinucleotides is a common DNA modification; CpG dinucleotides are considered to be mutational hotspots that cause genetic diseases and cancers through spontaneous deamination of 5-mC, resulting in C → T transition mutations. This study aimed to examine the methylation level of cytosine of EGFR codon 790 and investigate whether DNA methylation was involved in acquiring the T790M mutation. We examined 18 NSCLC tumor tissues, 7 normal lymph node tissues and 4 NSCLC cell lines (PC9, HCC827, 11-18 and A549). 5-mC was checked by bisulfite sequencing and quantified by pyrosequencing. We found that all tissue samples and cell lines had 5-mC in EGFR codon 790. The 5-mC range was 58.4–90.8%. Our results imply that hypermethylation of the CpG dinucleotide in EGFR codon 790 leads to the C → T transition mutation, causing resistance to EGFR-TKI treatment.
    Cancer Genetics 01/2015; DOI:10.1016/j.cancergen.2014.12.005 · 2.42 Impact Factor
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    ABSTRACT: Hepatocyte growth factor (HGF) expression is a poor prognostic factor in various types of cancer. Expression levels of HGF have been reported to be regulated by shorter poly(dA) sequences in the promoter region. In the present study, the poly(dA) mononucleotide tract in various types of human cancer cell lines was examined and compared with the HGF expression levels in those cells. Short deoxyadenosine repeat sequences were detected in five of the 55 cell lines used in the present study. The H69, IM95, CCK-81, Sui73 and H28 cells exhibited a truncated poly(dA) sequence in which the number of poly(dA) repeats was reduced by ≥5 bp. Two of the cell lines exhibited high HGF expression, determined by reverse transcription quantitative polymerase chain reaction and enzyme-linked immunosorbent assay. The CCK-81, Sui73 and H28 cells with shorter poly(dA) sequences exhibited low HGF expression. The cause of the suppression of HGF expression in the CCK-81, Sui73 and H28 cells was clarified by two approaches, suppression by methylation and single nucleotide polymorphisms in the HGF gene. Exposure to 5-Aza-dC, an inhibitor of DNA methyltransferase 1, induced an increased expression of HGF in the CCK-81 cells, but not in the other cells. Single-nucleotide polymorphism (SNP) rs72525097 in intron 1 was detected in the Sui73 and H28 cells. Taken together, it was found that the defect of poly(dA) in the HGF promoter was present in various types of cancer, including lung, stomach, colorectal, pancreas and mesothelioma. The present study proposes the negative regulation mechanisms by methylation and SNP in intron 1 of HGF for HGF expression in cancer cells with short poly(dA).
    Oncology letters 01/2015; 9(1):405-410. DOI:10.3892/ol.2014.2702 · 0.99 Impact Factor
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    ABSTRACT: Amatuximab is a chimeric monoclonal antibody that targets mesothelin, which is expressed in virtually all mesotheliomas and pancreatic adenocarcinomas. The objective of this study was to determine the dose-limiting toxicity and the maximum tolerated dose. Patients with mesothelioma, pancreatic adenocarcinoma or other mesothelin-positive solid tumors were eligible for this study. Amatuximab was administered weekly as an intravenous infusion in 4-week cycles at progressively increasing doses ranging from 50 to 200 mg/m2. Seventeen patients received amatuximab. Two dose-limiting toxicities were observed: one at 50 mg/m2 and one at 200 mg/m2; the maximum tolerated dose of this study was determined to be 200 mg/m2. Of the 17 patients, 13 patients (76.5 %) experienced treatment-related adverse events. The most common adverse events were grade 1 fatigue (29.4 %) and pyrexia (23.5 %). The maximum serum concentration and area under the concentration curve values increased in an almost dose-proportional manner. Three patients had stable disease. Amatuximab was generally well tolerated at doses up to 200 mg/m2. The pharmacokinetic profile of amatuximab in the Japanese population was similar to that seen in the United States population (Clinical Identifier: NCT01018784).
    Investigational New Drugs 12/2014; DOI:10.1007/s10637-014-0196-0 · 2.93 Impact Factor
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    ABSTRACT: Background S-1, a novel oral fluoropyrimidine, has potent antitumor activity against non–small-cell lung cancer (NSCLC). Meanwhile, leucovorin enhances the efficacy of 5-fluorouracil by inhibiting thymidylate synthase. Therefore, this phase II clinical trial evaluated the safety and efficacy of S-1 plus leucovorin combination therapy for previously treated patients with NSCLC. Patients and methods Patients with stage IIIB or IV NSCLC were prospectively enrolled if they received 1 or 2 prior chemotherapy regimens. S-1 (40–60 mg) and leucovorin (25 mg) were administered together orally twice per day for 7 consecutive days followed by 7 days of rest. This 2-week cycle was repeated for a maximum of 25 cycles until the onset of disease progression or unacceptable adverse events. Endpoints included objective tumor response, progression-free survival, overall survival, and safety. Results Among 33 patients, 6 (18.2%), 14 (42.4%), and 11 (33.3%) had partial response, stable disease, and progressive disease, respectively. Median progression-free and overall survival times were 3.5 and 11.7 months, respectively. The common grade 3 toxicities included stomatitis (18.2%), anorexia (12.1%), and neutropenia (9.1%). One patient had pneumatosis cystoides intestinalis, and another experienced paralytic ileus. There were no treatment-related deaths. Conclusions S-1 plus leucovorin combination therapy demonstrated promising efficacy and an acceptable toxicity profile in previously treated patients with NSCLC (Clinical Trials Registry No.: UMIN000004568).
    Lung Cancer 12/2014; 86(3). DOI:10.1016/j.lungcan.2014.10.010 · 3.74 Impact Factor
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    ABSTRACT: Crizotinib is the first clinically available tyrosine kinase inhibitor that targets anaplastic lymphoma kinase (ALK) and is associated with the development of complex renal cysts. We now describe a 39-year-old woman who developed infected complex renal cysts during crizotinib treatment. After 10 months of such treatment, she presented with a high fever and low back pain. Computed tomography findings were consistent with complex renal cysts and perilesional inflammation. Interventions including cyst drainage and antibiotic administration contributed to diagnosis and management of the infected cysts.
    Investigational New Drugs 11/2014; DOI:10.1007/s10637-014-0195-1 · 2.93 Impact Factor
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    ABSTRACT: We previously showed that tumor-derived heregulin, a ligand for HER3, is associated with both de novo and acquired resistance to cetuximab. We have now examined whether patritumab, a novel neutralizing monoclonal antibody to HER3, is able to overcome such resistance. Human colorectal cancer (DiFi) cells that are highly sensitive to cetuximab were engineered to stably express heregulin by retroviral infection, and the effects of cetuximab and patritumab on the resulting DiFi-HRG cells were examined. DiFi-HRG cells released substantial amounts of heregulin and showed resistance to cetuximab. Cetuximab alone inhibited EGFR and ERK phosphorylation in DiFi-HRG cells, but it had no effect on the phosphorylation of HER2, HER3, or AKT, suggesting that sustained AKT activation by HER2 and HER3 underlies cetuximab resistance in these cells. In contrast, patritumab in combination with cetuximab markedly inhibited the phosphorylation of EGFR, HER2, HER3, ERK, and AKT. The combination therapy also inhibited the growth of DiFi-HRG tumor xenografts in nude mice to a greater extent than did treatment with either drug alone. Activation of HER2-HER3 signaling associated with the operation of a heregulin autocrine loop confers resistance to cetuximab, and patritumab is able to restore cetuximab sensitivity through inhibition of heregulin-induced HER3 activation.
    Oncotarget 11/2014; · 6.63 Impact Factor
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    ABSTRACT: Purpose Erlotinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), and bevacizumab, an anti-vascular endothelial growth factor (VEGF) agent, are promising therapies for advanced non-small cell lung cancer (NSCLC). Our study was aimed to determine whether there were conditions under which the addition of bevacizumab would enhance the antitumor activity of erlotinib against NSCLC tumors in vitro and in vivo. Methods MTS was for NSCLC cell (PC9, 11–18, H1975, H157, H460 and A549) growth assay in vitro. ELISA was for VEGF protein assay in cells and tumor tissues. Mouse xenograft models were established with H157, H460 and A549 with primary resistance to erlotinib and treated with erlotinib plus bevacizumab or each agent alone. Erlotinib concentrations in tumors were determined by high-performance liquid chromatography. Results Bevacizumab alone did not inhibit NSCLC cell growth in vitro. In primarily erlotinib-resistant NSCLC cells, the levels of VEGF protein were highest in H157 cell followed in order by H460 and A549 cells. In vivo, bevacizumab alone significantly inhibited tumor growth only in xenograft models with high (H157) and/or moderate (H460) levels of VEGF protein. A combination of erlotinib and bevacizumab partially reversed resistance to erlotinib in H157 xenografts (high VEGF level) with increasing intratumoral erlotinib concentrations, but not in H460 (moderate) or A549 (low) xenografts. Conclusions These results support that combined with anti-VEGF therapy could enhance antitumor activity of anti-EGFR therapy and/or partially reverse resistance to EGFR TKI, by increasing EGFR TKI concentration in specific tumors that express high levels of VEGF protein. Electronic supplementary material The online version of this article (doi:10.1007/s00280-014-2610-x) contains supplementary material, which is available to authorized users.
    Cancer Chemotherapy and Pharmacology 10/2014; 74(6). DOI:10.1007/s00280-014-2610-x · 2.57 Impact Factor
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    ABSTRACT: Background: This Phase I, open-label study evaluated the safety/tolerability and maximum tolerated dose (MTD) of second-line nintedanib combined with docetaxel in Japanese patients with advanced non-small-cell lung cancer (NSCLC).Methods: Eligible patients received docetaxel 60 or 75 mg/m (Day 1) plus nintedanib 100, 150, or 200 mg twice daily (bid; Days 2-21) in 21-day cycles. Standard 3+3 dose escalations were performed separately in patient cohorts with a body surface area (BSA) of <1.5 m (BSA<1.5) and BSA≥1.5, respectively.Results: Forty-two patients (17 BSA<1.5, 25 BSA≥1.5) were treated. The MTD of nintedanib was 150 and 200 mg bid in BSA<1.5 and BSA≥1.5 patients, respectively in combination with 75 mg/m of docetaxel. Dose-limiting toxicities (all grade 3 hepatic enzyme elevations) occurred in 12 patients (six per cohort). Drug-related adverse events included neutropenia (95%), leukopenia (83%), fatigue (76%), alopecia (71%), decreased appetite (67%), and elevations in alanine aminotransferase (64%) and aspartate aminotransferase (64%). All hepatic enzyme elevations were reversible and manageable with dose reduction or discontinuation. Among 38 evaluable patients, 10 (26%) had a partial response and 18 (47%) had stable disease.Conclusions: Continuous treatment with second-line nintedanib combined with docetaxel was manageable and showed promising signs of efficacy in Japanese patients with advanced NSCLC.
    Journal of thoracic oncology: official publication of the International Association for the Study of Lung Cancer 10/2014; DOI:10.1097/JTO.0000000000000395 · 5.80 Impact Factor
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    ABSTRACT: Background With use of EGFR tyrosine-kinase inhibitor monotherapy for patients with activating EGFR mutation-positive non-small-cell lung cancer (NSCLC), median progression-free survival has been extended to about 12 months. Nevertheless, new strategies are needed to further extend progression-free survival and overall survival with acceptable toxicity and tolerability for this population. We aimed to compare the efficacy and safety of the combination of erlotinib and bevacizumab compared with erlotinib alone in patients with non-squamous NSCLC with activating EGFR mutation-positive disease. Methods In this open-label, randomised, multicentre, phase 2 study, patients from 30 centres across Japan with stage IIIB/IV or recurrent non-squamous NSCLC with activating EGFR mutations, Eastern Cooperative Oncology Group performance status 0 or 1, and no previous chemotherapy for advanced disease received erlotinib 150 mg/day plus bevacizumab 15 mg/kg every 3 weeks or erlotinib 150 mg/day monotherapy as a first-line therapy until disease progression or unacceptable toxicity. The primary endpoint was progression-free survival, as determined by an independent review committee. Randomisation was done with a dynamic allocation method, and the analysis used a modified intention-to-treat approach, including all patients who received at least one dose of study treatment and had tumour assessment at least once after randomisation. This study is registered with the Japan Pharmaceutical Information Center, number JapicCTI-111390. Findings Between Feb 21, 2011, and March 5, 2012, 154 patients were enrolled. 77 were randomly assigned to receive erlotinib and bevacizumab and 77 to erlotinib alone, of whom 75 patients in the erlotinib plus bevacizumab group and 77 in the erlotinib alone group were included in the efficacy analyses. Median progression-free survival was 16·0 months (95% CI 13·9–18·1) with erlotinib plus bevacizumab and 9·7 months (5·7–11·1) with erlotinib alone (hazard ratio 0·54, 95% CI 0·36–0·79; log-rank test p=0·0015). The most common grade 3 or worse adverse events were rash (19 [25%] patients in the erlotinib plus bevacizumab group vs 15 [19%] patients in the erlotinib alone group), hypertension (45 [60%] vs eight [10%]), and proteinuria (six [8%] vs none). Serious adverse events occurred at a similar frequency in both groups (18 [24%] patients in the erlotinib plus bevacizumab group and 19 [25%] patients in the erlotinib alone group). Interpretation Erlotinib plus bevacizumab combination could be a new first-line regimen in EGFR mutation-positive NSCLC. Further investigation of the regimen is warranted. Funding Chugai Pharmaceutical Co Ltd.
    The Lancet Oncology 10/2014; 15(11). DOI:10.1016/S1470-2045(14)70381-X · 24.73 Impact Factor
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    ABSTRACT: Certain genetically defined cancers are dependent on a single overactive oncogene for their proliferation and survival, a phenomenon known as "oncogene addiction". A new generation of drugs that selectively target such "driver oncogenes" manifests a clinical efficacy greater than that of conventional chemotherapy in appropriate genetically defined patients. MET is a proto-oncogene that encodes a receptor tyrosine kinase, and aberrant activation of MET signaling occurs in a subset of advanced cancers as result of various genetic alterations including gene amplification, polysomy, and gene mutation. Our preclinical studies have shown that inhibition of MET signaling either with the small-molecule MET inhibitor crizotinib or by RNA interference targeted to MET mRNA resulted in marked antitumor effects in cancer cell lines with MET amplification both in vitro and in vivo. Furthermore, patients with non-small cell lung cancer or gastric cancer positive for MET amplification have shown a pronounced clinical response to crizotinib. Accumulating preclinical and clinical evidence thus suggests that MET amplification is an "oncogenic driver" and therefore a valid target for treatment. However, the prevalence of MET amplification has not been fully determined, possibly in part because of the difficulty in evaluating gene amplification. In this review, we provide a rationale for targeting this genetic alteration in cancer therapy.
    09/2014; 6(3):1540-1552. DOI:10.3390/cancers6031540
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    ABSTRACT: Background: Recent clinical trials have shown that immune-checkpoint blockade yields a clinical response in a subset of individuals with advanced nonsmall-cell lung cancer (NSCLC). We examined whether the expression of programmed death-ligand 1 (PD-L1) is related to clinicopathologic or prognostic factors in patients with surgically resected NSCLC. Patients and methods: The expression of PD-L1 was evaluated by immunohistochemical analysis in 164 specimens of surgically resected NSCLC. Cell surface expression of PD-L1 in NSCLC cell lines was quantified by flow cytometry. Results: Expression of PD-L1 in tumor specimens was significantly higher for women than for men, for never smokers than for smokers, and for patients with adenocarcinoma than for those with squamous cell carcinoma. Multivariate analysis revealed that the presence of epidermal growth factor receptor gene (EGFR) mutations and adenocarcinoma histology were significantly associated with increased PD-L1 expression in a manner independent of other factors. Cell surface expression of PD-L1 was also significantly higher in NSCLC cell lines positive for activating EGFR mutations than in those with wild-type EGFR. The EGFR inhibitor erlotinib downregulated PD-L1 expression in the former cell lines but not in the latter, suggesting that PD-L1 expression is increased by EGFR signaling conferred by activating EGFR mutations. A high level of PD-L1 expression in resected tumor tissue was associated with a significantly shorter overall survival for NSCLC patients. Conclusions: High expression of PD-L1 was associated with the presence of EGFR mutations in surgically resected NSCLC and was an independent negative prognostic factor for this disease.
    Annals of Oncology 07/2014; 25(10). DOI:10.1093/annonc/mdu242 · 6.58 Impact Factor
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    ABSTRACT: The performance of scientifically and ethically valid prospective clinical trials is the only means by which to obtain reliable clinical evidence that can improve clinical practice and thus the outcome of patients with lung cancer. The efficacy of treatment for advanced lung cancer remains limited; many cooperative study groups for lung cancer have been established in Japan since 1990s, and they have completed several landmark investigator-initiated clinical trials. This review highlights eight active Japanese cooperative study groups for lung cancer and summarizes their achievements made through clinical trials. In addition to their benefits, the existence of multiple study groups for a single disease such as lung cancer presents several challenges including the provision of infrastructure to ensure the scientific integrity of trial results, the unnecessary duplication of effort and the wasting of limited resources, and the accrual and completion of large-scale phase III trials in the shortest possible time. Collaboration among Japanese cooperative groups has recently increased in order to overcome these challenges. Although institutional barriers to the performance of such large intergroup trials remain, further harmonization and collaboration among cooperative groups will be vital in allowing Japanese investigators to make further important contributions for the development of new lung cancer therapies.
    07/2014; DOI:10.1016/j.resinv.2014.06.004
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    ABSTRACT: Purpose: Irreversible EGFR-tyrosine kinase inhibitors (TKIs) are thought to be one strategy to overcome EGFR-TKI resistance induced by T790M gate-keeper mutations in non-small cell lung cancer (NSCLC), yet they display limited clinical efficacy. We hypothesized that additional resistance mechanisms that cooperate with T790M could be identified by profiling tyrosine phosphorylation in NSCLC cells with acquired resistance to reversible EGFR-TKI and harboring T790M. Experimental Design: We profiled PC9 cells with TKI-sensitive EGFR mutation and paired EGFR-TKI-resistant PC9GR (gefitinib-resistant) cells with T790M using immunoaffinity purification of tyrosine-phosphorylated peptides and mass-spectrometry-based identification/quantification. Profiles of erlotinib perturbations were examined. Results: We observed a large fraction of the tyrosine phosphoproteome was more abundant in PC9- and PC9GR-erlotinib treated cells, including phosphopeptides corresponding to MET, IGF, and AXL signaling. Activation of these receptor tyrosine kinases by growth factors could protect PC9GR cells against the irreversible EGFR-TKI afatinib. We identified a Src-family kinase (SFK) network as EGFR-independent and confirmed that neither erlotinib nor afatinib affected Src phosphorylation at the activation site. The SFK-inhibitor dasatinib plus afatinib abolished Src phosphorylation and completely suppressed downstream phosphorylated Akt and Erk. Dasatinib further enhanced anti-tumor activity of afatinib or T790M-selective EGFR-TKI (WZ4006) in proliferation and apoptosis assays in multiple NSCLC cell lines with T790M mediated resistance. This translated into tumor regression in PC9GR xenograft studies with combined afatinib and dasatinib. Conclusions: Our results identified both co-drivers of resistance along with T790M and support further studies of irreversible or T790M-selective EGFR inhibitors combined with dasatinib in NSCLC patients with acquired T790M.
    Clinical Cancer Research 06/2014; 20(15). DOI:10.1158/1078-0432.CCR-13-1559 · 8.19 Impact Factor
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    ABSTRACT: The majority of non-small cell lung cancer (NSCLC) patients harbor EGFR-activating mutations that can be therapeutically targeted by EGFR tyrosine kinase inhibitors (EGFR-TKI), such as erlotinib and gefitinib. Unfortunately, a subset of patients with EGFR mutations are refractory to EGFR-TKIs. Resistance to EGFR inhibitors reportedly involves SRC activation and induction of epithelial-to-mesenchymal transition (EMT). Here, we have demonstrated that overexpression of CRIPTO1, an EGF-CFC protein family member, renders EGFR-TKI-sensitive and EGFR-mutated NSCLC cells resistant to erlotinib in culture and in murine xenograft models. Furthermore, tumors from NSCLC patients with EGFR-activating mutations that were intrinsically resistant to EGFR-TKIs expressed higher levels of CRIPTO1 compared with tumors from patients that were sensitive to EGFR-TKIs. Primary NSCLC cells derived from a patient with EGFR-mutated NSCLC that was intrinsically erlotinib resistant were CRIPTO1 positive, but gained erlotinib sensitivity upon loss of CRIPTO1 expression during culture. CRIPTO1 activated SRC and ZEB1 to promote EMT via microRNA-205 (miR-205) downregulation. While miR-205 depletion induced erlotinib resistance, miR-205 overexpression inhibited CRIPTO1-dependent ZEB1 and SRC activation, restoring erlotinib sensitivity. CRIPTO1-induced erlotinib resistance was directly mediated through SRC but not ZEB1; therefore, cotargeting EGFR and SRC synergistically attenuated growth of erlotinib-resistant, CRIPTO1-positive, EGFR-mutated NSCLC cells in vitro and in vivo, suggesting that this combination may overcome intrinsic EGFR-inhibitor resistance in patients with CRIPTO1-positive, EGFR-mutated NSCLC.
    Journal of Clinical Investigation 06/2014; DOI:10.1172/JCI73048 · 13.77 Impact Factor

Publication Stats

5k Citations
1,142.26 Total Impact Points


  • 2013–2015
    • Kyushu University
      • • Graduate School of Medical Sciences
      • • Center for Clinical and Translational Research - CCTR
      Hukuoka, Fukuoka, Japan
    • Chiba Cancer Center
      Tiba, Chiba, Japan
  • 2014
    • Aichi Cancer Center
      Ōsaka, Ōsaka, Japan
  • 2005–2014
    • Kinki University
      • Faculty of Medicine
      Ōsaka, Ōsaka, Japan
  • 2011
    • Shandong Cancer Hospital (Shandong Provincial Institute of Cancer Prevention and Treatment)
      Chi-nan-shih, Shandong Sheng, China
  • 2007
    • Nara Hospital
      Ikuma, Nara, Japan
  • 1999–2005
    • Kumamoto University
      • • Graduate School of Medical Sciences
      • • Department of Respiratory Medicine
      • • Department of Tumor Genetics and Biology
      Kumamoto, Kumamoto Prefecture, Japan
    • National Cancer Institute (USA)
      • Basic Research Laboratory
      Maryland, United States
  • 2004
    • National Institutes of Health
      • Basic Research Laboratory
      Bethesda, MD, United States
  • 2002–2003
    • Thomas Jefferson University
      • Department of Microbiology & Immunology
      Philadelphia, PA, United States