Surgical resection of an intraluminal tumor in the azygos vein with an unknown primary site causing superior vena cava syndrome

Intraluminal tumor in the azygos vein is a rare disease that can cause superior vena cava (SVC) syndrome. Radiotherapy and endovascular stenting with or without chemotherapy are reported to have a high clinical success rate for the management of SVC syndrome with malignancy, but a poor survival rate. Here, we report a 69-year-old man who presented with swelling of the face and upper extremities, who was diagnosed with SVC syndrome caused by an intraluminal tumor in the azygos vein. Enhanced chest computed tomography revealed an intraluminal mass with a filling defect from the azygos vein to the SVC, with no extravascular extension or dissemination of the primary tumor. Surgical resection of the mass en bloc with the azygos vein and SVC reconstruction was performed. A poorly differentiated carcinoma was diagnosed on postoperative pathological evaluation. Twelve months after resection, the patient was well with no signs of recurrent disease. This case highlights that surgical resection should be considered as a treatment of choice for the management of SVC syndrome caused by an intraluminal malignancy in the azygos vein.

[Solitary Fibrous Tumor of Pleura Communicating with Pulmonary Artery and Vein]

A 68-year-old man was noted to have an abnormal shadow on chest X-ray. Chest computed tomography (CT) showed a 100 mm mass in the lower right thoracic cavity. The mass was lobulated and compressed the surrounding lung tissue and diaphragm. Contrast-enhanced CT showed that the mass was heterogeneously enhanced and contained expanded blood vessels within it. The expanded vessels communicated with the pulmonary artery and vein via the diaphragmatic surface of the right lung. The mass was diagnosed as a solitary fibrous tumor of the pleura (SFTP) by CT-guided lung biopsy. We performed partial resection of the lung including the tumor via right eighth intercostal lateral thoracotomy. Intraoperative examination showed that the tumor was pediculated from the diaphragmatic surface of the right lung. The stem was about 3 cm long and easily cut with a stapler. The tumor was definitively diagnosed as a malignant SFTP. No recurrence was found for 12 months postoperatively.

Acquired resistance mechanisms to afatinib in HER2-amplified gastric cancer cells

Cancer treatment, especially that for breast and lung cancer, has entered a new era and continues to evolve, with the development of genome analysis technology and the advent of molecular targeted drugs including tyrosine kinase inhibitors. Nevertheless, acquired drug resistance to molecular targeted drugs is unavoidable, creating a clinically challenging problem. We recently reported the antitumor effect of a pan-HER inhibitor, afatinib, against human epidermal growth factor receptor 2 (HER2)-amplified gastric cancer cells. The purpose of the present study was to identify the mechanisms of acquired afatinib resistance and to investigate the treatment strategies for HER2-amplified gastric cancer cells. Two afatinib-resistant gastric cancer cell lines were established from 2 HER2-amplified cell lines, N87 and SNU216. Subsequently, we investigated the molecular profiles of resistant cells. The activation of the HER2 pathway was downregulated in N87-derived resistant cells, whereas it was upregulated in SNU216-derived resistant cells. In the N87-derived cell line, both MET and AXL were activated, and combination treatment with afatinib and cabozantinib, a multikinase inhibitor that inhibits MET and AXL, suppressed the cell growth of cells with acquired resistance both in vitro and in vivo. In the SNU216-derived cell line, YES1, which is a member of the Src family, was remarkably activated, and dasatinib, a Src inhibitor, exerted a strong antitumor effect in these cells. In conclusion, we identified MET and AXL activation in addition to YES1 activation as novel mechanisms of afatinib resistance in HER2-driven gastric cancer. Our results also indicated that treatment strategies targeting individual mechanisms of resistance are key to overcoming such resistance.

Migration of a hookwire used as a video-assisted thoracoscopic surgery marker into the splenic artery

We present a case in which a hookwire that was used as a video-assisted thoracoscopic (VATS) surgery marker migrated into the splenic artery. The patient was a 70-year-old man with an 18-mm ground glass nodule (GGN) in the right S2. As the GGN was not located in the peripheral part of the lung, a percutaneous hookwire was placed as a marker under CT-guided just before the surgery. We performed VATS right S2 segmentectomy to remove the GGN and the marker; however, we could not locate the marker in the specimen. Histopathological examination revealed adenocarcinoma, TisN0M0, stage 0. CT findings after surgery showed that the marker had migrated into the splenic artery. We followed up the patient, and CT examination conducted 1, 3 and 6 months after the surgery showed no further migration and no damage of the splenic artery. We report the complication of percutaneous hookwire migration into a blood vessel.

Droplet digital PCR as a novel system for the detection of microRNA‑34b/c methylation in circulating DNA in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a rare malignancy arising from the pleura that is difficult to diagnose, contributing to its dismal prognosis. Previously, we reported that the degree of microRNA (miR)‑34b/c methylation in circulating DNA is associated with the development of MPM. Herein, we present a newly developed droplet digital PCR (ddPCR)‑based assay for the detection of miR‑34b/c methylation in circulating DNA in patients with MPM. We originally prepared two probes within a short amplicon of 60 bp, designing one from the positive strand and the other from the complementary strand. The two probes functioned cooperatively, and our established assay detected DNA methylation accurately in the preliminary validation. We subsequently verified this assay using clinical samples. Serum samples from 35 cases of MPM, 29 cases of pleural plaque and 10 healthy volunteers were collected from 3 different institutions and used in this study. We divided the samples into 2 groups (group A, n=33; group B, n=41). A receiver‑operating characteristic curve analysis using the samples in group A determined the optimal cut‑off value for the diagnosis of MPM, with a sensitivity of 76.9% and a specificity of 90%. On the other hand, the use of the same criterion yielded a sensitivity of 59.1% and a specificity of 100% in group B, and corresponding values of 65.7 and 94.9% for the entire cohort, indicating a moderate sensitivity and a high specificity. In addition, when the analysis was focused on stage II or more advanced MPM, the sensitivity improved to 81.8%, suggesting the possibility that the methylated allele frequency in MPM may be associated with the stage of disease progression. On the whole, the findings of this study indicate that miR‑34b/c methylation in circulating DNA is a promising biomarker for the prediction of disease progression in patients with MPM.

Application of amplicon-based targeted sequencing with the molecular barcoding system to detect uncommon minor EGFR mutations in patients with treatment-naïve lung adenocarcinoma

Background

In lung cancer, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor sensitizing mutations co-existing with rare minor EGFR mutations are known as compound mutations. These minor EGFR mutations can lead to acquired resistance after EGFR tyrosine kinase inhibitor treatment, so determining the mutation status of patients is important. However, using amplicon-based targeted deep sequencing based on next-generation sequencing to characterize mutations is prone to sequencing error. We therefore assessed the benefit of incorporating molecular barcoding with high-throughput sequencing to investigate genomic heterogeneity in treatment-naïve patients who have undergone resection of their non-small cell lung cancer (NSCLC) EGFR mutations.

Methods

We performed amplicon-based targeted sequencing with the molecular barcoding system (MBS) to detect major common EGFR mutations and uncommon minor mutations at a 0.5% allele frequency in fresh–frozen lung cancer samples.

Results

Profiles of the common mutations of EGFR identified by MBS corresponded with the results of clinical testing in 63 (98.4%) out of 64 cases. Uncommon mutations of EGFR were detected in seven cases (10.9%). Among the three types of major EGFR mutations, patients with the G719X mutation had a significantly higher incidence of compound mutations than those with the L858R mutation or exon 19 deletion (p = 0.0052). This was validated in an independent cohort from the Cancer Genome Atlas dataset (p = 0.018).

Conclusions

Our findings demonstrate the feasibility of using the MBS to establish an accurate NSCLC patient genotype. This work will help understand the molecular basis of EGFR compound mutations in NSCLC, and could aid the development of new treatment modalities.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5374-1) contains supplementary material, which is available to authorized users.

Tumor-suppressive effect of LRIG1, a negative regulator of ErbB, in non-small cell lung cancer harboring mutant EGFR

Epidermal growth factor receptor (EGFR) is a member of the ErbB (HER) family that is known to play important roles in the pathogenesis of various human cancers. Mutations of the EGFR gene are commonly found as oncogenic driver mutations and have been targeted for treatment of non-small cell lung cancer (NSCLC). Leucine-rich repeat and immunoglobulin-like domain protein-1 (LRIG1) is a cell-surface protein that is known as a negative regulator of the ErbB (HER) family. In this study, we first confirmed that the expression levels of LRIG1 were much lower in NSCLC than in non-malignant cells or tissues. Next, we focused on the effect of LRIG1 in NSCLC. For this purpose, we established clones stably overexpressing LRIG1, using EGFR-mutant (HCC827, HCC4011 and NCI-H1975) and wild-type (A549) cells. Transfection of LRIG1 was associated with a decrease in the expression and phosphorylation levels of EGFR in the HCC827, HCC4011 and NCI-H1975 cells. It was also associated with strong suppression of the cell proliferative, invasive, migratory and tumorigenic potential of the HCC827 cells. On the other hand, no such effects were observed in the A549 cells. In addition, LRIG1 also downregulated the expression and phosphorylation levels of other tyrosine kinase receptors, such as HER2, HER3, MET and IGF-1R, and prevented the epithelial-to-mesenchymal transition induced by TGF-β in the HCC827 cells. These findings suggest that LRIG1 exerts important tumor-suppressive effects in EGFR-mutant NSCLC and has the potential to become a novel therapeutic target for EGFR-mutant NSCLC.

Anti-tumor effect of neratinib against lung cancer cells harboring HER2 oncogene alterations

Human epidermal growth factor receptor 2 (HER2) is a member of the ErbB family of receptor tyrosine kinases. Numerous studies have reported the amplification and overexpression of HER2 in several types of cancer, including non-small cell lung cancer (NSCLC). However, the benefits of HER2-targeted therapy have not been fully established. In the present study, the anti-tumor effect of neratinib, an irreversible pan-HER tyrosine kinase inhibitor (TKI), against NSCLC cells harboring HER2 alterations was investigated. The sensitivity of normal bronchial epithelial cells (BEAS-2B) ectopically overexpressing wild-type or mutant HER2 to neratinib was assessed. Furthermore, the anti-tumor activity of neratinib in several NSCLC cell lines harboring HER2 alterations was determined in vitro and in vivo, and the association between their genetic alterations and sensitivity to neratinib treatment was investigated. BEAS-2B cells ectopically overexpressing wild-type HER2 or mutants (A775insYVMA, G776VC, G776LC, P780insGSP, V659E, G660D and S310F) exhibited constitutive autophosphorylation of HER2, as determined by western blotting. While these BEAS-2B cells were sensitive to neratinib, they were insensitive to erlotinib, a first-generation epidermal growth factor receptor-TKI. Neratinib also exerted anti-proliferative effects on HER2-altered (H2170, Calu-3 and H1781) NSCLC cell lines. Neratinib was also demonstrated to exert strong tumor growth inhibitory activity in mouse xenograft models using HER2-altered lung cancer cells. The results of the present study strongly suggest that neratinib has potential as a promising therapeutic option for the treatment of HER2-altered NSCLC.

Newly developed anti-S100A8/A9 monoclonal antibody efficiently prevents lung tropic cancer metastasis

The metastatic dissemination of cancer cells to remote areas of the body is the most problematic aspect in cancer patients. Among cancers, melanomas are notoriously difficult to treat due to their significantly high metastatic potential even during early stages. Hence, the establishment of advanced therapeutic approaches to regulate metastasis is required to overcome the melanoma disease. An accumulating mass of evidence has indicated a critical role of extracellular S100A8/A9 in melanoma distant metastasis. Lung S100A8/A9 is induced by melanoma cells from distant organs and it attracts these cells to its enriched lung environment since melanoma cells possess several receptors that sense the S100A8/A9 ligand. We hence aimed to develop a neutralizing antibody against S100A8/A9 that would efficiently block melanoma lung metastasis. Our protocol provided us with one prominent antibody, Ab45 that efficiently suppressed not only S100A8/A9-mediated melanoma mobility but also lung tropic melanoma metastasis in a mouse model. This prompted us to make chimeric Ab45, a chimera antibody consisting of mouse Ab45-Fab and human IgG2-Fc. Chimeric Ab45 also showed significant inhibition of the lung metastasis of melanoma. From these results, we have high hopes that the newly produced antibody will become a potential biological tool to block melanoma metastasis in future clinical settings.

exSSSRs (extracellular S100 soil sensor receptors)-Fc fusion proteins work as prominent decoys to S100A8/A9-induced lung tropic cancer metastasis

Within the "seed and soil" theory of organ tropic cancer metastasis is a growing compilation of evidence that S100A8/A9 functions as a soil signal that attracts cancer cells to certain organs, which prove beneficial to their growth. S100A8/A9-sensing receptors including Toll-like receptor 4 (TLR4), advanced glycation end products (RAGE), and also important receptors we recently succeeded in identifying (EMMPRIN, NPTNβ, MCAM, and ALCAM) have the potential to become promising therapeutic targets. In our study, we prepared extracellular regions of these novel molecules and fused them to human IgG2-Fc to extend half-life expectancy, and we evaluated the anti-metastatic effects of the purified decoy proteins on metastatic cancer cells. The purified proteins markedly suppressed S100A8/A9-mediated lung tropic cancer metastasis. We hence expect that our novel biologics may become a prominent medicine to prevent cancer metastasis in clinical settings through cutting the linkage between "seed and soil".

Activation of AXL as a Preclinical Acquired Resistance Mechanism Against Osimertinib Treatment in EGFR-Mutant Non-Small Cell Lung Cancer Cells

Osimertinib (AZD9291) has an efficacy superior to that of standard EGFR-tyrosine kinase inhibitors for the first-line treatment of patients with EGFR-mutant advanced non-small cell lung cancer (NSCLC). However, patients treated with osimertinib eventually acquire drug resistance, and novel therapeutic strategies to overcome acquired resistance are needed. In clinical or preclinical models, several mechanisms of acquired resistance to osimertinib have been elucidated. However, the acquired resistance mechanisms when osimertinib is initially used for EGFR-mutant NSCLC remain unclear. In this study, we experimentally established acquired osimertinib-resistant cell lines from EGFR-mutant NSCLC cell lines and investigated the molecular profiles of resistant cells to uncover the mechanisms of acquired resistance. Various resistance mechanisms were identified, including the acquisition of MET amplification, EMT induction, and the upregulation of AXL. Using targeted next-generation sequencing with a multigene panel, no secondary mutations were detected in our resistant cell lines. Among three MET-amplified cell lines, one cell line was sensitive to a combination of osimertinib and crizotinib. Acquired resistance cell lines derived from H1975 harboring the T790M mutation showed AXL upregulation, and the cell growth of these cell lines was suppressed by a combination of osimertinib and cabozantinib, an inhibitor of multiple tyrosine kinases including AXL, both in vitro and in vivo. Our results suggest that AXL might be a therapeutic target for overcoming acquired resistance to osimertinib. IMPLICATIONS: Upregulation of AXL is one of the mechanisms of acquired resistance to osimertinib, and combination of osimertinib and cabozantinib might be a key treatment for overcoming osimertinib resistance.

Comparative mutational evaluation of multiple lung cancers by multiplex oncogene mutation analysis

In patients presenting with synchronous or metachronous multiple lung cancer (MLC), it is important to distinguish between multiple primary lung cancer (MP) and intrapulmonary metastasis (IM). The present study was aimed at investigating the mutational profiles of synchronous/metachronous MLC and to compare the classification of paired tumors by multiplex gene mutation analysis with the histopathological evaluation. We carried out targeted sequencing of 20 lung cancer-related oncogenes using next-generation sequencing (NGS) in 82 tumors from 37 MLC patients who underwent surgical resection at our department. The patients were diagnosed as MP or IM cases based on the Martini and Melamed criteria, histopathological and gene mutational evaluations. Matching mutations between paired tumors was observed in 20 (54%) patients, who were diagnosed as IM cases by mutational evaluation. Patients who could not be clearly diagnosed by histopathological evaluation were classified as equivocal cases. Among the histopathological IM cases (n = 7), six (86%) were confirmed as IM cases also by mutational evaluation, and most of the paired tumors of these cases (n = 5) harbored multiple matching mutations. Among the histopathological MP cases (n = 17), mutational evaluation yielded a discordant diagnosis in eight (47%) cases. Of these, the paired tumors of four cases harbored multiple matching mutations, suggesting that the mutational diagnosis might be more suitable in these patients. Our findings suggest that multiplex mutational analysis could be a useful complementary tool for distinguishing between MP and IM in addition to histopathological evaluation.

Combined inhibition of MEK and PI3K pathways overcomes acquired resistance to EGFR-TKIs in non-small cell lung cancer

Compensatory activation of the signal transduction pathways is one of the major obstacles for the targeted therapy of non-small cell lung cancer (NSCLC). Herein, we present the therapeutic strategy of combined targeted therapy against the MEK and phosphoinositide-3 kinase (PI3K) pathways for acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in NSCLC. We investigated the efficacy of combined trametinib plus taselisib therapy using experimentally established EGFR-TKI-resistant NSCLC cell lines. The results showed that the feedback loop between MEK/ERK and PI3K/AKT pathways had developed in several resistant cell lines, which caused the resistance to single-agent treatment with either inhibitor alone. Meanwhile, the combined therapy successfully regulated the compensatory activation of the key intracellular signals and synergistically inhibited the cell growth of those cells in vitro and in vivo. The resistance mechanisms for which the dual kinase inhibitor therapy proved effective included (MET) mesenchymal-epithelial transition factor amplification, induction of epithelial-to-mesenchymal transition (EMT) and EGFR T790M mutation. In further analysis, the combination therapy induced the phosphorylation of p38 MAPK signaling, leading to the activation of apoptosis cascade. Additionally, long-term treatment with the combination therapy induced the conversion from EMT to mesenchymal-to-epithelial transition in the resistant cell line harboring EMT features, restoring the sensitivity to EGFR-TKI. In conclusion, our results indicate that the combined therapy using MEK and PI3K inhibitors is a potent therapeutic strategy for NSCLC with the acquired resistance to EGFR-TKIs.

Abstract 1233: Reducing sequence artifact in clinical sequencing of treatment-naïve NSCLC patient using molecular barcoding system

Background: Recently the clinical significance of compound mutations in cancer relapse and/or acquired resistance has been reported. Amplicon-based deep sequence enables analysis of tiny amount of input DNA, however, a major problem of these high-throughput DNA sequencing is the high rate (~1%) of errors causing potential sequence artifact. Molecular barcoding system, which has been developed to reduce sequencing artifacts as well as to improve mutation detection accuracy, was applied to analyze the frequency of compound EGFR mutations in early stage non-small-cell lung cancer (NSCLC) patients who undergo surgical resection without any presurgical treatment is less described.

Materials and Methods: From 590 consecutive patients, 64 adenocarcinoma cases who underwent surgical resection for primary lung cancer were analyzed by using amplicon-based targeted sequencing method incorporating molecular barcodes in order to detect genetic alterations of 47 genes including EGFR.

Results: Out of 64 samples, EGFR common mutation profiles of 63 (98.4%) by molecular-barcode sequencing corresponded to those by clinical test. Uncommon EGFR mutations were detected in 7 cases (10.9%). Among the three types of EGFR major mutation, G719X (60%, 3/5) showed a significantly higher incidence of EGFR double mutations than L858R (9.5%, 4/42) or Ex19del (0%, 0/17) (p = 0.0052). Co-mutations of other genes were observed in 20 EGFR-mutated cases. TP53 mutations were frequently detected in younger age (p = 0.0066) and pStage II-III cases (p = 0.042).

Conclusion: Amplicon sequencing incorporating molecular barcoding system is a feasible approach to characterize predictive or prognostic mutations in early stage treatment naïve NSCLC patients, revealing those case who harbor EGFR G719X mutation have a significantly higher incidence of EGFR double mutations, likely to have worse prognosis.

Citation Format: Kei Namba, Shuta Tomida, Yuta Takahashi, Eisuke Kurihara, Yusuke Ogoshi, Takahiro Yosioka, Hidejiro Torigoe, Hiroki Sato, Kazuhiko Shien, Hiromasa Yamamoto, Junichi Soh, Shinichi Toyooka. Reducing sequence artifact in clinical sequencing of treatment-naïve NSCLC patient using molecular barcoding system [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 1233.

Abstract 3922: Ganetespib demonstrates strong anti-tumor effect in acquired EGFR-TKI resistance NSCLC cells

Purpose: Epidermal growth factor receptor (EGFR) -tyrosine kinase inhibitors (TKIs) are the standard first-line treatment of advanced non-small cell lung cancer (NCSLC). However, almost all patients eventually acquire resistance to EGFR-TKIs, and novel therapeutic strategies to overcome the acquired resistance have been required. Heat-shock protein 90 (Hsp90) is a chaperon protein involved in folding and stabilization of client proteins essential for cancer cell growth and survival. Ganetespib (STA-9090) is one of the second-generation Hsp90 inhibitors with strong anti-tumor effect on NSCLC cells. In this study, we evaluated the anti-tumor effect of ganetespib in EGFR-TKI sensitive and acquired resistance NSCLC cell lines.

Materials and Methods: We treated 4 EGFR-mutant NSCLC cell lines (HCC827, HCC4006, PC-9 and HCC4011), and 14 experimentally established EGFR-TKIs (gefitinib or afatinib) resistance cell lines with ganetespib. The EGFR-TKI resistance mechanism consisted of EGFR T790M second mutation, MET amplification, epithelial-to-mesenchymal transition (EMT) and cancer stem cell-like features. We determined cell proliferation by MTS assay and calculated the IC50 values. We also performed Western blotting to investigate downstream signaling pathways.

Results: The IC50 values in parental NSCLC cell lines ranged from 1.3nM to 15nM, and those in acquired EGFR-TKI resistant cell lines ranged from 0.87nM to 25nM, which suggests strong anti-tumor effect of ganetespib. In addition, this effect was observed regardless of the resistant mechanisms, including EMT. Ganetespib suppressed EGFR activation in EGFR-TKI resistance cells harboring EGFR T790M second mutation. Also, ganetespib suppressed MET activation in EGFR-TKI resistance cells harboring MET amplification.

Conclusion: Ganetespib showed strong anti-tumor effect in acquired EGFR-TKI resistance NSCLC cells regardless of the resistant mechanisms, suggesting that ganetespib could be a promising therapeutic option in the treatment of NSCLC with acquired EGFR-TKI resistance.

Citation Format: Eisuke Kurihara, Kazuhiko Shien, Hidejiro Torigoe, Yuta Takahashi, Yusuke Ogoshi, Takahiro Yoshioka, Kei Namba, Hiroki Sato, Hiromasa Yamamoto, Junichi Soh, Shinichi Toyooka. Ganetespib demonstrates strong anti-tumor effect in acquired EGFR-TKI resistance NSCLC cells [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 3922.

Abstract 4776: Antitumor activity of pan-HER inhibitors in HER2-positive gastric cancer

Purpose: Molecularly targeted therapy has enabled outstanding advances in cancer treatment. Whereas various anti-HER2 drugs have been developed, trastuzumab is still the only anti-HER2 drug presently available for gastric cancer. Among HER2 targeting drug, afatinib and neratinib inhibit the activation of all HER family protein, and are called pan-HER inhibitors. In this study, we examined the effect of these pan-HER inhibitors to gastric cancer cells. Materials and Methods: We determined the molecular profiles of 12 gastric cancer cell lines. Protein level of HER2 and down-signal pathway molecules were analyzed by Western blotting, and copy number assay or gene expression assay were performed using qPCR. To detect HER2 mutation, we also performed direct-sequence of these cell lines. And next, we examined the antitumor effect of the pan-HER inhibitors afatinib and neratinib in those cell lines, in vitro and in vivo. In addition, we analyzed HER2 alteration in 123 primary gastric cancers resected from Japanese patients to clarify possible candidates with the potential to respond to these drugs. Results: HER2 was amplified in 5 out of 12 gastric cancer cell lines. Gene expression or protein level of HER2 were generally correlated with the copy number of HER2. HER2 mutation was found in one cell line, ECC10, at kinase domain (L755S). In the drug sensitivity analysis, both afatinib and neratinib showed an anti-tumor effect in all the HER2 amplified cell lines both in vitro and in vivo except MKN7 cell line. When the molecular profiles of the cells were compared based on the drug sensitivities, we found that cancer cells with lower mRNA expression levels of IGFBP7, a tumor suppressor gene by inhibiting the activation of IGF-1R, were less sensitive to pan-HER inhibitors. A combination therapy consisting of pan-HER inhibitors and an IGF-1R inhibitor, picropodophyllin, demonstrated a notable synergistic effect. Regarding HER2 alteration in 123 clinical samples, we found 19 cases of HER2 amplification and 3 cases of oncogenic mutations. Conclusion: Afatinib and neratinib are promising therapeutic options for the treatment of HER2-amplified gastric cancer. In addition to HER2 amplification, IGFBP7 might be a biomarker of sensitivity to these drugs, and IGF-1R-targeting therapy can overcome drug insensitiveness in HER2-amplified gastric cancer.

Citation Format: Takahiro Yoshioka, Kazuhiko Shien, Yuta Takahashi, Eisuke Kurihara, Kei Namba, Yusuke Ogoshi, Hidejiro Torigoe, Hiroki Sato, Hiromasa Yamamoto, Junichi Soh, Toshiyoshi Fujiwara, Shinichi Toyooka. Antitumor activity of pan-HER inhibitors in HER2-positive gastric cancer [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 4776.

Abstract 1832: Acquired resistance mechanisms to afatinib in lung cancer cells harboring HER2 alterations

Human epidermal growth factor receptor 2 (HER2) plays an important role in the pathogenesis of various cancers. HER2 alterations have been suggested to be a therapeutic target in non-small cell lung cancer (NSCLC), just as in breast and gastric cancers. We previously reported that the pan-HER inhibitor afatinib could be a useful therapeutic agent as HER2-targeted therapy for patients with NSCLC harboring HER2 alterations. However, acquired resistance to afatinib was observed in the clinical setting, similar to the case for other HER inhibitors. Thus, elucidation of the mechanisms underlying the development of acquired drug resistance and exploring means to overcome acquired drug resistance are important issues in the treatment of NSCLC. In this study, we experimentally established afatinib-resistant cell lines from NSCLC cell lines harboring HER2 alterations (Calu3, H2170, and H1781), by stepwise-escalation or high-concentration exposure methods, and investigated the mechanisms underlying the acquisition of drug resistance. The established cell lines showed several unique afatinib-resistance mechanisms, including MET amplification, loss of HER2 amplification and gene expression, epithelial-to-mesenchymal transition (EMT) and acquisition of cancer stem cell (CSC)-like features. The afatinib-resistant cell lines showing MET amplification were sensitive to the combination of afatinib plus crizotinib (a MET inhibitor), both in vitro and in vivo. The resistant cell lines with the loss of HER2 amplification obtained MEK inhibitors sensitivity in vitro and in vivo. Other resistant cell lines that showed EMT or had acquired CSC-like features remained sensitive to docetaxel, like the parental cells. These findings may provide clues to countering the resistance to afatinib in NSCLC patients with HER2 alterations.

Citation Format: Hidejiro Torigoe, Kazuhiko Shien, Tatsuaki Takeda, Takahiro Yoshioka, Kei Namba, Hiroki Sato, Ken Suzawa, Hiromasa Yamamoto, Junichi Soh, Masakiyo Sakaguchi, Shuta Tomida, Shinichiro Miyoshi, Shinichi Toyooka. Acquired resistance mechanisms to afatinib in lung cancer cells harboring HER2 alterations [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 1832.

Therapeutic strategies for afatinib-resistant lung cancer harboring HER2 alterations

Human epidermal growth factor receptor 2 (HER2) plays an important role in the pathogenesis of various cancers. HER2 alterations have been suggested to be a therapeutic target in non-small-cell lung cancer (NSCLC), just as in breast and gastric cancers. We previously reported that the pan-HER inhibitor afatinib could be a useful therapeutic agent as HER2-targeted therapy for patients with NSCLC harboring HER2 alterations. However, acquired resistance to afatinib was observed in the clinical setting, similar to the case for other HER inhibitors. Thus, elucidation of the mechanisms underlying the development of acquired drug resistance and exploring means to overcome acquired drug resistance are important issues in the treatment of NSCLC. In this study, we experimentally established afatinib-resistant cell lines from NSCLC cell lines harboring HER2 alterations, and investigated the mechanisms underlying the acquisition of drug resistance. The established cell lines showed several unique afatinib-resistance mechanisms, including MET amplification, loss of HER2 amplification and gene expression, epithelial-to-mesenchymal transition (EMT) and acquisition of cancer stem cell (CSC)-like features. The afatinib-resistant cell lines showing MET amplification were sensitive to the combination of afatinib plus crizotinib (a MET inhibitor), both in vitro and in vivo. The resistant cell lines which showed EMT or had acquired CSC-like features remained sensitive to docetaxel, like the parental cells. These findings may provide clues to countering the resistance to afatinib in NSCLC patients with HER2 alterations.

Antitumor activity of pan-HER inhibitors in HER2-positive gastric cancer

Molecularly targeted therapy has enabled outstanding advances in cancer treatment. Whereas various anti-human epidermal growth factor receptor 2 (HER2) drugs have been developed, trastuzumab is still the only anti-HER2 drug presently available for gastric cancer. In this study, we propose novel treatment options for patients with HER2-positive gastric cancer. First, we determined the molecular profiles of 12 gastric cancer cell lines, and examined the antitumor effect of the pan-HER inhibitors afatinib and neratinib in those cell lines. Additionally, we analyzed HER2 alteration in 123 primary gastric cancers resected from Japanese patients to clarify possible candidates with the potential to respond to these drugs. In the drug sensitivity analysis, both afatinib and neratinib produced an antitumor effect in most of the HER2-amplified cell lines. However, some cells were not sensitive to the drugs. When the molecular profiles of the cells were compared based on the drug sensitivities, we found that cancer cells with lower mRNA expression levels of IGFBP7, a tumor suppressor gene that inhibits the activation of insulin-like growth factor-1 receptor (IGF-1R), were less sensitive to pan-HER inhibitors. A combination therapy consisting of pan-HER inhibitors and an IGF-1R inhibitor, picropodophyllin, showed a notable synergistic effect. Among 123 clinical samples, we found 19 cases of HER2 amplification and three cases of oncogenic mutations. In conclusion, afatinib and neratinib are promising therapeutic options for the treatment of HER2-amplified gastric cancer. In addition to HER2 amplification, IGFBP7 might be a biomarker of sensitivity to these drugs, and IGF-1R-targeting therapy can overcome drug insensitiveness in HER2-amplified gastric cancer.

Induction chemoradiotherapy using docetaxel and cisplatin with definitive-dose radiation followed by surgery for locally advanced non-small cell lung cancer

Background

Induction chemoradiotherapy (CRT) followed by surgery is a therapeutic option for locally advanced non-small cell lung cancer (LA-NSCLC). Typically, around 40-50 Gy of radiation is applied as the induction-dose; however, a definitive-dose (DD) of radiation (60 Gy or higher) is occasionally applied to increase local control. We investigated the impact of induction CRT with DD radiation in LA-NSCLC patients treated with a single regimen of docetaxel and cisplatin.

Methods

We reviewed 110 patients with LA-NSCLC who underwent induction CRT followed by surgery using a single regimen (docetaxel and cisplatin) between January 1999 and December 2014 at our hospital. The clinical outcomes of a DD group (60 Gy or higher, n=11) and a non-DD group (less than 60 Gy, n=99) were investigated using a propensity score (PS)-matched analysis.

Results

An advanced clinical stage was significantly more common in the DD group than in the non-DD group (P=0.033). Before and after the PS-matching based on seven factors including clinical stage, there was no significant difference in the rates of postoperative (PO) complication, mortality, 5-year overall survival (OS), or 5-year recurrence-free survival (RFS) between the two groups. After the PS-matching, the pathological complete response (CR) rate was significantly higher in the DD group than in the non-DD group [50% (n=5/10) vs. 0% (n=0/10), P=0.033].

Conclusions

Induction CRT followed by surgery using docetaxel and cisplatin with DD radiation can be performed safely and is associated with a higher pathological CR rate than that attained using non-DD radiation in LA-NSCLC patients.

Elacridar, a third-generation ABCB1 inhibitor, overcomes resistance to docetaxel in non-small cell lung cancer

Docetaxel is a third-generation chemotherapeutic drug that is widely used in the treatment of patients with non-small cell lung cancer (NSCLC). However, the majority of patients with NSCLC eventually acquire resistance to the treatment. In the present study, the mechanism of acquired resistance to docetaxel treatment in lung cancer cells was investigated. The three NSCLC cell lines, H1299 with wild-type epidermal growth factor receptor (EGFR), EGFR-mutant HCC4006 and HCC827, and experimentally established docetaxel-resistant (DR) cells, H1299-DR, HCC827-DR, and HCC4006-DR were used with stepwise increases in concentrations of docetaxel. It was demonstrated that the established cell lines showed resistance to docetaxel and EGFR-tyrosine kinase inhibitors (TKIs). Molecular analysis revealed that all of the resistant cell lines highly expressed ATP binding cassette subfamily B member 1 (ABCB1), which is also known as P-glycoprotein or MDR1. Furthermore, HCC827-DR and HCC4006-DR cells exhibited a cancer stem cell-like marker and epithelial-to-mesenchymal transition features, respectively. Elacridar (GF120918), a third-generation inhibitor of ABCB1, was able to overcome resistance to docetaxel. Additionally, knockdown of ABCB1 using small interfering RNA (si)-ABCB1 recovered sensitivity to docetaxel. However, elacridar and si-ABCB1 could not recover sensitivity to EGFR-TKIs in established resistant cells. The results of the present study revealed that docetaxel-resistant NSCLC cells also acquired cross-resistance to EGFR-TKI therapy through mechanisms other than ABCB1, that ABCB1 serves an important role in acquired resistance to docetaxel in lung cancer, and that combination therapy with elacridar can overcome ABCB1-mediated docetaxel resistance.

Abstract 4194: Antitumor activity of multikinase inhibitors in HER2-positive gastric cancer cells

Background: The developments of novel anti-HER2 drugs including multikinase inhibitors have achieved advancing evolution for past several years, and the options in the treatment of HER2-positive malignant tumors have been increasing, especially in breast and lung cancers. On the other hand, regarding HER2-positive gastric cancer, trastuzumab is still the only anti-HER2 drug with the established clinical evidences. Afatinib, an irreversible human epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, binds to the kinase domain of HER2, and is one of the hopeful candidates as novel molecularly targeted drugs for HER2-positive gastric cancer. In this study, we investigated the antitumor effect of multikinase inhibitors including afatinib in gastric cancer cell lines.

Method: We examined the relation between molecular profiles and multikinase inhibitors sensitivities in 12 gastric cancer cell lines: ECC10, GCIY, KATO-III, MKN7, MKN74, N87, NUGC3, NUGC4, OCUM-1, SH-10-TC, SNU-16, and SNU-216. In addition to multikinase inhibitors including afatinib, we also examined trastuzumab and gefitinib sensitivity in 12 cell lines. HER2 copy number alteration, HER2 mutation, and protein expression status of HER2 and its downstream pathway molecules of these cell lines were analyzed by qPCR, direct sequencing, and Western blotting, respectively. Cell proliferation was determined by a MTS assay.

Result: Afatinib was effective in GCIY, N87, SNU-216, NUGC3, and NUGC4 cells. The range of IC50 for these cell lines was 2.1 to 39.4 nM. All these cell lines except for NUGC3 were HER2 amplified. NUGC4, the most afatinib sensitive cells, had also EGFR amplification. Interestingly, among the HER2 amplified cell lines, MKN7 cells were not sensitive to afatinib, nevertheless this cell line showed the activation of HER2 pathway with the expression of phospho-HER2 by Western blotting. In addition, MKN7 cells were not sensitive to other HER2-targeted drugs trastuzumab, and reported to be insensitive to lapatinib either. On the other hand, ECC10 with HER2-L755S mutation was not sensitive to afatinib. The range of IC50 in 7 insensitive cell lines was 0.80 to more than 10 µM. Three cell lines showed moderate sensitivity to gefitinib of which IC50 ranged from 100 to 1000uM. Inhibition rate of trastuzumab was under 25% in all 12 cell lines.

Conclusion: Afatinib, a multikinase inhibitor, is highly effective to HER2 amplified gastric cancer cell lines, and may become a novel treatment option in HER2-positive gastric cancer treatment. On the other hand, afatinib is not always effective even if cancer cells have HER2 mutation or amplification. In this study, we report the detailed predictive biomarkers of sensitivity to afatinib and other several multikinase inhibitors in HER2-positive gastric cancer cells.

Citation Format: Takahiro Yoshioka, Kazuhiko Shien, Kei Namba, Hidejiro Torigoe, Hiroki Sato, Hiromasa Yamamoto, Junichi Soh, Hiroaki Asano, Kazunori Tsukuda, Toshiyoshi Fujiwara, Shinichi Toyooka. Antitumor activity of multikinase inhibitors in HER2-positive gastric cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4194. doi:10.1158/1538-7445.AM2017-4194

Abstract 30: S100A11 is a prominent therapeutic target in malignant pleural mesothelioma

[Background & Purpose] Malignant pleural mesothelioma (MPM) is an aggressive tumor arising from the mesothelial cells that show a serious malignancy in thoracic cavity with a median survival time of 9-12 months. The therapeutic approaches in clinical standard are limited to surgery and chemotherapy for early and advanced stages, respectively. The strategies unfortunately provide only palliation, thus further advanced approach is required. S100A11, a Ca2+-binding small protein with two EF-hands, is frequently upregulated in various human cancer tissues. It has been reported that S100A11 plays an important role in progression of many cancers derived from thyroid, ovarian and lung tissues, but its roles and signature in MPM are poorly understood. In this study, we investigated the impact of S100A11 in MPM cell lines and resected tumors.

[Material & Methods] We explored the expression of S100A11 in 7 MPM cell lines (HP-1, H28, MSTO-211H, H2052, H290, H2452, and YUMC44) and 2 normal mesothelial cell lines (Met-5A and LP-9). We analyzed the effect of S100A11 on cell proliferation, colony formation, migration, invasion and downstream signaling. The efficacy of anti-S100A11 antibody on cell proliferation and downstream signaling was also determined.

[Results] We found that S100A11 protein was consistently upregulated in 7 MPM cell lines at a significant level in comparison to 2 normal mesothelial cells. The same phenomenon was also confirmed in MPM tissue sections by immunohistochemistry, i.e., S100A11 was strongly stained at MPM cells, but not at surrounding normal lung cells. Specific knockdown of S100A11 by small interfering RNA turned the aggressive cells into the attenuated phenotypes for proliferation, invasion and migration. Those were notably observed in both 2 MPM cell lines (H2052 and H2452). Interestingly, we found that MPM cell lines but not normal cells actively secreted the S100A11 protein. To pursue this, we next tried to inhibit the function of the secreted S100A11. Administration of S100A11 neutralizing antibody significantly inhibited the proliferation of 4 MPM cell lines (H2052, H2452, H28, and H290). The antibody had no effect on the proliferation of only one MPM cell line, MSTO-211H, which showed no secretion of S100A11. Taken together, these results suggest that S100A11 secreted from MPM cells can be a prominent target for effective MPM therapy.

[Conclusion] Our results suggest that S100A11 is a possible therapeutic target in MPM.

Citation Format: Hiroki Sato, Hiromasa Yamamoto, Kei Namba, Hidejiro Torigoe, Takahiro Yoshioka, Kazuhiko Shien, Junichi Soh, Shinichi Toyooka. S100A11 is a prominent therapeutic target in malignant pleural mesothelioma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 30. doi:10.1158/1538-7445.AM2017-30

Abstract 5517: Antitumor effect of LRIG1, negative regulator of ErbB, in lung cancer harboring mutant-EGFR

Introduction: EGFR is a member of the ErbB family of tyrosine kinase receptors (RTKs) and plays important roles in the pathogenesis of certain human cancers. In non-small cell lung cancer (NSCLC), mutations in EGFR gene are commonly known as oncogenic driver mutation and targeted for treatment. Leucine rich repeat and immunoglobulin-like domain protein-1 (LRIG1) is a cell surface protein and known as a negative regulator of ErbB family. In brain tumor, LRIG1 was reported to downregulate not only wild-type EGFR, but also EGFRvIII, mutant-type EGFR. But there has been no report about the relationship between LRIG1 and EGFR mutation in the kinase domain frequently found in lung cancer. In this study, we investigate the role of LRIG in EGFR mutant lung cancer from the view point of its effect on signal transduction and cell proliferation and invasion.

Method: We examined the LRIG1 expression levels in lung cancer cell lines and the surgically resected primary lung cancer tissues by quantitative PCR assay. We made stable clone of EGFR-mutant cell line (HCC827; exon19del E746-A750) overexpressing GFP tagged LRIG1, and compared with stable clone overexpressing GFP alone.

Results: The LRIG1 expression levels in lung cancer cell lines and the surgically resected primary lung cancer tissues were much lower than that in normal bronchial epithelial cells and their normal tissues, respectively. The introduction of LRIG1 decreased EGFR expression and their phosphorylation in EGFR-mutant cell line. LRIG1 strongly suppressed cell proliferation, invasion and migration of EGFR-mutant cell line. In addition, a phospho-RTK array revealed that LRIG1 also downregulated the other RTKs, such as HER2, HER3, MET, and IGF-1R.

Conclusion: Our findings demonstrates that LRIG1 decreases the expression and phosphorylation of mutant-EGFR protein and has strong anti-tumor effect in lung cancer harboring EGFR mutation. These findings suggest the importance of LRIG1 related studies to develop a novel strategy for EGFR mutant cancers.

Citation Format: Hidejiro Torigoe, Shinichi Toyooka, Masakiyo Sakaguchi, Kazuhiko Shien, Hiromasa Yamamoto, Junichi Soh, Hiroaki Asano, Shuta Tomida, Kazunori Tsukuda, Shinichiro Miyoshi. Antitumor effect of LRIG1, negative regulator of ErbB, in lung cancer harboring mutant-EGFR [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5517. doi:10.1158/1538-7445.AM2017-5517

Abstract 3156: Multiple acquired resistance mechanisms against third generation EGFR-TKI osimeritinib in non-smal cell lung cancer cells

Background Osimertinib (AZD9291; Tagrisso) is a third generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) known to be effective against the EGFR-T790M variant, which is accounts for half of the acquired resistance mechanisms to the first generation EGFR-TKIs. However, resistance to osimertinib is likely to progress and the study of potential osimertinib-resistance mechanisms in advanced is necessary. In this study, we investigated the molecular and cellular profiles of the acquired resistance cells to osimertinib in EGFR-mutant non-small cell lung cancers. Materials and Methods Five EGFR-mutant cell lines were exposed to osimertinib by stepwise escalation or high-concentration exposure methods, and resistant sublines to osimertinib were established. The molecular profiles and cellular phenotypes of these resistant sublines were characterized. Results EGFR-C797S mutation which was reported to be a major mechanism of resistance to osimertinib in clinical samples was not detected in established resistance cells by using direct sequencing. Several osimertinib-resistance cell lines displayed MET amplification, and some of these cells were sensitive to the combination of osimertinib plus MET inhibitor crizotinib. However, one cell line that displayed MET amplification was not sensitive to this combination therapy. On the other hand, several osimertinib-resistance cell lines displayed epithelial-to-mesenchymal transition (EMT) features. The HCC827-derived subline established by the high-concentration exposure method exhibited not only EMT features but also cancer stem cell (CSC)-like properties, including aldehyde dehydrogenase isoform 1 (ALDH1A1) and ATP binding cassette subfamily B member 1 (ABCB1) overexpression. Conclusion We established osimertinib-resistant cells and found that MET amplification, EMT, and CSC -like features were observed. These findings may provide clues to overcome acquired resistance to EGFR-TKIs. In some cell lines, however, the mechanisms of acquired resistance to osimertinib were not revealed yet.

Citation Format: Kei Namba, Kazuhiko Shien, Takahiro Yoshioka, Hidejiro Torigoe, Hiroki Sato, Hiromasa Yamamoto, Junichi Soh, Kazunori Tsukuda, Shinichi Toyooka. Multiple acquired resistance mechanisms against third generation EGFR-TKI osimeritinib in non-smal cell lung cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3156. doi:10.1158/1538-7445.AM2017-3156

Yes1 signaling mediates the resistance to Trastuzumab/Lap atinib in breast cancer

Background

Overexpression of human epidermal growth factor receptor 2 (HER2) is observed in approximately 15–23% of breast cancers and these cancers are classified as HER2-positive breast cancer. Trastuzumab is the first-line targeted therapeutic drug for HER2-positive breast cancer and has improved patient overall survival. However, acquired resistance to trastuzumab is still a critical issue in breast cancer treatment. We previously established a trastuzumab-resistant breast cancer cell line (named as BT-474-R) from a trastuzumab-sensitive HER2-amplified cell line BT-474. Lapatinib is also a molecular-targeted drug for HER2-positive breast cancer, which acquired the resistance to trastuzumab. Acquired resistance to lapatinib is also an issue to be conquered.

Methods

We established trastuzumab/lapatinib-dual resistant cell line (named as BT-474-RL2) by additionally treating BT-474-R with lapatinib. We analyzed the mechanisms of resistance to trastuzumab and lapatinib. Besides, we analyzed the effect of the detected resistance mechanism in HER2-positive breast cancer patients.

Results

Proto-oncogene tyrosine-protein kinase Yes1, which is one of the Src family members, was amplified, overexpressed and activated in BT-474-R and BT-474-RL2. Silencing of Yes1 by siRNA induced both BT-474-R and BT-474-RL2 to restore the sensitivity to trastuzumab and lapatinib. Pharmaceutical inhibition of Yes1 by the Src inhibitor dasatinib was also effective to restore the sensitivity to trastuzumab and lapatinib in the two resistant cell lines. Combination treatment with dasatinib and trastuzumab induced down-regulation of signaling molecules such as HER2 and Akt. Moreover, the combination treatments induced G1-phase cell-cycle arrest and apoptosis. Consistent with cell line data, high expression of Yes1 mRNA was correlated with worse prognosis in patients with HER2-positive breast cancer.

Conclusion

Yes1 plays an important role in acquired resistance to trastuzumab and lapatinib in HER2-positive breast cancer. Our data suggest that pharmacological inhibition of Yes1 may be an effective strategy to overcome resistance to trastuzumab and lapatinib.

Targeting the miR-200c/LIN28B axis in acquired EGFR-TKI resistance non-small cell lung cancer cells harboring EMT features

MicroRNA (miR)-200 family members (miR-200s) are frequently silenced in advanced cancer and have been implicated in the process of epithelial-to-mesenchymal transition (EMT). We previously reported that miR-200s were silenced through promoter methylation in acquired EGFR-tyrosine kinase inhibitor (TKI) resistant non-small cell lung cancer (NSCLC) cells harboring EMT features. In this study, we examined the functional role of miR-200s in NSCLC cells and investigated a novel approach to overcoming acquired EGFR-TKI resistance. In the analysis of NSCLC cell lines, each of the miR-200s expression-silenced cell lines showed promoter methylation. Significant correlations between miR-200c silencing and several oncogenic pathway alterations, including EMT-changes and LIN28B overexpression, were observed in the database analysis. In addition, EGFR-wild type cell lines had lower miR-200s expression levels than EGFR-mutant cell lines. The introduction of miR-200c using pre-miR-200c caused LIN28B suppression in cells with acquired EGFR-TKI resistance that harbored EMT features. Interestingly, both the introduction of miR-200c and the knockdown of LIN28B produced an antitumor effect in acquired EGFR-TKI resistance cells, whereas these manipulations were not effective in parental cells. The miR-200c/LIN28B axis plays an important role in cells with acquired resistance to EGFR-TKI that harbor EMT features and might be a useful therapeutic target for overcoming resistance.

Usefulness of Thoracoscopic Debridement for Chronic Empyema after an Extrapleural Pneumonectomy

We present the case of a 65-year-old Japanese man diagnosed with chronic empyema (without a bronchopleural fistula) that occurred 7 months after he underwent an extrapleural pneumonectomy for right malignant pleural mesothelioma (MPM). Following thoracic drainage and irrigation for 1 month, we performed surgery by a thoracoscopic approach, in light of his general condition. We performed debridement and removal of the Gore-Tex polytetrafluoroethylene (PTFE) patch that had been used for the reconstruction of the diaphragm and the pericardium. The empyema had not relapsed when he died from recurrence of the MPM at 4 months after the thoracoscopic surgery. This patient's case suggests that thoracoscopic debridement and patch removal can be a therapeutic option for not only early-stage (exudative or fibrinopurulent) empyema but also late-stage (organized and chronic) empyema without a bronchopleural fistula, particularly for patients in poor general condition.

Abstract 4392: Yes1 is the key molecule for the resistance to trastuzumab in breast cancer, and dasatinib overcomes the resistance

Background: Overexpression of human epidermal growth factor receptor 2 (HER2) was observed in approximately 15-23% of breast cancers and they are classified as HER2-positive breast cancer. Trastuzumab is a therapeutic drug for the first choice for HER2-positive breast cancer, showing good response. However, acquired resistance to trastuzumab is one of the critical clinical issues in breast cancer treatment, especially in the patients with recurrent breast cancer. Therefore, it is necessary to develop the effective therapy to overcome the resistance. In this study, we established a trastuzumab-resistant breast cancer cell line from a trastuzumab-sensitive cell line with HER2 amplification (BT-474). We analyzed the mechanisms of resistance to trastuzumab and demonstrated the anti-tumor effect of dasatinib.

Methods: Trastuzumab-resistant breast cancer cell line (BT-474-R) was established by treating BT-474 cells for long-term exposure with increasing doses of trastuzumab (from 0.1 μg/mL up to 40 μg/mL). Expression and activation of HER2 and its related molecules were investigated using western blotting and real-time PCR. Cell viability was evaluated using MTS assay. Cell cycle was analyzed using flow cytometry.

Results: Proto-oncogene tyrosine-protein kinase Yes1, which is one of the Src family members, was amplified, overexpressed and activated in BT-474-R. HER2 and Akt were also activated. Silencing of Yes1 by siRNA induced BT-474-R to recover sensitivity to trastuzumab. Pharmaceutical inhibition of Yes1 by Src inhibitor dasatinib was also effective to recovery sensitivity to trastuzumab in BT-474-R. Combination treatment of dasatinib and trastuzumab induced down-regulation of signaling molecules such as HER2 and Akt. Moreover, these combination treatments induced G1-phase cell-cycle arrest and apoptosis.

Conclusion: Yes1 plays an important role in acquired resistance to trastuzumab in HER2-positive breast cancer. Our data also suggest that pharmacological inhibition of Yes1 may become the new strategy to overcome resistance to trastuzumab.

Citation Format: Hiromasa Yamamoto, Tatsuaki Takeda, Hirotaka Kanzaki, Ken Suzawa, Kei Namba, Hiroki Sato, Hidejiro Torigoe, Mototsugu Watanabe, Yuho Maki, Junichi Soh, Hiroaki Asano, Kazunori Tsukuda, Shinichiro Miyoshi, Yoshihisa Kitamura, Toshiaki Sendo, Shinichi Toyooka. Yes1 is the key molecule for the resistance to trastuzumab in breast cancer, and dasatinib overcomes the resistance. [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 4392.

Induction S-1+Concurrent Radiotherapy Followed by Surgical Resection of Locally Advanced Non-small-cell Lung Cancer in an Elderly Patient

We present the case of a 77-year-old Japanese man diagnosed with lung squamous cell carcinoma with mediastinal lymph node metastasis. He was treated with induction chemoradiotherapy for T1bN2M0 stage IIIA disease. Considering his age, we selected S-1 as the chemotherapeutic drug. Observing an objective response with no severe adverse events, we performed a left upper lobectomy with sleeve resection of the pulmonary artery. No residual tumor cells were found in the resected specimens, and no critical complication was observed in the clinical course. This case suggests that induction chemoradiotherapy using S-1 combined with concurrent radiation followed by surgery can be a therapeutic option for elderly patients with locally advanced non-small-cell lung cancer.

[Cross-sectoral Approach of a Perioperative Management Center for General Thoracic Surgery]

Perioperative assessment and care, such as enhanced recovery after surgery (ERAS), is very important for improving the clinical outcomes of patients who have undergone surgery. However, professional assessments and care cannot be achieved through the actions of only 1 surgical department. We established a perioperative management center(PERIO) comprised of surgeons, dedicated nurses, anesthesiologists, dentists, physiotherapists, pharmacists, and nutritionists to perform intensive cross-sectoral perioperative management. In this manuscript, we investigated the impact of PERIO on the clinical outcomes of 127 elderly patients who underwent thoracic surgery for the resection of non-small cell lung cancer (NSCLC). We categorized these 127 patients into 3 groups:① those treated before the introduction of PERIO (between January 2006 to August 2008), ② those treated during the early phase after PERIO introduction (September 2008 to December 2011), and ③ those treated during the late phase after PERIO introduction( January 2012 to December 2014). Radical operations were performed significantly more frequently after PERIO introduction than before PERIO introduction, while the postoperative complication rates were similar among the 3 groups. The duration of postoperative hospitalization was reduced after the introduction of PERIO, and the hospital surplus increased after the introduction of PERIO. In conclusion, PERIO may play an important role in improving the clinical outcomes of thoracic surgery, especially for elderly patients with NSCLC.

Effect of mixed mutans streptococci colonization on caries development

OBJECTIVE

To evaluate the clinical importance of mixed mutans streptococci colonization in predicting caries in preschool children.

METHODS

Caries prevalence was examined twice, with a 6-month interval, in 410 preschool children aged 3-4 years at baseline. A commercial strip method was used to evaluate the mutans streptococci score in plaque collected from eight selected interdental spaces and in saliva. Mutans streptococci typing polymerase chain reaction (PCR) assays (Streptococcus sobrinus and Streptococcus mutans, including serotypes c, e, and f) were performed using colonies on the strips as template.

RESULTS

Twenty variables were examined in a univariate analysis to predict caries development: questionnaire variables, results of clinical examination, mutans streptococci scores, and PCR detection of S. sobrinus and S. mutans (including serotypes c, e, and f). Sixteen variables showed statistically significant associations (P < 0.04) in the univariate analysis. However, when entered into a logistic regression, only five variables remained significant (P < 0.05): caries experience at baseline; mixed colonization of S. sobrinus and S. mutans including S. mutans serotypes; high plaque mutans streptococci score; habitual use of sweet drinks; and nonuse of fluoride toothpaste.

CONCLUSION

'Mixed mutans streptococci colonization' is a novel measure correlated with caries development in their primary dentition.

Promotion of triplex formation by a fixed N-form sugar puckering: thermodynamic and kinetic studies

We analyzed the effect of a fixed N-form sugar puckering of TFO (triplex-forming oligonucleotide) on the pyrimidine motif triplex formation at neutral pH, a condition where pyrimidine motif triplexes are unstable. Both thermodynamic and kinetic analyses revealed that the binding constant of the pyrimidine motif triplex formation at pH 6.8 with modified TFO containing the fixed N-form sugar puckering was about 20-times larger than that observed with unmodified TFO. Kinetic data also demonstrated that the observed increase in the binding constant at neutral pH by the fixed N-form sugar puckering resulted from the considerable decrease in the dissociation rate constant. Our results certainly support the idea that the fixed N-form sugar puckering of TFO could be a key modification and may eventually lead to progress in therapeutic applications of the antigene strategy in vivo.

Thermodynamic analyses of triplex formation with homopurine oligonucleotide

We analyzed the thermodynamics of purine motif triplex formation by isothermal titration calorimetry. The signs of calorimetric enthalpy change, delta Hcal, and entropy change, delta S, of the triplex formation were negative in the temperature range between 15 and 35 degrees C. Since an observed negative delta S was unfavorable for the triplex formation, the triplex formation was driven by a large negative delta Hcal. delta Hcal decreased with increasing temperature, yielding a negative heat capacity change, delta Cp, of approximately -1.2 kcal mol-1 K-1. We found that the binding constant, Ka, increased with increasing temperature, leading to an apparent positive van't Hoff enthalpy change, delta Hvh, which was in sharp contrast with the large negative delta Hcal. The analyses of the observed temperature dependence of Ka and delta Hcal and the negative delta Cp suggest that the purine motif triplex formation near room temperature is not a simple two-state binding process but exhibits multiple states, which was previously observed for the pyrimidine motif triplex formation near room temperature.

Promotion of triplex formation by N3'-->P5' phosphoramidate modification: thermodynamic and kinetic studies

I examined the effect of N3'-->P5' phosphoramidate (PN) backbone modification of triplex-forming oligonucleotide (TFO) on the pyrimidine motif triplex formation at neutral pH, a condition where pyrimidine motif triplexes are unstable. Both thermodynamic and kinetic analyses have indicated that the PN modification of TFO increased the binding constant of the pyrimidine motif triplex formation at pH 6.8 by nearly 2 orders of magnitude. Kinetic data have also demonstrated that the observed increase in the binding constant at neutral pH by the PN modification resulted mainly from the considerable decrease in the dissociation rate constant rather than the increase in the association rate constant. The present results certainly support the idea that the PN modification of TFO could be a key modification and may eventually lead to progress in therapeutic applications of the antigene strategy in vivo.

Synergistic stabilization of triplex by combination of comb-type cationic copolymer and oligo-N3'-->P5' phosphoramidates

In the present study, we describe rapid formation of stable pyrimidine motif triplex at physiological pH. The triplex formation was achieved by the synergistic effect of poly(L-lysine)-graft-dextran (PLL-g-Dex) copolymer and N3'-->P5' phosphoramidate (PN) backbone modification of triplex-forming oligonucleotide (TFO). Either the PLL-g-Dex copolymer or the PN modification alone increased the binding constant by nearly two orders of magnitude for the triplex formation at neutral pH. The combination of both stabilizing factors that was the triplex formation with the PN TFO in the presence of the copolymer increased the binding constant by nearly four orders of magnitude. The kinetic study indicated that the copolymer increased the association rate constant, whereas the PN modification decreased the dissociation rate constant. No negative interference between these stabilizing effects was observed. The kinetically orchestrated effects in which the copolymer and the PN TFO contribute to distinct ingredients in triplex equilibrium achieved the rapid formation of the stable triplex.

Triplex formation involving 2',4'-BNA with 2-pyridone base analogue: efficient and selective recognition of C:G interruption

We examined the thermodynamic properties of 2',4'-bridged nucleic acid containing 2-pyridone as a nucleobase (PB) to recognize a C interruption in the homopurine strand of the target duplex for pyrimidine motif triplex formation at neutral pH. The triplex formation involving triplex-forming oligonucleotide with PB is highly sequence-selective to specifically recognize C:G target base pair rather than the other G:C, T:A, or A:T base pairs. PB.C:G triad gives significantly larger binding constant than T.C:G triad, which has been known to be the most stable combination in natural base.C:G triad. Our results certainly support the idea that PB could be a key nucleoside to recognize a C interruption in the homopurine strand of the target duplex with high binding affinity and selectivity, and reduce the restriction of target sequences for triplex formation.

Rational procedure for 3D-QSAR analysis using TRNOE experiments and computational methods: application to thermolysin inhibitors

The success or failure of 3D QSAR, particularly CoMFA, is most strongly dependent, especially for flexible compounds, on the conformation of the molecule used in the analysis, and on the orientation of the molecule relative to the other molecules in 3D space (i.e., alignment). The present study suggests a rational procedure for the estimation of binding conformation that uses the transferred nuclear Overhauser effect (TRNOE) experiment in combination with conformational analysis using CAMDAS (Conformational Analyzer with Molecular Dynamics And Sampling) program that is developed in our laboratory. In the next step the TRNOE-obtained conformation can be used as a reference template in order to obtain alignment of other ligands, that have a common binding site. In this step we used the SUPERPOSE program created in our laboratory, in order to estimate the binding conformation of other compounds, and to simultaneously obtain the alignment of compounds for CoMFA. The resulting CoMFA models could be expected to closely reproduce the interaction mode with protein represented by the reported X-ray results. In order to confirm the validity of our procedure described above, we show its application in obtaining CoMFA models of thermolysin inhibitors. We obtained twenty CoMFA models, and that with the highest q2 value (q2 = 0.701) was found to provide an interaction mode very similar to that represented by the X-ray results.

Promotion of triplex formation by 2'-O,4'-C-methylene bridged nucleic acid (2',4'-BNA) modification: thermodynamic and kinetic studies

We analyzed the effect of 2'-O,4'-C-methylene bridged nucleic acid (2',4'-BNA) modification of triplex-forming oligonucleotide (TFO) on pyrimidine motif triplex formation at neutral pH, a condition where pyrimidine motif triplexes are unstable. The binding constant of the pyrimidine motif triplex formation at pH 6.8 with 2',4'-BNA modified TFO was about 20 times larger than that observed with unmodified TFO. The observed increase in the binding constant at neutral pH by the 2',4'-BNA modification resulted from the considerable decrease in the dissociation rate constant.

Novel class of DNA binding motifs based on bistetrahydrofuran and bisfuran skeleton with long alkyl chains

Small molecules with DNA-binding affinity within the minor groove have become of great interest. In this paper, new DNA binding molecules; diamino-bistetrahydrofuran (bisTHF) and diamino-bisfuran are reported. The bisTHF ligand with RR configuration at the amino groups and C8 alkyl chains (RR8) stabilized GC-rich duplex. In contrast, bisfuran compounds stabilized AT-rich duplex. The binding affinity of RR8 with 12 mer duplex DNA was determined by isothermal titration calorimetry to be 3.3 x 10(8) M-1.

Thermodynamic and kinetic effects of N3'-->P5' phosphoramidate modification on pyrimidine motif triplex DNA formation

I have investigated the thermodynamic and kinetic effects of N3'-->P5' phosphoramidate (PN) backbone modification of triplex-forming oligonucleotide (TFO) on the pyrimidine motif triplex formation between a 23-bp target duplex and a 15-mer TFO using electrophoretic mobility shift assay, UV melting, isothermal titration calorimetry, and interaction analysis system. The thermodynamic and kinetic analyses have clearly indicated that the PN modification of TFO not only significantly increased the thermal stability of the pyrimidine motif triplex at neutral pH but also increased the binding constant of the pyrimidine motif triplex formation at room temperature and neutral pH by nearly 2 orders of magnitude. The consideration of the observed thermodynamic parameters has suggested that the more rigidity of the PN TFO in the free state relative to the unmodified TFO may enable the significant increase in the binding constant of the pyrimidine motif triplex formation at neutral pH. Kinetic data have also demonstrated that the observed PN modification-mediated promotion of pyrimidine motif triplex formation at neutral pH resulted from the considerable decrease in the dissociation rate constant rather than the increase in the association rate constant. This information will present an effective approach for designing chemically modified TFO with higher binding affinity in the triplex formation under physiological conditions, which may eventually lead to progress in therapeutic applications of the antigene strategy in vivo.

2'-O,4'-C-methylene bridged nucleic acid modification promotes pyrimidine motif triplex DNA formation at physiological pH: thermodynamic and kinetic studies

Extreme instability of pyrimidine motif triplex DNA at physiological pH severely limits its use in an artificial control of gene expression in vivo. Stabilization of the pyrimidine motif triplex at physiological pH is, therefore, crucial in improving its therapeutic potential. To this end, we have investigated the thermodynamic and kinetic effects of our previously reported chemical modification, 2'-O,4'-C-methylene bridged nucleic acid (2',4'-BNA) modification of triplex-forming oligonucleotide (TFO), on pyrimidine motif triplex formation at physiological pH. The thermodynamic analyses indicated that the 2',4'-BNA modification of TFO increased the binding constant of the pyrimidine motif triplex formation at neutral pH by approximately 20 times. The number and position of the 2',4'-BNA modification introduced into the TFO did not significantly affect the magnitude of the increase in the binding constant. The consideration of the observed thermodynamic parameters suggested that the increased rigidity itself of the 2',4'-BNA-modified TFO in the free state relative to the unmodified TFO may enable the significant increase in the binding constant at neutral pH. Kinetic data demonstrated that the observed increase in the binding constant at neutral pH by the 2',4'-BNA modification of TFO resulted from the considerable decrease in the dissociation rate constant. Our results certainly support the idea that the 2',4'-BNA modification of TFO could be a key chemical modification and may eventually lead to progress in therapeutic applications of the antigene strategy in vivo.

Promotion of duplex and triplex DNA formation by polycation comb-type copolymers

Triplex DNA has attracted considerable interest recently because of its possible biological functions in vivo and its wide variety of potential applications, such as regulation of gene expression, site-specific cleavage of duplex DNA, mapping of genomic DNA, and gene-targeted mutagenesis (1-3). A triplex is usually formed through the sequence-specific interaction of a single-stranded homopyrimidine or homopurine triplex-forming oligonucleotide (TFO) with the major groove of the homopurine-homopyrimidine stretch in duplex DNA (1-5). In the pyrimidine motif triplex, a homopyrimidine TFO binds parallel to the homopurine strand of the target duplex by Hoogsteen hydrogen bonding to form T[Symbol: see text]A:T and C(+[Symbol: see text])G:C triplets ([Symbol: see text] and : represent Hoogsteen hydrogen bonding and Watson Crick base pairing, respectively). (1-5). Because the cytosine bases in a homopyrimidine TFO are to be protonated to bind with the guanine bases of the G:C duplex, the formation of the pyrimidine motif triplex needs an acidic pH condition, and is thus unstable at physiological pH (6-8). On the other hand, in the purine motif triplex, a homopurine TFO binds antiparallel to the homopurine strand of the target duplex by reverse Hoogsteen hydrogen bonding to form A[Symbol: see text]A:T (or T[Symbol: see text]A:T) and G[Symbol: see text]G:C triplets (1-5). Although the purine motif triplex is pH-independent, triplexes involving guanine-rich TFOs are inhibited by physiological concentrations of certain monovalent cations (M(+)), especially K(+) (9,10).

Novel DNA-binding ligands with sequence selectivity based on hydrophobic structure

We have developed diamino-bistetrahydrofuran compounds (diamino-bisTHF) as new DNA binding molecules. Diamino-bisTHF (3:RR8) stabilized GC-rich duplex DNA with sequence specificity. DNA binding affinity increased as the alkyl chain was lengthened, indicating that the hydrophobic interaction is essential for DNA binding. It was also found that DNA binding affinity of the ligands depends on the stereochemistry of the amino group. In thermodynamic evaluation, diamino-bisTHF (3:RR8) showed a high affinity to the 12 bp duplex at a molar ratio of 1:1.