[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.

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, NPTNß, 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".

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.

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.

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.

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-ß 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.

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.

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.

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.

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.

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.

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.

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.

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.

Droplet digital PCR as a novel system for the detection of microRNA­34b/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 miR­34b/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 receiver­operating characteristic curve analysis using the samples in group A determined the optimal cut­off 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 miR­34b/c methylation in circulating DNA is a promising biomarker for the prediction of disease progression in patients with MPM.

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.

Ganetespib in Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitor-resistant Non-small Cell Lung Cancer.

BACKGROUND: The 90-kDa heat-shock protein (HSP90) is a chaperone protein expressed at high levels in cancer cells and is involved in the folding or stabilization of several client proteins, including epidermal growth factor receptor (EGFR). Ganetespib is a second-generation HSP90 inhibitor with a potent antitumor effect against various cancer types. MATERIALS AND METHODS: This study examined the antitumor effect of ganetespib in EGFR-mutant non-small cell lung cancer (NSCLC) cells and experimentally established EGFR-tyrosine kinase inhibitor (TKI)-resistant cells harboring various resistance mechanisms, including EGFR T790M mutation, met proto-oncogene amplification, and epithelial-mesenchymal transition. RESULTS: Ganetespib showed a potent antitumor effect at low concentrations, suppressing EGFR-related downstream pathway molecules and inducing cleavage of poly ADP-ribose polymerase in all examined EGFR-TKI-resistant cell lines in vitro. Ganetespib also inhibited in vivo tumor growth in resistant cells harboring EGFR T790M. CONCLUSION: Ganetespib might be a promising therapeutic option for the treatment of patients with EGFR-TKI-resistant NSCLC.

Therapeutic potential of targeting S100A11 in malignant pleural mesothelioma.

Malignant pleural mesothelioma (MPM) is an aggressive tumor with an unfavorable prognosis. The standard therapeutic approaches are limited to surgery, chemotherapy, and radiotherapy. Because the consequent clinical outcome is often unsatisfactory, a different approach in MPM treatment is required. S100A11, a Ca2+-binding small protein with two EF-hands, is frequently upregulated in various human cancers. Interestingly, it has been found that intracellular and extracellular S100A11 have different functions in cell viability. In this study, we focused on the impact of extracellular S100A11 in MPM and explored the therapeutic potential of an S100A11-targeting strategy. We examined the secretion level of S100A11 in various kinds of cell lines by enzyme-linked immunosorbent assay. Among them, six out of seven MPM cell lines actively secreted S100A11, whereas normal mesothelial cell lines did not secrete it. To investigate the role of secreted S100A11 in MPM, we inhibited its function by neutralizing S100A11 with an anti-S100A11 antibody. Interestingly, the antibody significantly inhibited the proliferation of S100A11-secreting MPM cells in vitro and in vivo. Microarray analysis revealed that several pathways including genes involved in cell proliferation were negatively enriched in the antibody-treated cell lines. In addition, we examined the secretion level of S100A11 in various types of pleural effusions. We found that the secretion of S100A11 was significantly higher in MPM pleural effusions, compared to others, suggesting the possibility for the use of S100A11 as a biomarker. In conclusion, our results indicate that extracellular S100A11 plays important roles in MPM and may be a therapeutic target in S100A11-secreting MPM.