Epidermal Growth Factor Receptor Blockers Research Articles

Dual Targeting of Epidermal Growth Factor Receptor and HER3 by MEHD7945A as Monotherapy or in Combination with Cisplatin Partially Overcomes Cetuximab Resistance in Head and Neck Squamous Cell Carcinoma Cell Lines

Aberrant signaling of the epidermal growth factor receptor (EGFR) plays a crucial role in the tumorigenesis of many cancer types, including head and neck squamous cell carcinoma (HNSCC), making it a compelling drug target. After initial promising results of EGFR-targeted therapies such as cetuximab, the problem of therapeutic resistance is emerging and new treatment options are necessary. In contrast to first-generation EGFR inhibitors, MEHD7945A (duligotuzumab) is a monoclonal antibody with dual EGFR/HER3 specificity. Consequently, treatment with MEHD7945A may result in a more pronounced therapeutic benefit. In this study, sensitivity to MEHD7945A as a single agent and in combination with cisplatin was investigated in cetuximab-sensitive and -resistant HNSCC cell lines under normal and reduced oxygen conditions. The results demonstrated that sensitivity to MEHD7945A was cell line dependent and influenced by oxygen concentration. An additive, but not synergistic, interaction between MEHD7945A and cisplatin was observed. In conclusion, MEHD7945A has the potential to partially overcome cetuximab resistance. Nevertheless, further research is warranted to determine additional resistance mechanisms to cetuximab treatment besides HER3 signaling. Unraveling these mechanisms will ultimately lead to the development of new therapeutic strategies to improve the response to EGFR blockage.

Decreased homodimerization and increased TIMP-1 complexation of uteroplacental and uterine arterial matrix metalloproteinase-9 during hypertension-in-pregnancy

Preeclampsia is a complication of pregnancy manifested as hypertension-in-pregnancy (HTN-Preg) and often intrauterine growth restriction (IUGR). Placental ischemia could be an initiating event, but the molecular mechanisms are unclear. To test the hypothesis that dimerization of matrix metalloproteinases (MMPs) plays a role in HTN-Preg and IUGR, the levels/activity of MMP-9, tissue inhibitor of metalloproteinase (TIMP-1), and their dimerization forms were measured in the placenta, uterus, and uterine artery of normal pregnant (Preg) rats and a rat model of reduced uteroplacental perfusion pressure (RUPP). Consistent with our previous report, blood pressure (BP) was higher, pup weight was lower, and gelatin zymography showed different gelatinolytic activity for pro-MMP-9, MMP-9, pro-MMP-2 and MMP-2 in RUPP vs Preg rats. Careful examination of the zymograms showed additional bands at 200 and 135kDa. Western blots with MMP-9 antibody suggested that the 200kDa band was a MMP-9 homodimer. Western blots with TIMP-1 antibody as well as reverse zymography suggested that the 135kDa band was a MMP-9/TIMP-1 complex. The protein levels and gelatinase activity of MMP-9 homodimer were decreased while MMP-9/TIMP-1 complex was increased in placenta, uterus and uterine artery of RUPP vs Preg rats. The epidermal growth factor (EGF) receptor blocker erlotinib and protein kinase C (PKC) inhibitor bisindolylmaleimide decreased MMP-9 homodimer and increased MMP-9/TIMP-1 complex in placenta, uterus and uterine artery of Preg rats. EGF and the PKC activator phorbol-12,13-dibutyrate (PDBu) reversed the decreases in MMP-9 homodimer and the increases in MMP-9/TIMP-1 complex in tissues of RUPP rats. Thus, the increased BP and decreased pup weight in placental ischemia model of HTN-Preg are associated with a decrease in MMP-9 homodimer and an increase in MMP-9/TIMP-1 complex in placenta, uterus, and uterine artery, which together would cause a net decrease in MMP-9 activity and reduce uteroplacental and vascular remodeling in the setting of HTN-Preg and IUGR. Enhancing EGFR/PKC signaling may reverse the MMP-9 unfavorable dimerization patterns and thereby promote uteroplacental and vascular remodeling in preeclampsia.

The role of RNase 7 in innate cutaneous defense against Pseudomonas aeruginosa.

The ribonuclease RNase 7 is a major skin-derived human antimicrobial protein expressed in keratinocytes. Here we show that the gram-negative pathogen Pseudomonas aeruginosa secretes factor(s) that induced RNase 7 gene and protein expression in human primary keratinocytes. The metalloprotease inhibitor marimastat, the epidermal growth factor receptor (EGFR) inhibitor AG1478 and the EGFR blocking antibody cetuximab significantly attenuated this induction, indicating an important role of the EGFR for the P.aeruginosa-mediated RNase 7 induction. In line with this, siRNA-mediated downregulation of ADAM17, a metalloprotease known to proteolytically mediate the release of soluble EGFR ligands, decreased the P.aeruginosa-mediated RNase 7 induction in keratinocytes. The impact of the EGFR was also demonstrated in a human 3D skin equivalent where blockade of the EGFR diminished induction of RNase 7 by P.aeruginosa. Blockade of Toll-like receptor 5 (TLR5), a pattern recognition receptor (PRR) known to be activated by P.aeruginosa, only moderately reduced the P.aeruginosa-mediated RNase 7 induction in keratinocytes. The functional relevance of RNase 7 to participate in cutaneous defense against P.aeruginosa was demonstrated by antibodies that neutralized the antimicrobial activity of RNase 7. These antibodies significantly inhibited the capacity of human stratum corneum skin extracts to control growth of P.aeruginosa. Taken together, our results indicate that P.aeruginosa induces the expression of RNase 7 in keratinocytes in an EGFR-dependent manner. Enhanced release of RNase 7 contributes to control cutaneous growth of P.aeruginosa.

MTE23.02 Biomarker Characterization: Challenges and Perspectives

Small molecule inhibitors are the current treatment for non-small-cell lung cancer (NSCLC), especially for tumors harboring an active mutation of epidermal growth factor receptor (EGFR). Approximately 90% of EGFR mutations are exon 19 deletions or exon 21 single-point L858R substitutions and are associated with sensitivity to EGFR tyrosine kinase inhibitors (EGFR TKIs), like gefitinib or erlotinib. However, less than 5% of EGFR-mutant NSCLC patients achieve a complete response to EGFR TKI and the overall median progression-free survival is no longer than 9-11 months. Accumulated studies report several mechanisms of early adaptive resistance that can occur as early as two hours after starting EGFR TKI therapy. The activation of signal transducer and activator of transcription 3 (STAT3) signaling is among these mechanisms of resistance. Furthermore, EGFR blockage enriches lung cancer stem cells through Notch3-dependent signaling pathway. We have previously demonstrated that NF-κB contributes to gefitinib resistance in EGFR-mutant NSCLC. The efficacy of EGFR tyrosine kinase inhibitors (TKIs) in EGFR-mutant non-small cell lung cancer (NSCLC) is jeopardized by the activation of signaling pathways. We examined the relevance of co-targeting EGFR, signal transducer and activator of transcription 3 (STAT3) and Src-YES-associated protein 1 (YAP1) signaling. We conducted clinical and preclinical studies of key components of signaling pathways limiting EGFR TKI efficacy in EGFR-mutant NSCLC. High levels of STAT3 or YAP1 mRNA expression were associated with worse outcome to EGFR TKI in two independent cohorts of EGFR-mutant NSCLC patients. In the initial cohort of 64 patients, median progression-free survival was shorter among the patients with high STAT3 than among those with low STAT3 (hazard ratio [HR] for disease progression, 3·02; 95% confidence interval [CI], 1·54-5·93; P=0·0013). Median progression-free survival was shorter among the patients with high YAP1 than among those with low YAP1 (HR for disease progression, 2·57; 95%CI, 1·30-5·09; P=0·0067). The results were similar in the validation cohort of 55 patients. We demonstrated that gefitinib augments STAT3 signaling in EGFR-mutant NSCLC cells. Gefitinib with TPCA-1 (STAT3 inhibitor) blocked STAT3, but not the YAP1 phosphorylation on tyrosine residue 357 by Src family kinases (SFKs) that occurs downstream of IL-6. The triple combination of gefitinib, TPCA-1 and AZD0530 (SFK inhibitor) ablated both STAT3 and YAP1 phosphorylation and markedly and safely suppressed tumor growth. Added value of our research: We found that EGFR TKI therapy activates STAT3 and that EGFR blockage enriches lung cancer stem cells with up-regulation of the YAP1 and Notch downstream effectors connective tissue growth factor (CTGF) and hairy-enhancer of split-1 (HES1), respectively. We sought to demonstrate that EGFR TKI treatment cannot abrogate STAT3 and Src-YAP1-Notch activation in EGFR-mutant NSCLC cell lines, leading us to examine whether the combination of gefitinib with compounds targeting STAT3 and Src, suppresses the mechanisms of resistance. Nine days after gefitinib treatment, STAT3 mRNA level was significantly increased, as well as the fraction of ALDH positive cells. TPCA-1, a compound that targets STAT3, increases sensitivity to gefitinib in PC-9 and H1975 cells; however, neither gefitinib nor TPCA-1 inhibits Src or YAP1. The addition of the Src inhibitor, saracatinib, to the doublet of gefitinib and TPCA-1, was highly synergistic and abrogated STAT3, and Src-YAP1-Notch signaling. Implications: Treatment with single EGFR TKI can no longer be considered adequate for patients with EGFR mutant NSCLC. Our findings ultimately suggest that a clinical trial evaluating the co-targeted inhibition of STAT3 and Src is warranted. As a result, STAT3 and YAP1 mRNA levels could become important predictive biomarkers. We searched PubMed for English language reports published up to December, 2015 using the terms “non-small-cell lung cancer”, “STAT3”, “interleukin-6”, “NF-κB”, “aldehyde-dehydrogenase (ALDH)”, “integrin-linked kinase (ILK)”, “glycoprotein 130 (gp130)”, “Src-homology 2 domain-containing phosphatase 2 (SHP2)”, “the complement C1r/C1s, Uegf, Bmp1 (CUB) domain-containing protein-1 (CDCP1)”, “AXL”, “ephrin type-A receptor-2 (EphA2)”, “Src family kinases (SFK)”, “YES-associated protein 1 (YAP1)”, “Notch”, “cell migration, invasion and metastases” and “STAT3 inhibitors”. STAT3, EGFR TKI, YAP1, NSCLC

Randomized Phase II Study of Duligotuzumab (MEHD7945A) vs. Cetuximab in Squamous Cell Carcinoma of the Head and Neck (MEHGAN Study).

Duligotuzumab, a novel dual-action humanized IgG1 antibody that blocks ligand binding to epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 3 (HER3), inhibits signaling from all ligand-dependent HER dimers, and can elicit antibody-dependent cell-mediated cytotoxicity. High tumor-expression of neuregulin 1 (NRG1), a ligand to HER3, may enhance sensitivity to duligotuzumab. This multicenter, open-label, randomized phase II study (MEHGAN) evaluated drug efficacy in patients with recurrent/metastatic (R/M) squamous cell carcinoma of the head and neck (SCCHN) progressive on/after chemotherapy and among patients with NRG1-high tumors. Patients received duligotuzumab (1100 mg IV, q2w) or cetuximab (400 mg/m2 load, 250 mg/m2 IV, q1w) until progression or intolerable toxicity. Tumor samples were assayed for biomarkers [NRG1, ERBB3, and human papillomavirus (HPV) status]. Patients (N = 121) were randomized (duligotuzumab:cetuximab; 59:62), median age 62 years; ECOG 0-2. Both arms (duligotuzumab vs. cetuximab, respectively) showed comparable progression-free survival [4.2 vs. 4.0 months; HR: 1.23 (90% confidence interval (CI): 0.89-1.70)], overall survival [7.2 vs. 8.7 months; HR 1.15 (90% CI: 0.81-1.63)], and objective response rate (12 vs. 14.5%), with no difference between patients with NRG1-high tumors or ERBB3-low tumors. Responses in both arms were confined to HPV-negative patients. Grade ≥3 adverse events (AEs) (duligotuzumab vs. cetuximab, respectively) included infections (22 vs. 11.5%) and GI disorders (17 vs. 7%), contributing to higher rates of serious AEs (41 vs. 29.5%). Metabolic disorders were less frequent with duligotuzumab (10 vs. 16%); any grade rash-related events were less with duligotuzumab (49 vs. 67%). While several lines of preclinical evidence had supported the premise that the blockade of HER3 in addition to that of EGFR may improve outcomes for patients with R/M SCCHN overall or specifically in those patients whose tumors express high levels of NRG1, this study provided definitive clinical evidence refuting this hypothesis. Duligotuzumab did not improve patient outcomes in comparison to cetuximab despite frequent expression of NRG1. These data indicate that inhibition of EGFR alone is sufficient to block EGFR-HER3 signaling, suggesting that HER2 plays a minimal role in this disease. Extensive biomarker analyses further show that HPV-negative SCCHN but not HPV-positive SCCHN are most likely to respond to EGFR blockage by cetuximab or duligotuzumab.

ADAM17-siRNA inhibits MCF-7 breast cancer through EGFR-PI3K-AKT activation.

A disintegrin and metalloproteinase-17 (ADAM17) can cut and release a wide variety of epidermal growth factor receptor (EGFR) ligands to promote survival, invasion and proliferation of cancer cell, and therefore, is considered to be a potential therapeutic target for cancer. The main goal of the present study was to observe the effects of ADAM17 small interfering RNA (ADAM17-siRNA) on human MCF-7 breast cancer and investigate its activation pathway. Invitro, MCF-7 cells were divided into ADAM17-siRNA groups, nonsense siRNA groups, AG1478 (selective EGFR blocker) groups, LY294002 [phosphatidylinositol 3-kinase (PI3K) phosphorylation inhibitor] groups, PD0325901 [mitogen extracellular kinase (MEK) inhibitor] groups and control groups. Invivo, MCF-7 cells were implanted subcutaneously into nude mice and then these mice were randomly divided into ADAM17-siRNA groups, vector groups and control groups. Our data showed that compared with the control groups, ADAM17-siRNA, AG1478 and LY294002 could inhibit the migration and proliferation of MCF-7 cells, but PD0325901 and nonsense siRNA did not show this effect. Except that specific ADAM17-siRNA could inhibit the expression of ADAM17 mRNA, others did not change it. Western blot analysis further confirmed that EGFR-PI3K-AKT signaling pathway is involved in ADAM17-siRNA inhibiting migration and proliferation of MCF-7 cells. Similarly to the former, the growth of MCF-7 breast cancer in nude mice was significantly inhibited by ADAM17-siRNA. Compared with the control group and the vector group, the tumor volume was smaller in the ADAM17-siRNA group, the tissues developed large areas of necrosis, immunohistochemistry showed low expressions of ADAM17 and Ki-67 and western blot analysis proved that the expression of ADAM17 protein in the tissue was also reduced. The present study suggests that ADAM17-siRNA inhibits MCF-7 breast cancer and is activated through the EGFR-PI3K-AKT signaling pathway.

Hypopharyngeal cancer: United Kingdom National Multidisciplinary Guidelines.

This is the official guideline endorsed by the specialty associations involved in the care of head and neck cancer patients in the UK. With an age standardised incidence rate of 0.63 per 100 000 population, hypopharynx cancers account for a small proportion of the head and neck cancer workload in the UK, and thus suffer from the lack of high level evidence. This paper discusses the evidence base pertaining to the management of hypopharyngeal cancer and provides recommendations on management for this group of patients receiving cancer care. Recommendations • Cross-sectional imaging with computed tomography of the head, neck and chest is necessary for all patients; magnetic resonance imaging of the primary site is useful particularly in advanced disease; and computed tomography and positron emission tomography to look for distant disease. (R) • Careful evaluation of the upper and lower extents of the disease is necessary, which may require contrast swallow or computed tomography and positron emission tomography imaging. (R) • Formal rigid endoscopic assessment under general anaesthetic should be performed. (R) • Nutritional status should be proactively managed. (R) • Full and unbiased discussion of treatment options should take place to allow informed patient choice. (G) • Early stage disease can be treated equally effectively with surgery or radiotherapy. (R) • Endoscopic resection can be considered for early well localised lesions. (R) • Bulky advanced tumours require circumferential or non-circumferential resection with wide margins to account for submucosal spread. (R) • Offer primary surgical treatment in the setting of a compromised larynx or significant dysphagia. (R) • Midline lesions require bilateral neck dissections. (R) • Consider management of silent nodal areas usually not addressed for other primary sites. (G) • Reconstruction needs to be individualised to the patients' needs and based on the experience of the unit with different reconstructive techniques. (G) • Consider tumour bulk reduction with induction chemotherapy prior to definitive radiotherapy. (R) • Consider intensity modulated radiation therapy where possible to limit the consequences of wide field irradiation to a large volume. (R) • Use concomitant chemotherapy in patients who are fit enough and consider epidermal growth factor receptor blockers for those who are less fit. (R).

Design, Synthesis and Biological Evaluation of Salicylamide Analogues as Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors

Blocking epidermal growth factor receptor (EGFR) has been the hotspot in the field of cancer therapy. Based on the fact that salicylanilides possess well inhibitory activity against EGFR tyrosine kinase, a series of salicylamide analogs bearing 4’-substitution were designed to explore new candidates exhibiting improved efficacy against EGFR. Many of the synthesized compounds inhibited EGFR in the micromolar range, especially compounds 15a and 15b (IC50 = 0.27 μM and 1.1μM, respectively). We report our findings as a basis for further development in salicylamide analogues as EGFR inhibitors. Keywords: EGFR inhibitors, in vitro enzyme assay, synthesis, molecular modeling, salicylamides, structure–activity relationships.

EGFR-targeted mAb therapy modulates autophagy in head and neck squamous cell carcinoma through NLRX1-TUFM protein complex.

EGFR-targeted therapy in head and neck squamous cell carcinoma (HNSCC) patients frequently results in tumor resistance to treatment. Autophagy is an emerging underlying resistance mechanism, however, the molecular autophagy machinery in HNSCC cells and potential biomarkers of patient response to EGFR-targeted therapy remain insufficiently characterized. Here we show that the EGFR blocking with cetuximab leads to varied autophagic responses, which modulate cancer cell susceptibility to EGFR inhibition. Inhibition of autophagy sensitizes HNSCC cells to EGFR blockade. Importantly, we identify a novel signaling hub centering on the NLRX1-TUFM protein complex, promoting autophagic flux. Defects in the expression of either NLRX1 or TUFM result in compromised autophagy when treated with EGFR inhibitors. As a previously undefined autophagy-promoting mechanism, we found that TUFM serves as a novel anchorage site, recruiting Beclin-1 to mitochondria, promoting its polyubiquitination, and interfering with its interaction with Rubicon. This protein complex is also essential for endoplasmic reticulum (ER) stress signaling induction, possibly as an additional mechanism to promote autophagy. Utilizing tumor specimens from a novel neoadjuvant clinical trial, we show that increased expression of the autophagy adaptor protein, SQSTM1/p62, is associated with poor response to cetuximab therapy. These findings expand our understanding of the components involved in HNSCC autophagy machinery that responds to EGFR inhibitors, and suggest potential combinatorial approaches to enhance its therapeutic efficacy.

Preclinical Study of a Combination of Erlotinib and Bevacizumab in Early Stages of Unselected Non-Small Cell Lung Cancer Patient-Derived Xenografts.

The differential outcomes of clinical studies of the targeted therapies for non-small cell lung cancer (NSCLC) indicate that better stratification of patients is required. This could be achieved with the help of patient-derived xenografts (PDX) of epidermal growth factor receptor (EGFR) wild-type patients resistant to erlotinib treatment. To explore the potential of patient-derived NSCLC xenografts to optimize therapy using 24 well-characterized early-stage NSCLC PDX. Patient tumor tissue was transplanted subcutaneously into nude mice. After engraftment, tumors were expanded and the sensitivity was tested. Gene expression analysis was used to identify differentially expressed genes between erlotinib responder (n = 3) and non-responder (n = 21). Tumor tissue was analyzed with TaqMan PCR, immunohistochemistry and ELISA to examine the response of the models. Gene expression analysis revealed vascular endothelial growth factor A (VEGFA) to be up-regulated in erlotinib non-responder. Because of that, the combination of erlotinib with bevacizumab was evaluated in one erlotinib-sensitive and four erlotinib-resistant PDX. Combination treatment was superior to monotherapy, leading to the highest and significant inhibition of tumor growth in all models investigated. A decline of VEGFA protein and an increase of VEGFA-mRNA were observed after bevacizumab treatment. Bevacizumab treatment resulted in a distinct decrease of blood vessel number. This study showed that with the help of preclinical PDX models, drug combinations for therapy improvement can be identified on a rational basis. It was observed that a dual blockage of EGFR and VEGFA was more effective than a monotherapy for the treatment of NSCLC in selected PDX models. PDX could be employed to optimize the treatment of cancer patients.

Protein phosphatase 2A (PP2A) activation promotes axonal growth and recovery in the CNS

Current treatments to restore neurological deficits caused by axonal disconnection following central nervous system (CNS) injury are extremely limited. Protein phosphatase 2A (PP2A), one of the main serine-threonine phosphatases in mammalian cells, dephosphorylates collapsin response mediator protein-2 (CRMP2) in the developing CNS. In our study, we found that the major CNS inhibiting substrates, including chondroitin sulfate proteoglycans (CSPGs) and myelin associated glycoproteins (MAG), activated epidermal growth factor receptor (EGFR), but inactivated PP2A and downstream CRMP2. Both EGFR inactivation and PP2A activation promoted axon elongation in vitro in the presence of inhibitory substrates. EGFR blockage by AG1478 selectively attenuated the inactive form of PP2A in pY307 phosphorylation, thus increasing PP2A activity. EGFR activation by EGF attenuated PP2A activity, whereas mutation of Y307 to phenylalanine abolished the effect. Furthermore, PP2A activity was down-regulated immediately after spinal cord injury (SCI) in rats. Chronic application of d-erythro-sphingosine (DES), the PP2A agonist, to spinal cord-lesioned rats enhanced the activity of this phosphatase and dephosphorylated CRMP2 around the lesion. PP2A activation induced significant axon sprouting in the lesioned spinal cord and promoted function recovery after SCI. These findings suggest that PP2A works downstream of EGFR and dephosphorylates CRMP2 after CNS injury. Therefore, therapies targeting PP2A may be effective following SCI.

PET of EGFR with (64) Cu-cetuximab-F(ab')2 in mice with head and neck squamous cell carcinoma xenografts.

Overexpression of the epidermal growth factor receptor (EGFR) is linked to an adverse outcome in various solid tumors. Cetuximab is an EGFR inhibitor, which in combination with radiotherapy improves locoregional control and survival in a subgroup of patients with head and neck squamous cell carcinomas (HNSCCs). The aim of this study was to develop and characterize an EGFR-directed PET tracer, (64) Cu-cetuximab-F(ab')2, to determine the systemic accessibility of EGFR. Mice with HNSCC xenografts, UT-SCC-8 (n = 6) or UT-SCC-45 (n = 6), were imaged 24 h post injection with (64) Cu-NODAGA-cetuximab-F(ab')2 using PET/CT. One mouse for each tumor model was co-injected with excess unlabeled cetuximab 3 days before radiotracer injection to determine non-EGFR-mediated uptake. Ex vivo biodistribution of the tracer was determined and tumors were analyzed by autoradiography and immunohistochemistry. The SUVmax of UT-SCC-8 tumors was higher than that of UT-SCC-45: 1.5 ± 1.0 and 0.8 ± 0.2 (p < 0.05), respectively. SUVmax after in vivo blocking of EGFR with cetuximab was 0.4. Immunohistochemistry showed that UT-SCC-8 had a significantly higher EGFR expression than UT-SCC-45: 0.50 ± 0.19 versus 0.12 ± 0.08 (p < 0.005), respectively. Autoradiography indicated that (64) Cu-cetuximab-F(ab')2 uptake correlated with EGFR expression in both tumors: r = 0.86 ± 0.06 (UT-SCC-8) and 0.90 ± 0.06 (UT-SCC-45). (64) Cu-cetuximab-F(ab')2 is a promising PET tracer to determine expression of EGFR in vivo. Clinically, this tracer has the potential to be used to determine cetuximab targeting of tumors and possibly to non-invasively monitor the response to EGFR-inhibitor treatment.

Hypoxic‐Induction of Arginase II is Associated with EGFR Activation and EGF Production

We have previously shown that hypoxia induces arginase II through epidermal growth factor receptor (EGFR) activation in human pulmonary microvascular endothelial cells (hPMVEC). We hypothesized that hypoxia‐induced EGFR activation occurs via epidermal growth factor (EGF) release. Before studying hPVMEC, HeLa cells were used to dissect cellular mechanisms. Cells were grown in normoxia (21% oxygen) or hypoxia (1% oxygen) for 48 hours and mRNA harvested. RT‐PCR analysis showed substantially higher levels of EGF, EGFR, and arginase II mRNA in the cells incubated in hypoxia than in those incubated in normoxia. Cells were incubated in normoxia or hypoxia for 24 hours, the media harvested and placed on naive cells which were than incubated in normoxia for 48 hours. Cells incubated with hypoxia‐conditioned media had greater arginase II protein levels compared to cells incubated with normoxia‐conditioned media. Cells were then incubated in hypoxia or normoxia for 48 hours with either vehicle or the EGFR kinase inhibitor AG1478 added to the media, and AG1478 treatment prevented hypoxia‐induced arginase II protein expression. Finally, cells were incubated in hypoxia and normoxia for 48 hours with either IgG or an EGFR blocking antibody added to the media, the hypoxia‐induced arginase II expression was substantially lower in the cells incubated with the EGFR blocking antibody than in those incubated with IgG. These findings suggest that hypoxia‐induced arginase II expression may be dependent on EGF‐mediated activation of EGFR. We speculate that the EGFR pathway may be a novel therapeutic target for pulmonary hypertensive disorders associated with hypoxia.

Analysis of ERBB ligand-induced resistance mechanism to crizotinib by primary culture of lung adenocarcinoma with EML4-ALK fusion gene.

Using cell line-based assays, the secretion of erythroblastic leukemia viral oncogene homologue (ERBB) ligands has been reported to contribute to resistance against crizotinib in lung cancer with the echinoderm microtubule-associated protein-like 4 and anaplastic lymphoma kinase fusion gene. However, it is difficult to predict the role of the ligands in each patient. Here, we report an analysis of the mechanism of resistance behind crizotinib resistance using a primary culture of cancer cells from pleural effusion of an anaplastic lymphoma kinase-positive lung cancer patient who was clinically resistant to crizotinib. Primary cancer cells were prepared as cancer tissue-originated spheroids (CTOSs) according to previously described methods. CTOSs were maintained in StemPro medium, and a sensitivity assay was performed under growth factor-free conditions, or under stimulation with epidermal growth factor (EGF) or neuregulin-1/heregulin. The effect of treatment with crizotinib alone or a combination of crizotinib and erlotinib was examined. Cancer cells (LB53) were established to be CTOSs from a patient who was clinically resistant to crizotinib. The CTOSs were sensitive to crizotinib under growth factor-free conditions in vitro, whereas resistant under stimulation with EGF or neuregulin-1. These ligands rescued the inhibition of intracellular signaling by crizotinib. Pleural effusion from the patient also activated EGF receptor signaling to the similar extent of EGF stimulation. The resistance to crizotinib by EGF was reversed by blocking EGF receptor signaling by erlotinib in vitro. Stimulation by ERBB ligands is suggested to be responsible for resistance to crizotinib in this patient. The CTOS method may enable analysis of resistance mechanism for targeted therapy in individual patients.

Effects of ROCK inhibitor Y27632 and EGFR inhibitor PD168393 on human neural precursors co-cultured with rat auditory brainstem explant

Hearing function lost by degeneration of inner ear spiral ganglion neurons (SGNs) in the auditory nervous system could potentially be compensated by cellular replacement using suitable donor cells. Donor cell-derived neuronal development with functional synaptic formation with auditory neurons of the cochlear nucleus (CN) in the brainstem is a prerequisite for a successful transplantation. Here a rat auditory brainstem explant culture system was used as a screening platform for donor cells. The explants were co-cultured with human neural precursor cells (HNPCs) to determine HNPCs developmental potential in the presence of environmental cues characteristic for the auditory brainstem region in vitro. We explored effects of pharmacological inhibition of GTPase Rho with its effector Rho-associated kinase (ROCK) and epidermal growth factor receptor (EGFR) signaling on the co-cultures. Pharmacological agents ROCK inhibitor Y27632 and EGFR blocker PD168393 were tested. Effect of the treatment on explant penetration by green fluorescent protein (GFP)-labeled HNPCs was evaluated based on the following criteria: number of GFP-HNPCs located within the explant; distance migrated by the GFP-HNPCs deep into the explant; length of the GFP+/neuronal class III β-tubulin (TUJ1)+ processes developed and phenotypes displayed. In a short 2-week co-culture both inhibitors had growth-promoting effects on HNPCs, prominent in neurite extension elongation. Significant enhancement of migration and in-growth of HNPCs into the brain slice tissue was only observed in Y27632-treated co-cultures. Difference between Y27632- and PD168393-treated HNPCs acquiring neuronal fate was significant, though not different from the fates acquired in control co-culture. Our data suggest the presence of inhibitory mechanisms in the graft–host environment of the auditory brainstem slice co-culture system with neurite growth arresting properties which can be modulated by administration of signaling pathways antagonists. Therefore the co-culture system can be utilized for screens of donor cells and compounds regulating neuronal fate determination.

Should the results of the new EPOC trial change practice in the management of patients with resectable metastatic colorectal cancer confined to the liver?

Biologic agents, specifically epidermal growth factor receptor blockers and vascular endothelial growth factor inhibitors, combined with cytotoxic agents have become a standard of care for the treatment of metastatic colorectal cancer (CRC) but lack proven benefit as adjuvant treatment of primary colon cancer. Patients with resectable CRC metastases limited to the liver represent an intermediate group in terms of their burden of disease and prognosis. In those patients, the 5-year life expectancy after surgery is approximately 35% to 40% compared with 75% in patients with stage III disease and 10% in unselected patients with stage IV disease. In patients with resectable liver-limited CRC randomly assigned to treatment with surgery alone or perioperative chemotherapy with infusional fluorouracil, leucovorin, and oxaliplatin (FOLFOX), the risk of cancer relapse after surgery in the cohort randomly assigned to perioperative FOLFOX was reduced by one quarter. A logical next step is to raise the question, Can outcomes be improved further by combining treatment with biologic and cytotoxic agents in the perioperative setting in this increasingly common patient population? The New EPOC (Eloxatin Peri-Operative Chemotherapy) trial was organized in the United Kingdom to address this question, and the results were published and recently updated. The trial compared two groups of patients who were determined to have resectable liver metastases, all of whom received perioperative chemotherapy with FOLFOX, oxaliplatin and capecitabine (XELOX), or fluorouracil, leucovorin, and irinotecan (FOLFIRI) with a random assignment to treatment with or without the addition of the epidermal growth factor receptor–blocking antibody cetuximab. The trial initially enrolled patients regardless of KRAS mutation status in the tumor but was later restricted to patients whose tumors were found to be KRAS (exon 2) wild type. On the basis of their study’s outcome, the investigators concluded that combinations of cetuximab with chemotherapy in the perioperative setting for treatment of patients with potentially resectable colorectal liver metastases conferred no survival benefit and were actually detrimental. Data from studies in patients with advanced disease show that the addition of cetuximab or panitumumab to combination chemotherapy in patients whose tumors harbor a KRAS (exon 2) or other RAS mutations can be detrimental, although overall, patients without RAS mutations benefit from the combination. If this biology applies in the setting of resected stage IV disease, the initial inclusion of patients who did not have RAS testing may have influenced the outcome. In the N0147 (Comparison of Combination Chemotherapy Regimens With or Without Cetuximab in Treating Patients Who Have Undergone Surgery for Stage III Colon Cancer) study, which assigned patients with resected stage III CRC to FOLFOX with or without cetuximab, there was a statistically nonsignificant trend toward a detrimental effect that was independent of RAS status in the cetuximab-treated cohort. The New EPOC investigators hypothesize that molecular interactions may be playing a role in the observed outcomes in both N0147 and New EPOC, suggesting that the interplay of chemotherapy with cetuximab is different in patients with microscopic residual disease than it is in those with gross residual disease. Organizing randomized clinical trials that involve surgery and chemotherapy is difficult, and few such combined modality studies have been completed. We congratulate the investigators for meeting their accrual goal, but we are concerned that the data they published may not support the conclusions that they drew from their study because of issues surrounding surgical quality control, inclusion of patients whose surgical outcomes did not meet the predetermined study goals, incomplete data, and diversity in both the population enrolled and the regimens they received. Surgery is both an art and a science, and its practice depends on the judgment and skills of the surgeons. Studies have shown that the experience of the surgeon and the surgical team can be an important variable in patient outcomes. The impact of quality assurance of the operative procedures performed in cancer surgery trials has been explicitly demonstrated in two large, randomized Dutch trials that addressed gastric and rectal cancer surgery, both of which were practice changing. In those trials, surgeons could only recruit to the JOURNAL OF CLINICAL ONCOLOGY COMMENTS AND CONTROVERSIES VOLUME 33 NUMBER 3 JANUARY 2

Sulf1 and Sulf2 expression in the nervous system and its role in limiting neurite outgrowth in vitro

Sulf1 and Sulf2 are endosulfatases that cleave 6-O-sulphate groups from Heparan Sulphate Proteoglycans (HSPGs). Sulfation levels of HSPGs are critical for their role in modulating the activity of various growth factor receptors. Sulf1 and Sulf2 mRNAs were found to be widely expressed in the rodent nervous system and their full-length proteins were found in many types of neuronal perikarya and axons in the cerebral cortex, cerebellum, spinal cord and dorsal root ganglia (DRG) of adult rats. Sulf1/2 were also strongly expressed by cultured DRG neurons. To determine if blocking Sulf1 or Sulf2 activity affected neurite outgrowth in vitro, cultured DRG neurons were treated with neutralising antibodies to Sulf1 or Sulf2. Blocking Sulf1 and Sulf2 activity did not affect neurite outgrowth from cultured DRG neurons grown on a laminin/polylysine substrate but ameliorated the inhibitory effects of chondroitin sulphate proteoglycans (CSPGs) on neurite outgrowth. Blocking epidermal growth factor receptor (ErbB1) activity also improved neurite outgrowth in the presence of CSPGs, but the effects of ErbB1 antagonists and blocking SULFs were not additive. It is proposed that Sulf1, Sulf2 and ErbB1 are involved in the signalling pathway from CSPGs that leads to inhibition of neurite outgrowth and may regulate structural plasticity and regeneration in the nervous system.

EBP50 inhibits the migration and invasion of human breast cancer cells via LIMK/cofilin and the PI3K/Akt/mTOR/MMP signaling pathway.

The scaffold protein ezrin-radixin-moesin-binding phosphoprotein 50 (EBP50, also known as NHERF1 or NHERF) inhibits epidermal growth factor (EGF)-induced breast cancer cell proliferation after 3 days by blocking EGF receptor (EGFR) phosphorylation. The loss of EBP50 stimulates EGFR activity and induces the appearance of epithelial-to-mesenchymal transition phenotypic features in biliary cancer cells. However, the involvement of EBP50 in breast cancer migration and invasion remains unknown. We report that EBP50 inhibits the migration and invasion of breast cancer cells by inhibiting the phosphorylation of LIN-11, Isl1, and MEC-3 protein domain kinase, as well as cofilin. This phosphorylation is a critical step in cofilin recycling and actin polymerization mediating cytoskeletal rearrangement. Additionally, EGF-induced phosphorylation of Akt and mTOR was suppressed by upregulation of EBP50. Our results indicate that EBP50 is significantly involved in breast cancer invasion/metastasis via LIMK/cofilin and the PI3K/Akt/mTOR/MMP signaling pathway.

Infection of keratinocytes with Trichophytum rubrum induces epidermal growth factor-dependent RNase 7 and human beta-defensin-3 expression.

Human keratinocytes are able to express various antimicrobial peptides (AMP) to protect the skin from exaggerated microbial colonization and infection. Recently, in vitro growth-inhibiting activity of the skin-derived AMP psoriasin, RNase 7 and human beta-defensin (hBD)-2 against dermatophytes such as Trichophyton (T.) rubrum have been reported. To evaluate whether keratinocytes are able to respond to T. rubrum infection by an induced expression of AMP we exposed primary keratinocytes to living conidia of T. rubrum. This led to conidia germination and mycelial growth which was paralleled by a strong gene induction of the skin-derived AMP RNase 7 and hBD-3. Gene expression of the AMP psoriasin (S100A7) and hBD-2 were only slightly induced. The T. rubrum-mediated RNase 7 gene induction was accompanied by increased secretion of RNase 7. Parallel treatment of the keratinocytes with T. rubrum and the cytokine combination IL-17A/IFN-γ resulted in synergistic induction of RNase 7 and hBD-3 expression. Since patients receiving therapy by inhibition of the epidermal growth factor receptor (EGFR) more often suffer from dermatophytoses we investigated whether EGFR may be involved in the T. rubrum-mediated RNase 7 and hBD-3 induction. Primary keratinocytes incubated with an EGFR blocking antibody as well as with the EGFR antagonist AG1478 showed a significantly diminished RNase 7 and hBD-3 induction upon exposure of the keratinocytes to T. rubrum indicating that EGFR is involved in the T. rubrum-mediated induction of RNase 7 and hBD-3. The growth of T. rubrum in vitro was inhibited by hBD-3 in a dose-dependent manner suggesting that hBD-3 may contribute to cutaneous innate defense against T. rubrum. Taken together our data indicate that keratinocytes are able to initiate a fast defense response towards T. rubrum by the increased expression of AMP active against T. rubrum. A dysregulation of AMP may contribute to chronic and recurring dermatophytoses.

Advances and new perspectives in the treatment of metastatic colon cancer.

During the last decade we have witnessed an unprecedented outburst of new treatment approaches for the management of metastatic colon cancer. Anti-angiogenic drugs, epidermal growth factor receptor blockers and multi-kinase inhibitors have all resulted in small but consistent improvement in clinical outcomes. However, this progress has paradoxically leaded us into new challenges. In many cases the clinical development was done in parallel and the lack of head-to-head comparison evolved into circumstances where several valid new "standards of care" are available. Even though desirable in essence, the availability of many options as well as different possible combinations frequently leaves the busy clinician in the difficult situation of having to choose between one or the other, sometimes without solid evidence to support each decision. In addition, progress never stops and new agents are continuously tested. For these reason this review will try to summarize all the clinical trials that constitute the theoretical framework that support our daily practice but will also procure the reader with rational answers to common clinical dilemmas by critically appraising the current literature. Lastly, we will provide with a compilation of promising new agents that may soon become our next line of defense against this deadly disease.