Antitumor activity of the HER2 dimerization inhibitor pertuzumab on human colon cancer cells in vitro and in vivo

A four-component combination derived from Huang-Qin Decoction significantly enhances anticancer activity of irinotecan

Huang-Qin Decoction (HQD) is a classic prescription for diarrhea in Chinese medicine treatment. Recent studies have demonstrated that HQD and its modified formulation PHY906 could ameliorate irinotecan (CPT-11) induced gastrointestinal (GI) toxicity and enhance its anticancer therapeutic efficacy. Nevertheless, which constituents in HQD are effective is still unclear so far. The study aims to screen out the key bioactive components combination from HQD that could enhance the anticancer effect of CPT-11. First, the potential bioactive constituents were obtained through system pharmacology strategy. Then the bioactivity of each constituent was investigated synthetically from the aspects of NCM460 cell migration, TNF-α release of THP-1-derived macrophage and MTT assay in HCT116 cell. The contribution of each constituent in HQD was evaluated using the bioactive index E_i, which taken the content and bioactivity into comprehensive consideration. And then, the most contributing constituents were selected out to form a key-component combination. At last, the bioefficacy of the key-component combination was validated in vitro and in vivo. As a result, a key-component combination (HB4) consisting of four compounds baicalin, baicalein, glycyrrhizic acid and wogonin was screened out. In vitro assessment indicated that HB4 could enhance the effect of CPT-11 on inhibiting cell proliferation and inducing apoptosis in HCT116. Furthermore, the in vivo study confirmed that HB4 and HQD have similar pharmacological activity and could both enhance the antitumor effect of CPT-11 in HCT116 xenograft model. Meanwhile, HB4 could also reduce the CPT-11 induced GI toxicity.

Pertuzumab and trastuzumab: the rationale way to synergy

It has now been 15 years since the HER2-targeted monoclonal antibody trastuzumab was introduced in clinical and revolutionized the treatment of HER2-positive breast cancer patients. Despite this achievement, most patients with HER2-positive metastatic breast cancer still show progression of their disease, highlighting the need for new therapies. The continuous interest in novel targeted agents led to the development of pertuzumab, the first in a new class of agents, the HER dimerization inhibitors. Pertuzumab is a novel recombinant humanized antibody directed against extracellular domain II of HER2 protein that is required for the heterodimerization of HER2 with other HER receptors, leading to the activation of downstream signalling pathways. Pertuzumab combined with trastuzumab plus docetaxel was approved for the first-line treatment of patients with HER2-positive metastatic breast cancer and is currently used as a standard of care in this indication. In the neoadjuvant setting, the drug was granted FDA-accelerated approval in 2013. Pertuzumab is also being evaluated in the adjuvant setting. The potential of pertuzumab relies in the dual complete blockade of the HER2/3 axis when administered with trastuzumab. This paper synthetises preclinical and clinical data on pertuzumab and highlights the mechanisms underlying the synergistic activity of the combination pertuzumab-trastuzumab which are essentially due to their complementary mode of action.

Niclosamide inhibition of STAT3 synergizes with erlotinib in human colon cancer

Niclosamide, an anthelmintic drug approved by the US Food and Drug Administration against cestodes, is used to treat tapeworm infection. In this study, we show that niclosamide can potentially inhibit signal transducer and activator of transcription 3 (STAT3) in colon cancer cell lines. Combined inhibition of epidermal growth factor receptor and STAT3 by erlotinib and niclosamide synergistically induces apoptosis and antiproliferation in colon cancer cell lines. Our findings suggest that erlotinib and niclosamide combination provides an effective therapeutic approach to improving the prognosis of colon cancer.

Dual targeting of HER3 and EGFR in colorectal tumors might overcome anti-EGFR resistance

Multiple genetic alterations have been associated with resistance to anti-EGFR therapy in metastatic colorectal cancer (CRC) patients. Research has been mainly focused on driver mutations in KRAS, NRAS, BRAF and PI3K. However, recent evidence suggests a crucial role for non-genetic mechanisms in conferring resistance to anti-EGFR therapy. Specifically, the HER3 receptor is capable of heterodimerizing with multiple EGFR family members resulting in downstream activation of the PI3K and MAPK pathways. Monoclonal antibodies targeted against the HER3 receptor are being investigated in clinical trials; however, preliminary data has shown limited clinical activity. Thus, given the relevance of the HER3 receptor in activating downstream effector pathways and in conferring resistance to anti-EGFR therapy, the therapeutic targeting of HER3 in combination with primary drivers of the tumor is also being investigated. Here, we review the role of HER3 as a promoter of clinical resistance to EGFR therapy and discuss therapeutic approaches that could potentially overcome this resistance.

Pertuzumab in gastrointestinal cancer

INTRODUCTION

Human epidermal growth factor receptor 2 (HER2) and HER3 are altered in multiple tumor types, including gastrointestinal cancer. The HER2/HER3 dimer is crucial for HER2-mediated signaling in HER2-positive tumors. HER2-targeting agents, including trastuzumab, lapatinib, trastuzumab emtansine, and pertuzumab, have been approved for the treatment of HER2-positive breast cancer, with trastuzumab also approved for the treatment of HER2-positive gastric cancer. Pertuzumab, a recombinant humanized immunoglobulin (Ig) G1 monoclonal antibody targeting HER-2, binds to the dimerization domain (extracellular domain II) of HER2, which leads to blocking of ligand-induced HER2 heterodimerization. It is under investigation in gastrointestinal cancers, including HER2-positive gastric cancer.

AREA COVERED

In this review, the authors summarize the biology of HER2/HER3 and its alterations in gastrointestinal cancers. The authors focus specifically on the current status of development of pertuzumab in gastrointestinal cancers.

EXPERT OPINION

The HER2/HER3 alteration in gastrointestinal cancers is quite interesting. In HER2-positive gastric cancer, the dual blockade of HER2 and HER3 using trastuzumab and pertuzumab is being tested in an international phase III trial, the JACOB study. This strategy may benefit HER2-positive gastric cancer patients more as in the case of HER2-positive breast cancer. In other gastrointestinal cancers, including biliary tract cancer, esophageal cancer, pancreatic cancer, and colorectal cancer, there is huge room for the development of pertuzumab.

ERBB3 knockdown induces cell cycle arrest and activation of Bak and Bax-dependent apoptosis in colon cancer cells

ERBB3 is an emerging target for cancer therapy among the EGFR family. Contrary to resistance against EGFR and ERBB2 targeting, the genetic inhibition of ERBB3 results in anti-tumorigenic in HCT116 colon cancer cells harboring constitutively active KRAS and PIK3CA mutations. Still, the anti-tumorigenic molecular mechanism has not been defined. We demonstrated in this study that ERBB3 knockdown resulted in cell cycle arrest and activation of Bak and Bax-dependent apoptosis. Apoptosis was irrelevant to the majority of BH3-only pro-apoptotic proteins and correlated with the transcriptional upregulation of Bak and p53-dependent Bax translocation. Treatment with LY294002, a PI3K inhibitor, resulted in cell cycle arrest without apoptosis and a concomitant down-regulation of cap-dependent translation by the suppression of the PI3K/AKT/mTOR pathway. However, the inhibition of cap-dependent translation by ERBB3 knockdown occurred without altering the PI3K/AKT/mTOR pathway. In addition, ERBB3 knockdown-induced cell cycle arrest was observed in most colon cancer cells but was accompanied by apoptosis in p53 wild-type cells. These results indicate that ERBB3 is a potential target for EGFR- and ERBB2-resistant colon cancer therapy.

Significance of human epidermal growth factor receptor 2 expression in colorectal cancer

The aim of the present study was to evaluate the protein expression level of human epidermal growth factor receptor 2 (HER-2) using immunohistochemistry (IHC), and assess the association with clinicopathological parameters and the prognosis of patients with colorectal cancer (CRC). In addition, the current study observed the consistency between the levels of HER-2 protein expression determined by IHC and HER-2 gene amplification determined by fluorescence in situ hybridization (FISH) in the CRC samples. Overexpression of HER-2 and gene amplification were examined with semiquantitative standardized IHC in 878 formalin-fixed paraffin-embedded CRC samples, while 102 of these cases were analyzed with FISH. A total of 102 cases (11.6%), out of the 878 cases, were determined by IHC to overexpress HER-2. Of these, 25 cases were strongly positive (IHC3+), while 77 cases revealed moderate staining (IHC2+). HER-2 overexpression was more frequent in early-stage cases compared with advanced-stage cases of CRC (P<0.001). However, there was no association observed between HER-2 overexpression and clinicopathological parameters. FISH analysis revealed that 64% (16/25) of the IHC3+ cases had HER-2 gene amplification. By contrast, only 6.5% (5/77) of the IHC2+ cases, and none of the 20 randomly selected IHC0 or 1+ cases, demonstrated HER-2 gene amplification. Furthermore, no associations were observed between HER-2 overexpression or gene amplification with the survival time. Thus, the present study observed that HER-2 overexpression does not correlate with other clinicopathological data or the survival rate, with the exception of clinical stages. However, IHC3+ and 2+ cases should be further analyzed by FISH to assess the status of the HER-2 gene in CRC. Patients with HER-2 gene amplification may constitute as potential candidates for targeted therapy with trastuzumab.

Epidermal growth factor/epidermal growth factor receptor signaling axis is a significant regulator of the proteasome expression and activity in colon cancer cells

Colon cancer is the third most common type of cancer worldwide. Epidermal growth factor receptor (EGFR) plays a crucial role in the (patho)physiology of the disease. EGFR controls vital cellular processes, while this action is associated with poor prognosis. In addition, K-Ras mutations are associated with the promotion of the disease and the anti-EGFR resistance. The ubiquitin-proteasome system plays also a very important role in cancer, modulating cell cycle and other cellular processes such as the growth and the survival of cancer cells. Proteasome inhibition affects, in several cases, the action and the protein levels of EGFR. Nevertheless, little is known whether the reversed option is possible. In this study, we, therefore, investigated the impact of epidermal growth factor (EGF)/EGFR signaling axis on gene expression and the proteolytic activity of the proteasome subunits, as well as whether Nrf2, an activator of proteasome expression, plays a role in this process. Moreover, we evaluated whether EGF regulates the expression of its own receptor and the proliferation rate of DLD-1 (K-Ras mutated) colon cancer cells. The obtained data showed that, although EGF has no significant effect on the proliferation of DLD-1 colon cancer cells, it significantly upregulates the expression of EGFR as well as the expression and the activity of the proteasome, suggesting that the EGF-mediated proteasome activation could possibly lead to enhanced EGFR degradation leading to autoregulation of EGF–EGFR pathway. Nrf2 activation did not induce proteasome gene expression in DLD-1 colon cancer cells.

HER2-signaling pathway, JNK and ERKs kinases, and cancer stem-like cells are targets of Bozepinib small compound

Identification of novel anticancer drugs presenting more than one molecular target and efficacy against cancer stem-like cells (CSCs) subpopulations represents a therapeutic need to combat the resistance and the high risk of relapse in patients. In the present work we show how Bozepinib [(RS)-2,6-dichloro-9-[1-(p-nitrobenzenesulfonyl)-1,2,3,5-tetrahydro-4,1-benzoxazepin-3-yl]-9H-purine], a small anti-tumor compound, demonstrated selectivity on cancer cells and showed an inhibitory effect over kinases involved in carcinogenesis, proliferation and angiogenesis. The cytotoxic effects of Bozepinib were observed in both breast and colon cancer cells expressing different receptor patterns. Bozepinib inhibited HER-2 signaling pathway and JNK and ERKs kinases. In addition, Bozepinib has an inhibitory effect on AKT and VEGF together with anti-angiogenic and anti-migratory activities. Moreover, the modulation of pathways involved in tumorigenesis by Bozepinib was also evident in microarrays analysis. Interestingly, Bozepinib inhibited both mamo- and colono-spheres formation and eliminated ALDH+ CSCs subpopulations at a low micromolar range similar to Salinomycin. Bozepinib induced the down-regulation of c-MYC, β-CATENIN and SOX2 proteins and the up-regulation of the GLI-3 hedgehog-signaling repressor. Finally, Bozepinib shows in vivo anti-tumor and anti-metastatic efficacy in xenotransplanted nude mice without presenting sub-acute toxicity. These findings support further studies on the therapeutic potential of Bozepinib in cancer patients.

EGF/EGFR signaling axis is a significant regulator of the proteasome expression and activity in colon cancer cells

Colon cancer is the third most common type of cancer worldwide. Epidermal growth factor receptor (EGFR) plays a crucial role in the (patho)physiology of the disease. EGFR controls vital cellular processes, while this action is associated with poor prognosis. In addition, K-Ras mutations are associated with the promotion of the disease and the anti-EGFR resistance. The ubiquitin-proteasome system plays also a very important role in cancer, modulating cell cycle and other cellular processes such as the growth and the survival of cancer cells. Proteasome inhibition affects, in several cases, the action and the protein levels of EGFR. Nevertheless, little is known whether the reversed option is possible. In this study, we, therefore, investigated the impact of epidermal growth factor (EGF)/EGFR signaling axis on gene expression and the proteolytic activity of the proteasome subunits, as well as whether Nrf2, an activator of proteasome expression, plays a role in this process. Moreover, we evaluated whether EGF regulates the expression of its own receptor and the proliferation rate of DLD-1 (K-Ras mutated) colon cancer cells. The obtained data showed that, although EGF has no significant effect on the proliferation of DLD-1 colon cancer cells, it significantly upregulates the expression of EGFR as well as the expression and the activity of the proteasome, suggesting that the EGF-mediated proteasome activation could possibly lead to enhanced EGFR degradation leading to autoregulation of EGF–EGFR pathway. Nrf2 activation did not induce proteasome gene expression in DLD-1 colon cancer cells.

The role of personalized medicine in metastatic colorectal cancer: an evolving landscape

Advances in the treatment of metastatic colorectal cancer have led to an improvement in survival from 12 months with fluorouracil monotherapy to approximately 2 years. This is partly as a result of the addition of irinotecan and oxaliplatin, but is also due to the use of monoclonal antibodies against the epidermal growth factor receptor (EGFR) and antiangiogenic drugs such as bevacizumab. However, there are significant molecular differences between tumours which can affect both prognosis and response to treatment. Personalized medicine aims to tailor treatment according to the characteristics of the individual patient and is now a clinical reality as testing for KRAS mutations to guide treatment with the anti-EGFR monoclonal antibodies cetuximab and panitumumab is now part of routine clinical practice. However, not all patients who are KRAS wild type respond to anti-EGFR therapy and a validated biomarker for antiangiogenic therapy is still lacking. Therefore, other biomarkers are needed to assist with predicting response to both existing drugs as well as to drugs currently under investigation. This review summarizes the molecular biology of colorectal cancer, focusing on the genetic features that are currently most clinically relevant. Current and emerging biomarkers are reviewed along with their roles in selecting patients for targeted treatment with currently licensed therapies and drugs being evaluated in clinical trials. The value of predictive biomarkers of chemosensitivity and potential future treatment strategies are also discussed.

Multi-drug inhibition of the HER pathway in metastatic colorectal cancer: results of a phase I study of pertuzumab plus cetuximab in cetuximab-refractory patients

PURPOSE

Resistance to cetuximab, a monoclonal antibody against the epithelial growth factor receptor (EGFR), in colorectal cancer (CRC) may result from compensatory signaling through ErbB receptors, ErbB2/neu/HER2 (HER2) and ErbB3/HER3 (HER3). Pertuzumab is a monoclonal antibody that blocks HER2 hetero-dimerization; thus the combination of pertuzumab and cetuximab could possibly overcome cetuximab resistance.

PATIENTS AND METHODS

This single-arm, open-label, multicenter phase I/II study was designed to assess the safety and efficacy of pertuzumab and cetuximab in patients with cetuximab-resistant KRAS wild type metastatic CRC. Thirteen patients were enrolled and received cetuximab in combination with pertuzumab at several dose levels in a 3 + 3 design. Patients were assessed for dose-limiting toxicity (DLT) during the first cycle. A phase II portion was planned, but not initiated due to toxicity.

RESULTS

Six of the thirteen patients (46 %) experienced DLTs, therefore the study was terminated early. Grade 3 or higher DLTs included dermatitis with desquamation and/or acneiform rash (n = 6), mucositis or stomatitis (n = 5), and diarrhea (n = 2). There was one Grade 5 event (myocardial infarction) attributed to underlying disease. Among the 13 patients, seven (54 %) were evaluable for response. The objective response rate was 14 %: one patient had a partial response lasting 6 months. Two patients had stable disease (29 %), and four had progressive disease (57 %). Median progression free survival was 2.1 months (95 % CI, 1.5-4.9) and median overall survival was 3.7 months (95 % CI, 1.6-7.9).

CONCLUSION

Combination pertuzumab and cetuximab in refractory CRC was associated with potential antitumor activity; however, the combination was not tolerable due to overlapping toxicities.

Comprehensive fluorogenic derivatization-liquid chromatography/tandem mass spectrometry proteomic analysis of colorectal cancer cell to identify biomarker candidate

Existing colorectal cancer biomarkers are insufficient for providing a quick and accurate diagnosis, which is critical for a good prognosis. More appropriate biomarkers are thus needed. To identify new colorectal cancer biomarker candidates, we conducted a comprehensive differential proteomic analysis of six cancer cell lines and a normal cell line, utilizing a fluorogenic derivatization-liquid chromatography-tandem mass spectrometry (FD-LC-MS/MS) approach. Two sets of intracellular biomarker candidates were identified: one for colorectal cancer, and the other for metastatic colorectal cancer. Our results suggest that cooperative expression of FABP5 and cyclophilin A might be linked to Her2 signaling. Upregulation of LDHB and downregulation of GAPDH suggest the existence of a specific nonglycolytic energy production pathway in metastatic colorectal cancer cells. Downregulation of 14-3-3ζ/δ, cystatin-B, Ran and thioredoxin could be a result of their secretion, which then stimulates metastasis via activity in the sera and ascitic fluids. We propose a possible flow scheme to describe the dynamics of protein expression in colorectal cancer cells leading to tumor progression and metastasis via cell proliferation, angiogenesis, disorganization of actin filaments and epithelial-mesenchymal transition. Our results suggest that colorectal tumor progression may be regulated by signaling mediated by Her2, hypoxia, and TGFβ.

The dual EGFR/HER2 inhibitor lapatinib synergistically enhances the antitumor activity of the histone deacetylase inhibitor panobinostat in colorectal cancer models

As key molecules that drive progression and chemoresistance in gastrointestinal cancers, epidermal growth factor receptor (EGFR) and HER2 have become efficacious drug targets in this setting. Lapatinib is an EGFR/HER2 kinase inhibitor suppressing signaling through the RAS/RAF/MEK (MAP/ERK kinase)/MAPK (mitogen-activated protein kinase) and PI3K (phosphoinositide 3-kinase)/AKT pathways. Histone deacetylase inhibitors (HDACi) are a novel class of agents that induce cell cycle arrest and apoptosis following the acetylation of histone and nonhistone proteins modulating gene expression and disrupting HSP90 function inducing the degradation of EGFR-pathway client proteins. This study sought to evaluate the therapeutic potential of combining lapatinib with the HDACi panobinostat in colorectal cancer (CRC) cell lines with varying EGFR/HER2 expression and KRAS/BRAF/PIK3CA mutations. Lapatinib and panobinostat exerted concentration-dependent antiproliferative effects in vitro (panobinostat range 7.2-30 nmol/L; lapatinib range 7.6-25.8 μmol/L). Combined lapatinib and panobinostat treatment interacted synergistically to inhibit the proliferation and colony formation in all CRC cell lines tested. Combination treatment resulted in rapid induction of apoptosis that coincided with increased DNA double-strand breaks, caspase-8 activation, and PARP cleavage. This was paralleled by decreased signaling through both the PI3K and MAPK pathways and increased downregulation of transcriptional targets including NF-κB1, IRAK1, and CCND1. Panobinostat treatment induced downregulation of EGFR, HER2, and HER3 mRNA and protein through transcriptional and posttranslational mechanisms. In the LoVo KRAS mutant CRC xenograft model, the combination showed greater antitumor activity than either agent alone, with no apparent increase in toxicity. Our results offer preclinical rationale warranting further clinical investigation combining HDACi with EGFR and HER2-targeted therapies for CRC treatment.

Copy number increase of HER-2 in colorectal cancers

HER-2 is involved in genetic instability and is overexpressed in a number of human carcinomas, including colorectal cancer (CRC). The choromosomal locus of HER-2, 17q21, is frequently amplified in breast cancer, but the correlation between copy-number variations and HER-2 overexpression in CRC has yet to be elucidated. The functional impact of such regions requires extensive investigation in large numbers of CRC samples. Case-matched tissues of colorectal adenocarcinomas and adjacent normal epithelia (n=134) were included in this study. Quantitative PCR was performed to examine the copy number and mRNA expression of HER-2 in CRC. The results showed that copy number gains of HER-2 were detected in a relatively high percentage of CRC samples (35.1%, 47 out of 134). A positive correlation was noted between the copy number increase of HER-2 and tumor progression. Furthermore, copy number gains of HER-2 showed a positive correlation with mRNA overexpression in CRC. However, the expression levels of HER-2 mRNA were also enhanced in the group of CRC samples with unaltered copy numbers. In conclusion, the findings suggest that a copy number increase of HER-2 is a potential diagnostic indicator for CRC; whether alone or in combination with other markers.

HER-dimerization inhibitors: evaluating pertuzumab in women's cancers

IMPORTANCE OF THE FIELD

Pertuzumab is a human EGF receptor (HER)-dimerization inhibitor that represent a novel class of agents aimed at blocking HER2 from pairing with other receptors of the HER family. In this review, we discuss the background and scientific rationale, related to pertuzumab as it has undergone development for women's cancers.

AREAS COVERED IN THIS REVIEW

Pre-clinical and clinical trials, published or presented at national meetings from 1995 to the present, are included in this review.

WHAT THE READER WILL GAIN

A Phase II trial in HER2-positive metastatic breast cancer showed promising activity of pertuzumab when it was combined with trastuzumab and a randomized Phase III trial is now underway. Pertuzumab, when evaluated in recurrent ovarian cancer showed limited activity when combined with chemotherapy in platinum-sensitive and platinum-resistant disease. However, a recent subset analysis suggests that HER3 mRNA levels may predict response to pertuzumab in ovarian cancer.

TAKE HOME MESSAGE

HER-dimerization inhibitors represent a novel mechanism of inhibition of HER pathways. Pertuzumab may play a role in the management of HER2-positive breast cancer. The potential benefit of pertuzumab in ovarian cancer is unclear, but low HER3 levels may suggest a sub-group of patients that can benefit from pertuzumab.