Mechanism of action of anti-HER2 monoclonal antibodies: scientific update on trastuzumab and 2C4

Emerging trends and therapeutic applications of monoclonal antibodies

Monoclonal antibodies (mAbs) are being used to prevent, detect, and treat a broad spectrum of malignancies and infectious and autoimmune diseases. Over the past few years, the market for mAbs has grown exponentially. They have become a significant part of many pharmaceutical product lines, and more than 250 therapeutic mAbs are undergoing clinical trials. Ever since the advent of hybridoma technology, antibody-based therapeutics were realized using murine antibodies which further progressed into humanized and fully human antibodies, reducing the risk of immunogenicity. Some of the benefits of using mAbs over conventional drugs include a drastic reduction in the chances of adverse reactions, interactions between drugs, and targeting specific proteins. While antibodies are very efficient, their higher production costs impede the process of commercialization. However, their cost factor has been improved by developing biosimilar antibodies, which are affordable versions of therapeutic antibodies. Along with biosimilars, innovations in antibody engineering have helped to design bio-better antibodies with improved efficacy than the conventional ones. These novel mAb-based therapeutics are set to revolutionize existing drug therapies targeting a wide spectrum of diseases, thereby meeting several unmet medical needs. In the future, mAbs generated by applying next-generation sequencing (NGS) are expected to become a powerful tool in clinical therapeutics. This article describes the methods of mAb production, pre-clinical and clinical development of mAbs, approved indications targeted by mAbs, and novel developments in the field of mAb research.

Depicting Biomarkers for HER2-Inhibitor Resistance: Implication for Therapy in HER2-Positive Breast Cancer

HER2 (human epidermal growth factor receptor 2) is highly expressed in a variety of cancers, including breast, lung, gastric, and pancreatic cancers. Its amplification is linked to poor clinical outcomes. At the genetic level, HER2 is encoded by the ERBB2 gene (v-erb-b2 avian erythroblastic leukemia viral oncogene homolog 2), which is frequently mutated or amplified in cancers, thus spurring extensive research into HER2 modulation and inhibition as viable anti-cancer strategies. An impressive body of FDA-approved drugs, including anti-HER2 monoclonal antibodies (mAbs), antibody-drug conjugates (ADCs), and HER2-tyrosine kinase inhibitors (TKIs), have demonstrated success in enhancing overall survival (OS) and disease progression-free survival (PFS). Yet, drug resistance remains a persistent challenge and raises the risks of metastatic potential and tumor relapse. Research into alternative therapeutic options for HER2+ breast cancer therefore proves critical for adapting to this ever-evolving landscape. This review highlights current HER2-targeted therapies, discusses predictive biomarkers for drug resistance, and introduces promising emergent therapies-especially combination therapies-that are aimed at overcoming drug resistance in the context of HER2+ breast cancer.

Prevention of Anthracyclines and HER2 Inhibitor-Induced Cardiotoxicity: A Systematic Review and Meta-Analysis

BACKGROUND

This meta-analysis and systematic review aim to consolidate evidence on cardiotoxicity prevention and treatment strategies in patients receiving anthracyclines or HER2 receptor inhibitors, vital treatments for breast cancer and hematologic malignancies. By synthesizing existing research, the goal is to provide impactful insights that enhance patient care and outcomes.

METHODS

Comprehensive research across PubMed, Scopus, EMBASE, and the Cochrane Central Register for Controlled Trials was conducted, selecting clinical trials focusing on cardioprotection in anthracyclines or HER2 inhibitor-treated individuals. Effect sizes were computed using OpenMeta (Analyst), with leave-out meta-analysis to assess potential small study effects. Meta-regression explored treatment duration and sample size effects. Evidence quality for primary outcomes was evaluated using ROB, Robins 2, and Newcastle-Ottawa tools.

RESULTS

Twenty -three studies involving a total of 14,652 patients (13,221 adults and 1431 kids) were included in the current systematic review and meta-analysis. The risk of bias and methodological quality of the included studies suggested good and moderate quality. Patients prescribed β-blockers demonstrated a 74% lower likelihood of exhibiting cardiotoxicity symptoms (OR 1.736). Similarly, the use of dexrazoxane was linked to a threefold decrease in cardiac abnormalities risk (OR 2.989), and ACE inhibitor administration showed half the risk compared with the control group (OR 1.956).

CONCLUSIONS

Through this systematic review and meta-analysis, it was shown that there is a reduction in cardiotoxicity from either anthracyclines or HER2 inhibitors in patients receiving pharmacoprophylaxis.

Breast cancer patient-derived organoids for the investigation of patient-specific tumour evolution

BACKGROUND

A reliable preclinical model of patient-derived organoids (PDOs) was developed in a case study of a 69-year-old woman diagnosed with breast cancer (BC) to investigate the tumour evolution before and after neoadjuvant chemotherapy and surgery. The results were achieved due to the development of PDOs from tissues collected before (O-PRE) and after (O-POST) treatment.

METHODS

PDO cultures were characterized by histology, immunohistochemistry (IHC), transmission electron microscopy (TEM), scanning electron microscopy (SEM), confocal microscopy, flow cytometry, real-time PCR, bulk RNA-seq, single-cell RNA sequencing (scRNA-seq) and drug screening.

RESULTS

Both PDO cultures recapitulated the histological and molecular profiles of the original tissues, and they showed typical mammary gland organization, confirming their reliability as a personalized in vitro model. Compared with O-PRE, O-POST had a greater proliferation rate with a significant increase in the Ki67 proliferation index. Moreover O-POST exhibited a more stem-like and aggressive phenotype, with increases in the CD24low/CD44low and EPCAMlow/CD49fhigh cell populations characterized by increased tumour initiation potential and multipotency and metastatic potential in invasive lobular carcinoma. Analysis of ErbB receptor expression indicated a decrease in HER-2 expression coupled with an increase in EGFR expression in O-POST. In this context, deregulation of the PI3K/Akt signalling pathway was assessed by transcriptomic analysis, confirming the altered transcriptional profile. Finally, transcriptomic single-cell analysis identified 11 cell type clusters, highlighting the selection of the luminal component and the decrease in the number of Epithelial-mesenchymal transition cell types in O-POST.

CONCLUSION

Neoadjuvant treatment contributed to the enrichment of cell populations with luminal phenotypes that were more resistant to chemotherapy in O-POST. PDOs represent an excellent 3D cell model for assessing disease evolution.

Antibody-drug conjugates targeting HER2 for the treatment of urothelial carcinoma: potential therapies for HER2-positive urothelial carcinoma

Urothelial carcinoma (UC) is a common cancer characterized by high morbidity and mortality rates. Despite advancements in treatment, challenges such as recurrence and low response rates persist. Antibody-drug conjugates (ADCs) have emerged as a promising therapeutic approach for various cancers, although their application in UC is currently limited. This review focuses on recent research regarding ADCs designed to treat UC by targeting human epidermal growth factor receptor 2 (HER2), a surface antigen expressed on tumor cells. ADCs comprise three main components: an antibody, a linker, and a cytotoxic payload. The antibody selectively binds to tumor cell surface antigens, facilitating targeted delivery of the cytotoxic drug, while linkers play a crucial role in ensuring stability and controlled release of the payload. Cleavable linkers release the drug within tumor cells, while non-cleavable linkers ensure stability during circulation. The cytotoxic payload exerts its antitumor effect by disrupting cellular pathways. HER2 is commonly overexpressed in UCs, making it a potential therapeutic target. Several ADCs targeting HER2 have been approved for cancer treatment, but their use in UC is still being tested. Numerous HER2 ADCs have demonstrated significant growth inhibition and induction of apoptosis in translational models of HER2-overexpressing bladder cancer. Ongoing clinical trials are assessing the efficacy and safety of ADCs targeting HER2 in UC, with the aim of determining tumor response and the potential of ADCs as a treatment option for UC patients. The development of effective therapies with improved response rates and long-term effectiveness is crucial for advanced and metastatic UC. ADCs targeting HER2 show promise in this regard and merit further investigation for UC treatment.

A comprehensive overview on antibody-drug conjugates: from the conceptualization to cancer therapy

Antibody-Drug Conjugates (ADCs) represent an innovative class of potent anti-cancer compounds that are widely used in the treatment of hematologic malignancies and solid tumors. Unlike conventional chemotherapeutic drug-based therapies, that are mainly associated with modest specificity and therapeutic benefit, the three key components that form an ADC (a monoclonal antibody bound to a cytotoxic drug via a chemical linker moiety) achieve remarkable improvement in terms of targeted killing of cancer cells and, while sparing healthy tissues, a reduction in systemic side effects caused by off-tumor toxicity. Based on their beneficial mechanism of action, 15 ADCs have been approved to date by the market approval by the Food and Drug Administration (FDA), the European Medicines Agency (EMA) and/or other international governmental agencies for use in clinical oncology, and hundreds are undergoing evaluation in the preclinical and clinical phases. Here, our aim is to provide a comprehensive overview of the key features revolving around ADC therapeutic strategy including their structural and targeting properties, mechanism of action, the role of the tumor microenvironment and review the approved ADCs in clinical oncology, providing discussion regarding their toxicity profile, clinical manifestations and use in novel combination therapies. Finally, we briefly review ADCs in other pathological contexts and provide key information regarding ADC manufacturing and analytical characterization.

Leveraging a Dual Variable Domain Immunoglobulin to Create a Site-Specifically Modified Radioimmunoconjugate

Site-specifically modified radioimmunoconjugates exhibit superior in vitro and in vivo behavior compared to analogues synthesized via traditional stochastic methods. However, the development of approaches to site-specific bioconjugation that combine high levels of selectivity, simple reaction conditions, and clinical translatability remains a challenge. Herein, we describe a novel solution to this problem: the use of dual-variable domain immunoglobulins (DVD-IgG). More specifically, we report the synthesis, in vitro evaluation, and in vivo validation of a 177Lu-labeled radioimmunoconjugate based on HER2DVD, a DVD-IgG containing the HER2-targeting variable domains of trastuzumab and the catalytic variable domains of IgG h38C2. To this end, we first modified HER2DVD with a phenyloxadiazolyl methlysulfone-modified variant of the chelator CHX-A″-DTPA (PODS-CHX-A''-DTPA) and verified the site-specificity of the conjugation for the reactive lysines within the catalytic domains via chemical assay, MALDI-ToF mass spectrometry, and SDS-PAGE. The chelator-bearing immunoconjugate was subsequently labeled with [177Lu]Lu3+ to produce the completed radioimmunoconjugate, [177Lu]Lu-CHX-A″-DTPAPODS-HER2DVD, in >80% radiochemical conversion and a specific activity of 29.5 ± 7.1 GBq/μmol. [177Lu]Lu-CHX-A″-DTPAPODS-HER2DVD did not form aggregates upon prolonged incubation in human serum, displayed 87% stability to demetalation over a 7 days of incubation in serum, and exhibited an immunoreactive fraction of 0.95 with HER2-coated beads. Finally, we compared the pharmacokinetic profile of [177Lu]Lu-CHX-A″-DTPAPODS-HER2DVD to that of a 177Lu-labeled variant of trastuzumab in mice bearing subcutaneous HER2-expressing BT-474 human breast cancer xenografts. The in vivo performance of [177Lu]Lu-CHX-A″-DTPAPODS-HER2DVD matched that of 177Lu-labeled trastuzumab, with the former producing a tumoral activity concentration of 34.1 ± 12.1 %ID/g at 168 h and tumor-to-blood, tumor-to-liver, and tumor-to-kidney activity concentration ratios of 10.5, 9.6, and 21.8, respectively, at the same time point. Importantly, the DVD-IgG did not exhibit a substantially longer serum half-life than the traditional IgG despite its significantly larger size (202 kDa for the former vs 148 kDa for the latter). Taken together, these data suggest that DVD-IgGs represent a viable platform for the future development of highly effective site-specifically labeled radioimmunoconjugates for diagnostic imaging, theranostic imaging, and radioimmunotherapy.

Privileged Scaffolds in Drug Discovery against Human Epidermal Growth Factor Receptor 2 for Cancer Treatment

HER2 is the membrane receptor tyrosine kinase showing overexpression in several human malignancies, particularly breast cancer. HER2 overexpression causes the activation of Ras- MAPK and PI3K/Akt/ NF-κB cellular signal transduction pathways that lead to cancer development and progression. HER2 is, therefore, presumed as one of the key targets for the development of tumor-specific therapies. Several preclinical have been developed that function by inhibiting the HER2 tyrosine kinase activity through the prevention of the dimerization process. Most HER2 inhibitors act as ATP competitors and prevent the process of phosphorylation, and abort the cell cycle progression and proliferation. In this review, the clinical drug candidates and potent pre-clinical newly developed molecules are described, and the core chemical scaffolds typically responsible for anti-HER2 activity are deciphered. In addition, the monoclonal antibodies that are either used in monotherapy or in combination therapy against HER2-positive cancer are briefly described. The identified key moieties in this study could result in the discovery of more effective HER2-targeted anticancer drug molecules and circumvent the development of resistance by HER2-specific chemotherapeutics in the future.

Discordance of positive immunohistochemical results among different primary HER2 antibodies used in breast cancer: A comparison between Histofine® HER2 Kit (MONO) SV2-61γ antibody and Ventana I-VIEW PATHWAY™ HER2 4B5 antibody

INTRODUCTION

Immunohistochemical (IHC) testing for human epidermal growth factor receptor 2 (HER2) expression status renders variable scores among different primary antibodies.

MATERIALS AND METHODS

We assessed HER2 expression status by IHC score using two types of kits, i.e., Roche Ventana I-VIEW PATHWAY™ HER2 using the 4B5 antibody that recognizes the intracellular domain (ICD) and Nichirei Biosciences Histofine® HER2 Kit (MONO) using the SV2-61γ antibody that recognizes the extracellular domain (ECD). In addition, we determined the presence or absence of the ECD in samples by Western blotting (WB) and examined its relationship with the IHC score.

RESULTS

Of 101 samples, 44 and 9 samples received a score of 2+/3+ by IHC with 4B5 and SV2-61γ, respectively. A verification by WB in samples with a discrepancy of IHC scores found that samples with the score of 2+/3+ with SV2-61γ showed a significantly higher protein intensity of p185HER2 with the ECD, whereas samples with a score of 2+/3+ with 4B5 but as 0/1+ with SV2-61γ showed a significantly higher protein intensity of p95HER2 without the ECD.

CONCLUSION

The nature of primary antibodies used for IHC and the presence or absence of the ECD in samples may contribute to different positive rates between 4B5 and SV2-61γ.

Neratinib Exerts Dual Effects on Cartilage Degradation and Osteoclast Production in Osteoarthritis by Inhibiting the Activation of the MAPK/NF-κB Signaling Pathways

Osteoarthritis (OA) is a degenerative disease caused by the progressive destruction of cartilage and subchondral bone. [1] Studies have shown that by inhibiting the degradation of cartilage cells and the loss of subchondral bone, OA can be prevented and treated. Neratinib, as a small molecule compound with anti-inflammatory and anti-tumor properties, is a very effective inhibitor of IL-1β-induced chondrocyte inflammation and anabolic metabolism. By investigating the effect of neratinib in ATDC5 chondrocytes, the study finds that neratinib reduces inflammation by inhibiting the MAPK and NF-κB signaling pathways, and at the same time reduces pyrolysis (indicated by the results of reverse transcription quantitative PCR and western blotting). For anabolic metabolism, after high-density cell culture, IL-1β-induced catalytic changes and degradation of the extracellular matrix were evaluated by toluidine blue staining. Since osteoclasts are key participants in the process of subchondral bone remodeling in OA, we also studied the effect of neratinib on the maturation of osteoclasts. The results showed that neratinib also acts as an anti-osteoclast agent in vitro. By inhibiting the NF-κB and MAPK pathways, it reduces the expression of osteoclast-related genes, thereby inhibiting RANKL-induced osteoclastogenesis. The results of in vivo animal experiments supported the conclusions from the experiments in vitro. Neratinib inhibited both the destruction of medial meniscus induced cartilage degradation and osteoclast formation, which proves that neratinib has a dual effect, protecting cartilage and inhibiting osteoclast formation. These results indicate that neratinib can be a brand-new latent strategy for the treatment of OA.

ERBB Signaling Pathway in Cancer Stem Cells

The epidermal growth factor receptor (EGFR) was first tyrosine kinase receptor linked to human cancers. EGFR or ERBB1 is a member of ERBB subfamily, which consists of four type I transmembrane receptor tyrosine kinases, ERBB1, 2, 3 and 4. ERBBs form homo/heterodimers after ligand binding except ERBB2 and consequently becomes activated. Different signal pathways, such as phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT), RAS/RAF/MEK/ERK, phospholipase Cγ and JAK-STAT, are triggered by ERBB activation. Since ERBBs, through these pathways, regulate stemness and differentiation of cancer stem cells (CSCs), their roles in CSC tumorigenicity have extensively been investigated. The hyperactivation of ERBBs and its downstream pathways stimulated by either genetic and/or epigenetic factors are frequently described in many types of human cancers. Their dysregulations make cells acquiring CSC characters such as survival, tumorigenicity and stemness. Because of the roles in tumor growth and progress, ERBBs are considered to be one of the drug targets as cancer treatment strategy. In this chapter, we will summarize the structure, function and roles of ERBB subfamily along with their relative pathways regulating the stemness and tumorigenicity of CSCs. Finally, we will discuss the targeting therapy strategies of cancer along with ERBBs in addition to some challenges and future perspectives.

Antibody-Drug Conjugates-A Tutorial Review

Antibody-drug conjugates (ADCs) are a family of targeted therapeutic agents for the treatment of cancer. ADC development is a rapidly expanding field of research, with over 80 ADCs currently in clinical development and eleven ADCs (nine containing small-molecule payloads and two with biological toxins) approved for use by the FDA. Compared to traditional small-molecule approaches, ADCs offer enhanced targeting of cancer cells along with reduced toxic side effects, making them an attractive prospect in the field of oncology. To this end, this tutorial review aims to serve as a reference material for ADCs and give readers a comprehensive understanding of ADCs; it explores and explains each ADC component (monoclonal antibody, linker moiety and cytotoxic payload) individually, highlights several EMA- and FDA-approved ADCs by way of case studies and offers a brief future perspective on the field of ADC research.

Nanobodies for Medical Imaging: About Ready for Prime Time?

Recent advances in medical treatments have been revolutionary in shaping the management and treatment landscape of patients, notably cancer patients. Over the last decade, patients with diverse forms of locally advanced or metastatic cancer, such as melanoma, lung cancers, and many blood-borne malignancies, have seen their life expectancies increasing significantly. Notwithstanding these encouraging results, the present-day struggle with these treatments concerns patients who remain largely unresponsive, as well as those who experience severely toxic side effects. Gaining deeper insight into the cellular and molecular mechanisms underlying these variable responses will bring us closer to developing more effective therapeutics. To assess these mechanisms, non-invasive imaging techniques provide valuable whole-body information with precise targeting. An example of such is immuno-PET (Positron Emission Tomography), which employs radiolabeled antibodies to detect specific molecules of interest. Nanobodies, as the smallest derived antibody fragments, boast ideal characteristics for this purpose and have thus been used extensively in preclinical models and, more recently, in clinical early-stage studies as well. Their merit stems from their high affinity and specificity towards a target, among other factors. Furthermore, their small size (~14 kDa) allows them to easily disperse through the bloodstream and reach tissues in a reliable and uniform manner. In this review, we will discuss the powerful imaging potential of nanobodies, primarily through the lens of imaging malignant tumors but also touching upon their capability to image a broader variety of nonmalignant diseases.

The pharmaceutical stability of trastuzumab after short-term storage at room temperature assessed by analytical techniques and tumour imaging by microSPECT/CT

We report the pharmaceutical stability of trastuzumab stored for a short time (12 h) at room temperature (RT; 20-25 °C) compared to trastuzumab stored at 2-8 °C. The physicochemical properties were evaluated by UV-visible and FTIR spectroscopy, SDS-PAGE and size-exclusion HPLC (SE-HPLC). Trastuzumab was reacted with benzylisothiocyanate diethylenetriaminepentaacetic acid (BzDTPA) to complex ¹¹¹In. The HER2-binding affinity of ¹¹¹In-BzDTPA-trastuzumab synthesised from trastuzumab stored at RT or at 2-8 °C was measured using HER2-positive SK-Br-3 human breast cancer (BC) cells. The tumour and normal tissue uptake of ¹¹¹In-BzDTPA-trastuzumab was studied by microSPECT/CT imaging and biodistribution studies in CD1 athymic mice with s.c. HER2-positive SK-Ov-3 human ovarian cancer xenografts. There were no differences in λ_max or molar absorptivity (ε) values in the UV-visible spectra of trastuzumab stored at RT or at 2-8 °C. FTIR spectroscopy suggested no differences in secondary structure. SDS-PAGE revealed protein bands corresponding to the expected molecular weights. SE-HPLC showed identical properties for trastuzumab stored at RT or at 2-8 °C. The dissociation constant (K_d) for binding of ¹¹¹In-BzDTPA-trastuzumab to HER2 on SK-Br-3 cells (2.2-4.4 nM) was not significantly different when the radioimmunoconjugates were synthesised from trastuzumab stored at RT or at 2-8 °C. MicroSPECT/CT demonstrated high uptake in SK-Ov-3 tumours in mice that was not significantly different using trastuzumab stored at RT or at 2-8 °C (33.7 ± 8.8% vs. 22.2 ± 8.1% i.d./g, respectively; P = 0.36). There were no significant differences in normal tissue uptake or in tumour/normal tissue (T/NT) ratios. We conclude that short-term storage of trastuzumab at RT for 12 h did not affect the physicochemical or biological properties of the drug.

The Evolving Landscape of HER2-Directed Breast Cancer Therapy

OPINION STATEMENT

The management of patients with HER2+ breast cancer has evolved significantly over the preceding decades. HER2 targeting strategies have advanced beyond focusing on the receptor alone to encompass a range of approaches. Current standard of care practices in these patients relies upon dual HER2 blockade with trastuzumab and pertuzumab in the adjuvant and metastatic settings. T-DM1 has proven particularly efficacious in patients with residual disease status post neoadjuvant therapy, with additional therapies approved in the subsequent lines to address recurrent and resistant disease. Advances continue to be made in HER2+ breast cancer with multiple novel agents on the horizon, employing diverse mechanisms of action that are described in this review.

Targeted therapeutic options and future perspectives for HER2-positive breast cancer

Over the past 2 decades, there has been an extraordinary progress in the regimens developed for the treatment of human epidermal growth factor receptor 2 (HER2)-positive breast cancer. Trastuzumab, pertuzumab, lapatinib, and ado-trastuzumab emtansine (T-DM1) are commonly recommended anti-HER2 target agents by the U.S. Food and Drug Administration. This review summarizes the most significant and updated research on clinical scenarios related to HER2-positive breast cancer management in order to revise the guidelines of everyday clinical practices. In this article, we present the data on anti-HER2 clinical research of neoadjuvant, adjuvant, and metastatic studies from the past 2 decades. We also highlight some of the promising strategies that should be critically considered. Lastly, this review lists some of the ongoing clinical trials, findings of which may soon be available.

Mechanism of action of the trastuzumab biosimilar CT-P6

Objectives: Therapeutic monoclonal antibody biosimilars are expected to help reduce the sizeable economic burden of targeted treatments. Trastuzumab (Herceptin®), a recombinant humanized monoclonal antibody that binds to the extracellular domain of HER2, is approved for use in HER2-overexpressing breast cancer (in both the adjuvant and metastatic settings) and HER2-positive gastric cancer. CT-P6 (Herzuma®) is a biosimilar of trastuzumab, designed to bind with high affinity and specificity to the same HER2 epitope as the reference product. We investigated whether CT-P6 exerts its effects through the same mechanism of action as trastuzumab. Methods: The mechanism of action of CT-P6 and trastuzumab, both as monotherapy and in combination with paclitaxel or pertuzumab, was compared in HER2-overexpressing breast cancer and gastric cancer cell models. Results: We confirmed that CT-P6 functions in a manner similar to trastuzumab by binding to the HER2 receptor, which is central to the effects of trastuzumab in all indications. Conclusions: Collectively, the results of this study show that the mechanisms of action of CT-P6 and trastuzumab are similar in HER2-positive breast cancer and gastric cancer models and, therefore, CT-P6 can be expected to perform similarly in the clinical setting.

Pan-HER-targeted approach for cancer therapy: Mechanisms, recent advances and clinical prospect

The Human Epidermal Growth Factor Receptor family is composed of 4 structurally related receptor tyrosine kinases that are involved in many human cancers. The efficacy and safety of HER inhibitors have been compared in a wide range of clinical trials, suggesting the superior inhibitory ability of multiple- HER-targeting blockade compared with single receptor antagonists. However, many patients are currently resistant to current therapeutic treatment and novel strategies are warranted to conquer the resistance. Thus, we performed a critical review to summarize the molecular involvement of HER family receptors in tumour progression, recent anti-HER drug development based on clinical trials, and the potential resistance mechanisms of anti-HER therapy.

ERBB1- and ERBB2-Positive Medullary Thyroid Carcinoma: A Case Report

Medullary thyroid carcinomas (MTCs) are rare thyroid tumors occurring in both sporadic and hereditary forms, whose pathogenesis is related to RET proto-oncogene alterations. MTCs originate from parafollicular cells, which produce calcitonin that represents the biochemical activity of MTC. Total thyroidectomy is the main treatment for MTC and often cures patients with confined diseases. In the presence of metastasis, the therapeutic approach depends on the rate of disease progression. We report a case of a 54-year-old female with a single, incidentally discovered, thyroid nodule of 1 cm, classified as suspicious MTC after a stimulation test with intravenous (iv) calcium. After surgery, we examined the nodule using immunohistochemistry, immunofluorescence, and electron microscopy. In addition to calcitonin, we found that it expressed intracellular positivity for the tyrosine kinase RTK receptors ERBB1 and ERBB2. Consistently with MTC features, the ultrastructural examination of the tumor displayed heterogeneous spindle-shaped cells containing two groups of secretory granules. Because of the significant correlation found between high ERBB1/ERBB2 levels in MTCs and extrathyroidal growth, the detection of ERBB1 and ERBB2 expression suggests that the two oncoproteins may be involved in the tumor proliferative responses and/or in the differentiation of parafollicular C-cells. The biological, prognostic, and therapeutic significance of these patterns would merit further investigations.

Breast Cancer Cell Apoptosis is Synergistically Induced by Curcumin, Trastuzumab, and Glutathione Peroxidase-1 but Robustly Inhibited by Glial Cell Line-Derived Neurotrophic Factor

We hypothesized that synergy between curcumin (CURC), trastuzumab (TZMB), and glutathione peroxidase-1 (GPX-1) accelerates breast cancer (BC) cell apoptosis which is inhibited by glial cell line-derived neurotrophic factor (GDNF). We measured survival of BC cell lines treated or cotreated with CURC and TZMB, and then with GDNF, before measuring expression levels of growth and apoptosis genes. These experiments were also repeated on SKBR3 cells transiently expressing GPX-1. CURC+TZMB cotreatment induced BC cell apoptosis more significantly than single treatment. GDNF highly inhibited CURC+TZMB toxicity and restored survival. Ectopic overexpression of GPX-1 per se induced SKBR3 cell death that was accelerated upon CURC+TZMB cotreatment. This substantial death induction was inhibited by GDNF more robustly than in single-treated cells. All these changes correlated with changes in expression levels of key molecules and were further confirmed by flow cytometry and correlation analysis. Our data indicate apoptotic induction is jointly shaped in BC cells by CURC, TZMB, and GPX-1 which correlates directly with their tripartite synergism and inversely with GDNF progrowth effects. In light of the active presence of GDNF in tumor microenvironment and necessity to overcome drug resistance, our findings can help in designing combined therapeutic strategies with implications for challenging TZMB resistance in BC.

Adding Pertuzumab to Trastuzumab and Taxanes in HER2 positive breast cancer

INTRODUCTION

The monoclonal antibody trastuzumab has improved the median disease free and overall survival of patients with early stage breast cancer that overexpresses the human epidermal growth factor receptor 2 (HER2). Despite this advance, some patients experience cancer relapse and novel approaches are always needed. One such advance is the monoclonal antibody pertuzumab, which prevents dimerisation between members of the HER family of transmembrane glycoprotein receptors.

AREAS COVERED

In this review, the authors analyse recent research which has focused on the development of new HER2 targeting agents for HER2-positive breast cancer, particularly pertuzumab, and its addition to trastuzumab and taxanes.

EXPERT OPINION

Pertuzumab has significantly improved disease control in patients with advanced HER2 positive breast cancer when added to chemotherapy and trastuzumab. Although pertuzumab has also increased response rates in the preoperative setting, this has not yet translated into increased overall survival. The authors believe that future research should focus on improvements in novel biomarkers to select patients for new treatments.

Cooperative antitumor activities of carnosic acid and Trastuzumab in ERBB2+ breast cancer cells

Background

ERBB2 is overexpressed in up to 20–30% of human breast cancers (BCs), and it is associated with aggressive disease. Trastuzumab (Tz), a humanized monoclonal antibody, improves the prognosis associated with ERBB2-amplified BCs. However, the development of resistance remains a significant challenge. Carnosic acid (CA) is a diterpene found in rosemary and sage, endowed with anticancer properties. In this in vitro study, we have investigated whether Tz and CA have cooperative effects on cell survival of ERBB2 overexpressing (ERBB2⁺) cells and whether CA might restore Tz sensitivity in Tz-resistant cells.

Methods

We have studied BC cell migration and survival upon CA and Tz treatment. In particular, migration ability was assessed by transwell assay while cell survival was assessed by MTT assay. In addition, we have performed cell cycle and apoptosis analysis by high-resolution DNA flow cytometry and annexin-V, resazurin and sytox blue staining by flow cytometry, respectively. The expression of proteins involved in cell cycle progression, ERBB2 signaling pathway, and autophagy was evaluated by immunoblot and immunofluorescence analysis. Cellular structures relevant to the endosome/lysosome and autophagy pathways have been studied by immunofluorescence and transmission electron microscopy.

Results

We report that, in ERBB2⁺ BC cells, CA reversibly enhances Tz inhibition of cell survival, cooperatively inhibits cell migration and induces cell cycle arrest in G0/G1. These events are accompanied by ERBB2 down-regulation, deregulation of the PI3K/AKT/mTOR signaling pathway and up-regulation of both CDKN1A/p21^WAF1 and CDKN1B/p27^KIP1. Furthermore, we have demonstrated that CA impairs late autophagy and causes derangement of the lysosomal compartment as shown by up-regulation of SQSTM1/p62 and ultrastructural analysis. Accordingly, we have found that CA restores, at least in part, sensitivity to Tz in SKBR-3 Tz-resistant cell line.

Conclusions

Our data demonstrate the cooperation between CA and Tz in inhibiting cell migration and survival of ERBB2⁺ BC cells that warrant further studies to establish if CA or CA derivatives may be useful in vivo in the treatment of ERBB2⁺ cancers.

Electronic supplementary material

The online version of this article (10.1186/s13046-017-0615-0) contains supplementary material, which is available to authorized users.

Challenges and future of biomarker tests in the era of precision oncology: Can we rely on immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH) to select the optimal patients for matched therapy?

Molecular techniques have improved our understanding of the pathogenesis of cancer development. These techniques have also fueled the rational development of targeted drugs for patient populations stratified by their genetic characteristics. These novel methods have changed the classic paradigm of diagnostic pathology; among them are IHC, FISH, polymerase chain reaction (PCR) and microarray technology. IHC and FISH detection methods for human epidermal growth factor receptor-2 (HER2), epidermal growth factor receptor (EGFR) and programmed death ligand-1 (PD-L1) were recently approved by the Food and Drug Administration (FDA) as routine clinical practice for cancer patients. Here, we discuss general challenges related to the predictive power of these molecular biomarkers for targeted therapy in cancer medicine. We will also discuss the prospects of utilizing new biomarkers for fibroblast growth factor receptor (FGFR) and hepatocyte growth factor receptor (cMET/MET) targeted therapies for developing new and robust predictive biomarkers in oncology.

Cooperative but distinct early co-signaling events originate from ERBB2 and ERBB1 receptors upon trastuzumab treatment in breast cancer cells

ERBB2 receptor belongs to the ERBB tyrosine kinase receptor family. At variance to the other family members, ERBB2 is a constitutively active orphan receptor. Upon ligand binding and activation, ERBB receptors form homo- or hetero-dimers with the other family members, including ERBB2, promoting an intracellular signaling cascade. ERBB2 is the preferred dimerization partner and ERBB2 heterodimers signaling is stronger and longer acting compared to heterodimers between other ERBB members. The specific contribution of ERBB2 in heterodimer signaling is still undefined. Here we report the formation of circular dorsal ruffles (CDRs) upon treatment of the ERBB2-overexpressing breast cancer cell lines SK-BR-3 and ZR751 with Trastuzumab, a therapeutic humanized monoclonal antibody directed against ERBB2. We found that in SK-BR-3 cells Trastuzumab leads to surface redistribution of ERBB2 and ERBB1 in CDRs, and that the ERBB2-dependent ERK1/2 phosphorylation and ERBB1 expression are both required for CDR formation. In particular, in these cells CDR formation requires activation of both the protein regulator of actin polymerization N-WASP, mediated by ERK1/2, and of the actin depolymerizing protein cofilin, mediated by ERBB1. Furthermore, we suggest that this latter event may be inhibited by the negative cell motility regulator p140Cap, as we found that p140Cap overexpression led to cofilin deactivation and inhibition of CDR formation. In conclusion, here we show for the first time an ERBB2-specific signaling contribution to an ERBB2/ERBB1 heterodimer, in the activation of a complex biological process such as the formation of CDRs.

Cellular glycosylation affects Herceptin binding and sensitivity of breast cancer cells to doxorubicin and growth factors

Alterations in protein glycosylation are a key feature of oncogenesis and have been shown to affect cancer cell behaviour perturbing cell adhesion, favouring cell migration and metastasis. This study investigated the effect of N-linked glycosylation on the binding of Herceptin to HER2 protein in breast cancer and on the sensitivity of cancer cells to the chemotherapeutic agent doxorubicin (DXR) and growth factors (EGF and IGF-1). The interaction between Herceptin and recombinant HER2 protein and cancer cell surfaces (on-rate/off-rate) was assessed using a quartz crystal microbalance biosensor revealing an increase in the accessibility of HER2 to Herceptin following deglycosylation of cell membrane proteins (deglycosylated cells B_max: 6.83 Hz; glycosylated cells B_max: 7.35 Hz). The sensitivity of cells to DXR and to growth factors was evaluated using an MTT assay. Maintenance of SKBR-3 cells in tunicamycin (an inhibitor of N-linked glycosylation) resulted in an increase in sensitivity to DXR (0.1 μM DXR P < 0.001) and a decrease in sensitivity to IGF-1 alone and to IGF-1 supplemented with EGF (P < 0.001). This report illustrates the importance of N-linked glycosylation in modulating the response of cancer cells to chemotherapeutic and biological treatments and highlights the potential of glycosylation inhibitors as future combination treatments for breast cancer.

Antibody-dependent cell cytotoxicity: immunotherapy strategies enhancing effector NK cells

Antibody-dependent cellular cytotoxicity (ADCC) is a set of mechanisms that target cells coated with IgG antibodies of the proper subclasses (IgG1 in the human) to be the prey of cell-to-cell cytolysis executed by immune cells expressing FcRIIIA (CD16A). These effectors include not only natural killer (NK) cells but also other CD16⁺ subsets such as monocyte/macrophages, NKT cells or γδ T cells. In cancer therapy, ADCC is exploited by antibodies that selectively recognize proteins on the surface of malignant cells. An approach to enhance antitumor activity is to act on effector cells so they are increased in their numbers or enhanced in their individual (on a cell per cell basis) ADCC performance. This enhancement can be therapeutically attained by cytokines (that is, interleukin (IL)-15, IL-21, IL-18, IL-2); immunostimulatory monoclonal antibodies (that is, anti-CD137, anti-CD96, anti-TIGIT, anti-KIR, anti-PD-1); TLR agonists or by adoptive infusions of ex vivo expanded NK cells which can be genetically engineered to become more efficient effectors. In conjunction with approaches optimizing IgG1 Fc affinity to CD16, acting on effector cells offers hope to achieve synergistic immunotherapy strategies.

The role of miR-26a and miR-30b in HER2+ breast cancer trastuzumab resistance and regulation of the CCNE2 gene

A subset of HER2+ breast cancer patients manifest clinical resistance to trastuzumab. Recently, miR-26a and miR-30b have been identified as trastuzumab response regulators, and their target gene CCNE2 seems to play an important role in resistance to trastuzumab therapy. Cell viability was evaluated in trastuzumab treated HER2+ BT474 wt (sensitive), BT474r (acquired resistance), HCC1954 (innate resistance), and MDA-MB-231 (HER2−) cell lines, and the expression of miR-26a, miR-30b, and their target genes was measured. BT474 wt cell viability decreased by 60% and miR-26a and miR-30b were significantly overexpressed (~3-fold, p = 0.003 and p = 0.002, respectively) after trastuzumab treatment, but no differences were observed in resistant and control cell lines. Overexpression of miR-30b sensitized BT474r cells to trastuzumab (p = 0.01) and CCNE2, was significantly overexpressed after trastuzumab treatment in BT474r cells (p = 0.032), but no significant changes were observed in sensitive cell line. When CCNE2 was silenced BT474r cell sensitivity to trastuzumab increased (p = 0.03). Thus, the molecular mechanism of trastuzumab action in BT474 cell line may be regulated by miR-26a and miR-30b and CCNE2 overexpression might play an important role in acquired trastuzumab resistance in HER2+ breast cancer given that resistance was diminished when CCNE2 was silenced.

Efficient Payload Delivery by a Bispecific Antibody-Drug Conjugate Targeting HER2 and CD63

Antibody-drug conjugates (ADC) are designed to be stable in circulation and to release potent cytotoxic drugs intracellularly following antigen-specific binding, uptake, and degradation in tumor cells. Efficient internalization and routing to lysosomes where proteolysis can take place is therefore essential. For many cell surface proteins and carbohydrate structures on tumor cells, however, the magnitude of these processes is insufficient to allow for an effective ADC approach. We hypothesized that we could overcome this limitation by enhancing lysosomal ADC delivery via a bispecific antibody (bsAb) approach, in which one binding domain would provide tumor specificity, whereas the other binding domain would facilitate targeting to the lysosomal compartment. We therefore designed a bsAb in which one binding arm specifically targeted CD63, a protein that is described to shuttle between the plasma membrane and intracellular compartments, and combined it in a bsAb with a HER2 binding arm, which was selected as model antigen for tumor-specific binding. The resulting bsHER2xCD63_his demonstrated strong binding, internalization and lysosomal accumulation in HER2-positive tumor cells, and minimal internalization into HER2-negative cells. By conjugating bsHER2xCD63_his to the microtubule-disrupting agent duostatin-3, we were able to demonstrate potent cytotoxicity of bsHER2xCD63_his-ADC against HER2-positive tumors, which was not observed with monovalent HER2- and CD63-specific ADCs. Our data demonstrate, for the first time, that intracellular trafficking of ADCs can be improved using a bsAb approach that targets the lysosomal membrane protein CD63 and provide a rationale for the development of novel bsADCs that combine tumor-specific targeting with targeting of rapidly internalizing antigens. Mol Cancer Ther; 15(11); 2688-97. ©2016 AACR.

Cell-specific biomarkers and targeted biopharmaceuticals for breast cancer treatment

Breast cancer is the second leading cause of cancer death among women, and its related treatment has been attracting significant attention over the past decades. Among the various treatments, targeted therapy has shown great promise as a precision treatment, by binding to cancer cell-specific biomarkers. So far, great achievements have been made in targeted therapy of breast cancer. In this review, we first discuss cell-specific biomarkers, which are not only useful for classification of breast cancer subtyping but also can be utilized as goals for targeted therapy. Then, the innovative and generic-targeted biopharmaceuticals for breast cancer, including monoclonal antibodies, non-antibody proteins and small molecule drugs, are reviewed. Finally, we provide our outlook on future developments of biopharmaceuticals, and provide solutions to problems in this field.

Novel approaches to target HER2-positive breast cancer: trastuzumab emtansine

The human epidermal growth factor receptor 2 (HER2) is overexpressed in 20% of breast carcinomas. Prior to the development of targeted therapies, HER2-positive breast cancer was associated with more aggressive disease and poor prognosis. Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate that results from the combination of trastuzumab and DM1, a derivative of the antimicrotubule agent maytansine. This molecule has the ability to enhance cytotoxic drug delivery to specifically targeted cells that overexpress HER2, therefore, maximizing efficacy while sparing toxicity. In recent years, T-DM1 has shown to improve outcomes in metastatic HER2-positive breast cancer that is resistant to trastuzumab. In addition, T-DM1 is currently being tested in the neoadjuvant and adjuvant settings to identify patients who may benefit from this therapy. This review focuses on the mechanism of action, early and late-phase clinical trials, and ongoing studies of T-DM1 in HER2-positive breast cancer.

Marked enhancement of lysosomal targeting and efficacy of ErbB2-targeted drug delivery by HSP90 inhibition

Targeted delivery of anticancer drugs to tumor cells using monoclonal antibodies against oncogenic cell surface receptors is an emerging therapeutic strategy. These strategies include drugs directly conjugated to monoclonal antibodies through chemical linkers (Antibody-Drug Conjugates, ADCs) or those encapsulated within nanoparticles that in turn are conjugated to targeting antibodies (Antibody-Nanoparticle Conjugates, ANPs). The recent FDA approval of the ADC Trastuzumab-TDM1 (Kadcyla; Genentech; San Francisco) for the treatment of ErbB2-overexpressing metastatic breast cancer patients has validated the strong potential of these strategies. Even though the activity of ANPs and ADCs is dependent on lysosomal traffic, the roles of the endocytic route traversed by the targeted receptor and of cancer cell-specific alterations in receptor dynamics on the efficiency of drug delivery have not been considered in these new targeted therapies. For example, constitutive association with the molecular chaperone HSP90 is thought to either retard ErbB2 endocytosis or to promote its recycling, traits undesirable for targeted therapy with ANPs and ADCs. HSP90 inhibitors are known to promote ErbB2 ubiquitination, targeting to lysosome and degradation. We therefore hypothesized that ErbB2-targeted drug delivery using Trastuzumab-conjugated nanoparticles could be significantly improved by HSP90 inhibitor-promoted lysosomal traffic of ErbB2. Studies reported here validate this hypothesis and demonstrate, both in vitro and in vivo, that HSP90 inhibition facilitates the intracellular delivery of Trastuzumab-conjugated ANPs carrying a model chemotherapeutic agent, Doxorubicin, specifically into ErbB2-overexpressing breast cancer cells, resulting in improved antitumor activity. These novel findings highlight the need to consider oncogene-specific alterations in receptor traffic in the design of targeted drug delivery strategies. We suggest that combination of agents that enhance receptor endocytosis and lysosomal routing can provide a novel strategy to significantly improve therapy with ANPs and ADCs.

Intracellular delivery of antibodies by chimeric Sesbania mosaic virus (SeMV) virus like particles

The therapeutic potential of antibodies has not been fully exploited as they fail to cross cell membrane. In this article, we have tested the possibility of using plant virus based nanoparticles for intracellular delivery of antibodies. For this purpose, Sesbania mosaic virus coat protein (CP) was genetically engineered with the B domain of Staphylococcus aureus protein A (SpA) at the βH-βI loop, to generate SeMV loop B (SLB), which self-assembled to virus like particles (VLPs) with 43 times higher affinity towards antibodies. CP and SLB could internalize into various types of mammalian cells and SLB could efficiently deliver three different monoclonal antibodies–D6F10 (targeting abrin), anti-α-tubulin (targeting intracellular tubulin) and Herclon (against HER2 receptor) inside the cells. Such a mode of delivery was much more effective than antibodies alone treatment. These results highlight the potential of SLB as a universal nanocarrier for intracellular delivery of antibodies.

Altered S-nitrosothiol homeostasis provides a survival advantage to breast cancer cells in HER2 tumors and reduces their sensitivity to trastuzumab

The monoclonal antibody trastuzumab against HER2/neu, which is overexpressed in 15-20% of breast cancers, has clinical efficacy but many patients do not respond to initial treatment or develop resistance during treatment. Nitric oxide (NO) regulates cell signaling by targeting specific cysteine residues in proteins, forming S-nitrosothiols (SNO) in a process known as S-nitrosylation. We previously reported that molecular characteristics in breast cancer may dictate the tumor response to impaired SNO homeostasis. In the present study, we explored the role of SNO homeostasis in HER2 breast tumors. The antiproliferative action of trastuzumab in HER2-overexpressing BT-474 and SKBR-3 cells was suppressed when S-nitrosoglutathione reductase (GSNOR/ADH5) activity, which plays a key role in SNO homeostasis, was specifically inhibited with the pyrrole derivative compound N6022. Moreover, GSNOR inhibition restored the activation of survival signaling pathways involved in the resistance to anti-HER2 therapies (AKT, Src and c-Abl kinases and TrkA/NRTK1, TrkB/NRTK2, EphA1 and EphA3 receptors) and reduced the apoptotic effect of trastuzumab. Accordingly, GSNOR inhibition augmented the S-nitrosylation of apoptosis-related proteins, including Apaf-1, pSer73/63 c-Jun, calcineurin subunit α and HSF1. In agreement with in vitro data, immunohistochemical analyses of 51 breast tumors showed that HER2 expression was associated with lower expression of GSNOR protein. Moreover, gene expression analysis confirmed that high ADH5/GSNOR gene expression was associated with high patient survival rates in HER2 tumors. In conclusion, our data provide evidence of molecular mechanisms contributing to the progression of HER2+ breast cancers and could facilitate the development of therapeutic options to counteract resistance to anti-HER2 therapies.

Microfluidic Preparation of a 89Zr-Labeled Trastuzumab Single-Patient Dose

(89)Zr-labeled antibodies are being investigated in several clinical trials; however, the time requirement for synthesis of clinical doses can hinder patient throughput because of scheduling difficulties. Additionally, low specific activity due to poor labeling efficiency can require larger amounts of the radiopharmaceutical to be administered, possibly leading to adverse side effects. Here, we describe the design and evaluation of a microfluidic reactor capable of synthesizing a single clinical dose of (89)Zr-labeled antibody. (89)Zr-labeled trastuzumab was chosen for this validation because it is currently being evaluated in clinical trials for imaging human epidermal growth factor receptor 2-positive cancer patients.

METHODS

A microreactor fabricated from polydimethylsiloxane/glass was silanated with trimethoxy(octadecyl) silane to reduce antibody adsorption. Desferrioxamine-p-benzyl-isothiocyanate (DFO-Bz-NCS) was conjugated to trastuzumab in an 8:1 molar ratio following the literature procedures using aseptic techniques. Radiolabeling was performed by pumping (89)Zr-oxalate and DFO-Bz-trastuzumab into the microfluidic reactor at a total rate of 20 μL/min in ratios varying from 1:37 to 1:592 mg:MBq at 37°C to achieve optimal labeling.

RESULTS

Silanated reactors showed low antibody adsorption in comparison to unmodified reactors (95% monoclonal antibody recovered vs. 0% recovered). Labeling of the modified trastuzumab was shown to be achievable at a specific activity above the reported literature value of 220 MBq/mg. A high radiochemical purity was achieved without an incubation period at specific activities of less than 148 MBq/mg; however, specific activities up to 592 MBq/mg could be achieved with an incubation period. Clinical doses were able to be prepared and passed all quality control guidelines set by the Food and Drug Administration. Samples were sterile, colorless, and radiochemically pure (100%); maintained the ability to bind to the intended receptor; formed a minimal amount of aggregates (1%-4%); and were completed within 45-60 min.

CONCLUSION

(89)Zr-labeled trastuzumab for use in a clinical setting was synthesized in a microfluidic reactor in under an hour while reducing the amount of handling required by a technician. Use of this compact platform not only could enable the use of radiolabeled antibodies to become a common practice, but also could spread the use of radiolabeled antibodies beyond locations with cyclotron facilities.

Design of liposomal formulations for cell targeting

Liposomes have gained extensive attention as carriers for a wide range of drugs due to being both nontoxic and biodegradable as they are composed of substances naturally occurring in biological membranes. Active targeting for cells has explored specific modification of the liposome surface by functionalizing it with specific targeting ligands in order to increase accumulation and intracellular uptake into target cells. None of the Food and Drug Administration-licensed liposomes or lipid nanoparticles are coated with ligands or target moieties to delivery for homing drugs to target tissues, cells or subcellular organelles. Targeted therapies (with or without controlled drug release) are an emerging and relevant research area. Despite of the numerous liposomes reviews published in the last decades, this area is in constant development. Updates urgently needed to integrate new advances in targeted liposomes research. This review highlights the evolution of liposomes from passive to active targeting and challenges in the development of targeted liposomes for specific therapies.

Superior antitumor activity of trastuzumab combined with capecitabine plus oxaliplatin in a human epidermal growth factor receptor 2-positive human gastric cancer xenograft model

In the treatment of human epidermal growth factor receptor 2 (HER2)-positive advanced gastric or gastroesophageal junction cancer, it has been reported that the combination of trastuzumab with capecitabine plus cisplatin, or with 5-fluorouracil (5-FU) plus cisplatin, significantly increased overall survival compared with chemotherapy alone (ToGA trial). In addition, adjuvant therapy with capecitabine plus oxaliplatin (XELOX) improved the survival of patients who received curative D2 gastrectomy (CLASSIC trial). However, the efficacy of the combination of trastuzumab with XELOX for patients with HER2-positive gastric cancer remains unknown. The aim of this study, was to investigate the efficacy of the combination of trastuzumab with XELOX in a HER2-positive human gastric cancer xenograft model. Combination treatment with these three agents (trastuzumab 20 mg/kg, capecitabine 359 mg/kg and oxaliplatin 10 mg/kg), was found to exhibit a significantly stronger antitumor activity in NCI-N87 xenografts compared with either trastuzumab or XELOX alone. In this model, treatment with trastuzumab alone or trastuzumab plus oxaliplatin enhanced the expression of thymidine phosphorylase (TP), a key enzyme in the generation of 5-FU from capecitabine in tumor tissues. In in vitro experiments, trastuzumab induced TP mRNA expression in NCI-N87 cells. In addition, NCI-N87 cells co-cultured with the natural killer (NK) cell line CD16(158V)/NK-92 exhibited increased expression of TP mRNA. When NCI-N87 cells were cultured with CD16(158V)/NK-92 cells in the presence of trastuzumab, the mRNA expression of cytokines reported to have the ability to induce TP was upregulated in tumor cells. Furthermore, a medium conditioned by CD16(158V)/NK-92 cells also upregulated the expression of TP mRNA in NCI-N87 cells. These results suggest that trastuzumab promotes TP expression, either by acting directly on NCI-N87 cells, or indirectly via a mechanism that includes trastuzumab-mediated interactions between NK and NCI-N87 cells. Therefore, the combination of trastuzumab with XELOX may be a potent therapy for HER2-positive gastric cancer.

Antibody-drug conjugates as novel anti-cancer chemotherapeutics

Over the past couple of decades, antibody-drug conjugates (ADCs) have revolutionized the field of cancer chemotherapy. Unlike conventional treatments that damage healthy tissues upon dose escalation, ADCs utilize monoclonal antibodies (mAbs) to specifically bind tumour-associated target antigens and deliver a highly potent cytotoxic agent. The synergistic combination of mAbs conjugated to small-molecule chemotherapeutics, via a stable linker, has given rise to an extremely efficacious class of anti-cancer drugs with an already large and rapidly growing clinical pipeline. The primary objective of this paper is to review current knowledge and latest developments in the field of ADCs. Upon intravenous administration, ADCs bind to their target antigens and are internalized through receptor-mediated endocytosis. This facilitates the subsequent release of the cytotoxin, which eventually leads to apoptotic cell death of the cancer cell. The three components of ADCs (mAb, linker and cytotoxin) affect the efficacy and toxicity of the conjugate. Optimizing each one, while enhancing the functionality of the ADC as a whole, has been one of the major considerations of ADC design and development. In addition to these, the choice of clinically relevant targets and the position and number of linkages have also been the key determinants of ADC efficacy. The only marketed ADCs, brentuximab vedotin and trastuzumab emtansine (T-DM1), have demonstrated their use against both haematological and solid malignancies respectively. The success of future ADCs relies on improving target selection, increasing cytotoxin potency, developing innovative linkers and overcoming drug resistance. As more research is conducted to tackle these issues, ADCs are likely to become part of the future of targeted cancer therapeutics.

Detection of pAkt protein in imprint cytology of invasive breast cancer: Correlation with HER2/neu, hormone receptors, and other clinicopathological variables

Purpose:

Akt is a serine/threonine protein kinase and has emerged as a crucial regulator of widely divergent cellular processes, including apoptosis, proliferation, differentiation, and metabolism. Activation of Akt/protein kinase B has been positively associated with human epidermal growth-factor receptor 2 (HER2)/neu overexpression in breast carcinoma and a worse outcome among endocrine treated patients. The Akt signaling pathway currently attracts considerable attention as a new target for effective therapeutic strategies. We therefore investigated the relationship between activation of Akt and clinicopathologic variables including hormone receptor and HER2/neu status.

Methods:

Archival tumor tissues from 100 patients with invasive breast carcinoma were analyzed by immunocytochemistry. This study describes the results of immunocytochemical pAkt expression in breast carcinoma imprints, prepared from cut surfaces of freshly removed tumors. Both nuclear and cytoplasmic expressions were evaluated for pAkt.

Results:

Nuclear and cytoplasmic positive scores of 72% (72/100) and 42% (42/100), respectively, were found. Coexistence of nuclear and cytoplasmic staining was observed in 32 cases (32/100). Nuclear positive staining correlated with HER2/neu overexpression (P = 0.043) and was significantly associated with positive involvement of axillary lymph nodes (P = 0.013). No correlation was found between cytoplasmic pAkt rate and clinicopathological parameters, estrogen receptor, progesterone receptor or HER2/neu expression.

Conclusions:

pAkt expression can be evaluated in cytological material and may add valuable information to current prognostic models for breast cancer. pAkt overexpression appears to be linked with potentially aggressive tumor phenotype in invasive breast carcinoma.

Genetics of CD33 in Alzheimer's disease and acute myeloid leukemia

The CD33 single-nucleotide polymorphism (SNP) rs3865444 has been associated with the risk of Alzheimer's disease (AD). Rs3865444 is in linkage disequilibrium with rs12459419 which has been associated with efficacy of an acute myeloid leukemia (AML) chemotherapeutic agent based on a CD33 antibody. We seek to evaluate the extent to which CD33 genetics in AD and AML can inform one another and advance human disease therapy. We have previously shown that these SNPs are associated with skipping of CD33 exon 2 in brain mRNA. Here, we report that these CD33 SNPs are associated with exon 2 skipping in leukocytes from AML patients and with a novel CD33 splice variant that retains CD33 intron 1. Each copy of the minor rs12459419T allele decreases prototypic full-length CD33 expression by ∼ 25% and decreases the AD odds ratio by ∼ 0.10. These results suggest that CD33 antagonists may be useful in reducing AD risk. CD33 inhibitors may include humanized CD33 antibodies such as lintuzumab which was safe but ineffective in AML clinical trials. Here, we report that lintuzumab downregulates cell-surface CD33 by 80% in phorbol-ester differentiated U937 cells, at concentrations as low as 10 ng/ml. Overall, we propose a model wherein a modest effect on RNA splicing is sufficient to mediate the CD33 association with AD risk and suggest the potential for an anti-CD33 antibody as an AD-relevant pharmacologic agent.

Imaging of HER2 may improve the outcome of external irradiation therapy for prostate cancer patients

Prostate cancer (PCa) is the most common type of cancer among males. Human epidermal growth factor receptor type 2 (HER2) expression in PCa has been reported by several studies and its involvement in the progression towards androgen-independent PCa has been discussed. External irradiation is one of the existing therapies, which has been demonstrated to be efficient in combination with androgen deprivation therapy for the treatment of advanced PCa. However, 20–40% of patients develop recurrent and more aggressive PCa within 10 years. The current study investigates the involvement of HER2 in survival and radioresistance in PCa cells and we hypothesized that, by monitoring HER2 expression, treatment may be personalized. The PCa cell lines, LNCap, PC3 and DU-145, received a 6 Gy single dose of external irradiation. The number of PC3 cells was not affected by a single dose of radiation, whereas a 5-fold decrease in cell number was detected in LNCap (P<0.00001) and DU-145 (P<0.0001) cells. The HER2 expression in PC3 exhibited a significant increase post irradiation, however, the expression was stable in the remaining cell lines. The administration of trastuzumab post-irradiation resulted in a 2-fold decrease in the PC3 cell number, while the drug did not demonstrate additional effects in LNCap and DU-145 cells, when compared with that of irradiation treatment alone. The results of the present study demonstrated that an increase in membranous HER2 expression in response to external irradiation may indicate cell radioresistance. Furthermore, imaging of HER2 expression prior to and following external irradiation may present a step towards personalized therapy in PCa.

International Union of Basic and Clinical Pharmacology. XC. multisite pharmacology: recommendations for the nomenclature of receptor allosterism and allosteric ligands

Allosteric interactions play vital roles in metabolic processes and signal transduction and, more recently, have become the focus of numerous pharmacological studies because of the potential for discovering more target-selective chemical probes and therapeutic agents. In addition to classic early studies on enzymes, there are now examples of small molecule allosteric modulators for all superfamilies of receptors encoded by the genome, including ligand- and voltage-gated ion channels, G protein-coupled receptors, nuclear hormone receptors, and receptor tyrosine kinases. As a consequence, a vast array of pharmacologic behaviors has been ascribed to allosteric ligands that can vary in a target-, ligand-, and cell-/tissue-dependent manner. The current article presents an overview of allostery as applied to receptor families and approaches for detecting and validating allosteric interactions and gives recommendations for the nomenclature of allosteric ligands and their properties.

Resistance to HER2-targeted therapies: a potential role for FOXM1

Despite the tremendous efficacy of trastuzumab against HER2-overexpressing metastatic breast cancers, a significant fraction of women demonstrate progressive disease during treatment. Multiple mechanisms have been proposed to mediate trastuzumab resistance. In this mini-review, we discuss the evidence supporting FOXM1 as a mediator of resistance and potential new therapeutic target in trastuzumab-refractory breast cancer. FOXM1 expression is significantly elevated in multiple breast cancer data sets. Some studies suggest a direct correlation between FOXM1 and HER2 expression levels. In addition, overexpression of FOXM1 reduces the sensitivity of HER2-positive breast cancer cells to trastuzumab or lapatinib. Conversely, knockdown or pharmacological inhibition of FOXM1 rescues resistance to HER2-targeted therapies. Current pre-clinical information supports further investigation of the role of FOXM1 in trastuzumab-resistant breast cancer.

In vitro modeling of HER2-targeting therapy in disseminated prostate cancer

Prostate cancer (PCa) is the most common cancer type among men. Treatments against advanced PCa are limited and in many cases only palliative. In a later, androgent independent, stage of PCa androgen receptors can be activated without interaction with ligand, i.e., by receptors of tyrosine kinase (RTK) family in the outlaw pathway. Human epidermal growth factor receptors HER2 and EGFR belong to RTK-family. HER2 is one of the main actors in the outlaw pathway with EGFR as the preferable heterodimerizing partner. We hypothesized that information on HER2 expression in advanced PCa could be useful for selection of patients for anti-RTK therapy and monitoring of therapy response. A panel of PCa cell lines (LNCap, PC3, DU-145) was subjected to a 8-week treatment using drugs influencing the RTK: trastuzumab (anti‑HER2), 17-DMAG (Hsp90 inhibitor), alone or in combination, and their HER2 and EGFR expressions were compared with non-treated cells. Treatment with trastuzumab decreased proliferation of LNCap and DU-145 cell lines, while 17-DMAG and trastuzumab/17‑DMAG combination affected all three cell lines. HER2 expression was significantly increased in PC3 cells, the most resistant cell line. On the contrary, in responding cells (LNCap and DU-145) HER2 expression decreased, accompanied by increased EGFR expression. However, additional treatment of cells with cetuximab (anti‑EGFR) did not give any additive effect to trastuzumab. In this study the response to anti-RTK therapy proved to vary between different PCa cell lines. We have demonstrated that RTK targeting treatments may affect the phenotypic profile of PCa tumor cells that correlates with therapy outcome. Observation of such changes during treatment could be used for monitoring and an improved therapy outcome.

Production of recombinant antibodies using bacteriophages

Recombinant antibody fragments such as Fab, scFv, diabodies, triabodies, single domain antibodies and minibodies have recently emerged as potential alternatives to monoclonal antibodies, which can be engineered using phage display technology. These antibodies match the strengths of conventionally produced monoclonal antibodies and offer advantages for the development of immunodiagnostic kits and assays. These fragments not only retain the specificity of the whole monoclonal antibodies but also easy to express and produce in prokaryotic expression system. Further, these antibody fragments are genetically stable, less expensive, easy to modify in response to viral mutations and safer than monoclonal antibodies for use in diagnostic and therapeutic applications. This review describes the potential of antibody fragments generated using phage display and their use as diagnostic reagents.