Targeting the function of the HER2 oncogene in human cancer therapeutics

In silico transcriptome screens identify epidermal growth factor receptor inhibitors as therapeutics for noise-induced hearing loss

Noise-induced hearing loss (NIHL) is a common sensorineural hearing impairment that lacks U.S. Food and Drug Administration-approved drugs. To fill the gap in effective screening models, we used an in silico transcriptome-based drug screening approach, identifying 22 biological pathways and 64 potential small molecule treatments for NIHL. Two of these, afatinib and zorifertinib [epidermal growth factor receptor (EGFR) inhibitors], showed efficacy in zebrafish and mouse models. Further tests with EGFR knockout mice and EGF-morpholino zebrafish confirmed their protective role against NIHL. Molecular studies in mice highlighted EGFR's crucial involvement in NIHL and the protective effect of zorifertinib. When given orally, zorifertinib was found in the perilymph with favorable pharmacokinetics. In addition, zorifertinib combined with AZD5438 (a cyclin-dependent kinase 2 inhibitor) synergistically prevented NIHL in zebrafish. Our results underscore the potential for in silico transcriptome-based drug screening in diseases lacking efficient models and suggest EGFR inhibitors as potential treatments for NIHL, meriting clinical trials.

[Research Progress of Antibody-conjugated Drugs in Non-small Cell Lung Cancer]

Lung cancer is the most common malignant tumor and the second most common malignant tumor in terms of mortality in the world. Non-small cell lung cancer (NSCLC) is the most common pathological type of lung cancer. Currently, the first-line standard treatment for advanced NSCLC is immunotherapy and targeted therapy. Although these treatments prolong the survival of patients, acquired drug resistance is still inevitable. Antibody-drug conjugates (ADCs) are a new type of anti-tumor drug made by coupling cytotoxic payloads to specific monoclonal antibodies via linkers. Compared with chemotherapy drugs, ADCs have the advantages of accurate recognition, local release, and high patient tolerance. In recent years, they have shown good clinical benefits in the treatment of NSCLC. This article provides an overview of the mechanism of action of ADCs, clinical studies progress in advanced NSCLC, and existing problems and challenges.
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Design, synthesis, computational study and cytotoxic evaluation of some new quinazoline derivatives containing pyrimidine moiety

Quinazoline derivatives, as an important category of heterocyclic compounds, have received much attention for the design and development of new drugs due to their various pharmacological properties. Besides, there is a great deal of evidence showing pyrimidine analogs as anticancer agents. Thus, in the present study, for the design of new target compounds with cytotoxic activity, we focused on various quinazolinone and pyrimidine hybrids. A new series of quinazoline-pyrimidine hybrid derivatives (6a-6n) have been designed and synthesized as novel antiproliferative agents. All the synthesized compounds characterized based on their IR, NMR and Mass spectroscopic data. Antiproliferative activities of the new compounds were evaluated against three human cancer cell lines (MCF-7, A549, SW-480). The compounds were found to have appropriate potential with IC50 values ranging from 2.3 ± 5.91 to 176.5 ± 0.7 μM against the tested cell lines. Compound 6n exerted the highest antiproliferative activity with IC50 values of 5.9 ± 1.69 μM, 2.3 ± 5.91 μM and 5.65 ± 2.33 μM against A549, SW-480 and MCF-7 respectively. The results indicated that 6n could induce apoptosis in A549 cell line in a dose dependent manner and arrest in the S phase of cell cycle. Docking studies were also done to investigate the detailed binding pattern of the synthesized compounds against EGFR. Furthermore, molecular dynamic simulation and binding free energy calculation have been done to rescore initial docking pose of the synthesized compounds using ensemble-based MMGB/PBSA free energy method. According to the results, free energy calculation confirmed biological activity of compounds and also, Arg 817 and Lys 721 residues had the pivotal role in the high potency of 6n. Finally, the drug likeness and in silico ADME study were also predicted.

In Silico Transcriptome-based Screens Identify Epidermal Growth Factor Receptor Inhibitors as Therapeutics for Noise-induced Hearing Loss

Noise-Induced Hearing Loss (NIHL) represents a widespread disease for which no therapeutics have been approved by the Food and Drug Administration (FDA). Addressing the conspicuous void of efficacious in vitro or animal models for high throughput pharmacological screening, we utilized an in silico transcriptome-oriented drug screening strategy, unveiling 22 biological pathways and 64 promising small molecule candidates for NIHL protection. Afatinib and zorifertinib, both inhibitors of the Epidermal Growth Factor Receptor (EGFR), were validated for their protective efficacy against NIHL in experimental zebrafish and murine models. This protective effect was further confirmed with EGFR conditional knockout mice and EGF knockdown zebrafish, both demonstrating protection against NIHL. Molecular analysis using Western blot and kinome signaling arrays on adult mouse cochlear lysates unveiled the intricate involvement of several signaling pathways, with particular emphasis on EGFR and its downstream pathways being modulated by noise exposure and Zorifertinib treatment. Administered orally, Zorifertinib was successfully detected in the perilymph fluid of the inner ear in mice with favorable pharmacokinetic attributes. Zorifertinib, in conjunction with AZD5438 - a potent inhibitor of cyclin dependent kinase 2 - produced synergistic protection against NIHL in the zebrafish model. Collectively, our findings underscore the potential application of in silico transcriptome-based drug screening for diseases bereft of efficient screening models and posit EGFR inhibitors as promising therapeutic agents warranting clinical exploration for combatting NIHL.

Highlights

In silico transcriptome-based drug screens identify pathways and drugs against NIHL.EGFR signaling is activated by noise but reduced by zorifertinib in mouse cochleae.Afatinib, zorifertinib and EGFR knockout protect against NIHL in mice and zebrafish.Orally delivered zorifertinib has inner ear PK and synergizes with a CDK2 inhibitor.

A comparative study of gastric adenocarcinoma HER2 IHC phenotype and mass spectrometry-based quantification

Introduction

Gastric cancer is a highly heterogeneous malignant tumor of the digestive system. Anti-HER2 treatment can inhibit downstream signaling pathways and improve clinical treatment and outcomes in patients with HER2 protein overexpression. Currently, two standard methods for evaluating HER2 expression status are immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH). However, these low-throughput assays often produce discordant or equivocal results.

Methods

In this study, we presented a new HER2 protein detection method based on mass spectrometry selected reaction monitoring (MS-SRM) and validated the method. We conducted a retrospective study on 118 formalin-fixed paraffin-embedded (FFPE) tissues from patients with advanced gastric adenocarcinoma in northern China, and we compared the MS-SRM results with those from IHC and correlated them with FISH.

Results

We established and validated the upper and lower detection limits (300-700 amol/μg) for abnormal HER2 protein expression in advanced gastric cancer. We also found that, among samples with mixed Lauren subtypes, those with a high level of HER2 expression had typical intestinal type features in pathology.

Discussion

This study demonstrated that the MS-SRM method can overcome the limitations and deficiencies of IHC, directly quantify the expression of HER2 protein in tumor cells and be used as a supplement to IHC. It has the potential to be used as a companion diagnosis for new drugs used to treat advanced gastric cancer. Large-scale clinical validation is required.

Design, synthesis and biological evaluation of novel 3,4-dihydro-2H-[1,4]oxazino [2,3-f]quinazolin derivatives as EGFR-TKIs

Starting with our previously reported work, a novel series of 3,4-dihydro-2H-[1,4]oxazino[2,3-f]quinazolin-derivatives were designed, synthesized and evaluated as potent EGFR tyrosine kinase inhibitors. All of the compounds showed significant inhibitory activities against EGFR^wt kinase (IC₅₀ ≤ 937.7 nM). Among them, compound 7j demonstrated the most potent inhibitory activity toward EGFR^wt tyrosine kinase with IC₅₀ value of 25.69 nM and showed good antiproliferative activities against NCI-H1563 and H1975 cells. The median cytotoxic concentration (CC₅₀) showed that most of the tested compounds displayed almost no cytotoxicity in vitro against 16HBE cells. In view of the reported compounds activity, the structure deserves further optimization as cancer treatment agents.

Breast cancer brain metastasis: Current evidence and future directions

Breast cancer is the most common cancer in women and the second leading cause of cancer-related deaths after lung cancer. Metastasis of the central nervous system is a terrible event for breast cancer patients, affecting their survival and quality of life. Compared with hormone receptor-positive/human epidermal growth factor receptor 2-negative breast cancer patients, brain metastases are more likely to affect patients with triple-negative breast cancer and human epidermal growth factor receptor 2-positive breast cancer. The treatment of breast cancer has improved greatly in the last two decades. However, brain metastases from breast cancer remain the leading cause of morbidity and mortality. Patients with breast cancer brain metastasis have been in an inferior position due to the lack of clinical research in this field, and they are often explicitly excluded from almost all clinical trials. The occurrence and progression of brain metastases will result in severe cognitive impairment and adverse physical consequences, so we must have a good understanding of the molecular mechanisms of breast cancer brain metastasis. In this article, we have retrieved the latest literature of molecules and pathways associated with breast cancer brain metastasis, summarized common therapy strategies, and discussed the prospects and clinical implications of targeting the molecules involved.

[Current Progress and Future Developments of Antibody Drug Conjugates in Lung Cancer]

Antibody drug conjugates (ADCs) are a novel class of anti-cancer drugs, which combined the specificity of monoclonal antibodies with the cytotoxic palyload via the linkers. Many ADCs have not only verified impressive activity in a variety of cancers, including breast cancer and hematological system tumors, but also in lung cancer. The aim of this study was to provide informations for practice by summarizing the mechanism of action, clinical application and problems and challenges of ADCs.
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Molecular Assessment of HER2 to Identify Signatures Associated with Therapy Response in HER2-Positive Breast Cancer

Trastuzumab, the prototype HER2-directed therapy, has markedly improved survival for women with HER2-positive breast cancers. However, only 40-60% of women with HER2-positive breast cancers achieve a complete pathological response to chemotherapy combined with HER2-directed therapy. The current diagnostic assays have poor positive-predictive accuracy in identifying therapy-responsive breast cancers. Here, we deployed quantitative single molecule localization microscopy to assess the molecular features of HER2 in a therapy-responsive setting. Using fluorescently labeled trastuzumab as a probe, we first compared the molecular features of HER2 in trastuzumab-sensitive (BT-474 and SK-BR-3) and trastuzumab-resistant (BT-474R and JIMT-1) cultured cell lines. Trastuzumab-sensitive cells had significantly higher detected HER2 densities and clustering. We then evaluated HER2 in pre-treatment core biopsies from women with breast cancer undergoing neoadjuvant therapy. A complete pathological response was associated with a high detected HER2 density and significant HER2 clustering. These results established the nano-organization of HER2 as a potential signature of therapy-responsive disease.

Human Epidermal Growth Factor Receptor 2-Targeting Approaches for Colorectal Cancer: Clinical Implications of Novel Treatments and Future Therapeutic Avenues

The treatment paradigm for colorectal cancer (CRC) has changed significantly over the past decade with targeted therapeutics. Human epidermal growth factor receptor 2 (HER2) amplification is seen among 3%-4% of patients with metastatic CRC (mCRC). The biological discovery of HER2 amplification in cancer cells has led to practice-changing drug development for several solid tumors, including breast, gastric, and esophageal cancers. HER2 amplification is now highly actionable in CRC with distinct therapeutic combinations, including the combination of monoclonal antibodies and HER2 receptor-specific tyrosine kinase inhibitors, as well as antibody-drug conjugates, that delivers targeted cytotoxic agents. However, it is essential to define the therapeutic role and sequence of these different combinations, some of which are already part of standard clinical practice. In this review article, we discuss recent clinical studies demonstrating the clinical benefits of each distinct therapeutic approach and their impacts on the current management of HER2-amplified mCRC. We also review ongoing clinical trials targeting the HER2 pathway in mCRC and elaborate on novel therapeutic opportunities in this space that may further define the changing paradigm of HER2-targeted therapy for CRC.

Metastatic profiling of HER2-positive breast cancer cell lines in xenograft models

Most studies on breast cancer metastasis have been performed using triple-negative breast cancer cells; thus, subtype-dependent metastatic ability of breast cancer is poorly understood. In this research, we performed intravenous injection (IVI) and intra-caudal arterial injections using nine human epidermal growth factor receptor-2 (HER2)-positive breast cancer cell lines for evaluating their metastatic abilities. Our results showed that MDA-MB-453, UACC-893, and HCC-202 had strong bone metastatic abilities, whereas HCC-2218 and HCC-1419 did not show bone metastasis. HER2-positive cell lines could hardly metastasize to the lung through IVI. From the genomic analysis, gene signatures were extracted according to the breast cancer subtypes and their metastatic preferences. The UACC-893 cell line was identified as a useful model for the metastasis study of HER2-positive breast cancer. Combined with our previous result on brain metastasis ability, we provide a characteristic metastasis profile of HER2-positive breast cancer cell lines in this study.

Innate-like NKp30+CD8+ T cells armed with TCR/CAR target tumor heterogeneity

Intratumoral heterogeneity is frequently associated with tumor immune escape, with MHC-class I and antigen expression loss rendering tumor cells invisible to T cell killing, representing a major challenge for the design of successful adoptive transfer protocols for cancer immunotherapy. While CD8⁺ T cell recognition of tumor cells is based on the detection of MHC-peptide complexes via specific T cell receptors (TCRs), Natural Killer (NK) cells detect tumor-associated NK ligands by an array of NK receptors. We have recently identified a population of innate-like CD8⁺ T cells marked by the expression of NKp30, a potent natural cytotoxicity activating NK receptor, whose tumor ligand, B7H6, is frequently upregulated on several cancer types. Here, we harnessed the dual-recognition potential of NKp30⁺CD8⁺ T cells, by arming these cells with TCRs or chimeric antigen receptors (CARs) targeting Epidermal Growth Factor Receptor 2 (ErbB2, or HER2), a tumor-associated target overexpressed in several malignancies. HER2-specific NKp30⁺CD8⁺ T cells killed not only HER2-expressing target cell lines, but also eliminated tumor cells in the absence of MHC-class I or antigen expression, making them especially effective in eliminating heterogeneous tumor cell populations. Our results show that NKp30⁺CD8⁺ T cells equipped with a specific TCR or CAR display a dual capacity to recognize and kill target cells, combining the anti-tumor activity of both CD8⁺ T and NK cells. This dual-recognition capacity allows these effector cells to target tumor heterogeneity, thus improving therapeutic strategies against tumor escape.

Combination of tucatinib and neural stem cells secreting anti-HER2 antibody prolongs survival of mice with metastatic brain cancer

Brain metastases are among the most severe complications of systemic breast cancer, and overexpression of the human epidermal growth factor receptor 2 (HER2) in breast cancer cells increases the incidence of brain metastases in patients. In this study, we engineered the human-derived, tumor cell tropic neural stem cells LM-NSC008 (LM008) to continuously secrete antibodies against HER2. These anti-HER2 antibodies impaired tumor cell proliferation by inhibiting the PI3K-Akt signaling pathway in HER2+ breast cancer cells in vitro. Importantly, our results demonstrate that the therapeutic combinatorial regimen consisting of LM-NSC008 anti-HER2 antibody-secreting cells and the HER2 kinase inhibitor tucatinib provide therapeutic benefit and prolong survival in preclinical models of HER2+ breast cancer brain metastases.

Brain metastases are a leading cause of death in patients with breast cancer. The lack of clinical trials and the presence of the blood–brain barrier limit therapeutic options. Furthermore, overexpression of the human epidermal growth factor receptor 2 (HER2) increases the incidence of breast cancer brain metastases (BCBM). HER2-targeting agents, such as the monoclonal antibodies trastuzumab and pertuzumab, improved outcomes in patients with breast cancer and extracranial metastases. However, continued BCBM progression in breast cancer patients highlighted the need for novel and effective targeted therapies against intracranial metastases. In this study, we engineered the highly migratory and brain tumor tropic human neural stem cells (NSCs) LM008 to continuously secrete high amounts of functional, stable, full-length antibodies against HER2 (anti-HER2Ab) without compromising the stemness of LM008 cells. The secreted anti-HER2Ab impaired tumor cell proliferation in vitro in HER2+ BCBM cells by inhibiting the PI3K-Akt signaling pathway and resulted in a significant benefit when injected in intracranial xenograft models. In addition, dual HER2 blockade using anti-HER2Ab LM008 NSCs and the tyrosine kinase inhibitor tucatinib significantly improved the survival of mice in a clinically relevant model of multiple HER2+ BCBM. These findings provide compelling evidence for the use of HER2Ab-secreting LM008 NSCs in combination with tucatinib as a promising therapeutic regimen for patients with HER2+ BCBM.

YES1 as a Therapeutic Target for HER2-Positive Breast Cancer after Trastuzumab and Trastuzumab-Emtansine (T-DM1) Resistance Development

Trastuzumab-emtansine (T-DM1) is a therapeutic agent molecularly targeting human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC), and it is especially effective for MBC with resistance to trastuzumab. Although several reports have described T-DM1 resistance, few have examined the mechanism underlying T-DM1 resistance after the development of acquired resistance to trastuzumab. We previously reported that YES1, a member of the Src family, plays an important role in acquired resistance to trastuzumab in HER2-amplified breast cancer cells. We newly established a trastuzumab/T-DM1-dual-resistant cell line and analyzed the resistance mechanisms in this cell line. At first, the T-DM1 effectively inhibited the YES1-amplified trastuzumab-resistant cell line, but resistance to T-DM1 gradually developed. YES1 amplification was further enhanced after acquired resistance to T-DM1 became apparent, and the knockdown of the YES1 or the administration of the Src inhibitor dasatinib restored sensitivity to T-DM1. Our results indicate that YES1 is also strongly associated with T-DM1 resistance after the development of acquired resistance to trastuzumab, and the continuous inhibition of YES1 is important for overcoming resistance to T-DM1.

Antisense Oligonucleotide-Mediated Splice Switching: Potential Therapeutic Approach for Cancer Mitigation

Splicing is an essential process wherein precursor messenger RNA (pre-mRNA) is reshaped into mature mRNA. In alternative splicing, exons of any pre-mRNA get rearranged to form mRNA variants and subsequently protein isoforms, which are distinct both by structure and function. On the other hand, aberrant splicing is the cause of many disorders, including cancer. In the past few decades, developments in the understanding of the underlying biological basis for cancer progression and therapeutic resistance have identified many oncogenes as well as carcinogenic splice variants of essential genes. These transcripts are involved in various cellular processes, such as apoptosis, cell signaling and proliferation. Strategies to inhibit these carcinogenic isoforms at the mRNA level are promising. Antisense oligonucleotides (AOs) have been developed to inhibit the production of alternatively spliced carcinogenic isoforms through splice modulation or mRNA degradation. AOs can also be used to induce splice switching, where the expression of an oncogenic protein can be inhibited by the induction of a premature stop codon. In general, AOs are modified chemically to increase their stability and binding affinity. One of the major concerns with AOs is efficient delivery. Strategies for the delivery of AOs are constantly being evolved to facilitate the entry of AOs into cells. In this review, the different chemical modifications employed and delivery strategies applied are discussed. In addition to that various AOs in clinical trials and their efficacy are discussed herein with a focus on six distinct studies that use AO-mediated exon skipping as a therapeutic strategy to combat cancer.

Quantitative analysis and pharmacokinetic study of a novel diarylurea EGFR inhibitor (ZCJ14) in rat plasma using a validated LC-MS/MS method

1-(4-(Pyrrolidin-1-yl-methyl)phenyl)-3-(4-((3-(trifluoromethyl) phenyl)amino)quinazolin-6-yl)urea (ZCJ14), a novel epidermal growth factor receptor (EGFR) inhibitor, with diarylurea moiety, displays anticancer effect. In the present study, an LCMS/MS method was established to determine the concentration of ZCJ14 in rat plasma. Furthermore, the method was applied to investigate the pharmacokinetic characteristics of ZCJ14. Chromatographic separation of ZCJ14 and internal standard (IS) [1-phenyl-3-(4-((3-(trifluoromethyl)phenyl)amino) quinazolin-6-yl)urea] was accomplished by gradient elution using the Kromasil C₁₈ column. The selected reaction monitoring transitions were performed at m/z 507.24→436.18 and 424.13→330.96 for ZCJ14 and IS, resp. The established method was linear over the concentration range of 10-1000 ng mL^-1. The intra- and inter-day precisions were < 11.0 % (except for LLOQ which was up to 14.3 %) and the respective accuracies were within the range of 87.5-99.0 %. The extraction recovery and matrix effect were within the range of 88.4-104.5 % and 87.3-109.9 %, resp. ZCJ14 was stable under all storage conditions. The validated method was successfully applied to the pharmacokinetic study of ZCJ14 in rats, and the pharmacokinetic parameters have been determined. The oral bioavailability of ZCJ14 was found to be 46.1 %. Overall, this accurate and reliable quantification method might be useful for other diarylurea moiety-containing drugs.

Antibody Drug Conjugates in Lung Cancer: State of the Current Therapeutic Landscape and Future Developments

While both targeted therapy and immunotherapy-based strategies have emerged as frontline standard-of-care for patients with advanced lung cancer, acquired resistance and disease progression remain inevitable in most cases. Chemotherapy is a common salvage option in this scenario, but is limited by a relatively narrow therapeutic index. The emergence of antibody-drug conjugates (ADCs) offer an appealing alternative. ADCs couple the specificity of a monoclonal antibody with the cytotoxic effects of chemotherapy to facilitate the targeted delivery of cytotoxic payloads directly to cancer cells. Here, we review the general structure and function of ADCs, followed by a discussion of emerging ADCs in lung cancer and the future applications of this increasingly relevant class of novel agents.

Trastuzumab Deruxtecan: Changing the Destiny of HER2 Expressing Solid Tumors

HER2 targeted therapies have significantly improved prognosis of HER2-positive breast and gastric cancer. HER2 overexpression and mutation is the pathogenic driver in non-small cell lung cancer (NSCLC) and colorectal cancer, however, to date, there are no approved HER2-targeted therapies with these indications. Trastuzumab deruxtecan (T-DXd) is a novel HER2-directed antibody drug conjugate showing significant anti-tumor activity in heavily pre-treated HER2-positive breast and gastric cancer patients. Preliminary data have shown promising objective response rates in patients with HER2-positive NSCLC and colorectal cancer. T-DXd has an acceptable safety profile, however with concerns regarding potentially serious treatment-emergent adverse events. In this review we focus on the pharmacologic characteristics and toxicity profile of T-Dxd, and provide an update on the most recent results of clinical trials of T-DXd in solid tumors. The referenced papers were selected through a PubMed search performed on 16 March 2021 with the following searching terms: T-DXd and breast cancer, or gastric cancer, or non-small cell lung cancer (NSCLC), or colorectal cancer. Oral presentation, abstracts, and posters presented at the American Society of Clinical Oncology (ASCO, Alexandria, VA, USA) 2020 and the European Society for Medical Oncology (ESMO, Lugano, Switzerland) 2020 annual meetings were retrieved for data on T-DXd. We also overview ongoing research and data of combination therapies currently under investigation, which will impact on future therapeutic strategies. Clinicaltrials.gov was searched to identify ongoing clinical trials of T-DXd alone or in combination in solid tumors.

Resistance and Overcoming Resistance in Breast Cancer

The incidence and mortality of breast cancer (BC) have increased in recent years, and BC is the main cause of cancer-related death in women worldwide. One of the most significant clinical problems in the treatment of patients with BC is the development of therapeutic resistance. Therefore, elucidating the molecular mechanisms involved in drug resistance is critical. The therapeutic decision for the management of patients with BC is based not only on the assessment of prognostic factors but also on the evaluation of clinical and pathological parameters. Although this has been a successful approach, some patients relapse and/or eventually develop resistance to treatment. This review is focused on recent studies on the possible biological and molecular mechanisms involved in both response and resistance to treatment in BC. Additionally, emerging treatments that seek to overcome resistance and reduce side effects are also described. A greater understanding of the mechanisms of action of treatments used in BC might contribute not only to the enhancement of our understanding of the mechanisms involved in the development of resistance but also to the optimization of the existing treatment regimens.

Computational Analysis of Phosphoproteomics Data in Multi-Omics Cancer Studies

Multiple types of molecular data for the same set of clinical samples are increasingly available and may be analyzed jointly in an integrative analysis to maximize comprehensive biological insight. This analysis is important as separate analyses of individual omics data types usually do not fully explain disease phenotypes. An increasing number of studies have now been focusing on multi-omics data integration, yet not many studies have included phosphoproteomics data, an important layer for understanding signaling pathways. Multi-omics integration methods with phosphoproteomics data are reviewed in the context of cancer research as well as multi-omics methods papers that would be promising to apply to phosphoproteomics data. Analysis of individual data types is still the major approach even in large cohort proteogenomics studies. Hence, a section is dedicated on possible integrative methods for multi-omics and phosphoproteomics data. In summary, this review provides the readers with both currently used integrative methods previously applied to phosphoproteomics and multi-omics data integration and other algorithms for multi-omics data integration promising for future application to phosphoproteomics data.

Acute Immune Response of Micro- and Nanosized Erythrocyte-Derived Optical Particles in Healthy Mice

Erythrocyte-derived particles activated by near-infrared (NIR) light present a platform for various phototheranostic applications. We have engineered such a platform with indocyanine green as the NIR-activated agent. A particular feature of these particles is that their diameters can be tuned from micro- to nanoscale, providing a potential capability for broad clinical utility ranging from vascular to cancer-related applications. An important issue related to clinical translation of these particles is their immunogenic effects. Herein, we have evaluated the early-induced innate immune response of these particles in healthy Swiss Webster mice following tail vein injection by measurements of specific cytokines in blood serum, the liver, and the spleen following euthanasia. In particular, we have investigated the effects of particle size and relative dose, time-dependent cytokine response for up to 6 h postinjection, functionalization of the nanosized particles with folate or Herceptin, and dual injections of the particles 1 week apart. Mean concentrations of interleukin (IL)-6, IL-10, tumor necrosis factor (TNF)-α, and monocyte chemoattractant protein (MCP)-1 in response to injection of microsized particles at the investigated relative doses were significantly lower than the corresponding mean concentrations induced by lipopolysaccharide (positive control) at 2 h. All investigated doses of the nanosized particles induced significantly higher concentrations of MCP-1 in the liver and the spleen as compared to phosphate buffer saline (PBS) (negative control) at 2 h. In response to micro- and nanosized particles at the highest investigated dose, there were significantly higher levels of TNF-α in blood serum at 2 and 6 h postinjection as compared to the levels associated with PBS treatment at these times. Whereas the mean concentration of TNF-α in the liver significantly increased between 2 and 6 h postinjection in response to the injection of the microsized particles, it was significantly reduced during this time interval in response to the injection of the nanosized particles. In general, functionalization of the nanosized particles was associated with a reduction of IL-6 and MCP-1 in blood serum, the liver, and the spleen, and TNF-α in blood serum. With the exception of IL-10 in the spleen in response to nanosized particles, the second injection of micro- or nanosized particles did not lead to significantly higher concentrations of other cytokines at the investigated dose as compared to a single injection.

YES1 amplification confers trastuzumab-emtansine (T-DM1) resistance in HER2-positive cancer

BACKGROUND

Trastuzumab-emtansine (T-DM1), one of the most potent HER2-targeted drugs, shows impressive efficacy in patients with HER2-positive breast cancers. However, resistance inevitably occurs and becomes a critical clinical problem.

METHODS

We modelled the development of acquired resistance by exposing HER2-positive cells to escalating concentrations of T-DM1. Signalling pathways activation was detected by western blotting, gene expression was analysed by qRT-PCR and gene copy numbers were determined by qPCR. The role of Yes on resistance was confirmed by siRNA-mediated knockdown and stable transfection-mediated overexpression. The in vivo effects were tested in xenograft model.

RESULTS

We found that Yes is overexpressed in T-DM1-resistant cells owing to amplification of chromosome region 18p11.32, where the YES1 gene resides. Yes activated multiple proliferation-related signalling pathways, including EGFR, PI3K and MAPK, and led to cross-resistance to all types of HER2-targeted drugs, including antibody-drug conjugate, antibody and small molecule inhibitor. The outcome of this cross-resistance may be a clinically incurable condition. Importantly, we found that inhibiting Yes with dasatinib sensitised resistant cells in vitro and in vivo.

CONCLUSIONS

Our study revealed that YES1 amplification conferred resistance to HER2-targeted drugs and suggested the potential application of the strategy of combining HER2 and Yes inhibition in the clinic.

HER family in cancer progression: From discovery to 2020 and beyond

The human epidermal growth factor receptor (HER) family of receptor tyrosine kinases (RTKs) are among the first layer of molecules that receive, interpret, and transduce signals leading to distinct cancer cell phenotypes. Since the discovery of the tooth-lid factor-later characterized as the epidermal growth factor (EGF)-and its high-affinity binding EGF receptor, HER kinases have emerged as one of the commonly upregulated or hyperactivated or mutated kinases in epithelial tumors, thus allowing HER1-3 family members to regulate several hallmarks of cancer development and progression. Each member of the HER family exhibits shared and unique structural features to engage multiple receptor activation modes, leading to a range of overlapping and distinct phenotypes. EGFR, the founding HER family member, provided the roadmap for the development of the cell surface RTK-directed targeted cancer therapy by serving as a prototype/precursor for the currently used HER-directed cancer drugs. We herein provide a brief account of the discoveries, defining moments, and historical context of the HER family and guidepost advances in basic, translational, and clinical research that solidified a prominent position of the HER family in cancer research and treatment. We also discuss the significance of HER3 pseudokinase in cancer biology; its unique structural features that drive transregulation among HER1-3, leading to a superior proximal signaling response; and potential role of HER3 as a shared effector of acquired therapeutic resistance against diverse oncology drugs. Finally, we also narrate some of the current drawbacks of HER-directed therapies and provide insights into postulated advances in HER biology with extensive implications of these therapies in cancer research and treatment.

Overcoming trastuzumab resistance in HER2-positive breast cancer using combination therapy

Human epidermal growth factor receptor 2 (HER2)-positive breast cancer (BC) comprises around 20-30% of all BC subtypes and is correlated with poor prognosis. For many years, trastuzumab, a monoclonal antibody, has been used to inhibit the HER2 activity. Though, the main resistance to trastuzumab has challenged the use of this drug in the management of HER2-positive BC. Therefore, the determination of resistance mechanisms and the incorporation of new agents may lead to the development of a better blockade of the HER family receptor signaling. During the last few years, some therapeutic drugs have been developed for treating patients with trastuzumab-resistant HER2-positive BC that have more effective influences in the management of this condition. In this regard, the present study aimed at reviewing the mechanisms of trastuzumab resistance and the innovative therapies that have been investigated in trastuzumab-resistant HER2-positive BC subjects.

Four generations of EGFR TKIs associated with different pathogenic mutations in non-small cell lung carcinoma

Non-small cell lung carcinoma (NSCLC) is a malignant tumour with poor prognosis and high mortality. Platinum-based dual-agent chemotherapy is the main therapeutic regimen for this disease. In recent years, because of the introduction of molecular targeted therapy, various targeted therapeutic agents against epidermal growth factor receptor (EGFR) have been rapidly developed, which has become a research hotspot for NSCLC treatment. Here, we review the latest studies describing the features and types of EGFR pathogenic mutations, currently established EGFR-tyrosine kinase inhibitors from the first to fourth generation, including their action mechanisms, acquired resistance, and clinical applications, and potential challenges and perspectives that current researchers should address.

Hypoxia Attenuates Trastuzumab Uptake and Trastuzumab-Emtansine (T-DM1) Cytotoxicity through Redistribution of Phosphorylated Caveolin-1

The antibody-drug conjugate trastuzumab-emtansine (T-DM1) offers an additional treatment option for patients with HER2-amplified tumors. However, primary and acquired resistance is a limiting factor in a significant subset of patients. Hypoxia, a hallmark of cancer, regulates the trafficking of several receptor proteins with potential implications for tumor targeting. Here, we have investigated how hypoxic conditions may regulate T-DM1 treatment efficacy in breast cancer. The therapeutic effect of T-DM1 and its metabolites was evaluated in conjunction with biochemical, flow cytometry, and high-resolution imaging studies to elucidate the functional and mechanistic aspects of hypoxic regulation. HER2 and caveolin-1 expression was investigated in a well-annotated breast cancer cohort. We find that hypoxia fosters relative resistance to T-DM1 in HER2⁺ cells (SKBR3 and BT474). This effect was not a result of deregulated HER2 expression or resistance to emtansine and its metabolites. Instead, we show that hypoxia-induced translocation of caveolin-1 from cytoplasmic vesicles to the plasma membrane contributes to deficient trastuzumab internalization and T-DM1 chemosensitivity. Caveolin-1 depletion mimicked the hypoxic situation, indicating that vesicular caveolin-1 is indispensable for trastuzumab uptake and T-DM1 cytotoxicity. In vitro studies suggested that HER2 and caveolin-1 are not coregulated, which was supported by IHC analysis in patient tumors. We find that phosphorylation-deficient caveolin-1 inhibits trastuzumab internalization and T-DM1 cytotoxicity, suggesting a specific role for caveolin-1 phosphorylation in HER2 trafficking. IMPLICATIONS: Together, our data for the first time identify hypoxic regulation of caveolin-1 as a resistance mechanism to T-DM1 with potential implications for individualized treatment of breast cancer.

Isolation of strawberry anthocyanin-rich fractions and their mechanisms of action against murine breast cancer cell lines

The aim of this study was the evaluation of the effects of strawberry anthocyanin extract treatment on two in vitro models of murine breast cancer cell lines, in an attempt to detect a specific pathway (AMP-activated protein kinase or AMPK) through which strawberries exert their anticancer activity. The anticancer activity of purified anthocyanin extracts from an Alba cultivar on two murine cancer cell lines, N202/1A (with high levels of the HER2/neu oncogene) and N202/1E (with low levels of the HER2/neu oncogene), was evaluated after 48 and 72 h of treatment. The cell viability and apoptosis, intracellular ROS rates, and cell oxidative damage were assessed. Western blot assays were performed to analyze the expression of several proteins related to apoptosis, autophagy, metastasis, the oxidative status, mitochondrial functionality, and the AMPK pathway. This study demonstrated that the anthocyanin extract of Alba strawberry shows an antiproliferative effect on cancer cells, through the induction of apoptosis and oxidative stress, by stimulating different molecular pathways. This study is one of the first studies that have tried to deepen the understanding of a candidate pathway for the explanation of the effects of strawberry on cancer cells. A relationship between the AMPK pathway and the anticancer effects of strawberries was demonstrated.

Clinical development of CT-P6 in HER2 positive breast cancer

Introduction: CT-P6 (trastuzumab-pkrb, Herzuma) is a trastuzumab biosimilar approved for use in HER2 positive breast cancer and HER2 positive gastric cancer. CT-P6 has been shown to exhibit similar safety and efficacy profiles to its reference product, trastuzumab. Preclinical and clinical studies have been performed to prove equivalence between CT-P6 and the trastuzumab originator. Areas Covered: In this review, we examine the evidence comparing CT-P6 with its reference product, trastuzumab. Both monoclonal antibodies function to target cells that overexpress HER2 on the cell surface. Preclinical pharmacologic modeling of CT-P6 shows a similar mechanism of action to trastuzumab, similar pharmacologic properties and a phase I trial in healthy volunteers showed similar pharmacokinetics. A multicenter phase III randomized clinical trial in patients with early breast cancer showed equivalent safety and efficacy between CT-P6 and trastuzumab. One-year follow-up of patients showed identical rates of cardiotoxicity. Expert Opinion: Preclinical and clinical studies showed CT-P6 pharmacologic profile, safety and efficacy are equivalent to trastuzumab. As such, it is a safe and effective alternative for use in patients with HER2 positive breast cancer and gastric cancer. Its implementation into clinical practice can potentially increase patient access and help financially alleviate overburdened health-care systems.

Systematic analysis of the intersection of disease mutations with protein modifications

BACKGROUND

Perturbed posttranslational modification (PTM) landscapes commonly cause pathological phenotypes. The Cancer Genome Atlas (TCGA) project profiles thousands of tumors allowing the identification of spontaneous cancer-driving mutations, while Uniprot and dbSNP manage genetic disease-associated variants in the human population. PhosphoSitePlus (PSP) is the most comprehensive resource for studying experimentally observed PTM sites and the only repository with daily updates on functional annotations for many of these sites. To elucidate altered PTM landscapes on a large scale, we integrated disease-associated mutations from TCGA, Uniprot, and dbSNP with PTM sites from PhosphoSitePlus. We characterized each dataset individually, compared somatic with germline mutations, and analyzed PTM sites intersecting directly with disease variants. To assess the impact of mutations in the flanking regions of phosphosites, we developed DeltaScansite, a pipeline that compares Scansite predictions on wild type versus mutated sequences. Disease mutations are also visualized in PhosphoSitePlus.

RESULTS

Characterization of somatic variants revealed oncoprotein-like mutation profiles of U2AF1, PGM5, and several other proteins, showing alteration patterns similar to germline mutations. The union of all datasets uncovered previously unknown losses and gains of PTM events in diseases unevenly distributed across different PTM types. Focusing on phosphorylation, our DeltaScansite workflow predicted perturbed signaling networks consistent with calculations by the machine learning method MIMP.

CONCLUSIONS

We discovered oncoprotein-like profiles in TCGA and mutations that presumably modify protein function by impacting PTM sites directly or by rewiring upstream regulation. The resulting datasets are enriched with functional annotations from PhosphoSitePlus and present a unique resource for potential biomarkers or disease drivers.

Detection of ERBB2 (HER2) Gene Amplification Events in Cell-Free DNA and Response to Anti-HER2 Agents in a Large Asian Cancer Patient Cohort

Background: HER2 antagonists have marked activity and are approved for the treatment of HER2 overexpressing breast and gastric cancers. Recent studies have shown that ERBB2 (HER2) gene amplification and overexpression may also be actionable in other tumor types. Inter- and intratumoral heterogeneity in HER2 status, however, poses a significant challenge in identifying patients that may benefit from HER2-targeted therapies. ERBB2 amplification as identified by circulating cell-free DNA (cfDNA), which circumvents tissue heterogeneity issues, is emerging as a robust biomarker predictive of response to anti-HER2 agents. Here, the prevalence and genomic landscape of ERBB2 alterations detectable by next-generation sequencing (NGS) of cfDNA was evaluated in a large cohort of Asian patients with advanced solid tumors. Methods: Results were queried for consecutive patients (n = 469) tested by a comprehensive 70/73-gene cfDNA NGS assay (Guardant360®) between November 2015 and June 2018. Patients with ERBB2 gene alterations including copy number amplifications (CNAs), single nucleotide variants (SNVs), and insertion-deletions (indels) were identified. Results: ERBB2 alterations were detected in 52 patients (11.1%); ERBB2 SNVs, CNAs, and indels were found in 27 (5.8%), 27 (5.8%), and 10 (2.1%) patients, respectively. ERBB2 amplification was most frequently identified in gastric (21.4%; 6/28), colorectal (11.1%; 5/45), lung (3.9%; 9/231), and breast (3.2%; 1/31) cancer patients. ERBB2 amplification was often mutually exclusive with other oncogenic alterations in gastric (83.3%; 5/6) and colorectal (60%; 3/5) cancer patients. ERBB2 copy number gains were also highest in gastric and colorectal cancers (median 4.8 and 6.6, respectively). We further report two cases of advanced gastric cancer patients, one treatment naïve, and the other having failed four lines of therapy, whose ERBB2 CNAs were identified by cfDNA and derived clinical benefit from HER2-based therapies. Conclusion: Our data indicate that ERBB2 amplification is a common event in solid tumors among Asian cancer patients. High ERBB2 incidence and copy number gains were observed in gastric and colorectal cancer patients, often in the absence of other oncogenic mutations, underscoring its likely role as the driver alteration in those settings. Finally, we show the potential of comprehensive cfDNA testing in identifying patients who are most likely to benefit from HER2-targeted therapies.

Exploration of the Structure and Recognition of a G-quadruplex in the her2 Proto-oncogene Promoter and Its Transcriptional Regulation

G-quadruplexes in oncogene promoters provide putative targets for transcriptional regulation. The structure of a putative G-quadruplex sequence (S1: GGAGAAGGAGGAGGTGGAGGAGGAGGG) in potassium solution in the her2 promoter has been resolved mainly through nuclear magnetic resonance (NMR) spectroscopy. By application of various NMR spectra, we proved the formation of a four-layer G-quadruplex composing of two G-tetrads and two G/A-mixed planes with a four-residues loop (A3-G4-A5-A6). Further evidence from a luciferase reporter assay, Q-RT-PCR and Western blotting indicates that S1 G-quadruplex formation can repress her2 promoter activity, and a selected G-quadruplex ligand cβ can enhance the repression by down regulating her2 transcription and expression. These findings provide a G-quadruplex target and perspective implications in her2 transcriptional regulation.

The Case for Proteomics and Phospho-Proteomics in Personalized Cancer Medicine

The concept of personalized medicine is predominantly been pursued through genomic and transcriptomic technologies, leading to the identification of multiple mutations in a large variety of cancers. However, it has proven challenging to distinguish driver and passenger mutations and to deal with tumor heterogeneity and resistant clonal populations. More generally, these heterogeneous mutation patterns do not in themselves predict the tumor phenotype. Analysis of the expressed proteins in a tumor and their modification states reveals if and how these mutations are translated to the functional level. It is already known that proteomic changes including posttranslational modifications are crucial drivers of oncogenesis, but proteomics technology has only recently become comparable in depth and accuracy to RNAseq. These advances also allow the rapid and highly sensitive analysis of formalin-fixed and paraffin-embedded biobank tissues, on both the proteome and phosphoproteome levels. In this perspective, pioneering mass spectrometry-based proteomic studies are highlighted that pave the way toward clinical implementation. It is argued that proteomics and phosphoproteomics could provide the missing link to make omics analysis actionable in the clinic.

Internal enhancement of DNA damage by a novel bispecific antibody-drug conjugate-like therapeutics via blockage of mTOR and PD-L1 signal pathways in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a refractory malignant tumor with poor prognosis, limited chemotherapeutic efficacy, and only about 5% of 5-year survival rate. We generated a dual-targeting ligand-based lidamycin (DTLL) to investigate its efficacy against pancreatic cancer after preparing its precursor, DTLP. DTLP was shown specifically binding to EGFR and HER2 on cell surface, followed by endocytosis into cytoplasm of pancreatic cancer cells. DTLL significantly promoted apoptosis and cell cycle arrest at G2/M stages and inhibited cell proliferation. Pancreatic tumors of either MIA-paca-2 cell line-derived (CDX) or patient-derived xenograft (PDX) mouse models were significantly regressed in response to DTLL. It suggested that DTLL might be a highly potent bispecific antibody-drug conjugate (ADC)-like agent for pancreatic cancer therapy. LDM is known to function as an antitumor cytotoxic agent by its induction of DNA damage in cancer cells, therefore, DTLL, as its derivative, also showed similar cytotoxicity. However, we found that DTLL might reverse the AKT/mTOR feedback activation induced by LDM at the first time. The results from both in vitro and in vivo experiments suggested that DTLL enhanced DNA damage via EGFR/HER2-dependent blockage of PI3K/AKT/mTOR and PD-L1 signaling pathways in cancer cells, leading to the inhibition of cell proliferation and immunosurveillance escape from pancreatic tumor. Our studies on DTLL functional characterization revealed its novel mechanisms on internal enhancement of DNA damage and implied that DTLL might provide a promising targeted therapeutic strategy for pancreatic cancer.

Caveolin-1 mediates cellular distribution of HER2 and affects trastuzumab binding and therapeutic efficacy

Human epidermal growth factor receptor 2 (HER2) gene amplification and/or protein overexpression in tumors is a prerequisite for initiation of trastuzumab therapy. Although HER2 is a cell membrane receptor, differential rates of endocytosis and recycling engender a dynamic surface pool of HER2. Since trastuzumab must bind to the extracellular domain of HER2, a depressed HER2 surface pool hinders binding. Using in vivo biological models and cultures of fresh human tumors, we find that the caveolin-1 (CAV1) protein is involved in HER2 cell membrane dynamics within the context of receptor endocytosis. The translational significance of this finding is highlighted by our observation that temporal CAV1 depletion with lovastatin increases HER2 half-life and availability at the cell membrane resulting in improved trastuzumab binding and therapy against HER2-positive tumors. These data show the important role that CAV1 plays in the effectiveness of trastuzumab to target HER2-positive tumors.

Trastuzumab binding to tumor cells depends on the availability of HER2 at the cell membrane. Here the authors show that caveolin-1 (CAV1) regulates HER2 density at the cell membranes and that CAV1 gene knockdown or protein depletion via the cholesterol modulator lovastatin, increases trastuzumab binding and anti-tumor activity.

Receptor Tyrosine Kinase-Targeted Cancer Therapy

In the past two decades, several molecular targeted inhibitors have been developed and evaluated clinically to improve the survival of patients with cancer. Molecular targeted inhibitors inhibit the activities of pathogenic tyrosine kinases. Particularly, aberrant receptor tyrosine kinase (RTK) activation is a potential therapeutic target. An increased understanding of genetics, cellular biology and structural biology has led to the development of numerous important therapeutics. Pathogenic RTK mutations, deletions, translocations and amplification/over-expressions have been identified and are currently being examined for their roles in cancers. Therapies targeting RTKs are categorized as small-molecule inhibitors and monoclonal antibodies. Studies are underway to explore abnormalities in 20 types of RTK subfamilies in patients with cancer or other diseases. In this review, we describe representative RTKs important for developing cancer therapeutics and predicting or evaluated resistance mechanisms.

An mTOR Signaling Modulator Suppressed Heterotopic Ossification of Fibrodysplasia Ossificans Progressiva

Fibrodysplasia ossificans progressiva (FOP) is a rare and intractable disorder characterized by extraskeletal bone formation through endochondral ossification. FOP patients harbor gain-of-function mutations in ACVR1 (FOP-ACVR1), a type I receptor for bone morphogenetic proteins. Despite numerous studies, no drugs have been approved for FOP. Here, we developed a high-throughput screening (HTS) system focused on the constitutive activation of FOP-ACVR1 by utilizing a chondrogenic ATDC5 cell line that stably expresses FOP-ACVR1. After HTS of 5,000 small-molecule compounds, we identified two hit compounds that are effective at suppressing the enhanced chondrogenesis of FOP patient-derived induced pluripotent stem cells (FOP-iPSCs) and suppressed the heterotopic ossification (HO) of multiple model mice, including FOP-ACVR1 transgenic mice and HO model mice utilizing FOP-iPSCs. Furthermore, we revealed that one of the hit compounds is an mTOR signaling modulator that indirectly inhibits mTOR signaling. Our results demonstrate that these hit compounds could contribute to future drug repositioning and the mechanistic analysis of mTOR signaling.

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Established a screening system for fibrodysplasia ossificans progressiva (FOP)

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Identified two hit compounds that are effective in multiple FOP model mice

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An mTOR signaling modulator opens the door to a therapeutic strategy

Targeting tumor cells with antibodies enhances anti-tumor immunity

Tumor-targeting antibodies were initially defined as a group of therapeutic monoclonal antibodies (mAb) that recognize tumor-specific membrane proteins, block cell signaling, and induce tumor-killing through Fc-driven innate immune responses. However, in the past decade, ample evidence has shown that tumor-targeting mAb (TTmAb) eradicates tumor cells via activation of cytotoxic T cells (CTLs). In this review, we specifically focus on how TTmAbs induce adaptive anti-tumor immunity and its potential in combination therapy with immune cytokines, checkpoint blockade, radiation, and enzyme-targeted small molecule drugs. Exploring the mechanisms of these preclinical studies and retrospective clinical data will significantly benefit the development of highly efficient and specific TTmAb-oriented anti-tumor remedies.

The Importance of the Right Framework: Mitogen-Activated Protein Kinase Pathway and the Scaffolding Protein PTPIP51

The protein tyrosine phosphatase interacting protein 51 (PTPIP51) regulates and interconnects signaling pathways, such as the mitogen-activated protein kinase (MAPK) pathway and an abundance of different others, e.g., Akt signaling, NF-κB signaling, and the communication between different cell organelles. PTPIP51 acts as a scaffold protein for signaling proteins, e.g., Raf-1, epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (Her2), as well as for other scaffold proteins, e.g., 14-3-3 proteins. These interactions are governed by the phosphorylation of serine and tyrosine residues of PTPIP51. The phosphorylation status is finely tuned by receptor tyrosine kinases (EGFR, Her2), non-receptor tyrosine kinases (c-Src) and the phosphatase protein tyrosine phosphatase 1B (PTP1B). This review addresses various diseases which display at least one alteration in these enzymes regulating PTPIP51-interactions. The objective of this review is to summarize the knowledge of the MAPK-related interactome of PTPIP51 for several tumor entities and metabolic disorders.

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.

Identification of key genes and associated pathways in KIT/PDGFRA wild‑type gastrointestinal stromal tumors through bioinformatics analysis

Gastrointestinal stromal tumors (GISTs) are the most common type of mesenchymal tumor in the gastrointestinal tract. The present study aimed to identify the potential candidate biomarkers that may be involved in the pathogenesis and progression of v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog (KIT)/platelet-derived growth factor receptor α (PDGFRA) wild-type GISTs. A joint bioinformatics analysis was performed to identify the differentially expressed genes (DEGs) in wild-type GIST samples compared with KIT/PDGFRA mutant GIST samples. Gene Ontology function and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of DEGs was conducted using Database for Annotation, Visualization and Integrated Discovery and KEGG Orthology-Based Annotation System (KOBAS) online tools, respectively. Protein-protein interaction (PPI) networks of the DEGs were constructed using Search Tool for the Retrieval of Interacting Genes online tool and Cytoscape, and divided into sub-networks using the Molecular Complex Detection (MCODE) plug-in. Furthermore, enrichment analysis of DEGs in the modules was analyzed with KOBAS. In total, 546 DEGs were identified, including 238 upregulated genes primarily enriched in ‘cell adhesion’, ‘biological adhesion’, ‘cell-cell signaling’, ‘PI3K-Akt signaling pathway’ and ‘ECM-receptor interaction’, while the 308 downregulated genes were predominantly involved in ‘inflammatory response’, ‘sterol metabolic process’ and ‘fatty acid metabolic process’, ‘small GTPase mediated signal transduction’, ‘cAMP signaling pathway’ and ‘proteoglycans in cancer’. A total of 25 hub genes were obtained and four modules were mined from the PPI network, and sub-networks also revealed these genes were primarily involved in significant pathways, including ‘PI3K-Akt signaling pathway’, ‘proteoglycans in cancer’, ‘pathways in cancer’, ‘Rap1 signaling pathway’, ‘ECM-receptor interaction’, ‘phospholipase D signaling pathway’, ‘ras signaling pathway’ and ‘cGMP-PKG signaling pathway’. These results suggested that several key hub DEGs may serve as potential candidate biomarkers for wild-type GISTs, including phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit γ, insulin like growth factor 1 receptor, hepatocyte growth factor, thrombospondin 1, Erb-B2 receptor tyrosine kinase 2 and matrix metallopeptidase 2. However, further experiments are required to confirm these results.

Effectiveness of EGFR/HER2-targeted drugs is influenced by the downstream interaction shifts of PTPIP51 in HER2-amplified breast cancer cells

Breast cancer is the most common female cancerous disease and the second most cause of cancer death in women. About 20–30% of these tumors exhibit an amplification of the HER2/ErbB2 receptor, which is coupled to a more aggressive and invasive growth of the cancer cells. Recently developed tyrosine kinase inhibitors and therapeutic antibodies targeting the HER2 receptor improved the overall survival time compared with sole radio- and chemotherapy. Upcoming resistances against the HER2-targeted therapy make a better understanding of the receptor associated downstream pathways an absolute need. In earlier studies, we showed the involvement of Protein Tyrosine Phosphatase Interacting Protein 51 (PTPIP51) in the mitogen-activated protein kinase (MAPK) pathway. The MAPK pathway is one of the most frequently overactivated pathways in HER2-amplified breast cancer cells. This study is aimed to elucidate the effects of four different TKIs on the interactome of PTPIP51, namely with the receptors EGFR and HER2, 14-3-3/Raf1 (MAPK pathway), its regulating enzymes, and the mitochondria-associated interaction partners in HER2 breast cancer cell lines (SK-BR3 and BT474) by using the Duolink proximity ligation assay, immunoblotting and knockdown of PTPIP51. Inhibition of both EGFR and HER2/ErbB2R shifted PTPIP51 into the MAPK pathway, but left the mitochondria-associated interactome of PTPIP51 unattended. Exclusively inhibiting HER2/ErbB2 by Mubritinib did not affect the interaction of PTPIP51 with the MAPK signaling. Selective inhibition of HER2 induced great alterations of mitochondria-associated interactions of PTPIP51, which ultimately led to the most-effective reduction of cell viability of SK-BR3 cells of all tested TKIs. The results clearly reveal the importance of knowing the exact mechanisms of the inhibitors affecting receptor tyrosine kinases in order to develop more efficient anti-HER2-targeted therapies.

An immunoconjugated up-conversion nanocomplex for selective imaging and photodynamic therapy against HER2-positive breast cancer

Photodynamic therapy represents a very attractive therapeutic tool considered to be effective, minimally invasive and minimally toxic. However, conventional photodynamic therapy actually has two main constraints: the limited penetration depth of visible light needed for its activation, and the lack of selectivity. Considering this, this work reports the synthesis and evaluation of a novel nanoconjugate for imaging and selective photodynamic therapy against HER2-positive breast cancer, a particularly aggressive form of the disease. It was demonstrated that upon 975 nm near infrared light exposure, the red emission of the NaYF4:Yb,Er up-conversion nanoparticles (UCNPs) can be used for optical imaging and simultaneously represent the source for the excitation of a covalently bound zinc tetracarboxyphenoxy phthalocyanine (ZnPc), a photosensitizer that in turn transfers energy to ground state molecular oxygen to produce cytotoxic singlet oxygen. The specificity of our nanoconjugates was achieved by immunoconjugation with Trastuzumab (Tras), a specific monoclonal antibody for selective detection and treatment of HER2-overexpressing malignant breast cancer cells. Selective tracking of SKBR-3 HER2-positive cells was verified by confocal microscopy analysis, and the photodynamic therapy effect was considerably improved when Trastuzumab was incorporated into the nanoconjugate, the UCNPs-ZnPc-Tras being practically inert in the absence of infrared light exposure but reducing the HER2-positive cell viability up to 21% upon 5 min of the irradiation. This theranostic nanoconjugate represents a valuable alternative for HER2-positive breast cancer imaging and selective photodynamic therapy.

Synthesis and evaluation of 2,9-disubstituted 8-phenylthio/phenylsulfinyl-9H-purine as new EGFR inhibitors

In present study, we described the synthesis and biological evaluation of a new class of EGFR inhibitors containing 2,9-disubstituted 8-phenylthio/phenylsulfinyl-9H-purine scaffold. Thirty-one compounds were synthesized. Among them, compound C9 displayed the IC₅₀ of 29.4 nM against HCC827 cell line and 1.9 nM against EGFR^L858R. Compound C12 showed moderate inhibitory activity against EGFR^{L858R/T790M/C797S} (IC₅₀ = 114 nM). Western bolt assay suggested that compound C9 significantly inhibited EGFR phosphorylation. In vivo test, compound C9 remarkably exhibited inhibitory effect on tumor growth at 5.0 mg/kg by oral administration in established nude mouse HCC827 xenograft model. These results indicate that the 2,9-disubstituted 8-phenylsulfinyl/phenylsulfinyl-9H-purine derivatives can act as potent EGFR(L858R) inhibitors and effective anticancer agents. Additionally, optimization of compound C12 may result in discovering the fourth-generation EGFR-TKIs.

JWA loss promotes cell migration and cytoskeletal rearrangement by affecting HER2 expression and identifies a high-risk subgroup of HER2-positive gastric carcinoma patients

Background and Aims

JWA, a microtubule-associated protein (MAP) involved in apoptosis, has been identified as a suppressor of metastasis, and it affects cell migration in melanoma and its downregulation in tumor is an idependent negative prognostic factor in resectable gastric cancer. HER2 overexpression has been observed in gastric cancer (GC) cells and implicated in the metastatic phenotype. However, the biological role of JWA in migration and its clinical value in HER2-positive GC remain elusive.

Results

JWA suppresses EGF-induced cell migration and actin cytoskeletal rearrangement by abrogating HER2 expression and downstream PI3K/AKT signaling in HER2-overexpressing GC cell lines. The modulation of HER2 by JWA is dependent on ERK activation and consequent PEA3 upregulation and activation. Reduced JWA expression is associated with high HER2 expression and with poor survival in patients with AGC, whereas HER2 expression alone is not associated with survival. However, concomitant low JWA and high HER2 expression is associated with unfavorable outcomes. Additionally, when patients were stratified by JWA expression, those with higher HER2 expression in the low JWA expression subgroup exhibited worse survival.

Methods

The impact of JWA on the EGF-induced migration of HER2-positive GC cells was studied using transwell assays and G-LISA assays. Western blotting, real-time PCR, electrophoretic mobility shift assays and luciferase assays were utilized to investigate the mechanisms by which JWA affects HER2. The association of JWA with HER2 and its clinical value were further analyzed by IHC in 128 pairs of advanced gastric cancer (AGC) and adjacent normal tissue samples.

Conclusions

This study characterizes a novel mechanism for regulating cell motility in HER2-overexpressing GC cells involving JWA-mediated MEK/ERK/PEA3 signaling activation and HER2 downregulation. Furthermore, JWA may be a useful prognostic indicator for advanced GC and may help stratify HER2-positive patient subgroups to better identify unfavorable outcomes.

Exploiting polypharmacology for improving therapeutic outcome of kinase inhibitors (KIs): An update of recent medicinal chemistry efforts

Polypharmacology has been increasingly advocated for the therapeutic intervention in complex pathological conditions, exemplified by cancer. Although kinase inhibitors (KIs) have revolutionized the treatment for certain types of malignancies, some major medical needs remain unmet due to the relentless advance of drug resistance and insufficient efficacy of mono-target KIs. Hence, "multiple targets, multi-dimensional activities" represents an emerging paradigm for innovative anti-cancer drug discovery. Over recent years, considerable leaps have been made in pursuit of kinase-centric polypharmacological anti-cancer therapeutics, providing avenues to tackling the limitation of mono-target KIs. In the review, we summarize the clinically important mechanisms inducing KI resistance and depict a landscape of recent medicinal chemistry efforts on exploring kinase-centric polypharmacological anti-cancer agents that targeting multiple cancer-related processes. In parallel, some inevitable challenges are emphasized for the sake of more accurate and efficient drug discovery in the field.

Interplay between Natural Killer Cells and Anti-HER2 Antibodies: Perspectives for Breast Cancer Immunotherapy

Overexpression of the human epidermal growth factor receptor 2 (HER2) defines a subgroup of breast tumors with aggressive behavior. The addition of HER2-targeted antibodies (i.e., trastuzumab, pertuzumab) to chemotherapy significantly improves relapse-free and overall survival in patients with early-stage and advanced disease. Nonetheless, considerable proportions of patients develop resistance to treatment, highlighting the need for additional and co-adjuvant therapeutic strategies. HER2-specific antibodies can trigger natural killer (NK) cell-mediated antibody-dependent cellular cytotoxicity and indirectly enhance the development of tumor-specific T cell immunity; both mechanisms contributing to their antitumor efficacy in preclinical models. Antibody-dependent NK cell activation results in the release of cytotoxic granules as well as the secretion of pro-inflammatory cytokines (i.e., IFNγ and TNFα) and chemokines. Hence, NK cell tumor suppressive functions include direct cytolytic killing of tumor cells as well as the regulation of subsequent antitumor adaptive immunity. Albeit tumors with gene expression signatures associated to the presence of cytotoxic lymphocyte infiltrates benefit from trastuzumab-based treatment, NK cell-related biomarkers of response/resistance to HER2-specific therapeutic antibodies in breast cancer patients remain elusive. Several variables, including (i) the configuration of the patient NK cell repertoire; (ii) tumor molecular features (i.e., estrogen receptor expression); (iii) concomitant therapeutic regimens (i.e., chemotherapeutic agents, tyrosine kinase inhibitors); and (iv) evasion mechanisms developed by progressive breast tumors, have been shown to quantitatively and qualitatively influence antibody-triggered NK cell responses. In this review, we discuss possible interventions for restoring/enhancing the therapeutic activity of HER2 therapeutic antibodies by harnessing NK cell antitumor potential through combinatorial approaches, including immune checkpoint blocking/stimulatory antibodies, cytokines and toll-like receptor agonists.