The Development of HKI‐272 and Related Compounds for the Treatment of Cancer

Molecular mechanisms of HER2-targeted therapy and strategies to overcome the drug resistance in colorectal cancer

HER2 amplification is one of the mechanisms that induce drug resistance to anti-EGFR therapy in colorectal cancer. In recent years, data from several randomized clinical trials show that anti-HER2 therapies improved the prognosis of patients with HER2-positive colorectal cancer. These results indicate that HER2 is a promising therapeutic target in advanced colorectal cancer. Despite the anti-HER2 therapies including monoclonal antibodies, tyrosine kinase inhibitors, and antibody-drug conjugates improving the outcomes, less than 30 % of the patients achieve objective response and eventually have drug resistance. It is necessary to explore the primary and secondary mechanisms for the resistance to anti-HER2 therapies, which will pave the way to overcome the drug resistance. Several studies have reported the potential mechanisms for the resistance to anti-HER2 therapies. In this review, we present a comprehensive overview of the recent advances in clinical research, mechanisms of treatment resistance, and strategies for reversing resistance in HER2-positive colorectal cancer patients.

Increasing the Throughput and Reproducibility of Activity-Based Proteome Profiling Studies with Hyperplexing and Intelligent Data Acquisition

Intelligent data acquisition (IDA) strategies, such as a real-time database search (RTS), have improved the depth of proteome coverage for experiments that utilize isobaric labels and gas phase purification techniques (i.e., SPS-MS3). In this work, we introduce inSeqAPI, an instrument application programing interface (iAPI) program that enables construction of novel data acquisition algorithms. First, we analyze biotinylated cysteine peptides from ABPP experiments to demonstrate that a real-time search method within inSeqAPI performs similarly to an equivalent vendor method. Then, we describe PairQuant, a method within inSeqAPI designed for the hyperplexing approach that utilizes protein-level isotopic labeling and peptide-level TMT labeling. PairQuant allows for TMT analysis of 36 conditions in a single sample and achieves ∼98% coverage of both peptide pair partners in a hyperplexed experiment as well as a 40% improvement in the number of quantified cysteine sites compared with non-RTS acquisition. We applied this method in the ABPP study of ligandable cysteine sites in the nucleus leading to an identification of additional druggable sites on protein- and DNA-interaction domains of transcription regulators and on nuclear ubiquitin ligases.

Targeting oncogenic kinases: Insights on FDA approved tyrosine kinase inhibitors

Protein kinases play pivotal roles in various biological functions, influencing cell differentiation, promoting survival, and regulating the cell cycle. The disruption of protein kinase activity is intricately linked to pathways in tumor development. This manuscript explores the transformative impact of protein kinase inhibitors on cancer therapy, particularly their efficacy in cases driven by targeted mutations. Focusing on key tyrosine kinase inhibitors (TKIs) like Bcr-Abl, Epidermal Growth Factor Receptor (EGFR), and Vascular Endothelial Growth Factor Receptor (VEGFR), it targets critical kinase families in cancer progression. Clinical trial details of these TKIs offer insights into their therapeutic potentials. Learning from FDA-approved kinase inhibitors, the review dissects trends in kinase drug development since imatinib's paradigm-shifting approval in 2001. TKIs have evolved into pivotal drugs, extending beyond oncology. Ongoing clinical trials explore novel kinase targets, revealing the vast potential within the human kinome. The manuscript provides a detailed analysis of advancements until 2022, discussing the roles of specific oncogenic protein kinases in cancer development and carcinogenesis. Our exploration on PubMed for relevant and significant TKIs undergoing pre-FDA approval phase III clinical trials enriches the discussion with valuable findings. While kinase inhibitors exhibit lower toxicity than traditional chemotherapy in cancer treatment, challenges like resistance and side effects emphasize the necessity of understanding resistance mechanisms, prompting the development of novel inhibitors like osimertinib targeting specific mutant proteins. The review advocates thorough research on effective combination therapies, highlighting the future development of more selective RTKIs to optimize patient-specific cancer treatment and reduce adverse events.

Engineering cell-free systems by chemoproteomic-assisted phenotypic screening

Phenotypic screening is a valuable tool to both understand and engineer complex biological systems. We demonstrate the functionality of this approach in the development of cell-free protein synthesis (CFPS) technology. Phenotypic screening identified numerous compounds that enhanced protein production in yeast lysate CFPS reactions. Notably, many of these were competitive ATP kinase inhibitors, with the exploitation of their inherent substrate promiscuity redirecting ATP flux towards heterologous protein expression. Chemoproteomic-guided strain engineering partially phenocopied drug effects, with a 30% increase in protein yield observed upon deletion of the ATP-consuming SSA1 component of the HSP70 chaperone. Moreover, drug-mediated metabolic rewiring coupled with template optimization generated the highest protein yields in yeast CFPS to date using a hitherto less efficient, but more cost-effective glucose energy regeneration system. Our approach highlights the utility of target-agnostic phenotypic screening and target identification to deconvolute cell-lysate complexity, adding to the expanding repertoire of strategies for improving CFPS.

Recent advances in multitarget-directed ligands via in silico drug discovery

To combat multifactorial refractory diseases, such as cancer, cardiovascular, and neurodegenerative diseases, multitarget drugs have become an emerging area of research aimed at 'synthetic lethality' (SL) relationships associated with drug-resistance mechanisms. In this review, we discuss the in silico design of dual and triple-targeted ligands, strategies by which specific 'warhead' groups are incorporated into a parent compound or scaffold with primary inhibitory activity against one target to develop one small molecule that inhibits two or three molecular targets in an effort to increase potency against multifactorial diseases. We also discuss the analytical exploration of structure-activity relationships (SARs), physicochemical properties, polypharmacology, scaffold feature extraction of US Food and Drug Administration (FDA)-approved multikinase inhibitors (MKIs), and updates regarding the clinical status of dual-targeted chemotypes.

Management and Mechanisms of Diarrhea Induced by Tyrosine Kinase Inhibitors in Human Epidermal Growth Factor Receptor-2-Positive Breast Cancer

Breast cancer has the highest incidence among female malignancies, significantly impacting women's health. Recently, numerous HER2-targeted therapies have achieved excellent clinical outcomes. Currently, anti-HER2 drugs are divided into three main categories: monoclonal antibodies, small-molecule tyrosine kinase inhibitors, and antibody-coupled drugs (ADCs). The main toxic side effects of small molecule TKI-based therapy are diarrhea, hand-foot syndrome, rash, nausea, and vomiting. Diarrhea is a potential predictor of tumor response, affecting up to 95% of cancer patients treated with TKIs. Severe gastrointestinal toxicity can result in the need for dose reductions and treatment interruptions. This not only compromises the efficacy of TKIs but also deteriorates human nutrition and quality of life. The majority of individuals develop diarrhea within 7 days of starting treatment, with approximately 30% developing grade 3 or higher diarrhea within 2-3 days of starting treatment. The severity of diarrhea typically correlates with the dosage of most TKIs. Current prevention and management strategies are primarily empirical, focusing on symptom alleviation rather than addressing the toxicological mechanisms underlying TKI-induced diarrhea. Consequently, anti-diarrheal drugs are often less effective in managing this condition in cancer patients receiving TKIs. Moreover, our understanding of the toxicological mechanisms responsible for such diarrhea remains limited, underscoring the urgent need to identify these mechanisms in order to develop effective anti-diarrheal medications tailored to this specific context. This review aims to elucidate management approaches and mechanisms for diarrhea induced by TKIs during HER2-positive breast cance.

Targeted Inhibitors of EGFR: Structure, Biology, Biomarkers, and Clinical Applications

Members of the EGFR family of tyrosine kinase receptors are major regulators of cellular proliferation, differentiation, and survival. In humans, abnormal activation of EGFR is associated with the development and progression of many cancer types, which makes it an attractive target for molecular-guided therapy. Two classes of EGFR-targeted cancer therapeutics include monoclonal antibodies (mAbs), which bind to the extracellular domain of EGFR, and tyrosine kinase inhibitors (TKIs), which mostly target the intracellular part of EGFR and inhibit its activity in molecular signaling. While EGFR-specific mAbs and three generations of TKIs have demonstrated clinical efficacy in various settings, molecular evolution of tumors leads to apparent and sometimes inevitable resistance to current therapeutics, which highlights the need for deeper research in this field. Here, we tried to provide a comprehensive and systematic overview of the rationale, molecular mechanisms, and clinical significance of the current EGFR-targeting drugs, highlighting potential candidate molecules in development. We summarized the underlying mechanisms of resistance and available personalized predictive approaches that may lead to improved efficacy of EGFR-targeted therapies. We also discuss recent developments and the use of specific therapeutic strategies, such as multi-targeting agents and combination therapies, for overcoming cancer resistance to EGFR-specific drugs.

A review of FDA approved drugs and their formulations for the treatment of breast cancer

Breast cancer is one of the most diagnosed solid cancers globally. Extensive research has been going on for decades to meet the challenges of treating solid tumors with selective compounds. This article aims to summarize the therapeutic agents which are either being used or are currently under approval for use in the treatment or mitigation of breast cancer by the US FDA, to date. A structured search of bibliographic databases for previously published peer-reviewed research papers on registered molecules was explored and data was sorted in terms of various categories of drugs used in first line/adjuvant therapy for different stages of breast cancer. We included more than 300 peer-reviewed papers, including both research and reviews articles, in order to provide readers an useful comprehensive information. A list of 39 drugs are discussed along with their current status, dose protocols, mechanism of action, pharmacokinetics, possible side effects, and marketed formulations. Another interesting aspect of the article included focusing on novel formulations of these drugs which are currently in clinical trials or in the process of approval. This exhaustive review thus shall be a one-stop solution for researchers who are working in the areas of formulation development for these drugs.

Detailed curriculum vitae of HER2-targeted therapy

With the booming development of precision medicine, molecular targeted therapy has been widely used in clinical oncology treatment due to a smaller number of side effects and its superior accuracy compared to that of traditional strategies. Among them, human epidermal growth factor receptor 2 (HER2)-targeted therapy has attracted considerable attention and has been used in the clinical treatment of breast and gastric cancer. Despite excellent clinical effects, HER2-targeted therapy remains in its infancy due to its resulting inherent and acquired resistance. Here, a comprehensive overview of HER2 in numerous cancers is presented, including its biological role, involved signaling pathways, and the status of HER2-targeted therapy.

One-Pot Synthesis of 1-Thia-4-azaspiro[4.4/5]alkan-3-ones via Schiff Base: Design, Synthesis, and Apoptotic Antiproliferative Properties of Dual EGFR/BRAFV600E Inhibitors

In this investigation, novel 4-((quinolin-4-yl)amino)-thia-azaspiro[4.4/5]alkan-3-ones were synthesized via interactions between 4-(2-cyclodenehydrazinyl)quinolin-2(1H)-one and thioglycolic acid catalyzed by thioglycolic acid. We prepared a new family of spiro-thiazolidinone derivatives in a one-step reaction with excellent yields (67-79%). The various NMR, mass spectra, and elemental analyses verified the structures of all the newly obtained compounds. The antiproliferative effects of 6a-e, 7a, and 7b against four cancer cells were investigated. The most effective antiproliferative compounds were 6b, 6e, and 7b. Compounds 6b and 7b inhibited EGFR with IC₅₀ values of 84 and 78 nM, respectively. Additionally, 6b and 7b were the most effective inhibitors of BRAF^V600E (IC₅₀ = 108 and 96 nM, respectively) and cancer cell proliferation (GI₅₀ = 35 and 32 nM against four cancer cell lines, respectively). Finally, the apoptosis assay results revealed that compounds 6b and 7b had dual EGFR/BRAF^V600E inhibitory properties and showed promising antiproliferative and apoptotic activity.

Design, Synthesis, Antibacterial Evaluation, Three-Dimensional Quantitative Structure-Activity Relationship, and Mechanism of Novel Quinazolinone Derivatives

Plant bacterial illnesses are common and cause dramatic damage to agricultural goods all over the world, yet there are few efficient bactericides to alleviate them at present. To discover novel antibacterial agents, two series of quinazolinone derivatives with novel structures were synthesized and their bioactivity against plant bacteria was tested. Combining CoMFA model search and the antibacterial bioactivity assay, D32 was identified as a potent antibacterial inhibitor against Xanthomonas oryzae pv. Oryzae (Xoo), with an EC₅₀ value of 1.5 μg/mL, much better in inhibitory capacity compared to bismerthiazol (BT) and thiodiazole copper (TC) (31.9 and 74.2 μg/mL). The activities of compound D32 against rice bacterial leaf blight in vivo were 46.7% (protective activities) and 43.9% (curative activities), better than commercial drug thiodiazole copper (29.3% protective activities and 30.6% curative activities). Flow cytometry, proteomics, reactive oxygen species, and key defense enzymes were used to further investigate the relevant mechanisms of action of D32. The identification of D32 as an antibacterial inhibitor and revelation of its recognition mechanism not only open the possibility of developing new therapeutic strategies for treatment of Xoo but also provide clues for elucidation of the acting mechanism of quinazolinone derivative D32, which is a possible clinical candidate worth in-depth study.

Targeted therapy for breast cancer: An overview of drug classes and outcomes

The last 25 years have seen significant growth in new therapeutic options for breast cancer, termed targeted therapies based on their ability to block specific pathways known to drive breast tumor growth and survival. Introduction of these drugs has been made possible through advances in the understanding of breast cancer biology. While the promise of targeted therapy for breast cancer has been clear for some time, the experience of the clinical use of multiple drugs and drug classes allows us to now present a summary and perspective as to the success and impact of this endeavor. Here we will review breast cancer targeted therapeutics in clinical use. We will provide the rationale for their indications and summarize clinical data in patients with different breast cancer subtypes, their impact on breast cancer progression and survival and their major adverse effects. The focus of this review will be on the development that has occurred within classes of targeted therapies and subsequent impact on breast cancer patient outcomes. We will conclude with a perspective on the role of targeted therapy in breast cancer treatment and highlight future areas of development.

Reactivity-based chemical-genetic study of protein kinases

The human protein kinase superfamily comprises over 500 members that operate in nearly every signal transduction pathway and regulate essential cellular processes. Deciphering the functional roles of protein kinases with small-molecule inhibitors is essential to enhance our understanding of cell signaling and to facilitate the development of new therapies. However, it is rather challenging to identify selective kinase inhibitors because of the conserved nature of the ATP binding site. A number of chemical-genetic approaches have been developed during the past two decades to enable selective chemical perturbation of the activity of individual kinases. Herein, we review the development and application of chemical-genetic strategies that feature the use of covalent inhibitors targeting cysteine residues to dissect the cellular functions of protein kinases.

The Ascension of Targeted Covalent Inhibitors

Covalent drugs have made a major impact on human health but until recently were shunned by the pharmaceutical industry over concerns about the potential for toxicity. A resurgence has occurred driven by the clinical success of targeted covalent inhibitors (TCIs), with eight drugs approved over the past decade. The opportunity to create unique drugs by exploiting the covalent mechanism of action has enabled clinically decisive target product profiles to be achieved. TCIs have revolutionized the treatment paradigm for non-small-cell lung cancer and chronic lymphocytic leukemia. This Perspective will highlight the clinical and financial success of this class of drugs and provide early insight into toxicity, a key factor that had hindered progress in the field. Further innovation in the TCI approach, including expanding beyond cysteine-directed electrophiles, kinases, and cancer, highlights the broad opportunity to deliver a new generation of breakthrough therapies.

Novel ADCs and Strategies to Overcome Resistance to Anti-HER2 ADCs

During recent years, a number of new compounds against HER2 have reached clinics, improving the prognosis and quality of life of HER2-positive breast cancer patients. Nonetheless, resistance to standard-of-care drugs has motivated the development of novel agents, such as new antibody-drug conjugates (ADCs). The latter are a group of drugs that benefit from the potency of cytotoxic agents whose action is specifically guided to the tumor by the target-specific antibody. Two anti-HER2 ADCs have reached the clinic: trastuzumab-emtansine and, more recently, trastuzumab-deruxtecan. In addition, several other HER2-targeted ADCs are in preclinical or clinical development, some of them with promising signs of activity. In the present review, the structure, mechanism of action, and potential resistance to all these ADCs will be described. Specific attention will be given to discussing novel strategies to circumvent resistance to ADCs.

Design, Synthesis and Molecular Modeling of Quinoline Based Derivatives as Anti-Breast Cancer Agents Targeting EGFR/AKT Signaling Pathway

Two series of quinoline-thiazole and quinoline-thiazolidinone hybrids were designed, synthesized and evaluated for their in vitro antitumor activity on MCF-7 breast cancer cell line. In comparison to lapatinib (IC₅₀ =4.69 µM), compounds 4b and 6b exhibited the best antiproliferative activity with IC₅₀ values of 33.19 and 5.35 µM, respectively. Although compound 6b showed higher cytotoxicity, compound 4b exhibited better inhibitory activity towards the EGFR pathway than compound 6b as represented by the significant reduction in the EGFR kinase activity and the levels of phosho-EGFR and phosho-AKT when compared to lapatinib as a reference standard. Moreover, compound 4b was capable of down-regulating the anti-apoptotic genes Bcl-2 and survivin and up-regulating the level of the pro-apoptotic gene BAX. Molecular modeling study was carried out to predict the binding interactions of both compounds into the target kinase. Finally, the physicochemical properties were investigated in silico as well.

Synthesis and Anti-Proliferation Activity Evaluation of Novel 2-Chloroquinazoline as Potential EGFR-TK Inhibitors

A novel series of 2-chloroquinazoline derivatives had been synthesized and their anti-proliferation activities against the four EGFR high-expressing cells A549, NCI-H1975, AGS and HepG2 cell lines were evaluated. The preliminary SAR study of the scaffold of new compounds showed that the compounds with a chlorine substituent on R³ had a better anti-proliferation activity than those substituted by hydrogen atom or vinyl group. Among them, 2-chloro-N-[2-chloro-4-(3-chloro-4-fluoroanilino)quinazolin-6-yl]acetamide (10b) had the best activity, and the corresponding IC₅₀ were 3.68, 10.06, 1.73 and 2.04 μM, respectively. And compound 10b had better or equivalent activity against four cell lines than Gefitinib. The activity of the compound 10b on the EGFR enzyme was subsequently tested. The Wound Healing of A549, AGS and HepG2 cells by this compound showed that the compound can inhibit the migration of cancer cells. Finally, the action channel of the compound 10b was supported by western blotting experiments. It provides useful information for the design of EGFR-TK inhibitors.

Sensitivity to targeted therapy differs between HER2-amplified breast cancer cells harboring kinase and helical domain mutations in PIK3CA

BACKGROUND

HER2-amplified breast cancer is a clinically defined subtype of breast cancer for which there are multiple viable targeted therapies. Resistance to these targeted therapies is a common problem, but the mechanisms by which resistance occurs remain incompletely defined. One mechanism that has been proposed is through mutation of genes in the PI3-kinase pathway. Intracellular signaling from the HER2 pathway can occur through PI3-kinase, and mutations of the encoding gene PIK3CA are known to be oncogenic. Mutations in PIK3CA co-occur with HER2-amplification in ~ 20% of cases within the HER2-amplified subtype.

METHODS

We generated isogenic knockin mutants of each PIK3CA hotspot mutation in HER2-amplified breast cancer cells using adeno-associated virus-mediated gene targeting. Isogenic clones were analyzed using a combinatorial drug screen to determine differential responses to HER2-targeted therapy. Western blot analysis and immunofluorescence uncovered unique intracellular signaling dynamics in cells resistant to HER2-targeted therapy. Subsequent combinatorial drug screens were used to explore neuregulin-1-mediated resistance to HER2-targeted therapy. Finally, results from in vitro experiments were extrapolated to publicly available datasets.

RESULTS

Treatment with HER2-targeted therapy reveals that mutations in the kinase domain (H1047R) but not the helical domain (E545K) increase resistance to lapatinib. Mechanistically, sustained AKT signaling drives lapatinib resistance in cells with the kinase domain mutation, as demonstrated by staining for the intracellular product of PI3-kinase, PIP3. This resistance can be overcome by co-treatment with an inhibitor to the downstream kinase AKT. Additionally, knockout of the PIP3 phosphatase, PTEN, phenocopies this result. We also show that neuregulin-1, a ligand for HER-family receptors, confers resistance to cells harboring either hotspot mutation and modulates response to combinatorial therapy. Finally, we show clinical evidence that the hotspot mutations have distinct expression profiles related to therapeutic resistance through analysis of TCGA and METABRIC data cohorts.

CONCLUSION

Our results demonstrate unique intracellular signaling differences depending on which mutation in PIK3CA the cell harbors. Only mutations in the kinase domain fully activate the PI3-kinase signaling pathway and maintain downstream signaling in the presence of HER2 inhibition. Moreover, we show there is potentially clinical importance in understanding both the PIK3CA mutational status and levels of neuregulin-1 expression in patients with HER2-amplified breast cancer treated with targeted therapy and that these problems warrant further pre-clinical and clinical testing.

Trans-(-)-Kusunokinin: A Potential Anticancer Lignan Compound against HER2 in Breast Cancer Cell Lines?

Trans-(−)-kusunokinin, an anticancer compound, binds CSF1R with low affinity in breast cancer cells. Therefore, finding an additional possible target of trans-(−)-kusunokinin remains of importance for further development. Here, a computational study was completed followed by indirect proof of specific target proteins using small interfering RNA (siRNA). Ten proteins in breast cancer were selected for molecular docking and molecular dynamics simulation. A preferred active form in racemic trans-(±)-kusunokinin was trans-(−)-kusunokinin, which had stronger binding energy on HER2 trans-(+)-kusunokinin; however, it was weaker than the designed HER inhibitors (03Q and neratinib). Predictively, trans-(−)-kusunokinin bound HER2 similarly to a reversible HER2 inhibitor. We then verified the action of (±)-kusunokinin compared with neratinibon breast cancer cells (MCF-7). (±)-Kusunokinin exhibited less cytotoxicity on normal L-929 and MCF-7 than neratinib. (±)-Kusunokinin and neratinib had stronger inhibited cell proliferation than siRNA-HER2. Moreover, (±)-kusunokinin decreased Ras, ERK, CyclinB1, CyclinD and CDK1. Meanwhile, neratinib downregulated HER, MEK1, ERK, c-Myc, CyclinB1, CyclinD and CDK1. Knocking down HER2 downregulated only HER2. siRNA-HER2 combination with (±)-kusunokinin suppressed HER2, c-Myc, CyclinB1, CyclinD and CDK1. On the other hand, siRNA-HER2 combination with neratinib increased HER2, MEK1, ERK, c-Myc, CyclinB1, CyclinD and CDK1 to normal levels. We conclude that trans-(±)-kusunokinin may bind HER2 with low affinity and had a different action from neratinib.

Oncogenic potential of human pluripotent stem cell-derived lung organoids with HER2 overexpression

Lung adenocarcinoma (LUAD) is the most common types among lung cancers generally arising from terminal airway and understanding of multistep carcinogenesis is crucial to develop novel therapeutic strategy for LUAD. Here we used human induced pluripotent stem cells (hiPSCs) to establish iHER2-hiPSCs in which doxycycline induced the expression of the oncoprotein human epidermal growth factor receptor 2 (HER2)/ERBB2. Lung progenitors that differentiated from iHER2-hiPSCs, which expressed NKX2-1/TTF-1 known as a lung lineage maker, were cocultured with human fetal fibroblast and formed human lung organoids (HLOs) comprising alveolar type 2-like cells. HLOs that overexpressed HER2 transformed to tumor-like structures similar to atypical adenomatous hyperplasia, which is known for lung precancerous lesion and upregulated the activities of oncogenic signaling cascades such as RAS/RAF/MAPK and PI3K/AKT/mTOR. The degree of morphological irregularity and proliferation capacity were significantly higher in HLOs from iHER2-hiPSCs. Moreover, the transcriptome profile of the HLOs shifted from a normal lung tissue-like state to one characteristic of clinical LUAD with HER2 amplification. Our results suggest that hiPSC-derived HLOs may serve as a model to recapitulate the early tumorigenesis of LUAD and would provide new insights into the molecular basis of tumor initiation and progression.

The Clinical Efficacy and Safety of Neratinib in Combination with Capecitabine for the Treatment of Adult Patients with Advanced or Metastatic HER2-Positive Breast Cancer

Human epidermal growth factor receptor 2 (HER2) positive cancers account for 15–20% of all breast tumors. Several drugs have been approved in the metastatic setting, including monoclonal antibodies, tyrosine kinase inhibitors (TKI) and, more recently, antibody-drug conjugates. Neratinib is a pan-HER, irreversible TKI with potent preclinical activity against trastuzumab-resistant breast cancer models. Based on Phase I and II clinical trials, the combination of neratinib plus capecitabine was compared to lapatinib and capecitabine, an established regimen for trastuzumab-resistant disease, in the randomized, Phase III NALA trial. In this trial, neratinib yielded increased progression-free survival, response duration and a benefit in time to intervention for CNS progression. However, there was no overall survival benefit, no increase in overall response rate and no improvement in QoL. The most frequent adverse event in the neratinib arm was diarrhea, which was manageable with prophylactic treatment with loperamide. Conclusion: Neratinib is a valuable addition to the therapeutic armamentarium to treat metastatic, HER2-positive breast cancer. The current positioning of the combination of neratinib and capecitabine based on the results of the NALA trial needs to consider the rapidly evolving scenario due to the recent introduction of new drugs, like the pure-HER2 TKI tucatinib and the antibody drug-conjugate trastuzumab-deruxtecan.

Monoclonal Antibodies, Small Molecule Inhibitors and Antibody-drug Conjugates as HER2 Inhibitors

Overexpression of human epidermal growth factor receptor (HER)-2 is found in a variety of cancers, often portending poor clinical outcomes. Therefore, HER2 is an attractive target for treatment. This review describes the research progress of HER2 targeted inhibitors in recent years. Excellent reviews are available, so we focus on the development, mechanisms of action, and structure-activity relationships of different types of inhibitors, including monoclonal antibodies, small molecule inhibitors, and antibody-drug conjugates (ADCs). In addition, the differences among them are compared.

Isatin-Hydrazones with Multiple Receptor Tyrosine Kinases (RTKs) Inhibitory Activity and In-Silico Binding Mechanism

Recently, we have reported a series of isatin hydrazone, two of them, namely, 3-((2,6-dichlorobenzylidene)hydrazono)indolin-2-one (1) and 3-((2-chloro-6-fluorobenzylidene)hydrazono)indolin-2-one (2) having potent cytotoxicity, showing cyclin-dependent kinases (CDK2) inhibitory activity and bearing recommended drug likeness properties. Since both compounds (1 and 2) showed inhibitory activity against CDK2, we assumed it would also have multiple receptor tyrosine kinases (RTKs) inhibitory activity. Considering those points, here, above-mentioned two isatin hydrazone 1 and 2 were synthesized using previously reported method for further investigation of their potency on RTKs (EGFR, VEGFR-2 and FLT-3) inhibitory activity. As expected, Compound 1 exhibited excellent inhibitory activity against epidermal growth factor receptor (EGFR, IC50 = 0.269 µM), vascular epidermal growth factor receptor 2 (VEGFR-2, IC50 = 0.232 µM) and FMS-like tyrosine kinase-3 (FLT-3, IC50 = 1.535 µM) tyrosine kinases. On the other hand, Compound 2 also exhibited excellent inhibitory activity against EGFR (IC50 = 0.369 µM), VEGFR-2 (IC50 = 0.266 µM) and FLT-3 (IC50 = 0.546 µM) tyrosine kinases. A molecular docking study with EGFR, VEGFR-2 and FLT-3 kinase suggested that both compounds act as type I ATP competitive inhibitors against EGFR and VEGFR-2, and type II ATP non-competitive inhibitors against FLT-3.

Combining Neratinib with CDK4/6, mTOR, and MEK Inhibitors in Models of HER2-positive Cancer

PURPOSE

Neratinib is an irreversible, pan-HER tyrosine kinase inhibitor that is FDA approved for HER2-overexpressing/amplified (HER2+) breast cancer. In this preclinical study, we explored the efficacy of neratinib in combination with inhibitors of downstream signaling in HER2+ cancers in vitro and in vivo.

EXPERIMENTAL DESIGN

Cell viability, colony formation assays, and Western blotting were used to determine the effect of neratinib in vitro. In vivo efficacy was assessed with patient-derived xenografts (PDX): two breast, two colorectal, and one esophageal cancer (with HER2 mutations). Four PDXs were derived from patients who received previous HER2-targeted therapy. Proteomics were assessed through reverse phase protein arrays and network-level adaptive responses were assessed through Target Score algorithm.

RESULTS

In HER2+ breast cancer cells, neratinib was synergistic with multiple agents, including mTOR inhibitors everolimus and sapanisertib, MEK inhibitor trametinib, CDK4/6 inhibitor palbociclib, and PI3Kα inhibitor alpelisib. We tested efficacy of neratinib with everolimus, trametinib, or palbociclib in five HER2+ PDXs. Neratinib combined with everolimus or trametinib led to a 100% increase in median event-free survival (EFS; tumor doubling time) in 25% (1/4) and 60% (3/5) of models, respectively, while neratinib with palbociclib increased EFS in all five models. Network analysis of adaptive responses demonstrated upregulation of EGFR and HER2 signaling in response to CDK4/6, mTOR, and MEK inhibition, possibly providing an explanation for the observed synergies with neratinib.

CONCLUSIONS

Taken together, our results provide strong preclinical evidence for combining neratinib with CDK4/6, mTOR, and MEK inhibitors for the treatment of HER2+ cancer.

Optimal Strategies for Successful Initiation of Neratinib in Patients with HER2-Positive Breast Cancer

Neratinib is an irreversible, pan-human epidermal growth factor inhibitor that has shown efficacy across human epidermal growth factor receptor 2 (HER2)-positive breast cancer settings. Neratinib is indicated for use as extended adjuvant therapy for HER2-positive early-stage breast cancer or, in combination with capecitabine, in the treatment of HER2-positive metastatic breast cancer. The primary tolerability concern with neratinib is diarrhea, and severe diarrhea early in treatment can lead to a substantial proportion of patients discontinuing neratinib, which may lead to reduced or nonexistent efficacy. In order to establish a set of treatment recommendations for use of neratinib, on May 12, 2020, an expert panel of oncologists and gastroenterologists met virtually to discuss the role of neratinib in the treatment of patients with HER2-positive breast cancer. The panel reviewed the current data on neratinib, including efficacy across settings and diarrhea management strategies. Based on these data and their clinical experience, the panelists developed a set of recommendations to guide selection of patients for neratinib, implement weekly dose escalation at initiation of therapy, and prophylactically manage diarrhea.

Melatonin potentiates the cytotoxic effect of Neratinib in HER2+ breast cancer through promoting endocytosis and lysosomal degradation of HER2

Complete blockade of the HER2 protein itself and HER signaling network is critical to achieving effective HER2-targeted therapies. Despite the success of HER2-targeted therapies, the diseases will relapse in a significant fraction of patients with HER2⁺ breast cancers. How to improve the therapeutic efficacy of existing HER2-targeted agents remains an unmet clinical need. Here, we uncover a role of Melatonin in diminishing HER2-mediated signaling by destruction of HER2 protein. Mechanistically, Melatonin treatment attenuated the protective effect of the HSP90 chaperone complex on its client protein HER2, triggering ubiquitylation and subsequent endocytic lysosomal degradation of HER2. The inhibitory effect of Melatonin on HER2 signaling substantially enhanced the cytotoxic effects of the pan-HER inhibitor Neratinib in HER2⁺ breast cancer cells. Lastly, we demonstrate that dual inhibition of HER2 by combined use of Melatonin and Neratinib effectively blocked the growth of HER2⁺ breast tumor xenografts in vivo. Our findings shed light on the potential use of Melatonin in a novel dual HER2 blockade strategy for HER2⁺ breast cancer treatment.

Overview of New Treatments with Immunotherapy for Breast Cancer and a Proposal of a Combination Therapy

According to data from the U.S. National Cancer Institute, cancer is one of the leading causes of death worldwide with approximately 14 million new cases and 8.2 million cancer-related deaths in 2018. More than 60% of the new annual cases in the world occur in Africa, Asia, Central America, and South America, with 70% of cancer deaths in these regions. Breast cancer is the most common cancer in women, with 266,120 new cases in American women and an estimated 40,920 deaths for 2018. Approximately one in six women diagnosed with breast cancer will die in the coming years. Recently, novel therapeutic strategies have been implemented in the fight against breast cancer, including molecules able to block signaling pathways, an inhibitor of poly [ADP-ribose] polymerase (PARP), growth receptor blocker antibodies, or those that reactivate the immune system by inhibiting the activities of inhibitory receptors like cytotoxic T-lymphocyte antigen 4 (CTLA-4) and programmed death protein 1 (PD-1). However, novel targets include reactivating the Th1 immune response, changing tumor microenvironment, and co-activation of other components of the immune response such as natural killer cells and CD8+ T cells among others. In this article, we review advances in the treatment of breast cancer focused essentially on immunomodulatory drugs in targeted cancer therapy. Based on this knowledge, we formulate a proposal for the implementation of combined therapy using an extracorporeal immune response reactivation model and cytokines plus modulating antibodies for co-activation of the Th1- and natural killer cell (NK)-dependent immune response, either in situ or through autologous cell therapy. The implementation of "combination immunotherapy" is new hope in breast cancer treatment. Therefore, we consider the coordinated activation of each cell of the immune response that would probably produce better outcomes. Although more research is required, the results recently achieved by combination therapy suggest that for most, if not all, cancer patients, this tailored therapy may become a realistic approach in the near future.

Quinoline-Based Molecules Targeting c-Met, EGF, and VEGF Receptors and the Proteins Involved in Related Carcinogenic Pathways

The quinoline ring system has long been known as a versatile nucleus in the design and synthesis of biologically active compounds. Currently, more than one hundred quinoline compounds have been approved in therapy as antimicrobial, local anaesthetic, antipsychotic, and anticancer drugs. In drug discovery, indeed, over the last few years, an increase in the publication of papers and patents about quinoline derivatives possessing antiproliferative properties has been observed. This trend can be justified by the versatility and accessibility of the quinoline scaffold, from which new derivatives can be easily designed and synthesized. Within the numerous quinoline small molecules developed as antiproliferative drugs, this review is focused on compounds effective on c-Met, VEGF (vascular endothelial growth factor), and EGF (epidermal growth factor) receptors, pivotal targets for the activation of important carcinogenic pathways (Ras/Raf/MEK and PI3K/AkT/mTOR). These signalling cascades are closely connected and regulate the survival processes in the cell, such as proliferation, apoptosis, differentiation, and angiogenesis. The antiproliferative biological data of remarkable quinoline compounds have been analysed, confirming the pivotal importance of this ring system in the efficacy of several approved drugs. Furthermore, in view of an SAR (structure-activity relationship) study, the most recurrent ligand–protein interactions of the reviewed molecules are summarized.

The root cause of drug resistance in HER2-positive breast cancer and the therapeutic approaches to overcoming the resistance

HER2 is a well-known oncogenic receptor tyrosine kinase. HER2 gene amplification occurs in about 20% of breast cancer (BC), which leads to overexpression of HER2 protein, known as HER2-positive BC. Inhibitors of HER2 have significantly improved the prognosis of patients with this subset of BC. Since 1998, seven HER2 inhibitors have been developed to treat this disease. However, drug resistance is common and remains a major unresolved clinical problem. Patients typically show disease progression after some time on treatment. This review discusses the complexity and diversified nature of HER2 signaling, the mechanisms of actions and therapeutic activities of all HER2 inhibitors, the roles of HER2 and other signaling proteins in HER2-positive BC resistant to the inhibitors, the non-cell-autonomous mechanisms of drug resistance, and the heterogeneity of tumor HER2 expression. The review presents the concept that drug resistance in HER2-positive BC results primarily from the inability of HER2 inhibitors to deplete HER2. Emerging therapeutics that are promising for overcoming drug resistance are also discussed.

Neratinib plus capecitabine for the treatment of advanced HER2-positive breast cancer

INTRODUCTION

Several agents are being developed for advanced HER2-positive breast cancer, such as potent tyrosine kinase inhibitors (TKI) targeting ErbB family receptors, novel antibody-drug conjugates, higher affinity anti-HER2 antibodies, among others. Neratinib is an irreversible pan-HER (EGFR, ERBB2, and ERBB4) TKI being tested in early and advanced HER2-positive breast cancer. In the NALA trial, neratinib plus capecitabine led to increased PFS and time to intervention for central nervous system disease over the standard regimen of lapatinib plus capecitabine. The main adverse event in the neratinib arm was diarrhea, which mandates for prophylactic treatment with loperamide.

AREAS COVERED

In this review, we analyze and discuss preclinical and clinical data with neratinib plus capecitabine. We summarize efficacy and safety results from phase I/II and III trials, and discuss this regimen within the landscape of treatment for patients with HER2-positive metastatic breast cancer progressing after two lines of HER2-directed treatment.

EXPERT OPINION

Neratinib plus capecitabine is a valid treatment option for patients with advanced HER2-positive breast cancer, after progression to at least two anti-HER2-based regimens. Given the multiple options that are being developed in this context, efforts should be employed to establish strong predictive biomarkers of efficacy to each drug and combination.

Neratinib for the treatment of early-stage, hormone receptor-positive, HER2-overexpressed breast cancer

HER2-positive breast cancer accounts for 18-20% of all breast cancers. Despite significant advances and the currently available adjuvant treatments for management of the disease, approximately 25% of HER2-positive early-stage breast cancer patients show relapse and die. Neratinib is an irreversible tyrosine kinase inhibitor. Multiple studies have reported its significant antitumor activity in metastatic HER2-positive breast cancer. It is administered orally and has also been tested in the adjuvant setting. In this article, we present a comprehensive review of the pharmacokinetics and pharmacodynamics of neratinib as well as its clinical efficacy, with an emphasis on early HER2-positive breast cancer and suggestions for future directions for neratinib research.

Evaluation of competitive binding interaction of neratinib and tamoxifen to serum albumin in multidrug therapy

Co-administration of two drugs to obtain a therapeutic goal is a common practice clinically and for effective use of drug therapy. However, the co-administration can sometimes cause adverse effects due to pharmacokinetic drug interactions. Breast Cancer treatment regimen include tyrosine kinase inhibitor neratinib (NRB) and/or tamoxifen (TMX). In this study neratinib and tamoxifen interaction with bovine serum albumin (BSA) and human serum albumin (HSA) individually and in combination using fluorescence spectroscopy was studied. The aim of this study was to find out whether there is a possibility of either of the two drugs interfering in the plasma protein binding of the other drug. Subdomain IIA of both the BSA and HSA was found to bind tamoxifen and neratinib. The λ_ex = 280 nm and 295 nm were used for the analysis of neratinib-SA, tamoxifen-SA, neratinib: SA in presence of constant concentration of tamoxifen and similarly tamoxifen-SA in presence of constant concentration of neratinib. The interaction study of the binary and the ternary systems suggest that neratinib doesn't affect the interaction between SA and tamoxifen. In contrast, the interaction between neratinib and SA was affected by tamoxifen. The binding constant and quenching constant values suggest that tamoxifen dislodges neratinib from its serum albumin complex whereas neratinib doesn't affect the interaction between SA and tamoxifen. Thus, it was concluded from the results the study that during simultaneous administration of neratinib and tamoxifen, their competition for the SA binding sites should be taken into account.

YES1 activation induces acquired resistance to neratinib in HER2-amplified breast and lung cancers

Molecular‐targeted therapies directed against human epidermal growth factor receptor 2 (HER2) are evolving for various cancers. Neratinib is an irreversible pan‐HER tyrosine kinase inhibitor and has been approved by the FDA as an effective drug for HER2‐positive breast cancer. However, acquired resistance of various cancers to molecular‐targeted drugs is an issue of clinical concern, and emergence of resistance to neratinib is also considered inevitable. In this study, we established various types of neratinib‐resistant cell lines from HER2‐amplified breast and lung cancer cell lines using several drug exposure conditions. We analyzed the mechanisms of emergence of the resistance in these cell lines and explored effective strategies to overcome the resistance. Our results revealed that amplification of YES1, which is a member of the SRC family, was amplified in two neratinib‐resistant breast cancer cell lines and one lung cancer cell line. Knockdown of YES1 by siRNA and pharmacological inhibition of YES1 by dasatinib restored the sensitivity of the YES1‐amplified cell lines to neratinib in vitro. Combined treatment with dasatinib and neratinib inhibited tumor growth in vivo. This combination also induced downregulation of signaling molecules such as HER2, AKT and MAPK. Our current results indicate that YES1 plays an important role in the emergence of resistance to HER2‐targeted drugs, and that dasatinib enables such acquired resistance to neratinib to be overcome.

Molecular Targeting Therapy against EGFR Family in Breast Cancer: Progress and Future Potentials

The epidermal growth factor receptor (EGFR) family contains four transmembrane tyrosine kinases (EGFR1/ErbB1, Her2/ErbB2, Her3/ErbB3 and Her4/ErbB4) and 13 secreted polypeptide ligands. EGFRs are overexpressed in many solid tumors, including breast, pancreas, head-and-neck, prostate, ovarian, renal, colon, and non-small-cell lung cancer. Such overexpression produces strong stimulation of downstream signaling pathways, which induce cell growth, cell differentiation, cell cycle progression, angiogenesis, cell motility and blocking of apoptosis.The high expression and/or functional activation of EGFRs correlates with the pathogenesis and progression of several cancers, which make them attractive targets for both diagnosis and therapy. Several approaches have been developed to target these receptors and/or the EGFR modulated effects in cancer cells. Most approaches include the development of anti-EGFRs antibodies and/or small-molecule EGFR inhibitors. This review presents the state-of-the-art and future prospects of targeting EGFRs to treat breast cancer.

Endocytic degradation of ErbB2 mediates the effectiveness of neratinib in the suppression of ErbB2-positive ovarian cancer

The tyrosine kinase receptor ErbB2 is frequently found to be overexpressed in multiple cancer types. Targeted therapeutic approaches against ErbB2 have shown promising results and received FDA approvals in the treatment of breast cancer. However, this approach has not been granted in ovarian cancers till now. In order to assess the validity of ErbB2-targeted therapy in ovarian cancer, we investigated the effectiveness of two FDA-approved tyrosine kinase inhibitors of ErbB2, lapatinib and neratinib, on the growth of ovarian cancers. We observed that both lapatinib and neratinib displayed inhibitory effects towards the proliferation and migration of ErbB2-positive ovarian cancer cells in vitro, with neratinib showing stronger suppression in general. Neratinib treatment led to the reduction of ErbB2 protein levels, with concomitant attenuation of the phosphorylation of AKT, MEK, and ERK1/2. Immunofluorescence assays revealed that neratinib induced the internalization and lysosomal degradation of ErbB2, which was accompanied by its hyperubiquitylation. Lapatinib and neratinib also repressed the in vivo growth of SKOV3 cells, and neratinib downregulated ErbB2 levels in xenograft tumors to cause potent inhibition. Therefore, the ubiquitylation-mediated endocytic degradation of ErbB2 incurred by neratinib treatment conferred potent inhibition of ovarian cancer growth. Clinical investigations of neratinib in ErbB2-positive ovarian cancer are warranted.

Synthesis and Anti-Tumor Activity Evaluation of Novel 7-Fluoro-4-(1- Piperazinyl) Quinolines

Background:

Three series of new 7-fluoro-4-(1-piperazinyl) quinolines (I1~I6, II1~II2 and IV1~IV4) were synthesized. Their anti-tumor activity was evaluated in vitro against three human carcinoma cell lines, namely SGC-7901 cells, BEL-7402 cells and A549 cells expressing high levels of EGFR by Methyl Thiazolyl Terazolium (MTT) assay.

Methods:

Three series of quinoline derivatives were synthesized, characterized and evaluated for their in vitro anti-tumor activities.

Results and Discussion:

Structures of the newly synthesized compounds were confirmed by spectral analysis. The preliminary bioassay indicated that compounds I1, I10 and II1 exhibited better anti-tumor activity than the rest of the target compounds and gefitinib against A549 cell based assay, which demonstrated that compounds I1, I10 and II1 are potential agents for cancer therapy. Results suggested that the substitutes on piperazinyl influenced anti-tumor activities remarkably.

Conclusion:

These results are useful for discovering more potent novel anti-tumor compounds and further studies are ongoing.

Structural and chemical insights into the covalent-allosteric inhibition of the protein kinase Akt

The Ser/Thr kinase Akt (Protein Kinase B/PKB) is a master switch in cellular signal transduction pathways. Its downstream signaling influences cell proliferation, cell growth, and apoptosis, rendering Akt a prominent drug target. The unique activation mechanism of Akt involves a change of the relative orientation of its N-terminal pleckstrin homology (PH) and the kinase domain and makes this kinase suitable for highly specific allosteric modulation. Here we present a unique set of crystal structures of covalent-allosteric interdomain inhibitors in complex with full-length Akt and report the structure-based design, synthesis, biological and pharmacological evaluation of a focused library of these innovative inhibitors.

Thieno[2,3-d]pyrimidine as a promising scaffold in medicinal chemistry: Recent advances

Thienopyrimidine scaffold is a fused heterocyclic ring system that structurally can be considered as adenine, the purine base that is found in both DNA and RNA-bioisosteres. Thienopyrimidines exist in three distinct isomeric forms. The current review discusses thieno[2,3-d]pyrimidine as a one of the opulent heterocycles in drug discovery. Its broad range of medical applications such as anticancer, anti-inflammatory, anti-microbial, and CNS protective agents has inspired us to study its structure-activity relationship (SAR), along with its relevant synthetic strategies. The present review briefly summarizes synthetic approaches for the preparation of thieno[2,3-d]pyrimidine derivatives. In addition, the promising biological activities of this scaffold are also illustrated with explanatory diagrams for their SAR studies.

Neratinib in HER2-Positive Breast Cancer Patients

OBJECTIVE

To review the chemistry, pharmacology, pharmacokinetics, safety, and efficacy of neratinib in human epidermal growth factor receptor (HER2)+ breast cancer (BC).

DATA SOURCES

A PubMed search was performed using the term neratinib between September 12, 2018, and November 21, 2018. References of published articles and reviews were also assessed for additional information.

STUDY SELECTION AND DATA EXTRACTION

English-language preclinical and clinical studies on the chemistry, pharmacology, pharmacokinetics, safety, and efficacy of neratinib were evaluated.

DATA SYNTHESIS

Neratinib, an irreversible inhibitor of HER1, HER2, and HER4, is Food and Drug Administration approved for the extended adjuvant treatment of stage I-III HER2+ BC to follow trastuzumab-based therapy. A phase III study has demonstrated statistically significant improvement in 5-year disease-free survival rate (90.2 vs 87.7; hazard ratio = 0.73, 95% CI = 0.57-0.92, P = 0.0083). Its most common adverse effect is diarrhea, observed in more than 90% of patients. The incidence of grade 3/4 diarrhea (~40%) is reduced by half with loperamide prophylaxis, which is recommended for the first 8 weeks of neratinib therapy. Other common adverse reactions are nausea and fatigue. The patients need to be monitored for liver function tests and drug interactions with acid-reducing agents, CYP3A4 inhibitors/inducers, and P-glycoprotein substrates with narrow therapeutic window. Relevance to Patient Care and Clinical Practice: American Society of Clinical Oncology and National Comprehensive Cancer Network clinical guidelines suggest the use of neratinib for extended adjuvant therapy following 1-year trastuzumab in stage I to III HER2+ BC. Diarrhea remains a clinically significant but manageable adverse event.

CONCLUSION

Neratinib significantly improves treatment outcomes and has manageable toxicity in stage I to III HER2+ BC patients.

Synthesis, antitumour and antioxidant activities of novel α,β-unsaturated ketones and related heterocyclic analogues: EGFR inhibition and molecular modelling study

New α,β-unsaturated ketones 4a,b; 5a-c; and 6a,b; as well as 4-H pyran 7; pyrazoline 8a,b; isoxazoline 9; pyridine 10-11; and quinoline-4-carboxylic acid 12a,b derivatives were synthesized and evaluated for in vitro antitumour activity against HepG2, MCF-7, HeLa, and PC-3 cancer cell lines. Antioxidant activity was investigated by the ability of these compounds to scavenge the 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS^•+). Compounds 6a, 6b, 7, and 8b exhibited potent antitumour activities against all tested cell lines with [IC₅₀] ≅5.5-18.1 µΜ), in addition to significantly high ABTS^•+ scavenging activities. In vitro EGFR kinase assay for 6a, 6b, 7, and 8b as the most potent antitumour compounds showed that; compounds 6b, and 7 exhibited worthy EGFR inhibition activity with IC₅₀ values of 0.56 and 1.6 µM, respectively, while compounds 6a and 8b showed good inhibition activity with IC₅₀ values of 4.66 and 2.16 µM, respectively, compared with sorafenib reference drug (IC₅₀ = 1.28 µM). Molecular modelling studies for compounds 6b, 7, and 8b were conducted to exhibit the binding mode towards EGFR kinase, which showed similar interaction with erlotinib.

Synthesis and biological evaluation of 2-styrylquinolines as antitumour agents and EGFR kinase inhibitors: molecular docking study

A new series of 4,6-disubstituted 2-(4-(dimethylamino)styryl)quinoline 4a,b–9a,b was synthesized by the reaction of 2-(4-(dimethylamino)styryl)-6-substituted quinoline-4-carboxylic acids 3a,b with thiosemicarbazide, p-hydroxybenzaldehyde, ethylcyanoacetate, and 2,4-pentandione. In addition, the antitumour activity of all synthesized compounds 3a,b–9a,b was studied via MTT assay against two cancer cell lines (HepG2 and HCT116). Furthermore, epidermal growth factor receptor (EGFR) inhibition, using the most potent antitumour compounds, 3a, 3b, 4a, 4b, and 8a, was evaluated. The interpretation of the results showed clearly that the derivatives 3a, 4a, and 4b exhibited the highest antitumour activities against the tested cell lines HepG2 and HCT116 with IC₅₀ range of 7.7–14.2 µg/ml, in comparison with the reference drugs 5-fluorouracil (IC₅₀ = 7.9 and 5.3 µg/ml, respectively) and afatinib (IC₅₀ = 5.4 and 11.4 µg/ml, respectively). In vitro EGFR screening showed that compounds 3a, 3b, 4a, 4b, and 8a exhibited moderate inhibition towards EGFR with IC₅₀ values at micromolar levels (IC₅₀ range of 16.01–1.11 µM) compared with the reference drugs sorafenib (IC₅₀ = 1.14 µM) and erlotinib (IC₅₀ = 0.1 µM). Molecular docking was performed to study the mode of interaction of compounds 3a and 4b with EGFR kinase.

Predicting the Efficacy of HER2-Targeted Therapies: A Look at the Host

HER2 is overexpressed in 20% of invasive breast cancers (BCs) and correlates with a more aggressive disease. Until the advent of targeted agents, HER2 was associated with worse outcomes. Rationally designed HER2-targeted agents have been developed and introduced into clinical practice for women with HER2-amplified BC, improving disease-free and overall survival for primary and metastatic tumors. Trastuzumab, a recombinant humanized anti-HER2 monoclonal antibody, combined with chemotherapy, remains the standard of care for patients with HER2-positive BCs. However, many patients do not respond to this agent, whereas newer drugs have proven to be efficacious in clinical trials. The identification of biomarkers that select sensitive tumors and patients who will benefit from these new agents would help the incorporation of these therapies, limiting the risk of side effects and overtreatment and improving the outcomes of all patients with early-stage HER2-positive BC. We review the mechanisms of action of HER2-targeting agents, focusing on the involvement of the immune system and related predictive biomarkers.

Synthesis and photophysical properties of a fluorescent cyanoquinoline probe for profiling ERBB2 kinase inhibitor response

A fluorescent probe targeting the ERBB2 receptor tyrosine was designed, synthesized and evaluated as reporter of ERBB2 dynamics in overexpressing BT474, i.e. Her2(+), cells. Two cyanoquinazoline (CQ) probes modeled after type-I (CQ1) or active state and type-II (CQ2) or inactive state inhibitors were designed and synthesized with extended π systems that impart binding-induced, turn-on fluorescence. Solution spectroscopy revealed that CQ1 exhibited attractive photophysical properties and displayed turn-on emission in the presence of purified, soluble ERBB2 kinase domain, while CQ2 was found to be non-emissive, likely due to quenching via a photoinduced electron transfer mechanism. Live cell imaging with CQ1 revealed that this probe targeted an intracellular population of ERBB2, which increased following treatment with type-I inhibitors, gefinitib and canertinib, but showed no response to type-II inhibitors. CQ1 thus provides a novel means of imaging the dynamic response of ERBB2(+) cells to kinase inhibitors.

Neratinib for the treatment of HER2-positive early stage breast cancer

INTRODUCTION

Despite the advances in the treatment of HER2-positive breast cancer, resistance to actual chemotherapeutic regimens eventually occurs. Neratinib, an orally available pan-inhibitor of the ERBB family, represents an interesting new option for early-stage HER2-positive breast cancer. Areas covered: In this article, the development of neratinib, with a special focus on its potential value in the treatment of early-stage HER2-positive breast cancer, has been reviewed. For this purpose, a literature search was conducted, including preclinical studies, early-phase trials in advanced cancer with neratinib in monotherapy and in combination, and phase II and large phase III trials in the early setting. Management of neratinib-induced toxicity, future perspectives for the drug, and ongoing trials are also discussed in this review. Expert commentary: Neratinib is emerging as a promising oral drug for the treatment of HER2-positive breast cancer. Although FDA and EMA approval is derived from the extended adjuvant treatment, this setting may not be the ideal scenario to obtain the beneficial effects of neratinib. Confirmatory data in the neoadjuvant setting and subgroup analysis from the ExTENET trial might bring some light into the best setting for neratinib therapy. Data from confirmatory trials in the metastatic setting are also required.

Co-targeting the HER and IGF/insulin receptor axis in breast cancer, with triple targeting with endocrine therapy for hormone-sensitive disease

PURPOSE

Interactions between HER2, estrogen receptor (ER), and insulin-like growth factor I receptor (IGF1R) are implicated in resistance to monotherapies targeting these receptors. We have previously shown in pre-clinical studies synergistic anti-tumor effects for co-targeting each pairwise combination of HER2, IGF1R, and ER. Strikingly, synergy for HER2/IGF1R targeting occurred not only in a HER2+ model, but also in a HER2-normal model. The purpose of the current study was therefore to determine the generalizability of synergistic anti-tumor effects of co-targeting HER2/IGF1R, the anti-tumor activity of triple-targeting HER2/IGF1R/ER in hormone-dependent cell lines, and the effect of using the multi-targeting drugs neratinib (pan-HER) and BMS-754807 (dual IGF1R/insulin receptor).

METHODS

Proliferation and apoptosis assays were performed in a large panel of cell lines representing varying receptor expression levels. Mechanistic effects were studied using phospho-protein immunoblotting. Analyses of drug interaction effects were performed using linear mixed-effects regression models.

RESULTS

Enhanced anti-proliferative effects of HER/IGF-insulin co-targeting were seen in most, though not all, cell lines, including HER2-normal lines. For ER+ lines, triple targeting with inclusion of anti-estrogen generally resulted in the greatest anti-tumor effects. Double or triple targeting generally resulted in marked increases in apoptosis in the sensitive lines. Mechanistic studies demonstrated that the synergy between drugs was correlated with maximal inhibition of Akt and ERK pathway signaling.

CONCLUSIONS

Dual HER/IGF-insulin targeting, and triple targeting with inclusion of anti-estrogen drugs, shows striking anti-tumor activity across breast cancer types, and drugs with broader receptor specificity may be more effective than single receptor selective drugs, particularly for ER- cells.

Discovery and development of pyrotinib: A novel irreversible EGFR/HER2 dual tyrosine kinase inhibitor with favorable safety profiles for the treatment of breast cancer

The discovery and development of a novel irreversible EGFR/HER2 dual tyrosine kinase inhibitor SHR1258 (pyrotinib) for the treatment of HER2-postive breast cancer is presented. The structure-activity relationship of lead series and their pharmacokinetic properties were evaluated to identify the potential candidates for further in vivo efficacy studies and preclinical safety assessments. Metabolic pathway and drug-drug interaction were also investigated in preclinical settings. In particular, major metabolites in human and animal species were assessed with regard to potential toxicity or off-target side effects. Overall, the potent and selective EGFR/HER2 dual inhibitor, pyrotinib, displayed robust anti-tumor effects on HER2-overexpressing xenograft models and sufficiently safety windows in animals as well as favorable pharmacokinetic properties in human, which substantially ensures current clinical development. Finally, recent advances of pyrotinib in clinical studies are highlighted with very encouraging outcomes in patients with HER2-postive advanced breast cancer.

Insights into the molecular interactions of thymoquinone with histone deacetylase: evaluation of the therapeutic intervention potential against breast cancer

Many HDAC inhibitors have passed through the gateway of clinical trials. However, they have limited therapeutic implications due to their pleiotropic pharmaceutical properties and off-target effects. In view of this, dietary active phytochemicals were evaluated. Based upon the chemical and structural insights of HDAC active pockets, thymoquinone (TQ) was investigated to uncover its active participation in HDAC inhibition. The synergistic analysis of docking and molecular dynamics simulation disclosed the elementary interaction and stability of TQ with human HDACs. The in silico findings were corroborated with an in vitro analysis, demonstrating the efficient role of TQ in the attenuation of global HDAC activity. Furthermore, TQ also elicited downstream effects of HDAC inhibition: reactivation of HDAC target genes (p21 and Maspin), induction of the pro-apoptotic gene Bax, down regulation of the anti-apoptotic gene Bcl-2 and arrest of the cell cycle at the G2/M phase. Finally, the result of a higher cytotoxicity of TQ towards MCF-7 breast cancer cells in comparison to normal cells indicates the potential of TQ to be an anticancer drug.