In vitro and in vivo efficacy of afatinib as a single agent or in combination with gemcitabine for the treatment of nasopharyngeal carcinoma

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.

Nasopharyngeal Carcinoma: The Role of the EGFR in Epstein-Barr Virus Infection

Epstein-Barr virus (EBV), a type 4 γ herpes virus, is recognized as a causative agent in nasopharyngeal carcinoma (NPC). Incidence of EBV-positive NPC have grown in recent decades along with worse outcomes compared with their EBV-negative counterparts. Latent membrane protein 1 (LMP1), encoded by EBV, induces NPC progression. The epidermal growth factor receptor (EGFR), a member of the ErbB family of receptor tyrosine kinases (RTK), is a driver of tumorigenesis, including for NPC. Little data exist on the relationship between EGFR and EBV-induced NPC. In our initial review, we found that LMP1 promoted the expression of EGFR in NPC in two main ways: the NF-κB pathway and STAT3 activation. On the other hand, EGFR also enhances EBV infection in NPC cells. Moreover, activation of EGFR signalling affects NPC cell proliferation, cell cycle progression, angiogenesis, invasion, and metastasis. Since EGFR promotes tumorigenesis and progression by downstream signalling pathways, causing poor outcomes in NPC patients, EGFR-targeted drugs could be considered a newly developed anti-tumor drug. Here, we summarize the major studies on EBV, EGFR, and LMP1-regulatory EGFR expression and nucleus location in NPC and discuss the clinical efficacy of EGFR-targeted agents in locally advanced NPC (LA NPC) and recurrent or metastatic NPC (R/M NPC) patients.

Combination of Epithelial Growth Factor Receptor Blockers and CDK4/6 Inhibitor for Nasopharyngeal Carcinoma Treatment

Simple Summary

Our findings indicated that the EGF-EGFR pathway was highly activated in very young patients with recurrent or metastatic NPC. High EGFR expression in patients with metastatic NPC resulted in poor clinical outcomes. To examine whether the EGFR pathway serves as a therapeutic target for NPC, NPC patient-derived xenograft (PDX) and NPC cell lines were treated with EGFR inhibitors (EGFRi) and a cell cycle blocker. Either EGFRi or cell cycle blocker treatment alone could reduce NPC cell growth and PDX tumor growth. Furthermore, combination treatment exerted an additive suppression effect on PDX tumor growth. This study provides promising evidence that EGFRi used in combination with a cell cycle blocker may be used to treat patients with NPC.

Abstract

Background: Nasopharyngeal carcinoma (NPC) involves host genetics, environmental and viral factors. In clinical observations, patients of young and old ages were found to have higher recurrence and metastatic rates. Methods: Cytokine array was employed to screen druggable target(s). The candidate target(s) were confirmed through patient-derived xenografts (PDXs) and a new EBV-positive cell line, NPC-B13. Results: Overexpression of epithelial growth factor (EGF) and EGF receptor (EGFR) was detected in young patients than in older patients. The growth of NPC PDX tumors and cell lines was inhibited by EGFR inhibitors (EGFRi) cetuximab and afatinib when used separately or in combination with the cell cycle blocker palbociclib. Western blot analysis of these drug-treated PDXs demonstrated that the blockade of the EGF signaling pathway was associated with a decrease in the p-EGFR level and reduction in PDX tumor size. RNA sequencing results of PDX tumors elucidated that cell cycle-related pathways were suppressed in response to drug treatments. High EGFR expression (IHC score ≥ grade 3) was correlated with poor survival in metastatic patients (p = 0.008). Conclusions: Our results provide encouraging preliminary data related to the combination treatment of EGFRi and palbociclib in patients with NPC.

Optimization, Characterization and in vivo Evaluation of Paclitaxel-Loaded Folate-Conjugated Superparamagnetic Iron Oxide Nanoparticles

Background

Paclitaxel (PTX) has interesting anticancer activity. However, it is insoluble in water, which seriously hinders its use in clinical. Superparamagnetic iron oxide nanoparticles (SPIONs) are used as an ideal drug delivery system. Therefore, we proposed a folic acid (FA) targeting drug-loaded SPIONs to reduce its adverse reaction.

Methods

To improve the hydrophilicity of PTX, the structure of PTX was modified by succinic anhydride to obtain 2ʹ-succinate paclitaxel (SPTX). FA conjugated Polyethylene glycol (PEG)/polyethyleneimine (PEI)-SPIONs SPTX-loaded nanoparticles (SPTX@FA@PEG/PEI-SPIONs) were prepared by solvent volatilization and hydrogen bond adsorption, and the nano-formulation was optimized by response surface methodology (RSM). The characteristics, antitumor effect in vitro, pharmacokinetics, and biodistribution of SPTX@FA@PEG/PEI-SPIONs were evaluated.

Results

SPTX was successfully loaded on the surface of FA@PEG/PEI-SPIONs. The formation of SPTX@FA@PEG/PEI-SPIONs was exhibited water-dispersive monodispersity with high stability by RSM, and dynamic light scattering (DLS) was 178.1±3.12 nm, particle size observed in the transmission electron microscope (TEM) was 13.01±1.10 nm, and the encapsulation efficiency (EE) and loading efficiency (LE) were 81.1±1.66% and 14.8±1.46%, respectively. It enhanced the stability in normal physiological condition, accelerated drug release at tumorous pH, and preferentially prolonged the circulation time. In vitro, the SPTX@FA@PEG/PEI-SPIONs significantly targeted to folate receptor (FR) positive cancers cell (HNE-1) via the receptor-ligand mediated pathway, resulting in effective cytotoxic activity. Pharmacokinetic results demonstrated that SPTX@FA@PEG/PEI-SPIONs (t_1/2=3.41 h) had longer than free SPTX or PTX (t_1/2=1.67 h) in rats in vivo. Tissue distribution studies showed that SPTX@FA@PEG/PEI-SPIONs were present at high levels in the liver and help in targeting the folate receptors present on the kidneys.

Conclusion

These results suggest that SPTX@FA@PEG/PEI-SPIONs offer a highly promising approach to control drug release, improve drug pharmacokinetics and actively target the nasopharyngeal carcinoma.

Synergistic activity of agents targeting growth factor receptors, CDKs and downstream signaling molecules in a panel of pancreatic cancer cell lines and the identification of antagonistic combinations: Implications for future clinical trials in pancreatic cancer

Pancreatic cancer is one of the most aggressive, heterogeneous and fatal type of human cancers for which more effective therapeutic agents are urgently needed. Here, we investigated the sensitivity of a panel of seven human pancreatic cancer cell lines (HPCCLs) to treatment with various tyrosine kinase inhibitors (TKIs), cyclin-dependent kinase (CDK) inhibitors, an inhibitor of STAT3 stattic, and a cytotoxic agent gemcitabine both as single agents and in combination. The membranous expression of various receptors and the effect of selected agents on cell cycle distribution, cell signaling pathways and migration was determined using flow cytometry, western blot analysis and scratch wound healing assays, respectively. While the expression of both HER-3 and HER-4 was low or negative, the expression of EGFR and HER2 was high or intermediate in all HPCCLs. Of all the agents examined, the CDK1/2/5/9 inhibitor, dinacicilib, was the most potent agent which inhibited the proliferation of all seven HPCCLs with IC₅₀ values of ≤10 nM, followed by SRC targeting TKI dasatinib (IC₅₀ of ≤258 nM), gemcitabine (IC₅₀ of ≤330 nM), stattic (IC₅₀ of ≤2 µM) and the irreversible pan-HER TKI afatinib (IC₅₀ of ≤2.95 µM). Treatment with afatinib and dasatinib inhibited the ligand-induced phosphorylation of EGFR and SRC respectively. Statistically significant associations were found between HER2 expression and response to treatment with the ALK/IGF-IR/InsR inhibitor ceritinib and fibroblast growth factor receptor (FGFR)1/2/3 inhibitor AZD4547, HER3 and IGF-IR expression and their response to treatment with TKIs targeting HER family members (erlotinib and afatinib), and c-MET and ALK7 expression and their response to treatment with stattic. Interestingly, treatment with a combination of afatinib with dasatinib and gemcitabine with dasatinib resulted in synergistic tumor growth inhibition in all HPCCLs examined. In contrast, the combination of afatinib with dinaciclib was found to be antagonistic. Finally, the treatment with afatinib, dasatinib and dinaciclib strongly inhibited the migration of all HPCCLs examined. In conclusion, the CDK1/2/5/9 inhibitor dinaciclib, irreversible pan-HER TKI afatinib and SRC targeting TKI dasatinib were most effective at inhibiting the proliferation and migration of HPCCLs and the combination of afatinib with dasatinib and gemcitabine with dasatinib led to synergistic tumor growth inhibition in all HPCCLs examined. Our results support further investigation on the therapeutic potential of these combinations in future clinical trials in pancreatic cancer.

Study on the chemodrug-induced effect in nasopharyngeal carcinoma cells using laser tweezer Raman spectroscopy

To explore the effect in nasopharyngeal carcinoma (NPC) cells after treatment with chemodrugs, Raman profiles were characterized by laser tweezer Raman spectroscopy. Two NPC cell lines (CNE2 and C666-1) were treated with gemcitabine, cisplatin, and paclitaxel, respectively. The high-quality Raman spectra of cells without or with treatments were recorded at the single-cell level with label-free laser tweezers Raman spectroscopy (LTRS) and analyzed for the differences of alterations of Raman profiles. Tentative assignments of Raman peaks indicated that the cellular specific biomolecular changes associated with drug treatment include changes in protein structure (e.g. 1655 cm^-1), changes in DNA/RNA content and structure (e.g. 830 cm^-1), destruction of DNA/RNA base pairs (e.g. 785 cm^-1), and reduction in lipids (e.g. 970 cm^-1). Besides, both principal components analysis (PCA) combined with linear discriminant analysis (LDA) and the classification and regression trees (CRT) algorithms were employed to further analyze and classify the spectral data between control group and treated group, with the best discriminant accuracy of 96.7% and 90.0% for CNE2 and C666-1 group treated with paclitaxel, respectively. This exploratory work demonstrated that LTRS technology combined with multivariate statistical analysis has promising potential to be a novel analytical strategy at the single-cell level for the evaluation of NPC-related chemotherapeutic drugs.

Appropriate Sequence for Afatinib and Cisplatin Combination Improves Anticancer Activity in Head and Neck Squamous Cell Carcinoma

Despite a better understanding in head and neck tumors pathogenesis as well as improvements in radiotherapy and surgery, locally advanced head and neck squamous cell carcinoma (HNSCC) remains of poor prognosis. One promising target is the epidermal growth factor receptor (EGFR), which is overexpressed in the majority of HNSCC and is associated to tumor progression and resistance to treatment. However, in several clinical trials, the combination of EGFR inhibitors with chemotherapy and/or radiotherapy generates moderate results. In this study, we investigated the anti-tumor activity of afatinib, an irreversible pan-EGFR inhibitor, combined to cisplatin in different schedules of exposure. For that, we used two human EGFR wild-type HNSCC cell lines and we evaluated the cytotoxicity of the two drugs combined in different sequences. The efficiency of each strategy was assessed by evaluating the effects on cell cycle distribution, DNA damage, cell death and downstream pathways of ErbB family receptors. We demonstrated that cisplatin treatment followed by afatinib exposure displayed more cytotoxic effects than the opposite timing or than simultaneous association. This higher anticancer activity is probably due to afatinib-induced cell cycle arrest, which prevents the repair of cisplatin-induced DNA damage and promotes cell death by various mechanisms including apoptosis. These data suggest the importance of an appropriate timing administration between an EGFR inhibitor and a conventional chemotherapy in order to obtain the best clinical benefit for patients with a head and neck cancer.

Phase I dose-escalation trial of afatinib, an irreversible ErbB family blocker, in combination with gemcitabine or docetaxel in patients with relapsed or refractory solid tumors

Background Afatinib, an irreversible ErbB family blocker, has shown synergistic antitumor activity and manageable tolerability in combination with chemotherapy. This phase I study assessed oral afatinib plus intravenous gemcitabine or docetaxel in patients with relapsed/refractory solid tumors. Methods Patients received afatinib (30, 40, or 50 mg) plus gemcitabine (1000 or 1250 mg/m²) or docetaxel (60 or 75 mg/m²). Dose escalation proceeded via a 3 + 3 design until the maximum tolerated dose (MTD) was reached. Adverse events (AEs), pharmacokinetics and antitumor activity were also assessed. Results Dose-limiting toxicities during Cycle 1 were reported in 6/39 patients receiving afatinib/gemcitabine (most commonly diarrhea, thrombocytopenia and vomiting) and 16/54 patients receiving afatinib/docetaxel (most commonly febrile neutropenia and stomatitis). The MTDs were established as afatinib 40 mg/gemcitabine 1000 mg/m² and afatinib 30 mg/docetaxel 60 mg/m². The most common drug-related AEs were diarrhea, asthenia and rash with afatinib/gemcitabine, and diarrhea, asthenia and stomatitis with afatinib/docetaxel. No relevant pharmacokinetic interactions were observed for either combination. Both combinations demonstrated clinical activity and durable disease control at the MTDs. Compared with the MTD, higher response rates were achieved with afatinib 30 mg/docetaxel 75 mg/m² (28% vs 6%); however, this regimen was associated with problematic febrile neutropenia, an expected AE with docetaxel, that is often managed with growth factor support. Conclusions Afatinib/gemcitabine and afatinib/docetaxel demonstrated manageable safety profiles, with evidence of clinical efficacy at the MTDs. For afatinib/docetaxel, a dose level of afatinib 30 mg/docetaxel 75 mg/m² produced higher response rates. Trial registration: NCT01251653 ( ClinicalTrials.gov ).

Simultaneous targeting of EGFR, HER2, and HER4 by afatinib overcomes intrinsic and acquired cetuximab resistance in head and neck squamous cell carcinoma cell lines

The epidermal growth factor receptor (EGFR, HER1) is a therapeutic target in head and neck squamous cell carcinoma (HNSCC). After initial promising results with EGFR-targeted therapies such as cetuximab, therapeutic resistance has become a major clinical problem, and new treatment options are therefore necessary. Moreover, the relationship between HER receptors, anti-EGFR therapies, and the human papillomavirus (HPV) status in HNSCC is not fully understood. In contrast to first-generation EGFR inhibitors, afatinib irreversibly inhibits multiple HER receptors simultaneously. Therefore, treatment with afatinib might result in a more pronounced therapeutic benefit, even in patients experiencing cetuximab resistance. In this study, the cytotoxic effect of afatinib as single agent and in combination with cisplatin was investigated in cetuximab-sensitive, intrinsically cetuximab-resistant, and acquired cetuximab-resistant HNSCC cell lines with different HPV status under normoxia and hypoxia. Furthermore, the influence of cetuximab resistance, HPV, and hypoxia on the expression of HER receptors was investigated. Our results demonstrated that afatinib was able to establish cytotoxicity in cetuximab-sensitive, intrinsically cetuximab-resistant, and acquired cetuximab-resistant HNSCC cell lines, independent of the HPV status. However, cross-resistance between cetuximab and afatinib might be possible. Treatment with afatinib caused a G₀ /G₁ cell cycle arrest as well as induction of apoptotic cell death. Additive to antagonistic interactions between afatinib and cisplatin could be observed. Neither cetuximab resistance nor HPV status significantly influenced the expression of HER receptors in HNSCC cell lines. In contrast, the expression of EGFR, HER2, and HER3 was significantly altered under hypoxia. Oxygen deficiency is a common characteristic of HNSCC tumors, and these hypoxic tumor regions often contain cells that are more resistant to treatment. However, we observed that afatinib maintained its cytotoxic effect under hypoxia. In conclusion, our preclinical data support the hypothesis that afatinib might be a promising therapeutic strategy to treat patients with HNSCC experiencing intrinsic or acquired cetuximab resistance.

Afatinib

Afatinib (BIBW 2992, US: Gilotrif^TM, other countries: Giotrif©) is an irreversible blocker of the ErbB family, acting at the tyrosine kinases of these proteins. In 2013, it was approved by the FDA and the EMA for the treatment of adults with advanced, EGFR mutation-positive non-small-cell lung cancer. Further investigations for the treatment of many other tumors with afatinib, e.g., HNSCC and breast cancer, are ongoing.