A phase I clinical and pharmacokinetic study of oral CI-1033 in combination with docetaxel in patients with advanced solid tumors

Mechanism of sensitivity to cisplatin, docetaxel, and 5-fluorouracil chemoagents and potential erbB2 alternatives in oral cancer with growth differentiation factor 15 overexpression

The aim of this study was to: (a) explore the potential mechanism of cancer cell sensitivity to cisplatin, docetaxel, and 5‐fluorouracil (TPF) in oral squamous cell carcinoma (OSCC) patients overexpressing growth differentiation factor 15 (GDF15); and (b) identify potential alternative agents for patients who might not benefit from inductive TPF chemotherapy. The results indicated that OSCC cells overexpressing GDF15 were sensitive to TPF through a caspase‐9‐dependent pathway both in vitro and in vivo. Immunoprecipitation combined with mass spectrometry revealed that the erbB2 protein was a potential GDF15‐binding protein, which was verified by coimmunoprecipitation. Growth differentiation factor 15 overexpression promoted OSCC cell proliferation through erbB2 phosphorylation, as well as downstream AKT and Erk signaling pathways. When GDF15 expression was blocked, the phosphorylation of both the erbB2 and AKT/Erk pathways was downregulated. When OSCC cells with GDF15 overexpression were treated with the erbB2 phosphorylation inhibitor, CI‐1033, cell proliferation and xenograft growth colony formation were significantly blocked (P < .05). Thus, GDF15‐overexpressing OSCC tumors are sensitive to TPF chemoagents through caspase‐9‐dependent pathways. Growth differentiation factor 15 overexpression promotes OSCC proliferation through erbB2 phosphorylation. Thus, ErbB2 inhibitors could represent potential targeted drugs or an alternative therapy for OSCC patients with GDF15 overexpression.

Epidermal growth factor receptor inhibitor-induced diarrhea: clinical incidence, toxicological mechanism, and management

The epidermal growth factor receptor (EGFR) family is a class of receptor tyrosine kinase playing a central role in carcinogenesis and cancer progression. The members of this family, particularly EGFR and human epidermal growth factor receptor 2 (HER2), are the most extensively studied drug targets for malignancy. Today, numerous tyrosine kinase inhibitors targeting EGFR family have been developed to combat non-small-cell lung cancer and breast cancer. However, severe gastrointestinal (GI) toxicity leading to dose reduction and treatment discontinuation hampers the therapeutic outcome of EGFR inhibitors. Diarrhea is one of the most frequent GI side effects, especially when it comes to second-generation EGFR inhibitors. Enterocytes apoptosis and increased inflammation accompany with many oral EGFR inhibitors. Loperamide and budesonide are the first-line treatment to manage such adverse effects. However, current prophylaxis and management are all empirical interventions to relieve the symptom. They do not specifically target the toxicological mechanism of EGFR inhibitors. Hereby, those anti-diarrhea agents do not work well when used in cancer patients experiencing EGFR inhibitor-induced diarrhea. On the other hand, the toxicological mechanism of EGFR inhibitor-induced diarrhea is poorly understood. Thus, determining the mechanism behind such diarrhea is urgently in need for developing genuinely effective anti-diarrhea agents. This review aims to call attention to EGFR inhibitor-induced diarrhea, a highly occurring and devastating cancer drug toxicity.

Neutropenia and docetaxel exposure in metastatic castration-resistant prostate cancer patients: A meta-analysis and evaluation of a clinical cohort

The incidence of neutropenia in metastatic castration‐resistant prostate cancer (mCRPC) patients treated with docetaxel has been reported to be lower compared to patients with other solid tumors treated with a similar dose. It is suggested that this is due to increased clearance of docetaxel in mCRPC patients, resulting in decreased exposure. The aims of this study were to (1) determine if exposure in mCRPC patients is lower vs patients with other solid tumors by conducting a meta‐analysis, (2) evaluate the incidence of neutropenia in patients with mCRPC vs other solid tumors in a clinical cohort, and (3) discuss potential clinical consequences. A meta‐analysis was conducted of studies which reported areas under the plasma concentration‐time curves (AUCs) of docetaxel and variability. In addition, grade 3/4 neutropenia was evaluated using logistic regression in a cohort of patients treated with docetaxel. The meta‐analysis included 36 cohorts from 26 trials (n = 1150 patients), and showed that patients with mCRPC had a significantly lower mean AUC vs patients with other solid tumors (fold change [95% confidence interval (CI)]: 1.8 [1.5‐2.2]), with corresponding AUCs of 1.82 and 3.30 mg∙h/L, respectively. Logistic regression, including 812 patient, demonstrated that patients with mCRPC had a 2.2‐fold lower odds of developing grade 3/4 neutropenia compared to patients with other solid tumors (odds ratio [95%CI]: 0.46 [0.31‐0.90]). These findings indicate that mCRPC patients have a lower risk of experiencing severe neutropenia, possibly attributable to lower systemic exposure to docetaxel.

Pharmacology of Epidermal Growth Factor Inhibitors

Research into the molecular bases of malignant diseases has yielded the development of many novel agents with potential antitumor activity. Evidence for a causative role for the epidermal growth factor receptor (EGFR), which is now regarded as an excellent target for cancer chemotherapy in human cancer, leads to the development of EGFR inhibitors. Two classes of anti-EGFR agents are currently in clinical use: monoclonal antibodies directed at the extracellular domain of the receptor, and the low-molecular-weight receptor tyrosine kinase inhibitors acting intracellularly by competing with adenosine triphosphate for binding to the tyrosine kinase portion of the EGFR. The effect on the receptor interferes with key biological functions including cell cycle arrest, potentiation of apoptosis, inhibition of angiogenesis and cell invasion and metastasis. Cetuximab, a monoclonal antibody, and the receptor tyrosine kinase inhibitors gefitinib and erlotinib are currently approved for the treatment of patients with cancer. New agents with clinical activity are entering the clinic, and new combinatorial approaches are being explored with the aim of improving the potency and pharmacokinetics of EGFR inhibition, to increase the synergistic activity in combination with chemotherapy and overcome resistance to the EGFR inhibitors.

The Potential of panHER Inhibition in Cancer

Purpose: Hyper-activation of the HER (erbB) family receptors, HER 1-4, leads to up-regulation of the three vital signaling pathways: mitogen activated protein kinase, phosphoinositide 3-kinase/AKT, and Janus kinase/signal transducer and activator of transcription pathways. Blocking HER1/EGFR has a limited anticancer effect due to either secondary mutation e.g., T790M or by-pass signaling of other HER members. The emergence of an anti-panHER approach to blockade of these pathways as a cancer treatment may provide a solution to this resistance. This review aimed to provide an overview of the HER signaling pathways and their involvement in tumor progression and examine the current progress in panHER inhibition.

Methods: Recent literature associated with HER signaling pathways and panHER inhibition was reviewed through PubMed and Medline database, followed by critical comparison and analysis.

Results: Pre-clinical studies and clinical trials of panHER inhibitors show promising results, and the potential to improve patient outcomes in solid cancers.

Conclusion: The use of panHER inhibitors in cancers with HER-family hyper-activation, such as other epithelial cancers and sarcoma, is a new direction to research and has potential in clinical cancer therapy in the future.

Role of epidermal growth factor receptor in breast cancer

Decades of research in molecular oncology have brought about promising new therapies which are designed to target specific molecules which promote tumor growth and survival. The epidermal growth factor receptor (EGFR) is one of the first identified important targets of these novel antitumor agents. Approximately half of cases of triple-negative breast cancer (TNBC) and inflammatory breast cancer (IBC) overexpress EGFR. Thus, EGFR inhibitors for treatment of breast cancer have been evaluated in several studies. However, results so far have been disappointing. One of the reasons for these unexpected results is the lack of biomarkers for predicting which patients are most likely to respond to EGFR inhibitors. Recent studies have shown that EGFR and its downstream pathway regulate epithelial-mesenchymal transition, migration, and tumor invasion and that high EGFR expression is an independent predictor of poor prognosis in IBC. Further, recent studies have shown that targeting EGFR enhances the chemosensitivity of TNBC cells by rewiring apoptotic signaling networks in TNBC. These studies indicate that EGFR-targeted therapy might have a promising role in TNBC and IBC. Further studies of the role of EGFR in TNBC and IBC are needed to better understand the best way to use EGFR-targeted therapy-e.g., as a chemosensitizer or to prevent metastases-to treat these aggressive diseases.

Emerging targeted therapies for breast cancer

Increased understanding of the molecular events involved in cancer development has led to the identification of a large number of novel targets and, in parallel, to the development of multiple approaches to anticancer therapy. Targeted therapy focuses on specific molecules in the malignant cell signal transduction machinery, including crucial molecules involved in cell invasion, metastasis, apoptosis, cell-cycle control, and tumor-related angiogenesis. In breast cancer, two new targeted agents have recently been approved: lapatinib, directed against the human epidermal growth factor receptor 2 (HER2); and bevacizumab, directed against vascular endothelial growth factor (VEGF). Multiple other targeted agents are under evaluation in clinical trials, including inhibitors of the epidermal growth factor receptor (EGFR), dual EGFR and HER2 inhibitors, other VEGF or VEGF-receptor inhibitors, and agents that alter crucial signaling pathways, such as RAS/MEK/ERK; phosphatidylinositol-3-kinase/Akt/ mammalian target of rapamycin; insulin-like growth factor/insulin-like growth factor receptor; poly (ADP-ribose) polymerase 1; and others. In this review, we present the most promising studies of these new targeted therapies and novel combinations of targeted therapies with traditional cytotoxic agents.

Role of Trastuzumab in the Adjuvant Treatment of HER2-Positive Early Breast Cancer

Amplification of the human epidermal growth factor receptor 2 ( HER2) gene occurs in 18–23% of invasive breast carcinomas and is associated with a worse prognosis. This novel transforming gene was identified in 1985, and in 1987 HER2 amplification was demonstrated to be central to the aggressive, malignant phenotype of these cancers and a significant predictor of both time to relapse and overall survival. These observations led to the development of the first monoclonal antibody targeting the extracellular domain of HER2, trastuzumab (Herceptin®, Genentech and Hoffman LaRoche, Switzerland), which was approved by the US FDA for metastatic breast cancer in 1998. In 2005, results from four major trastuzumab adjuvant trials demonstrated a marked reduction in risk of recurrence, and trastuzumab is now an essential component of the adjuvant treatment of H ER2-positive early breast cancer. Concerns regarding cardiac safety and mechanisms of resistance to trastuzumab remain important issues and are being addressed in ongoing research efforts.

Antiangiogenic drugs: current knowledge and new approaches to cancer therapy

Angiogenesis--process of new blood-vessel growth from existing vasculature--is an integral part of both normal developmental processes and numerous pathologies such as cancer, ischemic diseases and chronic inflammation. Angiogenesis plays a crucial role facilitating tumour growth and the metastatic process, and it is the result of a dynamic balance between proangiogenic and antiangiogenic factors. The potential to block tumour growth and metastases by angiogenesis inhibition represents an intriguing approach to the cancer treatment. Angiogenesis continues to be a topic of major scientific interest; and there are currently more antiangiogenic drugs in cancer clinical trials than those that fit into any other mechanistic category. Based on preclinical studies, researchers believe that targeting the blood vessels which support tumour growth could help treatment of a broad range of cancers. Angiogenic factors or their receptors, endothelial cell proliferation, matrix metalloproteinases or endothelial cell adhesion, are the main targets of an increasing number of clinical trials approved to test the tolerance and therapeutic efficacy of antiangiogenic agents. Unfortunately, contrary to initial expectations, it has been described that antiangiogenic treatment can cause different toxicities in cancer patients. The purpose of this article is to provide an overview of current attempts to inhibit tumour angiogenesis for cancer therapy.

HER2-targeted therapy in breast cancer. Monoclonal antibodies and tyrosine kinase inhibitors

There is strong clinical evidence that trastuzumab, a monoclonal antibody targeting the human epidermal growth factor receptor (HER) two tyrosine kinase receptor, is an important component of first-line treatment of patients with HER2-positive metastatic breast cancer. In particular the combination with taxanes and vinorelbine has been established. In the preoperative setting inclusion of trastuzumab has significantly increased the pathological complete response rate. Results from large phase III trials evaluating adjuvant therapy in HER2-positive early breast cancer indicate that the addition of trastuzumab to chemotherapy improves disease-free and overall survival. The use of lapatinib, a dual tyrosine kinase inhibitor of both HER1 and HER2, in combination with capecitabine in the second-line treatment of HER2-positive patients with metastatic breast cancer previously treated with trastuzumab has been established. There is modest, but still insufficient, support that the compound passes the blood-brain barrier. Several trials are ongoing both in the adjuvant and metastatic settings and we have to await the results of these to clarify the role of trastuzumab and lapatinib. The clinical problem of tumours developing resistance to HER2-directed therapy is becoming increasingly important. Several issues about optimal selection of patients, prevention of resistance and use of different treatment options are still unresolved. In this article, we summarise the current knowledge on clinical evidence of HER2-directed therapy and the potential mechanisms of underlying resistance, including the possible clinical implications and review new therapeutic options.

Cutaneous reactions related to systemic immunomodulators and targeted therapeutics

The arrival of targeted therapeutics into the oncology clinic, while enthusiastically anticipated, introduced the oncologist to dermatologic events that can pose challenging management issues. The dermatologic effects of these targeted agents appear to be more frequent than those with cytotoxic therapy and are not uniform; that is, different agents have distinct dermatologic toxicities. Interestingly, dermatologic toxicity may correlate with antitumor activity with some of these targeted agents. The correlation of rash with response and survival in particular mandates the development of effective and appropriate management strategies. The nature and challenges of the dermatologic events observed to date with epidermal growth factor receptor inhibitors, multikinase inhibitors, proteosome inhibitors, BCR-ABL tyrosine kinase inhibitors, and immunomodulatory drugs will be addressed in this review.

Multimodality imaging of the HER-kinase axis in cancer

The human epidermal growth factor receptor (HER) family of receptor tyrosine kinases controls critical pathways involved in epithelial cell differentiation, growth, division, and motility. Alterations and disruptions in the function of the HER-kinase axis can lead to malignancy. Many therapeutic agents targeting the HER-kinase axis are approved for clinical use or are in preclinical/clinical development. The ability to quantitatively image the HER-kinase axis in a noninvasive manner can aid in lesion detection, patient stratification, new drug development/validation, dose optimization, and treatment monitoring. This review summarizes the current status in multimodality imaging of the HER-kinase axis using PET, SPECT, optical, and MR imaging. The targeting ligands used include small-molecule tyrosine kinase inhibitors, peptides, proteins, antibodies, and engineered antibody fragments. EGFR and HER2 imaging have been well documented in the past, and imaging of HER3, HER4, HER heterodimers, and HER-kinase mutants deserves significant research effort in the future. Successful development of new HER-kinase-targeted imaging agents with optimal in vivo stability, targeting efficacy, and desirable pharmacokinetics for clinical translation will enable maximum benefit in cancer patient management.

Pharmacogenomics of lung cancer: with a view to address EGFR-targeted therapies

Epidermal growth factor receptor (EGFR)-targeted therapies have demonstrated variable success in treating individuals with non-small-cell lung cancer. Understanding the molecular mechanisms of response and resistance to this class of treatment has led to patient selection strategies that may improve outcomes. The second generation of EGFR-targeted therapies is now under clinical evaluation and may prove to be successful at circumventing a portion of primary or acquired resistance to first-generation tyrosine kinase inhibitors. These principles are generally applicable to the field of targeted therapy and predictive pharmacogenomics.

Mechanisms for oncogenic activation of the epidermal growth factor receptor

The Epidermal growth factor receptor (EGFR) is a membrane spanning glycoprotein, which frequently has been implicated in various cancer types. The mechanisms by which EGFR becomes oncogenic are numerous and are often specific for each cancer type. In some tumors, EGFR is activated by autocrine/paracrine growth factor loops, whereas in others activating mutations promote EGFR signaling. Overexpression and/or amplification of the EGFR gene are prevalent in many cancer types leading to aberrant EGFR signaling. In addition, failure to attenuate receptor signaling by receptor downregulation can also lead to cellular transformation. Heterodimerization of EGFR with ErbB2 inhibits downregulation of EGFR and thereby prolongs growth factor signaling. This also indicates that cross-talk between EGFR and heterologous receptor systems serves as another mechanism for oncogenic activation of EGFR. Because of its role in tumor promotion, the EGFR has been intensely studied as a therapeutic target. There are currently two major mechanisms by which the EGFR is targeted: antibodies binding to the extracellular domain of EGFR and small-molecule tyrosine-kinase inhibitors. However, tumorigenesis is a multi-step process involving several mutations, which might explain why EGFR therapeutics has only been partially successful. This highlights the importance of pinpointing the mechanisms by which EGFR becomes oncogenic in a particular cancer. In this review, each of the above mentioned mechanisms will be discussed, as a detailed molecular and genetic understanding of how EGFR contributes to the malignant phenotype might offer new promise for the design, development and clinical evaluation of future tumor-specific anticancer approaches.

Second-generation epidermal growth factor receptor tyrosine kinase inhibitors in non-small cell lung cancer

Inhibiting epidermal growth factor receptor (EGFR) signaling has proven to be an effective strategy for treating non-small cell lung cancer (NSCLC) patients and the first generation of agents developed for this purpose, gefitinib and erlotinib, stimulated a unique escalation in both biologic and clinical research within the field. Second-generation EGFR-targeted agents that aim to further improve patient outcomes are now in preclinical and clinical trials. This review discusses four promising agents that are currently being studied in NSCLC: EKB-569, HKI-272, CI-1033, and ZD6474.

Combination of radiotherapy with EGFR antagonists for head and neck carcinoma

The introduction of biologically sound radiation fractionation regimens and combinations of radiotherapy with chemotherapy have gradually improved both the survival of patients with locally advanced head and neck squamous cell carcinoma (HNSCC) and the prospect of organ preservation. Long-term follow-up, however, has shown that some of the radiation-chemotherapy combinations are associated with increased late toxicity. This observation, in conjunction with advances in tumor biology, has led to the launch of investigations into molecular markers and targets for therapeutic interventions. Research on the epidermal growth factor receptor (EGFR)-mediated signaling pathway has enriched our understanding of the biology of HNSCC, in terms of carcinogenesis and cellular processes governing tumor response to therapy. The finding that the addition of an antibody-based inhibitor of the EGFR pathway to radiotherapy significantly improves locoregional control and overall survival rates in patients with locally advanced HNSCC, without increasing radiation-induced toxicity, has resulted in the growing acceptance of such combined regimens as a frontline therapy option for locally advanced HNSCC. Because such therapy has benefited only an additional 10%-15% of patients, studies are being undertaken to identify markers and mechanisms of resistance to EGFR antagonists that are essential for the further refinement of therapy. Overall, preclinical and clinical studies on EGFR have validated the concept that selective tumor radiation sensitization can be achieved by modulating a specific perturbed signaling pathway, and these studies have increased the enthusiasm for developing and investigating other novel agents targeting other cellular processes.