Mechanisms of cutaneous toxicities to EGFR inhibitors

Epidermal growth factor receptor inhibitor-related skin toxicity: mechanisms, treatment, and its potential role as a predictive marker

The human epidermal growth factor receptor (HER1/EGFR/ErbB1) signaling is aberrant and overexpressed in many solid malignancies making it an appealing target for biologic agents. Among the classes of drugs targeting EGFR are monoclonal antibodies and EGFR tyrosine kinase inhibitors, which have been shown effective and generally well tolerated in different clinical settings. The majority of patients treated with EGFR inhibitors (EGFRIs) develop specific dose-dependent skin toxicity. This side effect may lead to physical and psychosocial discomfort which can result in dose reduction or treatment interruption. The relationship between rash and clinical outcome has stimulated interest in this particular toxicity as a possible surrogate marker of efficacy in patients treated with targeted agents against EGFR. This review aims to summarize and update the current knowledge of the clinical presentation, predictive and prognostic value, and the management of EGFRI-related skin toxicity.

Review: side effects of approved molecular targeted therapies in solid cancers

Major advances have been achieved in the field of biologically based therapies for cancer in the last few years, and some of the recently approved molecular-targeted therapies are now being used in daily clinical practice. These molecular targets are also expressed in normal cells, which explains the different grades of toxicity, resulting from the disruption of normal cellular function. In general, targeted molecular therapies have good toxicity profiles, but some patients are exquisitely sensitive to these drugs and can develop particular and severe toxicities. In this article, we review the toxicity and safety of various small molecules and monoclonal antibodies used in solid tumors, with discussion of the pathophysiology, correlation with response, and strategies for prevention and management.

Severe skin reaction secondary to concomitant radiotherapy plus cetuximab

The therapeutic use of monoclonal antibodies against the epidermal growth factor receptor (EGFR) is specifically associated with dermatologic reactions of variable severity. Recent evidence suggests superiority of the EGFR inhibitor (EGFRI) cetuximab plus radiotherapy compared to radiotherapy alone in patients with squamous cell carcinoma of the head and neck. Although not documented in a study population, several reports indicate a possible overlap between radiation dermatitis and the EGFRI-induced skin rash. We here present a case of severe skin reaction secondary to the addition of cetuximab to radiotherapy.

Current status of antivascular therapy and targeted treatment in the clinic

Antivascular and targeted therapy are now an integrated part of the treatment of myelogenous leukemias, GIST tumours, B-cell lymphomas and breast cancer. In various malignancies improved responses and prolongation of survival for several months is regularly reported. The progress in this field is relevant for hyperthermia. Heat has among other effects documented antivascular effects, and can be considered as one of the established methods in the field based on several randomised phase III studies. Hyperthermia should be considered for combination with other antiangiogenic agents.

Consensus guidelines for the management of radiation dermatitis and coexisting acne-like rash in patients receiving radiotherapy plus EGFR inhibitors for the treatment of squamous cell carcinoma of the head and neck

BACKGROUND

Radiation dermatitis occurs to some degree in most patients receiving radiotherapy, with or without chemotherapy. Patients with squamous cell carcinoma of the head and neck (SCCHN) who receive radiotherapy in combination with epidermal growth factor receptor (EGFR) inhibitors, such as cetuximab, may develop a characteristic acne-like rash in addition to dermatitis.

DESIGN

An advisory board of 11 experienced radiation oncologists, medical oncologists and dermatologists discussed the management options for skin reactions in patients receiving EGFR inhibitors and radiotherapy for SCCHN. Skin toxicity was categorised according to the National Cancer Institute-Common Terminology Criteria for Adverse Events (version 3) grading.

RESULTS

Both general and grade-specific approaches for the management of dermatitis in this patient group are presented. It was concluded that where EGFR inhibitor-related acne-like rash and dermatitis coexist within irradiated fields, management should be based on the grade of dermatitis: for grade 1 (or no dermatitis), treatment recommendations for EGFR-related acne-like rash outside irradiated fields should be followed; for grades 2 and above, treatment recommendations for dermatitis were proposed.

CONCLUSIONS

This paper presents comprehensive consensus guidelines for the treatment of dermatitis in patients with SCCHN receiving EGFR inhibitors in combination with radiotherapy.

EGF-receptor targeting with monoclonal antibodies in colorectal carcinomas: rationale for a pharmacogenomic approach

Monoclonal antibodies directed against the EGF-receptor (EGFR) have recently been approved for the treatment of metastatic colorectal cancer (CRC) patients with EGFR-positive tumors at immunohistochemistry (IHC). Surprisingly, data demonstrate a lack of correlation between the tumor’s EGFR expression at IHC and outcome. Indeed, as pointed out from small experiences, patients with EGFR-IHC-negative metastatic CRC have the same chance as EGFR-IHC-positive patients to benefit from an anti-EGFR monoclonal antibody, underlying the importance of different, more reliable, selection criteria. In particular, the identification of such predictive factors is important as these agents are expensive, have side effects and are really only effective in a minority of patients. Several potential clinical and biological predictive markers of activity and/or efficacy for such agents have been evaluated in retrospective series with promising results. Moving from clinical data suggesting that there could be a subpopulation of CRC patients that are more liable to benefit from anti-EGFR monoclonal antibodies, here we review major studies on determinants of outcome in this field.

Clinical significance and treatment of skin rash from erlotinib in non-small cell lung cancer patients: results of an Experts Panel Meeting

Advances in the knowledge of tumor biology and mechanisms of oncogenesis has granted the singling out of several molecular targets for non-small cell lung cancer (NSCLC) treatment. Among these targets, epidermal growth factor receptor (EGFR), or HER1, has received particular attention in lung cancer treatment. Erlotinib, an orally available inhibitor of EGFR tyrosine kinase in a phase III randomized placebo-controlled trial (BR.21), has been proven to prolong survival in NSCLC patients after first or second line chemotherapy. Skin rash is the most common adverse event associated with erlotinib treatment and it is often cause of negative impact on patients' quality of life. There is no specific treatment for this toxicity due to the lack of evidence-based data and recommendations. A panel of Italian oncologists, who had participated to clinical trials and to the Expanded Access Program for erlotinib in NSCLC treatment, and dermatologists with experience with cutaneous toxicity from EGFR inhibitors, attended a Meeting held in Rome on December 2006 to discuss skin rash from erlotinib and to provide suggestions for managing this frequent side-effect.

The epidermal growth factor receptor system in skin repair and inflammation

The epidermal growth factor (EGF) family comprises multiple mediators such as transforming growth factor-alpha, amphiregulin, heparin binding-EGF, and epiregulin, which are crucially involved in the tissue-specific proliferation/differentiation homeostasis. Typically, they act in an autocrine and paracrine manner on their specific cell membrane receptor and mount an effective reparative response to any attack to biophysical integrity. In addition, the EGFR can be activated by transactivation from a variety of G-protein-coupled receptors, integrins, and cytokine receptors, so that it acts as the major transducer of disparate cell functions, including changes in proliferation rate, cellular shape, attachment and motility, and regulation of proinflammatory activation. However, numerous experimental observations indicate that the different EGFR ligands are not redundant, but may rather provide distinct and specific contributions to keratinocyte functions. Importantly, increasing evidence now suggests that the EGFR pathway has a major impact on the inflammatory/immune reactions of the skin, in the apparent effort of enhancing innate immune defense while opposing overactivation of keratinocyte pro-inflammatory functions. This review covers the molecular mechanisms and functions activated by this major growth factor system in the regulation of keratinocyte biology and focuses on the complex contribution of EGFR signaling to the inflammatory processes in the skin.

Targeting the epidermal growth factor receptor in colorectal carcinoma

Colorectal cancer continues to be a common cause of death in this country, accounting for more than 55,000 deaths in 2006. The introduction of targeted biologic therapies, such as the epidermal growth factor receptor and tyrosine kinase inhibitors, has expanded the treatment options and has shown promise for patients with advanced disease. This article gives a history of the treatment of colorectal cancer, with a focus on the efficacy and toxicity of epidermal growth factor receptor inhibitors and their implications for the nursing community.

Insights into the pathophysiology and management of dermatologic toxicities to EGFR-targeted therapies in colorectal cancer

Epidermal growth factor receptors (EGFRs) play an important role in the development of the skin and up-regulation of these receptors is associated with many cancer-related processes, such as inhibition of apoptosis and uncontrolled cell proliferation. Accordingly, treatment of metastatic colorectal cancer with EGFR inhibitors may lead to adverse cutaneous effects that can decrease the patient's quality of life and could possibly lead to reduced, interrupted, or discontinued therapy. Effective management of these adverse effects may lessen the chance of suboptimal therapy and requires an understanding of the underlying pathophysiology, as well as knowledge of useful strategies for alleviating these effects.

Epidermal growth factor receptor inhibitor-associated cutaneous toxicities: an evolving paradigm in clinical management

Epidermal growth factor receptor inhibitors (EGFRIs) have demonstrated improved overall survival in patients with non-small cell lung cancer, pancreatic cancer, and colorectal cancer; however, their use is associated with dermatologic reactions of varying severity. The similar spectrum of events observed with monoclonal antibodies and tyrosine kinase inhibitors suggests such toxicities are a class effect. While such reactions do not necessarily require any alteration in EGFRI treatment, being best addressed through symptomatic treatment, there is limited evidence on which to base such therapies. In October 2006, at an international and interdisciplinary EGFRI dermatologic toxicity forum, the underlying mechanisms of these toxicities were discussed and commonly used therapeutic interventions were evaluated. Our aim was to reach a current consensus on management strategies. A three-tiered, EGFRI-focused toxicity grading system is suggested for the purposes of therapeutic decision making, and as a framework on which to build a stepwise approach to intervention. This approach to successful management is specifically tailored to accurately categorize dermatologic toxicity associated with EGFRIs, and can be easily applied by all health care professionals. The goal is to maximize quality of life in patients who are being treated with these agents--many of whom will be on these drugs for several months or even years.

Redistribution of LRIG proteins in psoriasis

The human leucine-rich repeats and immunoglobulin-like domains (LRIG) family is composed of three members, LRIG1, -2, and -3, which are all expressed in human skin. LRIG1 negatively regulates growth factor signaling and is involved in the regulation of epidermal stem cell quiescence. Ablation of Lrig1 in mice results in psoriasiform epidermal hyperplasia. Hence, the LRIG proteins may be important for epidermal homeostasis and in psoriasis. Therefore, we analyzed the LRIG mRNA levels and the cellular and subcellular distribution of LRIG proteins in normal and psoriatic skin. The mRNA levels of LRIG1, -2, and -3 were not significantly different in psoriatic epidermis compared to clinically normal epidermis from the same patient. Immunohistochemistry showed that all three LRIG proteins were expressed in unique and specific patterns both in normal and psoriatic skin. Intriguingly, in psoriatic epidermis, the LRIG protein expression patterns were altered compared to normal skin. These results indicate that the LRIG proteins may have a role in epidermal homeostasis and psoriasis.

Targeting the Raf-MEK-ERK mitogen-activated protein kinase cascade for the treatment of cancer

Mitogen-activated protein kinase (MAPK) cascades are key signaling pathways involved in the regulation of normal cell proliferation, survival and differentiation. Aberrant regulation of MAPK cascades contribute to cancer and other human diseases. In particular, the extracellular signal-regulated kinase (ERK) MAPK pathway has been the subject of intense research scrutiny leading to the development of pharmacologic inhibitors for the treatment of cancer. ERK is a downstream component of an evolutionarily conserved signaling module that is activated by the Raf serine/threonine kinases. Raf activates the MAPK/ERK kinase (MEK)1/2 dual-specificity protein kinases, which then activate ERK1/2. The mutational activation of Raf in human cancers supports the important role of this pathway in human oncogenesis. Additionally, the Raf-MEK-ERK pathway is a key downstream effector of the Ras small GTPase, the most frequently mutated oncogene in human cancers. Finally, Ras is a key downstream effector of the epidermal growth factor receptor (EGFR), which is mutationally activated and/or overexpressed in a wide variety of human cancers. ERK activation also promotes upregulated expression of EGFR ligands, promoting an autocrine growth loop critical for tumor growth. Thus, the EGFR-Ras-Raf-MEK-ERK signaling network has been the subject of intense research and pharmaceutical scrutiny to identify novel target-based approaches for cancer treatment. In this review, we summarize the current status of the different approaches and targets that are under evaluation and development for the therapeutic intervention of this key signaling pathway in human disease.

Cetuximab induce antibody-dependent cellular cytotoxicity against EGFR-expressing esophageal squamous cell carcinoma

To evaluate the possibility of treatment with antiepidermal growth factor receptor (EGFR) mAb, Cetuximab against esophageal squamous cell carcinoma (SCC), we performed detail analysis of the antibody-dependent cellular cytotoxicity (ADCC) mediated by Cetuximab against esophageal SCC. Esophageal SCC cell lines with various levels of EGFR (n = 8) were evaluated for their Cetuximab-mediated ADCC by (51)Cr-release assay. As a result, Cetuximab was able to induce ADCC against EGFR-expressing esophageal SCC and the activities reflected the degree of EGFR expression on the esophageal SCC. The activities of Cetuximab-mediated ADCC by patients' PBMC were impaired in comparison with those by healthy donors' PBMC. Moreover, the inhibition of transforming growth factor (TGF)-beta could enhance Cetuximab-mediated ADCC against TGF-beta-producing SCC. In conclusion, Cetuximab was able to induce ADCC against EGFR-expressing esophageal SCC. Some modalities aiming at enhancing the Cetuximab-mediated ADCC may be necessary for successful Cetuximab treatment of patients with esophageal SCC.

Molecular mechanisms of cardiotoxicity of tyrosine kinase inhibition

Cancer therapy has progressed remarkably in recent years. In no area has this been more apparent than in the development of "targeted therapies", particularly those using drugs that inhibit the activity of certain tyrosine kinases, activating mutations or amplifications of which are causal, or strongly contributory, to tumorigenesis. However, some of these therapies have been associated with toxicity to the heart. Here we summarize what is known about the cardiotoxicity of cancer drugs that target tyrosine kinases. We focus on basic mechanisms through which interruption of specific signalling pathways leads to cardiomyocyte dysfunction and/or death, and contrast this with therapeutic responses in cancer cells.

A phase I clinical trial with monoclonal antibody ch806 targeting transitional state and mutant epidermal growth factor receptors

An array of cell-surface antigens expressed by human cancers have been identified as targets for antibody-based therapies. The great majority of these antibodies do not have specificity for cancer but recognize antigens expressed on a range of normal cell types (differentiation antigens). Over the past two decades, our group has analyzed thousands of mouse monoclonal antibodies for cancer specificity and identified a battery of antibodies with limited representation on normal human cells. The most tumor-specific of these antibodies is 806, an antibody that detects a unique epitope on the epidermal growth factor receptor (EGFR) that is exposed only on overexpressed, mutant, or ligand-activated forms of the receptor in cancer. In vitro immunohistochemical specificity analysis shows little or no detectable 806 reactivity with normal tissues, even those with high levels of wild-type (wt)EGFR expression. Preclinical studies have demonstrated that 806 specifically targets a subset of EGFR expressed on tumor cells, and has significant anti-tumor effects on human tumor xenografts, primarily through abrogation of signaling pathways. The present clinical study was designed to examine the in vivo specificity of a chimeric form of mAb 806 (ch806) in a tumor targeting/biodistribution/pharmacokinetic analysis in patients with diverse tumor types. ch806 showed excellent targeting of tumor sites in all patients, no evidence of normal tissue uptake, and no significant toxicity. These in vitro and in vivo characteristics of ch806 distinguish it from all other antibodies targeting EGFR.

New approaches to molecular cancer therapeutics

Cancer drug development is leading the way in exploiting molecular biological and genetic information to develop "personalized" medicine. The new paradigm is to develop agents that target the precise molecular pathology driving the progression of individual cancers. Drug developers have benefited from decades of academic cancer research and from investment in genomics, genetics and automation; their success is exemplified by high-profile drugs such as Herceptin (trastuzumab), Gleevec (imatinib), Tarceva (erlotinib) and Avastin (bevacizumab). However, only 5% of cancer drugs entering clinical trials reach marketing approval. Cancer remains a high unmet medical need, and many potential cancer targets remain undrugged. In this review we assess the status of the discovery and development of small-molecule cancer therapeutics. We show how chemical biology approaches offer techniques for interconnecting elements of the traditional linear progression from gene to drug, thereby providing a basis for increasing speed and success in cancer drug discovery.

Non-Rash Skin Toxicities Associated with Novel Targeted Therapies

Many novel targeted agents have emerged against a variety of malignancies. Although papulopustular rash is the most commonly observed side effect associated with many of these agents, several non-rash skin toxicities have been identified that frequently result in the delay or discontinuation of anticancer therapy. These toxicities include skin hyperpigmentation, xerosis, pruritus, hair growth and color abnormalities, periungual and nail alterations, and hand-foot skin reaction. It is important to recognize these toxicities, so that they can be diagnosed early and treatment or dose modification can be initiated, if necessary. This review discusses several non-rash dermatologic toxicities observed with targeted therapeutic agents and guidelines for their diagnosis and treatment.