Antibody-induced epidermal growth factor receptor dimerization mediates inhibition of autocrine proliferation of A431 squamous carcinoma cells

T-Cadherin is an auxiliary negative regulator of EGFR pathway activity in cutaneous squamous cell carcinoma: impact on cell motility

Genetic and epigenetic studies in different cancers, including cutaneous carcinomas, have implicated T-cadherin (T-cad) as a tumor suppressor. Immunohistochemical and in vitro studies have suggested that T-cad loss promotes incipient invasiveness in cutaneous squamous cell carcinoma (SCC). Molecular mechanisms are unknown. This study found that the main consequence of T-cad silencing in SCC is facilitation of ligand-dependent EGFR activation, whereas T-cad overexpression impedes EGFR activation. Gain- and loss-of-function studies in A431 SCC cells demonstrate T-cad-controlled responsiveness to EGF with respect to pharmacological inhibition of EGFR and to diverse signaling and functional events of the EGFR activation cascade (EGFR phosphorylation, internalization, nuclear translocation, cell retraction/de-adhesion, motility, invasion, integrin β1, and Rho small GTPases such as RhoA, Rac1, and Cdc42 activation). Further, T-cad modulates the EGFR pathway activity by influencing membrane compartmentalization of EGFR; T-cad upregulation promotes retention of EGFR in lipid rafts, whereas T-cad silencing releases EGFR from this compartment, rendering EGFR more accessible to ligand stimulation. This study reveals a mechanism for fine-tuning of EGFR activity in SCC, whereby T-cad represents an auxiliary "negative" regulator of the EGFR pathway, which impacts invasion-associated behavioral responses of SCC to EGF. This action of T-cad in SCC may serve as a paradigm explaining other malignancies displaying concomitant T-cad loss and enhanced EGFR activity.

PREPARATION OF GELATIN NANOPARTICLES WITH EGFR SELECTION ABILITY VIA BIOTINYLATED-EGF CONJUGATION FOR LUNG CANCER TARGETING

Lung cancer is the most malignant cancer today, and specific drug delivery has been developed for superior outcome. In this study, gelatin nanoparticles (GPs) were firstly employed as native carriers. Second, NeutrAvidinFITC was then grafted on the particle surface (GP-Av); finally much more amount of biotinylated EGF were able to be conjugated with NeutrAvidinFITC forming ligand- binding nanoparticles (GP-Av-bEGF) to enhance the targeting efficiency. These nanoparticles were applied as EGFR-seeking agents to detect lung cancer cells.

Results of particle characterization show that the modification process had no influence on size (230 nm). Round and smooth nanoparticles were observed by AFM. The surface property of nanoparticles was characterized by surface plasmon resonance (SPR) and flowcytometry analysis as well as by examining the interaction of the modified EGF on particle surface with the ability to recognize EGFR.

The binding ability of GPs with or without EGF modification is different. SPR assay showed that EGF-conjugated particles (GP-Av-bEGF) have stronger and faster bonding signal than the unmodified one (GP-Av). Free EGF competition results from SPR and A549 cell (lung adenocarcinoma cells) culture also confirmed the EGF receptormediated endocytosis mechanism for nanoparticles with EGF-modified binding. The in vitro targeting ability was confirmed by the uptake rate of different cells via flow cytometry assay. GP-Av-bEGF resulted in higher entrance efficiency on A549 than on normal lung cells (HFL1) and U2-OS (osteosarcoma cells) due to A549 possessing more amounts of EGFR. The targeting ability of GP-Av-bEGF nanoparticles with specific EGFR tracing ability was proved, which holds promise for further anticancer drug applications.

Superior antitumoral activity of dimerized targeted single-chain TRAIL fusion proteins under retention of tumor selectivity

Although targeting of the death receptors (DRs) DR4 and DR5 still appears a suitable antitumoral strategy, the limited clinical responses to recombinant soluble TNF-related apoptosis inducing ligand (TRAIL) necessitate novel reagents with improved apoptotic activity/tumor selectivity. Apoptosis induction by a single-chain TRAIL (scTRAIL) molecule could be enhanced >10-fold by generation of epidermal growth factor receptor (EGFR)-specific scFv-scTRAIL fusion proteins. By forcing dimerization of scFv-scTRAIL based on scFv linker modification, we obtained a targeted scTRAIL composed predominantly of dimers (Db-scTRAIL), exceeding the activity of nontargeted scTRAIL ∼100-fold on Huh-7 hepatocellular and Colo205 colon carcinoma cells. Increased activity of Db-scTRAIL was also demonstrated on target-negative cells, suggesting that, in addition to targeting, oligomerization equivalent to an at least dimeric assembly of standard TRAIL per se enhances apoptosis signaling. In the presence of apoptosis sensitizers, such as the proteasomal inhibitor bortezomib, Db-scTRAIL was effective at picomolar concentrations in vitro (EC(50) ∼2 × 10(-12) M). Importantly, in vivo, Db-scTRAIL was well tolerated and displayed superior antitumoral activity in mouse xenograft (Colo205) tumor models. Our results show that both targeting and controlled dimerization of scTRAIL fusion proteins provides a strategy to enforce apoptosis induction, together with retained tumor selectivity and good in vivo tolerance.

NSC 74859-mediated inhibition of STAT3 enhances the anti-proliferative activity of cetuximab in hepatocellular carcinoma

BACKGROUND

Cetuximab [an epidermal growth factor receptor (EGFR) inhibitor], which was shown to be effective in rectal and non-small cell lung cancers (NSCLCs), was only modestly effective in clinical trials of hepatocellular carcinoma (HCC). STAT3, which is thought to be a determinant of HCC sensitivity to antitumour drugs, may be involved.

AIMS

To evaluate the efficacy of combination therapy using cetuximab and NSC 74859 (a novel STAT3 inhibitor) in EGFR and STAT3 overexpressing hepatoma cells.

METHODS

Hepatoma cell lines were treated with cetuximab, NSC 74859 or a combination of both drugs. Efficacy of treatment was evaluated by determining cell viability using MTT assays and proliferation by cell counting. Expression and activation of STAT3 were determined using Western blot analysis. We evaluated the role of STAT3 in single and combination therapy using siRNA-mediated knock-down of STAT3 or STAT3 overexpression strategies.

RESULTS

HepG2 and Huh-7 cells, which had lower levels of pSTAT3 than SK-HEP1 cells, were more sensitive to cetuximab treatment when compared with SK-HEP1 cells. Although none of these cell lines was sensitive to NSC 74859 alone, NSC 74859 potentiated the antiproliferative effect of cetuximab in all three cell lines. siRNA knock-down of STAT3 increased the sensitivity of these cell lines to cetuximab, whereas STAT3 overexpression antagonized these effects.

CONCLUSIONS

Enhanced growth inhibition in hepatoma cells treated with both NSC 74859 and cetuximab suggests that cetuximab resistance is probably mediated via STAT3. Combination therapy using both inhibitors of EGFR and STAT3 signalling warrants further investigation under in vivo condition.

A universal combinatorial design of antibody framework to graft distinct CDR sequences: a bioinformatics approach

Antibody (Ab) humanization is crucial to generate clinically relevant biologics from hybridoma-derived monoclonal antibodies (mAbs). In this study, we integrated antibody structural information from the Protein Data Bank with known back-to-mouse mutational data to build a universal consensus of framework positions (10 heavy and 7 light) critical for the preservation of the functional conformation of the Complimentarity Determining Region of antibodies. On the basis of FR consensus, we describe here a universal combinatorial library suitable for humanizing exogenous antibodies by CDR-grafting. The six CDRs of the murine anti-human EGFR Fab M225 were grafted onto a distinct (low FR sequence similarity to M225) human FR sequence that incorporates at the 17 FR consensus positions the permutations of the naturally observed amino acid diversities. Ten clones were selected from the combinatorial library expressing phage-displayed humanized M225 Fabs. Surprisingly, 2 of the 10 clones were found to bind EGFR with stronger affinity than M225. Cell-based assays demonstrated that the 10 selected clones retained epitope specificity by blocking EGFR phosphorylation and thus hindering cellular proliferation. Our results suggest that there is a universal and structurally rigid near-CDR set of FR positions that cooperatively support the binding conformation of CDRs.

Bispecific designed ankyrin repeat proteins (DARPins) targeting epidermal growth factor receptor inhibit A431 cell proliferation and receptor recycling

The EGF receptor (EGFR) has been implicated in the development and progression of many tumors. Although monoclonal antibodies directed against EGFR have been approved for the treatment of cancer in combination with chemotherapy, there are limitations in their clinical efficacy, necessitating the search for robust targeting molecules that can be equipped with new effector functions or show a new mechanism of action. Designed ankyrin repeat proteins (DARPins) may provide the targeting component for such novel reagents. Previously, four DARPins were selected against EGFR with (sub)nanomolar affinity. As any targeting module should preferably be able to inhibit EGFR-mediated signaling, their effect on A431 cells overexpressing EGFR was examined: three of them were shown to inhibit proliferation by inducing G(1) arrest, as seen for the Food and Drug Administration-approved antibody cetuximab. To understand this inhibitory mechanism, we mapped the epitopes of the DARPins using yeast surface display. The epitopes for the biologically active DARPins overlapped with the EGF-binding site, whereas the fourth DARPin bound to a different domain, explaining the lack of a biological effect. To optimize the biological activity of the DARPins, we combined two DARPins binding to different epitopes with a flexible linker or with a leucine zipper, leading to a homodimer. The latter DARPin was able to reduce surface EGFR by inhibiting receptor recycling, leading to a dramatic decrease in cell viability. These results indicate that multispecific EGFR-specific DARPins are superior to cetuximab and may form the basis of new opportunities in tumor targeting and tumor therapy.

Role of β4 integrin phosphorylation in human invasive squamous cell carcinoma: regulation of hemidesmosome stability modulates cell migration

Hemidesmosomes (HDs) are multiprotein structures that anchor epithelia to the basement membrane. During squamous cell carcinoma (SCC) invasion, there is a reduction in the number of HDs, which may facilitate dissemination. Mechanisms of HD disassembly are incompletely understood. Previous work has shown that epidermal growth factor (EGF)-induced phosphorylation of the β4 integrin on three of its serines, S(1356)S(1360)S(1364), can induce HD disassembly in normal cells. Here, we examine the role of β4 integrin serine phosphorylation in SCC. We have found that around 60% of invasive cutaneous SCC show increased β4 phosphorylation on S(1356) when compared with carcinoma in situ or normal tissue. To assess the mechanisms by which SCC increases β4 phosphorylation, we performed in vitro analyses. Compared with keratinocytes, SCC cells showed increased levels of S(1356) phosphorylation in the absence of EGF, correlating with reduced HD-like structures. In addition, phospho-S(1356) signal was largely segregated from other HD components. Epidermal growth factor receptor and PKC inhibitors inhibited basal levels of S(1356) phosphorylation in SCC, suggesting that cells use intrinsic mechanisms to activate the EGF signaling pathway to induce β4 phosphorylation. Moreover, these inhibitors stabilized HD-like structures in SCC cells and reduced their migratory ability. Mutation of S(1356)S(1360)S(1364) in SCC cells to non-phosphorylatable alanines stabilized HD-like structures and substantially reduced migration, while mutation into phosphorylation mimicking aspartate reduced HD-like structures but had no effect on migration, suggesting that serine phosphorylation function is releasing anchorage rather than promoting migration. Altogether these results suggest that β4 serine phosphorylation may have an important role during SCC invasion by destabilizing HDs and facilitating migration.

Phase II trial of cetuximab in the treatment of persistent or recurrent squamous or non-squamous cell carcinoma of the cervix: a Gynecologic Oncology Group study

PURPOSE

The Gynecologic Oncology Group (GOG) conducted a phase II trial to assess the efficacy and tolerability of the anti-EGFR antibody cetuximab, in persistent or recurrent carcinoma of the cervix.

PATIENTS AND METHODS

Eligible patients had cervical cancer, measurable disease, and GOG performance status ≤2. Treatment consisted of cetuximab 400 mg/m(2) initial dose followed by 250 mg/m(2) weekly until disease progression or prohibitive toxicity. The primary endpoints were progression-free survival (PFS) at 6 months and response. The study used a 2-stage group sequential design.

RESULTS

Thirty-eight patients were entered with 3 exclusions, leaving 35 evaluable for analysis. Thirty-one patients (88.6%) received prior radiation as well as either 1 (n=25, 71.4%) or 2 (n=10) prior cytotoxic regimens. Twenty-four patients (68.6%) had a squamous cell carcinoma. Grade 3 adverse events possibly related to cetuximab included dermatologic (n=5), GI (n=4), anemia (n=2), constitutional (n=3), infection (n=2), vascular (n=2), pain (n=2), and pulmonary, neurological, vomiting and metabolic (n=1 each). No clinical responses were detected. Five patients (14.3%; two-sided 90% CI, 5.8% to 30%) survived without progression for at least 6 months. The median PFS and overall survival (OS) times were 1.97 and 6.7 months, respectively. In this study, all patients with PFS at 6 months harbored tumors with squamous cell histology.

CONCLUSION

Cetuximab is well tolerated but has limited activity in this population. Cetuximab activity may be limited to patients with squamous cell histology.

A glimpse of the future: where will new combinations of diagnostics and therapies take us?

The field of radiation oncology has evolved, especially in the past 20 years. Advances in technology, particularly in computing power, software, and imaging, have fueled contributions to cancer care. It is currently fashionable to say that many of these advances have only served to increase costs of care without clear evidence of benefit, and certainly, efforts to evaluate the value of radiation oncology treatments are needed. However, it is undeniable that the future of radiation oncology depends on discovering such advances and to demonstrate that these increase the therapeutic index of treatment. Across the global radiation oncology community, investigations are proceeding in which innovative means are being used to achieve this goal. We review some of these novel methods to improve the therapeutic index of radiation therapy.

Development of targeted therapy for squamous cell carcinomas of the head and neck

Targeted therapy is a very exciting era in the treatment of squamous cell carcinomas of the head and neck. After adding cetuximab to conventional chemotherapy and radiation therapy, we are strongly considering the role of induction chemotherapy with the addition of docetaxel. At the same time, other new treatments, especially targeted agents and novel combined regimens, are being evaluated in ongoing clinical trials. For example, several trials are attempting to combine docetaxel and cetuximab in chemoradiation or induction settings. However, in the near future we are likely to see a strong presence of targeted agents that have been found to be not only effective, but also less toxic than conventional chemotherapeutic agents. Their toxicity profiles make them eligible for addition to radiation treatment strategies, as well as other chemotherapy agents, or even for replacing these chemotherapy agents. In this article, we are going to review the indications and current role of cetuximab, tyrosine kinase inhibitors (gefitinib and erlotinib), dual inhibitors, IGF receptor inhibitors, as well as other agents that are in development for treatment of head and neck squamous cell carcinomas.

Analysis of the anti-tumor effect of cetuximab using protein kinetics and mouse xenograft models

BACKGROUND

The binding of EGFR and its ligands leads to autophosphorylation of receptor tyrosine kinase as well as subsequent activation of signal transduction pathways that are involved in regulating cellular proliferation, differentiation, and survival. An EGFR inhibitor, cetuximab binds to EGFR and consequently blocks a variety of cellular processes. KRAS/BRAF mutations are known to be associated with a low response rate to cetuximab. In the present study, to clarify the anti-tumor mechanisms of cetuximab, we evaluated the KRAS/BRAF status, phosphorylation level of the EGFR pathway, and the tumor suppression effect in vivo, using a human colon cancer cell line HT29, which exhibited the highest EGFR expression in response to the cetuximab therapy among the 6 colorectal cancer cell lines tested.

FINDINGS

The conventional growth suppression assay did not work efficiently with cetuximab. EGF, TGF-α, and IGF activated the EGFR/MAPK cell signaling pathway by initiating the phosphorylation of EGFR. Cetuximab partially inhibited the EGFR/MAPK pathway induced by EGF, TGF-α, and IGF. However, cetuximab exposure induced the EGFR, MEK, and ERK1/2 phosphorylation by itself. Mouse xenograft tumor growth was significantly inhibited by cetuximab and both cetuximab-treated and -untreated xenograft specimens exhibited phosphorylations of the EGFR pathway proteins.

CONCLUSIONS

We have confirmed that cetuximab inhibited the EGFR/MAPK pathway and reduced tumor growth in the xenografts while the remaining tumor showed EGFR pathway activation. These results suggest that: ( i ) The effect of cetuximab in growth signaling is not sufficient to induce complete growth suppression in vitro; ( ii ) time-course monitoring may be necessary to evaluate the effect of cetuximab because EGFR signaling is transmitted in a minute order; and ( iii ) cetuximab treatment may have cells acquired resistant selectively survived in the heterogeneous cancer population.

Differential and synergistic effects of epidermal growth factor receptor antibodies on unliganded ErbB dimers and oligomers

Antibodies directed against the epidermal growth factor receptor (EGFR) offer a potentially powerful therapeutic approach against cancers driven by the EGFR pathway. EGFR antibodies are believed to halt cell surface activation by blocking ligand-induced receptor tyrosine kinase activation, i.e., ligand binding, a change in conformation, or the monomer-dimer transition. In this work, we demonstrate that wild-type EGFR and the truncated de2-7-EGFR (tumor-associated mutant) formed unliganded homo-oligomers and examined the effects of two clinically relevant antibodies on the conformation and quaternary state of these ligand-free EGFR oligomers on the surface of cells. The EGFR antibodies were mAb528, a ligand-blocking antibody that binds domain III, and mAb806, a conformationally sensitive antibody that binds near the dimer interface in domain II. We used a model cellular system, BaF/3 cells, with GFP-tagged receptors in the absence of interference from secreted ligands or other erbB receptor members. Different antibody-mediated effects (conformational transition, receptor cross-linking, or receptor dissociation) were distinguished by combining two complementary biophysical techniques: image correlation spectroscopy (submicrometer scale clustering) and homo-Forster resonance energy transfer (association and/or conformation on a 1-10 nm scale). mAb528 cross-linked EGFR into an inactive EGFR dimer of dimers but had no effect when added to de2-7-EGFR oligomers. mAb806 had a minor effect on EGFR dimers as expected from its poor binding to a conformationally shielded epitope on wtEGFR but bound de2-7-EGFR oligomers, causing a conformational change in the intracellular C-terminal GFP-tagged tail. The combination of the two antibodies had synergistic effects, increasing the level of cross-linking of de2-7-EGFR, but did not lead to enhanced cross-linking of EGFR. The results reveal new modes of receptor-antibody interactions for EGFR and de2-7-EGFR.

Targeting epidermal growth factor receptor in the treatment of non-small-cell lung cancer

IMPORTANCE OF THE FIELD

The management of non-small-cell lung cancer (NSCLC) has undergone a paradigm shift in the last decade, with the survival advantage demonstrated by the incorporation of anti-epidermal growth factor receptor (EGFR) agents to the standard treatment of advanced/metastatic NSCLC.

AREAS COVERED IN THIS REVIEW

We review the existing data regarding the distinct anti-EGFR agents in the NSCLC treatment and the potential role of the investigated biomarkers in the clinical outcome.

WHAT THE READER WILL GAIN

Tyrosine kinase inhibitors have been used in first-line, second-line and more settings with extremely good results in a subgroup of patients. Cetuximab remains the only anti-EGFR monoclonal antibody to show survival benefit when combined with a cytotoxic agent in the front-line setting. Anti-EGFR treatment is associated with a dramatic clinical benefit in a subgroup of patients, emphasizing the importance of customizing treatment. Several biomarkers have been investigated for their predictive or prognostic value. Validation of identification of biomarkers remains a focus of intense research that may ultimately guide therapeutic decision making, as none of these is considered ideal to discriminate responding from non-responding patients. However, the current evidence of the EGFR mutation analysis from a recent randomised trial suggests that EGFR mutation analysis is quite a good predictive marker for responsiveness to anti-EGFR TKIs. Moreover, the identification of surrogate markers to indicate optimal activity of the anti-EGFR agent is also needed. This review article provides data from large clinical trials using anti-EGFR agents and correlates these results with the tested biomarkers.

TAKE HOME MESSAGE

EGFR inhibition has shown very encouraging results and has improved the outcome of the NSCLC treatment. However, a plateau of significant clinical benefit seems to have been reached and we believe that the time to move away from the traditional treatment approach to more individualizing therapies has come.

Short-term outcomes of cetuximab combined with standard chemotherapy as first line setting for Chinese patients with non-small cell lung cancer: a report of 12 cases

Cetuximab combined with chemotherapy has been used to treat Non-small cell lung cancer (NSCLC) in recent years, however, the data from China was rare. This study was to summarize our experiences in treating NSCLC patients with cetuximab in the first line setting. From October 1st 2006 to Jun 30th 2010, twelve NSCLC patients were treated with cetuximab combined standard chemotherapy as first line setting in Sun Yat-sen University Cancer Center entered the study and the short-term efficacy and safety were analyzed. A total of 132 cycles of cetuximab treatment, with a median of nine cycles in the whole group were administered. The ORR was 41.7% (5/12), DCR was 83.3% (10/12), median TTP was 5.5 months (2-23), and median OS was 9 months (2-48) in the whole group. There were 75% (9/12) patients occurred acne-like rash within first 3 weeks, their ORR was 55.6% (5/9), DCR was 100% (9/9), however, ORR and DCR in patients who didn't occurred acne-like rash within first 3 weeks were 0 and 33.3% (1/3), the difference ORR between two group was insignificant (P = 0.091), however, DCR was significant different (P = 0.007). There no treatment-associated death and no cetuximab-associated discontinuation. The incidence of acne-like rash was 83.3% (10/12) and 75% (9/12) occurred within first 3 weeks, there were eight patients suffered side effects associated with chemotherapy. So we can draw a conclusion that the short-term outcome of cetuximab application in first line setting for patients with NSCLC were promising since the higher ORR and DCR, especially those occurred acne-like rash within the first 3 weeks, and the addition of cetuximab in this population was safe.

EGFR Targeting in Hormone-Refractory Prostate Cancer: Current Appraisal and Prospects for Treatment

The incidence of prostate cancer increases with age and because of its high prevalence this disease has become a major public health concern. Despite advances in our understanding of the biological mechanisms responsible for the development of this cancer, the transition to the hormone refractory stage (HRPC) and metastatic progression pose real problems of clinical management. Currently, docetaxel chemotherapy has been shown to have a slight but significant impact on survival, though the gain in median survival is still less than three months. Research is therefore continuing to improve treatment outcomes. The progression of prostate cancer is accompanied by the overexpression of EGFR (epidermal growth factor receptor) in a very large majority of cases, suggesting that this may play a mechanistic role. Unfortunately, although preclinical findings seem to be promising for therapies targeting the EGFR in HRPC, current clinical results are disappointing. These results should however encourage us to look for different ways of using anti-EGFR agents or combining them with other targeted therapies.

Targeted radionuclide therapy in head and neck cancer

There is great potential for targeted radionuclide therapy (TRT) in the treatment of head and neck cancer. In recent years, developments in fields such as antigen screening, protein engineering, and cancer biology have facilitated the rational design of targeted pharmaceuticals, with monoclonal antibodies forming the most rapidly expanding category. TRT may be a promising way to improve targeted treatment, especially in head and neck cancer, because of the intrinsic radiosensitivity of this tumor type. TRT may also provide a good foundation on which to build rational biologic combination therapies. In the next few years the use of TRT may offer new opportunities for further improvement of the therapeutic ratio that potentially may obviate or reduce the need for conventional cytotoxics.

Cetuximab, paclitaxel, carboplatin, and radiation for head and neck cancer: a toxicity analysis

OBJECTIVE

To determine the feasibility and toxicity of the addition of cetuximab to paclitaxel, carboplatin, and concurrent radiation for patients with head and neck cancer.

MATERIALS AND METHODS

Patients with stage III or IV locally advanced squamous cell cancer of the head and neck, without distant organ metastases, were eligible. Patients received 4 weeks of induction cetuximab followed by weekly cetuximab, paclitaxel, carboplatin, and concurrent radiation.

RESULTS

Thirty-two patients were assessable for chemoradiation toxicities. Grade 3 and grade 4 mucositis occurred in 53% and 16% of patients, respectively. Grade 3 and grade 4 radiation dermatitis occurred in 44% and 9% of patients, respectively. Grade 3/4 radiation dermatitis was associated with the use of intensity modulated radiation therapy (64% vs.14%, respectively, P < 0.0001). Grade 3 and grade 4 cetuximab associated acneiform rash developed in 6% and 3% of patients. Overall 21 patients (66%) had any grade 3 toxicity and 10 patients (31%) had any grade 4 toxicity. The percentages of the intended total dose delivered of carboplatin, cetuximab, paclitaxel, and radiation were 86%, 89%, 89%, and 96%, respectively.

CONCLUSION

Cetuximab, when combined with paclitaxel, carboplatin and intensity modulated radiation therapy, increases dermatologic toxicity but does not increase mucosal toxicity as compared with previous Brown University Oncology Group studies of paclitaxel, carboplatin, and conventional radiation for patients with head and neck cancer.

Colorectal cancer in review: the role of the EGFR pathway

IMPORTANCE OF THE FIELD

The overexpression of EGFR has been documented in 30-90% of cases of advanced colorectal cancer (CRC). An increased understanding of the EGFR pathway in CRC has paved the way for the development of other targeted agents to augment therapeutic efficacy as well as for efforts to circumvent tumor resistance to therapy.

AREAS COVERED IN THIS REVIEW

Our aim is to discuss the recent progress in the role of the EGFR pathway, the status of anti-EGFR therapeutic agents currently in use and the rationale for the development of novel agents that work along the pathway for the treatment of CRC.

WHAT THE READER WILL GAIN

The readers will learn about the development and evolution of mAbs directed against EGFR as well as tyrosine kinase inhibitors in the management of CRC patients. In the same vein, determination of optimal dosing and better methods of defining those subsets of patients most likely to benefit will be discussed.

TAKE HOME MESSAGE

All these data must encourage clinicians and basic researches to continue in their efforts to untangle the network behind EGFR and try to focus all that effort towards improving patient's quality of life as well as survival.

Effect of cetuximab treatment in squamous cell carcinomas

The purpose of this study was to assess the effects of the monoclonal antibody cetuximab in a panel of cultured squamous cell carcinoma cell lines. This antibody, targeting the epidermal growth factor receptor (EGFR), is emerging as a promising agent for treatment of several cancers. As this antibody comes into clinical use, the identification of predictive markers of therapeutic benefit remains a pressing issue. Cells were first characterized according to EGFR expression, cell doubling time, and BRAF and K-ras mutations. The effects of cetuximab on cell-cycle distribution, proliferation, as well as cell growth rate were then evaluated. Cetuximab decreased cell proliferation in three out of four cell lines in a time-dependent manner, and all cell lines were found to exhibit wild type K-ras and BRAF genes. A possible correlation between EGFR expression and cetuximab effect on growth inhibition rate was observed, whereas reduction of cell doubling time seemed to be more dependent on initial growth rate. In addition, other factors may further influence the long-term treatment response of cetuximab. Moreover, the time-dependent manner of cetuximab response demonstrates the importance of long-term measurements for this substance.

Enhanced antibody half-life improves in vivo activity

Improved affinity for the neonatal Fc receptor (FcRn) is known to extend antibody half-life in vivo. However, this has never been linked with enhanced therapeutic efficacy. We tested whether antibodies with half-lives extended up to fivefold in human (h)FcRn transgenic mice and threefold in cynomolgus monkeys retain efficacy at longer dosing intervals. We observed that prolonged exposure due to FcRn-mediated enhancement of half-life improved antitumor activity of Fc-engineered antibodies in an hFcRn/Rag1(-/-) mouse model. This bridges the demand for dosing convenience with the clinical necessity of maintaining efficacy.

Targeting the epidermal growth factor receptor in epithelial ovarian cancer: current knowledge and future challenges

The epidermal growth factor receptor is overexpressed in up to 60% of ovarian epithelial malignancies. EGFR regulates complex cellular events due to the large number of ligands, dimerization partners, and diverse signaling pathways engaged. In ovarian cancer, EGFR activation is associated with increased malignant tumor phenotype and poorer patient outcome. However, unlike some other EGFR-positive solid tumors, treatment of ovarian tumors with anti-EGFR agents has induced minimal response. While the amount of information regarding EGFR-mediated signaling is considerable, current data provides little insight for the lack of efficacy of anti-EGFR agents in ovarian cancer. More comprehensive, systematic, and well-defined approaches are needed to dissect the roles that EGFR plays in the complex signaling processes in ovarian cancer as well as to identify biomarkers that can accurately predict sensitivity toward EGFR-targeted therapeutic agents. This new knowledge could facilitate the development of rational combinatorial therapies to sensitize tumor cells toward EGFR-targeted therapies.

Integrating epidermal growth factor receptor-targeted therapies into platinum-based chemotherapy regimens for newly diagnosed non-small-cell lung cancer

Cytotoxic chemotherapy treatment for patients with advanced non-small-cell lung cancer (NSCLC) has reached a plateau, but further improvements are expected with integration of targeted therapies. Epidermal growth factor receptor (EGFR)-directed therapies are of particular interest because the EGFR is frequently expressed in tumors and associated with poorer outcome. Thus, blockade of the EGFR should improve outcome. Blockade can be achieved by tyrosine kinase inhibitors (TKIs) or monoclonal antibodies (MoAbs). Both approaches have been evaluated in advanced NSCLC. As single agents, EGFR-directed TKIs have demonstrated efficacy in patients previously treated with chemotherapy. When combined with first-line platinum-based chemotherapy, TKIs failed to improve the outcome. In contrast, MoAbs in combination with platinum-based first-line chemotherapy showed promising efficacy in phase II trials. Two phase III trials with chemotherapy with or without cetuximab have been performed in patients with advanced NSCLC. Other EGFR-directed MoAbs and TKIs are in earlier stages of clinical development.

The development, optimization and validation of an ELISA bioanalytical method for the determination of Cetuximab in human serum

Cetuximab is a chimeric IgG1 monoclonal antibody that inhibits epidermal growth factor receptor (EGFR). Additionally, Cetuximab, used in combination therapy, potentiates the effects of chemotherapy and radiation therapy in eradicating well-established tumors. Recently, a combination of Cetuximab and newly developed chemotherapeutic candidate drugs is being investigated for use as a new-generation chemotherapy cocktail. Therefore, there is an increasing need for a highly selective immunoassay to detect Cetuximab at low concentration levels in human serum. We report a newly developed ELISA that is validated under FDA-GLP regulations for the detection of Cetuximab. It is highly selective and achieves a lower limit of quantitation of 0.31 µg/mL. We have validated a selective and sensitive bioanalytical method.

The drug-resistance to gefitinib in PTEN low expression cancer cells is reversed by irradiation in vitro

Background

Despite of the recent success of EGFR inhibitory agents, the primary drug-resistant becomes a major challenge for EGFR inhibitor therapies. PTEN gene is an important positive regulatory factor for response to EGFR inhibitor therapy. Low-expression of PTEN is clearly one of the important reasons why tumor cells resisted to tyrosine kinase inhibitors.

Methods

To investigate the drug-resistance reversal to gefitinb and the mechanism in PTEN low expression cells which radiated with X-rays in vitro, We demonstrated that H-157 lung cancer cells (low-expression of PTEN but phospho-EGFR overexpressed tumor cells) exposed to X-rays. The PTEN expressions and radiosensitizing effects of tyrosine kinase inhibitor before and after irradiation were observed. The cell-survival rates were evaluated by colony-forming assays. The cell apoptosis was investigated using FCM. The expressions of phospho-EGFR and PTEN were determined by Western blot analysis.

Results

The results showed that the PTEN expressions were significantly enhanced by X-rays. Moreover, the cell growth curve and survival curve were down-regulated in the gefitinib-treated groups after irradiation. Meanwhile, the radiation-induced apoptosis of tumor cells was increased by inhibition of the EGFR through up-regulation of PTEN.

Conclusion

These results suggested that PTEN gene is an important regulator on TKI inhibition, and the resistance to tyrosine kinase inhibitors might be reversed by irradiation in PTEN low expression cancer cells.

Targeting EGFR resistance networks in head and neck cancer

A core set of oncoproteins is overexpressed or functionally activated in many types of cancer, and members of this group have attracted significant interest as subjects for development of targeted therapeutics. For some oncoproteins such as EGFR/ErbB1, both small molecule and antibody agents have been developed and applied in the clinic for over a decade. Analysis of clinical outcomes has revealed an initially unexpected complexity in the response of patients to these agents. Diverse factors, including developmental lineage of the tumor progenitor cell, co-mutation or epigenetic modulation of genes encoding proteins in an extended EGFR signaling network or regulating core survival responses in individual tumors, and environmental factors including inflammatory agents and viral infection, all have been identified as modulating response to treatment with EGFR-targeted drugs. Second and third generation therapeutic strategies increasingly incorporate knowledge of cancer type-specific signaling environments, in a more personalized treatment approach. This review takes squamous cell carcinoma of the head and neck (SCCHN) as a specific example of an EGFR-involved cancer with idiosyncratic biological features that influence design of treatment modalities, with particular emphasis on commonalities and differences with other cancer types.

Cetuximab/C225-induced intracellular trafficking of epidermal growth factor receptor

The monoclonal antibody C225 interacts with the ectodomain of the epidermal growth factor (EGF) receptor (EGFR) to block ligand binding and initiates receptor endocytosis and intracellular trafficking. The data herein show that C225-dependent EGFR trafficking relocalizes the receptor to the endoplasmic reticulum (ER) and nucleus. This mechanism, which also involves interaction of the C225-internalized receptor with the Sec61 translocon within the ER, is, in most respects, analogous to the pathway previously described for EGF-induced trafficking to the ER and nucleus. However, although inhibition of receptor tyrosine kinase activity blocks EGF-induced nuclear localization of the receptor, the same kinase inhibitors stimulate C225-dependent nuclear localization of EGFR in the nucleus. In contrast, the kinase inhibitor Lapatinib fails to stimulate nuclear accumulation of the receptor in C225-treated cells and does not provoke receptor dimerization as do inhibitors that recognize the open conformation of the receptor kinase. This suggests that inhibitor-dependent receptor dimerization may facilitate C225-induced receptor trafficking.

A truncated soluble epidermal growth factor receptor-Fc fusion ligand trap displays anti-tumour activity in vivo

A number of therapeutic strategies including small molecule tyrosine kinase inhibitors and monoclonal antibodies have been developed to target the epidermal growth factor receptor (EGFR) signalling axis for the treatment of cancer. To date, the focus of therapeutic intervention has been the EGFR itself. In the current study, we have assembled and expressed in mammalian cells a soluble, EGFR ligand trap comprising the first 501 amino acids of the mature EGFR sequence fused in-frame with a human IgG Fc domain. The fusion protein, designated sEGFR501.Fc, was secreted as a 220 kDa disulphide-linked homodimer that exhibited high affinity (0.4-8 nM) in competition assays for a number of EGFR ligands including EGF and transforming growth factor-alpha (TGF-alpha). sEGFR501.Fc inhibited EGF-stimulated tyrosine phosphorylation of the EGFR of the lung cancer cell lines A549 and H1437, and inhibited and blocked the proliferation of H1437 cells. Administration of sEGFR501.Fc to mice bearing human tumour xenografts derived from A431 (epidermoid carcinoma) and DU145 (androgen-independent prostate cancer) tumour cell lines resulted in modest retardation of tumour growth. These results provide proof-in-principle that using high affinity soluble receptors is a viable method for inhibiting multi-ligand systems, and the impetus to optimize this approach and develop reagents with greater affinity and broader specificity.

Ligand-based targeted therapy for cancer tissue

BACKGROUND

Limited accessibility of drugs to the tumor tissues, the requirement of high doses, intolerable cytotoxicity, the development of multiple drug resistance and non-specific targeting are obstacles to the clinical use of cancer drugs and cancer therapy.

OBJECTIVE

Drug delivery through carrier systems to cancerous tissue is no longer simply wrapping up cancer drugs in a new formulation for different routes of delivery, rather the focus is on targeted cancer therapy.

METHODS

This review summarizes the exploitation of drug-loaded nanocarrier conjugates with various targeting moieties for the delivery and targeting of anticancer drugs and describes the current status of and challenges in the field of nanocarrier-aided drug delivery and drug targeting.

CONCLUSION

The discovery of targeting ligand to cancer cells and the development of ligand-targeted therapy will help us to improve therapeutic efficacy and reduce side effects. Unlike other forms of therapy, it will allow us to maintain quality of life for patients, while efficiently attacking the cancer tissue. It indicates that ligands have a pivotal role in cancer cell targeting.

Cetuximab plus chemotherapy in patients with advanced non-small-cell lung cancer (FLEX): an open-label randomised phase III trial

BACKGROUND

Use of cetuximab, a monoclonal antibody targeting the epidermal growth factor receptor (EGFR), has the potential to increase survival in patients with advanced non-small-cell lung cancer. We therefore compared chemotherapy plus cetuximab with chemotherapy alone in patients with advanced EGFR-positive non-small-cell lung cancer.

METHODS

In a multinational, multicentre, open-label, phase III trial, chemotherapy-naive patients (>or=18 years) with advanced EGFR-expressing histologically or cytologically proven stage wet IIIB or stage IV non-small-cell lung cancer were randomly assigned in a 1:1 ratio to chemotherapy plus cetuximab or just chemotherapy. Chemotherapy was cisplatin 80 mg/m(2) intravenous infusion on day 1, and vinorelbine 25 mg/m(2) intravenous infusion on days 1 and 8 of every 3-week cycle) for up to six cycles. Cetuximab-at a starting dose of 400 mg/m(2) intravenous infusion over 2 h on day 1, and from day 8 onwards at 250 mg/m(2) over 1 h per week-was continued after the end of chemotherapy until disease progression or unacceptable toxicity had occurred. The primary endpoint was overall survival. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00148798.

FINDINGS

Between October, 2004, and January, 2006, 1125 patients were randomly assigned to chemotherapy plus cetuximab (n=557) or chemotherapy alone (n=568). Patients given chemotherapy plus cetuximab survived longer than those in the chemotherapy-alone group (median 11.3 months vs 10.1 months; hazard ratio for death 0.871 [95% CI 0.762-0.996]; p=0.044). The main cetuximab-related adverse event was acne-like rash (57 [10%] of 548, grade 3).

INTERPRETATION

Addition of cetuximab to platinum-based chemotherapy represents a new treatment option for patients with advanced non-small-cell lung cancer.

FUNDING

Merck KGaA.

Cetuximab-mediated cellular cytotoxicity is inhibited by HLA-E membrane expression in colon cancer cells

Cetuximab, an anti-epidermal growth factor receptor monoclonal antibody, has been shown to increase the median survival of colorectal cancer patients. We previously reported that the expression of HLA-E is significantly increased in primary human colorectal cancer, perhaps contributing to tumour escape from immune surveillance. To establish if HLA-E could be a factor that renders colorectal cancer cells less susceptible to antibody-dependent cellular cytotoxicity (ADCC), in the present study we analysed Cetuximab-mediated cytotoxicity against several colorectal cancer cell lines expressing, or not, HLA-E at the cell surface. We first observed that colorectal cancer cells treated with Cetuximab were killed more efficiently by ADCC. Interestingly, treatment of target cells with recombinant human-beta2-microglobulin inhibits Cetuximab-mediated ADCC through HLA-E membrane stabilization. The specific immunosuppressive role of HLA-E was confirmed using an anti-NKG2A monoclonal antibody, that restored the ability of immune cells to kill their target. This result demonstrates that HLA-E at the cell surface can reliably suppress the ADCC effect. On the other hand, Cetuximab induced a direct growth inhibition but only at high concentrations; furthermore, the CDC effect was quite moderate, and we failed to observe a pro-apoptotic effect. Taking into account that our findings suggest that ADCC activity is the main anti-tumour effect observed at clinically achievable concentrations of Cetuximab at the tumour site, we suggest that determination of HLA-E in colorectal cancer could be relevant to predict success of Cetuximab treatment.

Persistent elimination of ErbB-2/HER2-overexpressing tumors using combinations of monoclonal antibodies: relevance of receptor endocytosis

Monoclonal antibodies (mAbs) to ErbB-2/HER2 or to its sibling, the epidermal growth factor receptor (EGFR), prolong survival of cancer patients, especially when combined with cytotoxic therapies. However, low effectiveness of therapeutic mAbs and the evolution of patient resistance call for improvements. Here we test in animals pairs of anti-ErbB-2 mAbs and report that pairs comprising an antibody reactive with the dimerization site of ErbB-2 and an antibody recognizing another distinct epitope better inhibit ErbB-2-overexpressing tumors than other pairs or the respective individual mAbs. Because the superiority of antibody combinations extends to tumor cell cultures, we assume that nonimmunological mechanisms contribute to mAb synergy. One potential mechanism, namely the ability of mAb combinations to instigate ErbB-2 endocytosis, is demonstrated. Translation of these lessons to clinical applications may enhance patient response and delay acquisition of resistance.

Alternative dosing schedules for cetuximab: a role for biweekly administration?

The anti-epidermal growth factor receptor targeted monoclonal antibody (MoAb) cetuximab has established efficacy as a single agent and in combination with other modalities (chemotherapy, radiation therapy) in head and neck cancer and metastatic colorectal cancer. The agent is typically administered weekly; however, the development of a biweekly dosing regimen for cetuximab would provide treatment flexibility when combined with biweekly or longer chemotherapy regimens. The feasibility for biweekly dosing with cetuximab is supported by several factors. Biweekly dosing with MoAbs has been effective in multiple tumor types. Although cetuximab is currently administered on a weekly schedule, pharmacokinetic data demonstrate that cetuximab has a long terminal half-life, allowing administration of a biweekly schedule. Results from phase I studies show that a biweekly schedule of cetuximab is well tolerated, exhibits similar pharmacokinetics and pharmacodynamics to conventional weekly dosing, and does not seem to compromise efficacy. Additional studies are therefore warranted to further evaluate biweekly dosing for cetuximab in order to optimize treatment outcomes and convenience for patients.

Novel human antibody therapeutics: the age of the Umabs

Monoclonal antibodies represent a major and increasingly important category of biotechnology products for the treatment of human diseases. The state-of-the-art of antibody technology has evolved to the point where therapeutic monoclonal antibodies, that are practically indistinguishable from antibodies induced in humans, are routinely generated. We depict how our science-based approach can be used to further improve the efficacy of antibody therapeutics, illustrated by the development of three monoclonal antibodies for various cancer indications: zanolimumab (directed against CD4), ofatumumab (directed against CD20) and zalutumumab (directed against epidermal growth factor receptor).

Autocrine production of amphiregulin predicts sensitivity to both gefitinib and cetuximab in EGFR wild-type cancers

PURPOSE

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors, gefitinib and erlotinib, lead to significant tumor regressions in 10% to 15% of non-small cell lung cancer (NSCLC) patients with EGFR activating mutations. However, 30% to 40% of NSCLC patients, majority of whom are EGFR wild-type, develop stable disease following EGFR tyrosine kinase inhibitor therapy. EGFR-directed antibodies (cetuximab) are effective treatments for head and neck squamous cell carcinomas, which seldom contain EGFR mutations. The determinant(s) of efficacy of EGFR-targeted therapies in EGFR wild-type cancers is not well defined.

EXPERIMENTAL DESIGN

We examined the relationship of EGFR ligands, EGF, transforming growth factor-alpha,and amphiregulin and the efficacy of gefitinib and cetuximab in EGFR wild-type NSCLC (n=10) and head and neck squamous cell carcinoma (n=4) cell lines. We compared amphiregulin expression using immunohistochemistry in EGFR wild-type NSCLC patients (n=24) that developed either stable or progressive disease following erlotinib or gefitinib treatment.

RESULTS

Cell lines which produced >or=20 pmol/L amphiregulin, as detected by an ELISA, were significantly more likely to be growth inhibited by both gefitinib and cetuximab than those that produced minimal or no amphiregulin. In these cell lines, both cetuximab and gefitinib led to cell cycle arrest at the G(1)-S boundary and was associated with preferential inhibition of extracellular signal-regulated kinase 1/2 but not Akt signaling. Amphiregulin expression was significantly higher in NSCLC patients that developed stable disease compared with those that developed disease progression following gefitinib or erlotinib treatment.

CONCLUSIONS

Amphiregulin expression may help select EGFR wild-type patients who are likely to develop stable disease from EGFR-targeted therapies.

Targeting important pathways in head and neck cancer: from the bench to the clinic

Radiation therapy as single or combined modality (concurrent chemoradiotherapy) has been the cornerstone of treatment for squamous cell carcinoma of the head and neck for a long time. Fortunately, advances in tumor biology have provided new insights of tumor proliferation, metastases, migration and cell cycle regulation. The success seen with the use of cetuximab alone or in combination with conventional treatments has led the roadmap to discover other potential target mechanisms which may translate into better response rate with less local and systemic toxicity and improved overall survival. In this review, we discuss other cellular pathways that have shown to be involved in the carcinogenesis of squamous cell carcinoma of the head and neck and the actual efforts to target these mechanisms.

Growth inhibition of an established A431 xenograft tumor by a full-length anti-EGFR antibody following gene delivery by AAV

Therapeutic monoclonal antibodies continue to achieve clinical success for the treatment of many different diseases, particularly cancer. However, the production and purification of antibodies continues to be a time and labor-intensive process with considerable technical challenges. Gene-based delivery of antibodies may address this, via direct production within the host that achieves therapeutic levels. In this report, we validate the feasibility that gene-based delivery is a viable approach for efficacious delivery of antibodies in the preclinical and, presumably, clinical setting. We demonstrate high and sustained in vivo expression of the murine antihuman epidermal growth factor receptor antibody 14E1 following intramuscular delivery by adeno-associated virus (AAV) 2/1. Incorporating the Furin/2A technology for monocistronic expression of both heavy and light chains, we achieved sustained serum levels of full-length 14E1 peaking over 1 mg ml(-1) in athymic nude mice. In the A431 xenograft tumor model, 14E1 was capable of significantly inhibiting tumor growth and prolonging survival when AAV was administered prior to tumor challenge. Furthermore, 14E1 demonstrated significant antitumor efficacy against well-established tumors (approximately 400 mm(3)) when AAV was administered up to 20 days after tumor challenge. Here we demonstrate for the first time growth inhibition of a well-established tumor by a full-length antibody following delivery by AAV.

Displayed correlation between gene expression profiles and submicroscopic alterations in response to cetuximab, gefitinib and EGF in human colon cancer cell lines

Background

EGFR is frequently overexpressed in colon cancer. We characterized HT-29 and Caco-2, human colon cancer cell lines, untreated and treated with cetuximab or gefitinib alone and in combination with EGF.

Methods

Cell growth was determined using a variation on the MTT assay. Cell-cycle analysis was conducted by flow cytometry. Immunohistochemistry was performed to evaluate EGFR expression and scanning electron microscopy (SEM) evidenced the ultrastructural morphology. Gene expression profiling was performed using hybridization of the microarray Ocimum Pan Human 40 K array A.

Results

Caco-2 and HT-29 were respectively 66.25 and 59.24 % in G0/G1. They maintained this level of cell cycle distribution after treatment, suggesting a predominantly differentiated state. Treatment of Caco-2 with EGF or the two EGFR inhibitors produced a significant reduction in their viability. SEM clearly showed morphological cellular transformations in the direction of cellular death in both cell lines treated with EGFR inhibitors. HT-29 and Caco-2 displayed an important reduction of the microvilli (which also lose their erect position in Caco-2), possibly invalidating microvilli absorption function. HT-29 treated with cetuximab lost their boundary contacts and showed filipodi; when treated with gefitinib, they showed some vesicles: generally membrane reshaping is evident. Both cell lines showed a similar behavior in terms of on/off switched genes upon treatment with cetuximab. The gefitinib global gene expression pattern was different for the 2 cell lines; gefitinib treatment induced more changes, but directly correlated with EGF treatment.

In cetuximab or gefitinib plus EGF treatments there was possible summation of the morphological effects: cells seemed more weakly affected by the transformation towards apoptosis. The genes appeared to be less stimulated than for single drug cases.

Conclusion

This is the first study to have systematically investigated the effect of cetuximab or gefitinib, alone and in combination with EGF, on human colon cancer cell lines. The EGFR inhibitors have a weaker effect in the presence of EGF that binds EGFR. Cetuximab treatment showed an expression pattern that inversely correlates with EGF treatment. We found interesting cyto-morphological features closely relating to gene expression profile. Both drugs have an effect on differentiation towards cellular death.

Overview of the efficacy of cetuximab in recurrent and/or metastatic squamous cell carcinoma of the head and neck in patients who previously failed platinum-based therapies

BACKGROUND

The epidermal growth factor receptor (EGFR) inhibitor cetuximab is active in recurrent and/or metastatic squamous cell carcinoma of the head and neck (SCCHN). The activity of cetuximab was compared with that of commonly used treatments in this setting.

METHODS

All patients had recurrent and/or metastatic SCCHN and had progressed on cisplatin- or carboplatin-based chemotherapy. Efficacy data from 3 prospective studies (n=278 patients) that administered cetuximab as a single agent (n=103 patients) or combined with either cisplatin/carboplatin (n=96 patients) or cisplatin (n=79 patients) were compared with the results from a retrospective study of patients who received various second-line treatments (all treatments including best supportive care only, n=151 patients; chemotherapy, n=43 patients). Safety data considered were only those from the cetuximab studies.

RESULTS

Over the 3 cetuximab trials, overall response rates from 10% to 13% and disease control rates from 46% to 56% were observed. The median time to disease progression ranged between 2.2 months and 2.8 months, and the median overall survival ranged between 5.2 months and 6.1 months. No patients who progressed on cetuximab alone responded to additional platinum. These survival data compared favorably with those from the retrospective study (median survival, 3.4 months [n=151 patients] and 3.6 months [n=43 patients]). Cetuximab-based treatments generally were tolerated well, and cetuximab did not increase the side effects associated with platinum therapy.

CONCLUSIONS

Cetuximab has the potential to prolong survival in patients with recurrent and/or metastatic SCCHN who fail on platinum therapy compared with various second-line therapies. Cetuximab did not increase the toxicities associated with chemotherapy. The results obtained by treatment with cetuximab alone after platinum failure did not appear to differ from the results obtained by reintroducing platinum in combination with cetuximab.