Immune biomarkers of anti-EGFR monoclonal antibody therapy

The tumor antigen (TA)-targeted monoclonal antibodies (mAb) cetuximab and panitumumab target the human epidermal growth factor receptor and have been integrated into treatment regimens for advanced squamous cell carcinoma of the head and neck (SCCHN). The therapeutic efficacy of these mAbs has been found to be enhanced when combined with radiotherapy and chemotherapy. However, clinical trials indicate that these findings are limited to fewer than 20% of treated patients. Therefore, identifying patients who are likely to benefit from these agents is crucial to improving therapeutic strategies. Interestingly, it has been noted that TA-targeted mAbs mediate their effects by contributing to cell-mediated cytotoxicity in addition to inhibition of downstream signaling pathways. Here, we describe the potential immunogenic mechanisms underlying these clinical findings, their role in the varied clinical response and identify the putative biomarkers of antitumor activity. We review potential immunological biomarkers that affect mAb therapy in SCCHN patients, the implications of these findings and how they translate to the clinical scenario, which are critical to improving patient selection and ultimately outcomes for patients undergoing therapy.

Regorafenib: a review of its use in previously treated patients with progressive metastatic colorectal cancer

Regorafenib (Stivarga) is an inhibitor of multiple protein kinases, including those involved in oncogenesis, tumour angiogenesis and maintenance of the tumour microenvironment. The drug is approved as monotherapy for the treatment of metastatic colorectal cancer (mCRC) in patients who have previously received all standard systemic anticancer treatments (US, EU and Canada) or in patients with unresectable, advanced or recurrent colorectal cancer (Japan). In the randomized, controlled COloRectal cancer treated with REgorafenib or plaCebo after failure of standard Therapy (CORRECT) trial, regorafenib 160 mg once daily for the first 3 weeks of each 4-week cycle plus best supportive care (BSC) was associated with a significantly longer median overall survival than placebo plus BSC in patients with previously treated, progressive mCRC. The drug was also associated with significantly longer progression-free survival and better disease control rates than placebo, although objective response rates were similar in both treatment groups. Regorafenib did not appear to compromise health-related quality of life over the study duration and had a generally acceptable tolerability profile. The introduction of regorafenib expands the currently limited range of effective treatment options in patients with previously treated, progressive mCRC.

Targeting of EGFR and HER2 with therapeutic antibodies and siRNA: a comparative study in glioblastoma cells

BACKGROUND

The epidermal growth factor receptors, EGFR (HER1) and HER2, have proven prognostic relevance in a variety of human malignancies and both are functionally involved in the molecular pathogenesis of malignant gliomas.

MATERIAL AND METHODS

We selectively inhibited EGFR and HER2 in glioblastoma cell lines via EGFR- and HER2-specific siRNAs and through the binding of the therapeutic antibodies cetuximab and trastuzumab. The expression of EGFR and HER2 was verified by real-time PCR and western blot analyses. We examined the growth rate, cell cycle distribution, cell migration, clonogenic survival, and radiosensitivity of U251MG and LN-229 glioblastoma cell lines to determine the physiological and cell biological effects of EGFR and HER2 targeting.

RESULTS

EGFR and HER2 targeting using the therapeutic antibodies cetuximab and trastuzumab had no effect on cellular growth rate, cell cycle distribution, cell migration, clonogenic survival, and radiosensitivity in the cell lines U251 and LN-229. In contrast, siRNA knock-down of EGFR and HER2, reduced the growth rate by 40-65 %. The knock-down of EGFR did not change the cell migration rate in the cell lines U251 and LN-229. However, knock-down of HER2 reduced the cell migration rate by 50 %. Radiobiological analysis revealed that EGFR knock-down induced no radiosensitization in U251MG and LN-229 cells. However, the knock-down of HER2 induced radiosensitization in U251MG cells.

CONCLUSION

The epidermal growth factor receptor HER2 is a promising anti-tumor target for the therapy of glioblastoma. HER2 targeting may represent a promising strategy to induce cell physiological and radiobiological anti-tumor effects in glioblastoma.

Concurrent chemoradiotherapy versus induction chemotherapy followed by chemoradiotherapy (sequential approach) in the management of head and neck cancer

Concurrent chemoradiation is considered the standard-of-care for locally advanced head and neck cancer of the hypopharynx, oropharynx and larynx, as well as unresectable disease. This paradigm was challenged by the introduction of induction chemotherapy (IC), which demonstrated non-inferiority in regards of overall survival (OS), along with increased organ preservation, when compared to the surgery and radiotherapy. More recently, IC followed by concurrent chemoradiation, the so-called sequential approach was developed in an attempt to decrease metastatic spread and improve locoregional control (LRC) rates, with much controversy amongst experts. A careful evaluation by a multidisciplinary team is necessary to recognize which patients should be offered this therapeutic approach due to a significantly greater rate of toxicity. Herein, we analyze the most current available evidence regarding the use of sequential therapy versus concurrent chemoradiation. Different factors including toxicity profile, adherence and patient characteristics play a major role in choosing the most appropriate treatment regimen.

Dose KRAS Mutation Status Affect on the Effect of VEGF Therapy in Metastatic Colon Cancer Patients?

Purpose

Mutations affecting the KRAS gene are an established negative predictor for anti-epidermal growth factor receptor (anti-EGFR) therapies in metastatic colorectal cancer (CRC). However, the role of KRAS mutation as a biomarker for anti-vascular endothelial growth factor (VEGF) remains controversial.

Materials and Methods

We analyzed retrospective data from 32 CRC patients who were available for KRAS mutation status and received cytotoxic chemotherapy plus bevacizumab as a first-line therapy. Six of 32 patients received anti-EGFR therapies. We used KRAS mutation status as a predictive or prognostic factor in CRC patients receiving bevacizumab.

Results

We observed mutations in KRAS in 59.4% of patients. Bevacizumab was used in combination with oxaliplatin based regimens. There was no significant difference for progression free survival (PFS) and overall survival (OS) in patients with oxaliplatin based cytotoxic chemotherapy plus bevacizumab according to the status of KRAS mutation. After first-line therapy, 28 patients (87.5%) received second-line therapy. In univariate analysis, KRAS mutations did not have a major prognostic value for PFS (hazard ratio, 1.007; 95% confidence interval [CI], 0.469 to 2.162; p>0.05) or OS (hazard ratio, 0.548; 95% CI, 0.226 to 1.328; p>0.05). In addition, anti-EGFR therapies did not affect the impact on OS.

Conclusion

KRAS mutation is neither a predictive for bevacizumab nor a prognostic for OS in CRC patients receiving anti-VEGF therapy.

Incidence of cetuximab-related infusion reactions in oncology patients treated at the University of North Carolina Cancer Hospital

PURPOSE

The primary purpose of this study was to determine the rate of infusion reactions to cetuximab in oncology patients treated at the University of North Carolina Cancer Hospital. Secondarily, we sought to evaluate predictors of grade 3-4 hypersensitivity, including geography.

METHODS

Data were collected by retrospective chart review for patients treated with cetuximab at the University of North Carolina Cancer Hospital between 15 November 2006 and 31 December 2010. Data were analyzed for occurrence of hypersensitivity reaction in 125 patients with various cancer types.

RESULTS

Of the 125 subjects, 31 (24.8%) experienced an infusion reaction of any grade. Of 125, 18 (14.4%) experienced a grade 3 or 4 reaction. The odds ratio for patients with an allergy history having a grade 3 or 4 reaction was 2.57 (95% CI 0.93 to 7.09, p = 0.07). Pretreatment with steroids was associated with absence of grade 3 or 4 reaction with an odds ratio of 0.21 (95% CI 0.05 to 0.83, p = 0.04). Mapping of reaction rates by county revealed higher rates in some of the more rural counties of North Carolina, however, statistical power was lacking.

CONCLUSIONS

Rates of hypersensitivity reaction at UNC are similar to rates seen in other areas of the southeastern United States and higher than in other regions of the United States and Europe. Rates of both hypersensitivity reactions and grade 3 to 4 hypersensitivity reactions have not substantially changed over time. Geography, allergy history, and perhaps smoking or cancer type may help predict who will react to cetuximab. Steroids should be strongly considered as premedication in addition to diphenhydramine.

Protein engineering to target complement evasion in cancer

The complement system is composed of soluble factors in plasma that enhance or "complement" immune-mediated killing through innate and adaptive mechanisms. Activation of complement causes recruitment of immune cells; opsonization of coated cells; and direct killing of affected cells through a membrane attack complex (MAC). Tumor cells up-regulate complement inhibitory factors - one of several strategies to evade the immune system. In many cases as the tumor progresses, dramatic increases in complement inhibitory factors are found on these cells. This review focuses on the classic complement pathway and the role of major complement inhibitory factors in cancer immune evasion as well as on how current protein engineering efforts are being employed to increase complement fixing or to reverse complement resistance leading to better therapeutic outcomes in oncology. Strategies discussed include engineering of antibodies to enhance complement fixation, antibodies that neutralize complement inhibitory proteins as well as engineered constructs that specifically target inhibition of the complement system.

Cetuximab: a guide to its use in combination with FOLFIRI in the first-line treatment of metastatic colorectal cancer in the USA

Cetuximab (Erbitux(®)) is a monoclonal antibody that targets the epidermal growth factor receptor (EGFR). In the USA, the approval of cetuximab has been recently expanded to include the first-line treatment of patients with KRAS mutation-negative (wild-type), EGFR-expressing, metastatic colorectal cancer (mCRC) when used in combination with FOLFIRI (irinotecan, fluorouracil, leucovorin [folinic acid]). The addition of cetuximab to first-line treatment with FOLFIRI improved progression-free survival, overall survival, and objective response rates relative to treatment with FOLFIRI alone in patients with EGFR-expressing mCRC with KRAS wild-type tumors. Therefore, cetuximab plus FOLFIRI is a useful biomarker-directed option in the first-line treatment of this patient population.

Effect of radiotherapy on expression of hyaluronan and EGFR and presence of mast cells in squamous cell carcinoma of the head and neck

Head and neck squamous cell carcinoma is a common form of cancer, and despite improvements in treatment during the last decades, survival rates have not significantly increased. There is therefore a need to better understand how these tumours and the adjacent tissues react to radiotherapy, the most common type of treatment for this group of tumours. In order to improve this understanding, the expression of hyaluronan (HA) and epidermal growth factor receptor (EGFR) and the presence of mast cells were mapped before and after radiotherapy using immunohistochemistry. The results showed HA and EGFR to have similar expression patterns in tumour tissue and histologically normal squamous epithelium prior to radiotherapy. Following radiotherapy, EGFR increased in histologically normal epithelium. An increased number of mast cells were also observed as a result of radiotherapy. No expression of EGFR was observed in the connective tissue either prior to or following radiotherapy.

Aseptic meningitis: a rare side effect of cetuximab therapy

Cetuximab, a chimeric IgG1 monoclonal antibody against the epidermal growth factor receptor, is indicated for the treatment of epidermal growth factor receptor-expressing metastatic colorectal cancer and recurrent or metastatic squamous cell cancer of the head and neck after failure of platinum-based therapy. The commonly reported side effects of cetuximab are infusion-related reactions, skin rash, fatigue, malaise and nausea. We report a case of aseptic meningitis developing as a rare side effect in a patient of stage IVB squamous maxillary cancer treated with cetuximab. To our knowledge, there have been very few cases of cetuximab-induced aseptic meningitis reported in literature. Clinicians should recognize that self-limiting aseptic meningitis can occur with administration of cetuximab. Our case report may serve as an additional reference for clinicians encountered with aseptic meningitis in the setting of using cetuximab.

The subconjunctival use of cetuximab and bevacizumab in inhibition of corneal angiogenesis

PURPOSE

To investigate the effects of cetuximab and bevacizumab on experimental rat model of corneal angiogenesis.

METHODS

The right eyes of 28 male Sprague-Dawley rats were included in silver nitrate cauterization-induced corneal angiogenesis model. They were divided into four groups: (1) silver nitrate cauterization-induced and 0.15 ml serum physiologic was given to the angiogenesis group, (2) bevacizumab was given 1.25 mg to the bevacizumab group, (3) cetuximab was given 5 mg to the cetuximab group, and (4) 1.25 mg bevacizumab plus 5 mg cetuximab were given to the bevacizumab + cetuximab group. All eyes were exposed to the treatment on days 1, 4, and 7 of the experiment, and drugs were given subconjunctivally. The left eyes were untreated and used as sham. On day 8, the treated eyes were evaluated biomicroscopically. Then, the rats were sacrificed, and corneal specimens were prepared for histopathologic examinations.

RESULTS

The degree of angiogenesis inhibition was observed as 50.8% in bevacizumab, 54.3% in cetuximab, and 15.8% in bevacizumab + cetuximab groups by biomicroscopic evaluation. According to the histopathological and immunohistochemical findings obtained from the present study, the amount of angiogenesis was determined to have decreased considerably in both the bevacizumab and cetuximab groups; also, relatively less inhibiton was observed in the bevacizumab + cetuximab group.

CONCLUSION

Subconjunctival injection of cetuximab and bevacizumab is effective in reducing corneal angiogenesis in silver nitrate cauterization induced angiogenesis model of rats. Further investigation is needed to assess the potential side-effects of the drugs, especially cetuximab.

Anaphylactic reactions to oligosaccharides in red meat: a syndrome in evolution

OBJECTIVE

While most allergic responses to food are directed against protein epitopes and occur within 30 minutes of ingesting the allergen, recent studies suggest that delayed reactions may occur, sometimes mediated by IgE antibodies directed against carbohydrate moieties. The objective of this review is to summarize the clinical features and management of delayed hypersensitivity reactions to mammalian meat mediated by IgE antibodies to galactose-alpha 1,3-galactose (alpha-gal), an oligosaccharide.

METHODS

A PubMed search was conducted with MeSH terms: galactosyl-(1,3) galactose, oligosaccharides, cetuximab, allergy/hypersensitivity, and anaphylaxis. Reported cases with alpha-gal-mediated reactions were reviewed. This research study was approved by the Institutional Review Board of East Tennessee State University.

RESULTS

Thirty-two cases of adults presenting with red-meat induced allergy thought to be related to oligosaccharides have been reported in the literature so far, making this a rare and evolving syndrome. Most of these patients demonstrated delayed reactions to beef, as was seen in the case reported by us in this manuscript. IgE specific to alpha-gal was identified in most patients with variable response to skin testing with beef and pork. Inhibition studies in some cases showed that the IgE antibodies to beef were directed towards alpha-gal in the meat rather than the protein. The patients often reported history of tick bites, the significance of which is unclear at present. Reactions to cetuximab, a monoclonal antibody, are mediated by a similar mechanism, with IgE antibodies directed against an alpha-gal moiety incorporated in the drug structure.

CONCLUSION

Alpha-gal is an oligosaccharide recently incriminated in delayed anaphylactic reactions to mammalian meats such as to beef, pork, and lamb. It appears that anaphylactic reactions to the anti-cancer biological agent, cetuximab, may be linked mechanistically to the same process. More studies are required to understand the underlying molecular basis for these delayed reactions in specific, and their broader implications for host defense in general.

An update on the current and emerging targeted agents in metastatic colorectal cancer

Over the past 8 to 10 years, significant advances have been made in the treatment of metastatic colorectal cancer (mCRC). In particular, the development of the targeted biologic agents bevacizumab, cetuximab, and panitumumab, and their integration with cytotoxic chemotherapy regimens has led to improvements in clinical efficacy. Despite these gains, the overall impact of current targeted agents in the treatment of mCRC has been relatively modest, and while 2-year survival has improved, no gains have been made, as of yet, in 5-year survival. Intense efforts continue to be focused on developing novel targeted agents with a different spectrum of activity. Presently, five novel targeted molecules are in phase III trials, including the antiangiogenesis agents aflibercept and ramucirumab, two novel receptor tyrosine kinase inhibitors, regorafenib and brivanib, and the Akt inhibitor perifosine. There are an additional 52 phase II trials investigating a wide range of other candidate molecules. The potential list of approved targeted agents in mCRC seems likely to increase over the next 5 to 10 years. To maximize their potential clinical impact, however, it will be critically important to introduce efficient molecular diagnostic methodologies into the drug development process for the identification and validation of predictive biomarkers for chemosensitivity. This article reviews the development of targeted agents for the treatment of mCRC, including the three molecules currently approved by the US Food and Drug Administration (FDA), as well as the main non-FDA-approved therapeutics currently undergoing phase II and III clinical testing.

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.

Peripheral glutamate signaling in head and neck areas

The major excitatory neurotransmitter glutamate is also found in the periphery in an increasing number of nonexcitable cells. In line with this it became apparent that glutamate can regulate a broad array of peripheral biological responses, as well. Of particular interest is the discovery that glutamate receptor reactive reagents can influence tumor biology. However, the knowledge of glutamate signaling in peripheral tissues is still incomplete and, in the case of head and neck areas, is almost lacking. The roles of glutamate signaling pathways in these regions are manifold and include orofacial pain, periodontal bone production, skin and airway inflammation, as well as salivation. Furthermore, the interrelations between glutamate and cancers in the oral cavity, thyroid gland, and other regions are discussed. In summary, this review shall strengthen the view that glutamate receptor reagents may also be promising targets for novel therapeutic concepts suitable for a number of diseases in peripheral tissues. The contents of this review cover the following sections: Introduction; The "Glutamate System"; The Taste of Glutamate; Glutamate Signaling in Dental Regions; Glutamate Signaling in Head and Neck Areas; Glutamate Signaling in Head and Neck Cancer; A Brief Overview of Glutamate Signaling in Other Cancers; and Conclusion.

Synergistic activity of ixabepilone plus other anticancer agents: preclinical and clinical evidence

Ixabepilone demonstrates marked synergistic activity in combination with capecitabine, which served as the rationale for the evaluation of this combination in the clinic. Ixabepilone plus capecitabine is currently approved for patients with locally advanced or metastatic breast cancer (MBC) progressing after treatment with an anthracycline and a taxane; approval was based on the results of two phase III trials comparing the combination with capecitabine monotherapy. An array of preclinical studies in multiple solid tumor types show that ixabepilone demonstrates therapeutic synergy with targeted therapies including trastuzumab, bevacizumab, brivanib, and cetuximab; with immune-modulating agents such as anti-CTLA-4 antibody; and with other chemotherapy drugs such as irinotecan and epirubicin. Notably, experiments in several xenograft models show that ixabepilone provides greater antitumor synergism when combined with bevacizumab than either paclitaxel or nab-paclitaxel combined with bevacizumab. These preclinical findings provide a foundation for ongoing phase II clinical trials using ixabepilone in combination with trastuzumab or lapatinib in HER2-positive breast cancer; with bevacizumab in breast cancer, endometrial cancer, renal cancer, and non-small cell lung cancer (NSCLC); with cetuximab in breast cancer, NSCLC, and pancreatic cancer; and with brivanib, dasatinib, sorafinib, sunitinib, or vorinostat in MBC. Preliminary results from several of these trials suggest that ixabepilone-based combinations have promising anticancer activity.

Kinetic analysis of novel mono- and multivalent VHH-fragments and their application for molecular imaging of brain tumours

BACKGROUND AND PURPOSE

The overexpression of epidermal growth factor receptor (EGFR) and its mutated variant EGFRvIII occurs in 50% of glioblastoma multiforme. We developed antibody fragments against EGFR/EGFRvIII for molecular imaging and/or therapeutic targeting applications.

EXPERIMENTAL APPROACH

An anti-EGFR/EGFRvIII llama single-domain antibody (EG(2)) and two higher valency format constructs, bivalent EG(2)-hFc and pentavalent V2C-EG(2) sdAbs, were analysed in vitro for their binding affinities using surface plasmon resonance and cell binding studies, and in vivo using pharmacokinetic, biodistribution, optical imaging and fluorescent microscopy studies.

KEY RESULTS

Kinetic binding analyses by surface plasmon resonance revealed intrinsic affinities of 55 nM and 97 nM for the monovalent EG(2) to immobilized extracellular domains of EGFR and EGFRvIII, respectively, and a 10- to 600-fold increases in apparent affinities for the multivalent binders, V2C-EG(2) and EG(2)-hFc, respectively. In vivo pharmacokinetic and biodistribution studies in mice revealed plasma half-lives for EG(2), V2C-EG(2) and EG(2)-hFc of 41 min, 80 min and 12.5 h, respectively, as well as a significantly higher retention of EG(2)-hFc compared to the other two constructs in EGFR/EGFRvIII-expressing orthotopic brain tumours, resulting in the highest signal in the tumour region in optical imaging studies. Time domain volumetric optical imaging fusion with high-resolution micro-computed tomography of microvascular brain network confirmed EG(2)-hFc selective accumulation/retention in anatomically defined tumour regions.

CONCLUSIONS

Single domain antibodies can be optimized for molecular imaging applications by methods that improve their apparent affinity and prolong plasma half-life and, at the same time, preserve their ability to penetrate tumour parenchyma.

Erlotinib added to carboplatin and paclitaxel as first-line treatment of ovarian cancer: a phase II study based on surgical reassessment

BACKGROUND

The purpose of this study was to determine whether adding the anti-epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor erlotinib to carboplatin/paclitaxel improved pathologic complete response (pCR) at reassessment surgery in epithelial ovarian, fallopian tube, or primary peritoneal cancers (OFPC).

METHODS

Patients with stage III-IV OFPC initiated treatment within 12 weeks of initial cytoreductive surgery or, after histologic confirmation of diagnosis, neoadjuvantly. Treatment included paclitaxel (175 mg/m²) and carboplatin (AUC 6) every 3 weeks for up to 6 cycles, plus oral erlotinib 150 mg daily. The primary objective was to determine whether the pCR rate at reassessment surgery was at least 60% after optimal cytoreduction at initial surgery (< 1cm residual disease), or at least 40% after suboptimal cytoreduction (at least 1cm residual disease) using a two-stage design (alpha=0.10, beta=0.10).

RESULTS

The study population included 56 patients with stage III-IV OFPC. EGFR gene amplification was present in 15% of the 20 tumors evaluated. Twenty-eight patients had protocol therapy after optimal cytoreduction (stratum I), 23 had protocol therapy either after suboptimal cytoreduction (stratum II), and 5 received neoadjuvant therapy prior to cytoreduction (stratum III). Pathologic CR was confirmed in 8 patients (29%; 95% confidence intervals 13%, 49%) in stratum I and 3 patients (11%, 95% C.I. 2%, 28%) in stratum II, which did not meet the prespecified efficacy endpoint in either stratum.

CONCLUSIONS

Among unselected patients, erlotinib plus carboplatin-paclitaxel did not improve pCR rates compared with historical experience with carboplatin-paclitaxel alone in patients with stage III-IV OFPC.

Optical imaging predicts tumor response to anti-EGFR therapy

To evaluate cetuximab treatment in head and neck squamous cell carcinoma xenografts and cell lines, we investigated a preclinical model of head and neck squamous cell carcinoma. Head and neck squamous cell carcinoma cell lines SCC-1, FaDu, CAL27, UM-SCC-5 and UM-SCC-22A were used to generate subcutaneous flank xenografts in SCID mice. Mice were divided into control and cetuximab treatment groups, mice in the latter group received 250 μg cetuximab once weekly for four weeks. After completion of therapy, SCC-1 (p < 0.001), UM-SCC-5 (p < 0.001), UM-SCC-22A (p = 0.016) and FaDu (p = 0.007) tumors were significantly smaller than control, while CAL27 tumors were not different from controls (p = 0.90). Mice were systemically injected with 50 μg of the Cy5.5-cetuximab bioconjugate and imaged by stereomicroscopy to determine if tumor fluorescence predicted tumor response. Intact tumor fluorescence did not predict response. Tissue was harvested from untreated xenografts to evaluate ex vivo imaging. Cell lines were then evaluated in vitro for fluorescence imaging after Cy5.5-cetuximab bioconjugate labeling. The location of fluorescence observed in labeled cells was significantly different for cell lines that responded to treatment, relative to unresponsive cells. Tumors from cell lines that showed low internalized signal in vitro responded best to treatment with cetuximab. This preclinical model may aid in determining which cancer patients are best suited for cetuximab therapy.

Toxic epidermal necrolysis caused by cetuximab plus minocycline in head and neck cancer

We present a unique case of toxic epidermal necrolysis (TEN) caused by cetuximab plus minocycline during chemoradiation for recurrent squamous cell carcinoma of the head and neck (SCCHN). In April 2008, a 49-year-old man was diagnosed with recurrent SCCHN. He received surgery and postoperative adjuvant therapy with cetuximab plus chemoradiation. Because of exacerbation of acneform rash by cetuximab, minocycline was added thereafter. However, TEN appeared after the fifth course of weekly cetuximab, and cetuximab plus minocycline was assumed to be the cause. Cetuximab plus minocycline carries a risk of evoking TEN, and the side effects of chemoradiation for SCCHN mask some early signs of TEN. Noticing the transformation of skin lesions makes early diagnosis possible, and prompt cessation of the causative agent is essential for patients with TEN. We review the literature on cetuximab, minocycline, and TEN and discuss the impact of TEN on cancer therapy.

Assessment of Epidermal Growth Factor Receptor (EGFR) expression in human meningioma

PURPOSE

This study explores whether meningioma expresses epidermal growth factor receptor (EGFR) and determines if there is a correlation between the WHO grade of this tumor and the degree of EGFR expression.

METHODS

Following institutional review board approval, 113 meningioma specimens from 89 patients were chosen. Of these, 85 were used for final analysis. After a blinded review, immunohistochemical stains for EGFR were performed. Staining intensity (SI) was scored on a scale 0-3 (from no staining to strong staining). Staining percentage of immunoreactive cells (SP) was scored 1-5 (from the least to the maximum percent of the specimen staining). Immunohistochemical score (IHS) was calculated as the product of SI and SP.

RESULTS

Eighty-five samples of meningioma were classified in accordance with World Health Organization (WHO) criteria: benign 57/85 (67%), atypical 23/85 (27%), and malignant 5/85 (6%). The majority of samples demonstrated a moderate SI for EGFR. IHS for EGFR demonstrated a significant association between SI and histopathologic subtype. Also, there was a correlation between the SP and histopathologic subtype (p = 0.029). A significant association was determined when the benign and the atypical samples were compared to the malignant with respect to the SP (p = 0.009). While there was a range of the IHS for the benign and the atypical histologic subtypes, malignant tumors exhibited the lowest score and were statistically different from the benign and the atypical specimens (p < 0.001).

CONCLUSIONS

To our knowledge, this represents the largest series of meningioma samples analyzed for EGFR expression reported in the literature. EGFR expression is greatest in benign meningiomas and may serve a potential target for therapeutic intervention with selective EGFR inhibitors.

Molecular diagnostics for head and neck pathology

Molecular diagnostic techniques are quickly finding a role in the detection and diagnosis of tumors, and in predicting their behavior. They may also prove useful in developing new therapeutic approaches to head and neck cancer. The surgeon working in the craniomaxillofacial region should have an understanding of these technologies, their availability in various settings, and how they affect various aspects of treatment, particularly in the detection and treatment of malignancies. This article offers an overview of recent advances in molecular diagnostic techniques, with their implications for diagnosis and management of head and neck tumors.

Cetuximab (erbitux)

Cetuximab, a recombinant chimeric monoclonal antibody, has been successfully used in the treatment of the head and neck and colorectal cancers. We present a review of its mechanism of action, indications, side effects and economic issues, accompanied by a clinical example from our institution.

Targeting EGFR with photodynamic therapy in combination with Erbitux enhances in vivo bladder tumor response

BACKGROUND

Photodynamic therapy (PDT) is a promising cancer treatment modality that involves the interaction of the photosensitizer, molecular oxygen and light of specific wavelength to destroy tumor cells. Treatment induced hypoxia is one of the main side effects of PDT and efforts are underway to optimize PDT protocols for improved efficacy. The aim of this study was to investigate the anti-tumor effects of PDT plus Erbitux, an angiogenesis inhibitor that targets epidermal growth factor receptor (EGFR), on human bladder cancer model. Tumor-bearing nude mice were assigned to four groups that included control, PDT, Erbitux and PDT plus Erbitux and tumor volume was charted over 90-day period.

RESULTS

Our results demonstrate that combination of Erbitux with PDT strongly inhibits tumor growth in the bladder tumor xenograft model when compared to the other groups. Downregulation of EGFR was detected using immunohistochemistry, immunofluorescence and western blotting. Increased apoptosis was associated with tumor inhibition in the combination therapy group. In addition, we identified the dephosphorylation of ErbB4 at tyrosine 1284 site to play a major role in tumor inhibition. Also, at the RNA level downregulation of EGFR target genes cyclin D1 and c-myc was observed in tumors treated with PDT plus Erbitux.

CONCLUSION

The combination therapy of PDT and Erbitux effectively inhibits tumor growth and is a promising therapeutic approach in the treatment of bladder tumors.

Phase I and pharmacokinetic study of cetuximab and irinotecan in children with refractory solid tumors: a study of the pediatric oncology experimental therapeutic investigators' consortium

PURPOSE

To determine the dose of cetuximab that can be safely combined with irinotecan for treatment of pediatric and adolescent patients with refractory solid tumors.

PATIENTS AND METHODS

This open-label, phase I study enrolled patients ages 1 to 18 years with advanced refractory solid tumors, including tumors of the CNS. Patient cohorts by age group (children, ages 1 to 12 years; adolescents, ages 13 to 18 years) received escalating weekly doses of cetuximab (75, 150, 250 mg/m(2)) in a 3 + 3 design, plus irinotecan (16 or 20 mg/m(2)/d) for 5 days for 2 consecutive weeks every 21 days. The primary end points were establishing the maximum-tolerated dose (MTD), recommended phase II dose (RPIID), and pharmacokinetics of the combination. Preliminary safety and efficacy data were also collected.

RESULTS

Twenty-seven children and 19 adolescents received a median of 7.1 and 6.0 weeks of cetuximab therapy, respectively. Cetuximab 250 mg/m(2) weekly plus irinotecan 16 mg/m(2)/d (pediatric) or 20 mg/m(2)/d (adolescent) have been established as the MTD/RPIID. Dose-limiting toxicities included diarrhea and neutropenia. Mild to moderate (grade 1 to 2) acneiform rash occurred in a majority of patients; no grade 3 to 4 rashes were observed. Cetuximab demonstrated dose-dependent clearance in both children and adolescents, similar to that in adults. There were two confirmed partial responses, both in patients with CNS tumors. Stable disease was achieved in 18 patients overall, including 10 patients with CNS tumors (38.5%).

CONCLUSION

The cetuximab/irinotecan combination can be given safely to children and adolescents with cancer. Promising activity, particularly in CNS tumors, warrants phase II evaluation of this regimen.

Assessment of cetuximab efficacy by bioluminescence monitoring of intracranial glioblastoma xenograft in mouse

A glioblastoma multiforme xenograft was established in athymic nude mice via inoculation of glioblastoma cells that stably express luciferase (U87MG-LucNeo), and was monitored weekly using bioluminescence imaging (BLI). In the control groups, a steep rise in the signal was associated with the death of mice. As an adjuvant therapy, cetuximab (0.5 mg, two times) was intraperitoneally administered 4 weeks after nitrosourea treatment. For a salvage therapy, cetuximab (0.5 mg, two times) was intraperitoneally administered when recovery of the bioluminescence signal was detected after nitrosourea monotherapy. The antitumor effects of cetuximab adjuvant therapy were superior to those of nitrosourea monotherapy and cetuximab salvage therapy. This finding was consistent with the results from a survival comparison among nitrosourea monotherapy, adjuvant and salvage therapy with cetuximab. These results suggest that BLI could be used as a simple tool for predicting the efficacy of various anticancer treatments in mouse models of brain tumors. The administration of cetuximab as an adjuvant to the conventional chemotherapeutic agent is more efficient than salvage therapy.

A phase I clinical study of VB4-845: weekly intratumoral administration of an anti-EpCAM recombinant fusion protein in patients with squamous cell carcinoma of the head and neck

VB4-845 is a scFv-Pseudomonas exotoxin A fusion construct that targets epithelial cell adhesion molecule (EpCAM). A phase I trial was conducted to determine the maximum tolerated dose (MTD) of VB4-845 when administered as weekly intratumoral (IT) injections to patients with squamous cell carcinoma of the head and neck (SCCHN). Secondary objectives included the evaluation of the safety, tolerability, pharmacokinetic profile, and immunogenicity, and a preliminary assessment of tumor response. Twenty patients with advanced, recurrent SCCHN were treated weekly for four weeks in ascending dose cohorts of 100, 200, 330, 500, 700, and 930 microg. The MTD was established as 930 microg with a dose limiting toxicity of elevated liver enzymes in two of five patients. VB4-845 therapy was well tolerated with common treatment-related adverse events of injection site reactions, fever, gastrointestinal disorders, and elevated liver enzyme levels. All patients developed antibodies to VB4-845 by the end of the study, but only seven patients had neutralizing antibodies. Preliminary efficacy data found 87.5% of EpCAM-positive patients had a positive response to VB4-845 therapy. Noninjected dermal metastases were also resolved in one patient. VB4-845 IT therapy is safe and feasible and warrants further clinical evaluation for the treatment of SCCHN.

Interaction of antibodies with ErbB receptor extracellular regions

Antibodies to the extracellular region of the ErbB receptors have played key roles in the development of a mechanistic understanding of this family of receptor tyrosine kinases. An extensively studied class of such antibodies inhibits activation of ErbB receptors, and these antibodies have been the focus of intense development as anti-cancer agents. In this review we consider the properties of ErbB receptors antibodies in light of the current structure-based model for ErbB receptor homo- and hetero-dimerization and activation. Crystal structures of the Fab fragments from five different inhibitory antibodies in complex with the extracellular regions of EGFR and ErbB2 have been determined. These structures highlight several different modes of binding and mechanisms of receptor inhibition. Information about antibody interactions with the structurally well-characterized soluble extracellular regions of ErbB receptors can be combined with the rich knowledge of the effects of these antibodies in cultured cells, and in vivo, to provide insights into the conformation and activation of ErbB receptors at the cell surface.

Dysregulation of apoptotic signaling in cancer: molecular mechanisms and therapeutic opportunities

Apoptosis is a tightly regulated cell suicide program that plays an essential role in the maintenance of tissue homeostasis by eliminating unnecessary or harmful cells. Defects in this native defense mechanism promote malignant transformation and frequently confer chemoresistance to transformed cells. Indeed, the evasion of apoptosis has been recognized as a hallmark of cancer. Given that multiple mechanisms function at many levels to orchestrate the regulation of apoptosis, a multitude of opportunities for apoptotic dysregulation are present within the intricate signaling network of cell. Several of the molecular mechanisms by which cancer cells are protected from apoptosis have been elucidated. These advances have facilitated the development of novel apoptosis-inducing agents that have demonstrated single-agent activity against various types of cancers cells and/or sensitized resistant cancer cells to conventional cytotoxic therapies. Herein, we will highlight several of the central modes of apoptotic dysregulation found in cancer. We will also discuss several therapeutic strategies that aim to reestablish the apoptotic response, and thereby eradicate cancer cells, including those that demonstrate resistance to traditional therapies.

Molecular mechanisms of head and neck cancer

Despite advances in understanding the underlying genetics, squamous cell carcinoma of the head and neck (SCCHN) remains a major health risk and one of the leading causes of mortality in the world. Current standards of treatment have significantly improved long-term survival rates of patients, but second tumors and metastases still remain the most frequent cause of high mortality in SCCHN patients. A better understanding of the underlying genetic mechanisms of SCCHN tumorigenesis will help in developing better diagnostics and, hence, better cures. In this article we will briefly outline the current state of diagnostics and treatment and our understanding of the molecular causes of SCCHN.