Combination of an EGFR blocker and a COX-2 inhibitor for the treatment of advanced cutaneous squamous cell carcinoma

Immunohistochemical Expression Levels of Epidermal Growth Factor Receptor, Cyclooxygenase-2, and Ki-67 in Canine Cutaneous Squamous Cell Carcinomas

Squamous cell carcinoma (SCC) stands as the second most prevalent skin cancer in dogs, primarily attributed to UV radiation exposure. Affected areas typically include regions with sparse hair and pale or depigmented skin. The significance of spontaneous canine cutaneous SCC as a model for its human counterpart is underscored by its resemblance. This study assesses the expression of key markers-Epidermal Growth Factor Receptor (EGFR), Cyclooxygenase-2 (Cox-2), and Ki-67-in canine cutaneous SCC. Our objective is to investigate the association between their expression levels and classical clinicopathological parameters, unraveling the intricate relationships among these molecular markers. In our retrospective analysis of 37 cases, EGFR overexpression manifested in 43.2% of cases, while Cox-2 exhibited overexpression in 97.3%. The EGFR, Cox-2 overexpression, and Ki-67 proliferation indices, estimated through immunohistochemistry, displayed a significant association with the histological grade, but only EGFR labeling is associated with the presence of lymphovascular emboli. The Ki-67 labeling index expression exhibited an association with EGFR and Cox-2. These findings propose that EGFR, Cox-2, and Ki-67 hold promise as valuable markers in canine SCC. EGFR, Cox-2, and Ki-67 may serve as indicators of disease progression, offering insights into the malignancy of a lesion. The implications extend to the potential therapeutic targeting of EGFR and Cox-2 in managing canine SCC. Further exploration of these insights is warranted due to their translational relevance and the development of targeted interventions in the context of canine SCC.

Cutaneous Squamous Cell Carcinoma: An Updated Review

Representing the second most common skin cancer, the incidence and disease burden of cutaneous squamous cell carcinoma (cSCC) continues to increase. Surgical excision of the primary site effectively cures the majority of cSCC cases. However, an aggressive subset of cSCC persists with clinicopathological features that are indicative of higher recurrence, metastasis, and mortality risks. Acceleration of these features is driven by a combination of genetic and environmental factors. The past several years have seen remarkable progress in shaping the treatment landscape for advanced cSCC. Risk stratification and clinical management is a top priority. This review provides an overview of the current perspectives on cSCC with a focus on staging, treatment, and maintenance strategies, along with future research directions.

Aggressive Cutaneous Squamous Cell Carcinoma of the Head and Neck: A Review

Non-melanoma skin cancer of the head and neck (NMSCHN) is one of the most common malignancies worldwide, and its incidence is growing at a significant rate. It has been found to be aggressive in its spread and has the capacity to metastasize to regional lymph nodes. Cutaneous squamous cell carcinoma (cSCC) has a considerably high mortality rate. It has remarkable characteristics: diameter >2 cm, depth >5 mm, high recurrence, perineural invasion, and locoregional metastases. Aggressive cSCC lesions most commonly metastasize to the parotid gland. Also, immunocompromised patients have a higher risk of developing this aggressive cancer along with the worst prognostic outcomes. It is very important to discuss and assess the risk factors, prognostic factors, and outcomes of patients with cSCC, which will give clinicians future directives for making modifications to their treatment plans. The successful treatment of aggressive cSCC of the head and neck includes early detection and diagnosis, surgery alone or adjuvant chemotherapy, and radiotherapy as required. Multimodal therapy options should be considered by clinicians for better outcomes of aggressive cSCC of the head and neck.

Investigational Treatments for Epidermolysis Bullosa

Epidermolysis bullosa (EB) is a heterogeneous group of rare inherited blistering skin disorders characterized by skin fragility following minor trauma, usually present since birth. EB can be categorized into four classical subtypes, EB simplex, junctional EB, dystrophic EB and Kindler EB, distinguished on clinical features, plane of blister formation in the skin, and molecular pathology. Treatment for EB is mostly supportive, focusing on wound care and patient symptoms such as itch or pain. However, therapeutic advances have also been made in targeting the primary genetic abnormalities as well as the secondary inflammatory footprint of EB. Pre-clinical or clinical testing of gene therapies (gene replacement, gene editing, RNA-based therapy, natural gene therapy), cell-based therapies (fibroblasts, bone marrow transplantation, mesenchymal stromal cells, induced pluripotential stem cells), recombinant protein therapies, and small molecule and drug repurposing approaches, have generated new hope for better patient care. In this article, we review advances in translational research that are impacting on the quality of life for people living with different forms of EB and which offer hope for improved clinical management.

Functional genomic analysis identifies drug targetable pathways in invasive and metastatic cutaneous squamous cell carcinoma

Although cutaneous squamous cell carcinoma (cSCC) is treatable in the majority of cases, deadly invasive and metastatic cases do occur. To date there are neither reliable predictive biomarkers of disease progression nor FDA-approved targeted therapies as standard of care. To address these issues, we screened patient-derived primary cultured cells from invasive/metastatic cSCC with 107 small-molecule inhibitors. In-house bioinformatics tools were used to cross-analyze drug responses and DNA mutations in tumors detected by whole-exome sequencing (WES). Aberrations in molecular pathways with evidence of potential drug targets were identified, including the Eph-ephrin and neutrophil degranulation signaling pathways. Using a screening panel of siRNAs, we identified EPHA6 and EPHA7 as targets within the Eph-ephrin pathway responsible for mitigating decreased cell viability. These studies form a plausible foundation for detecting biomarkers of high-risk progressive disease applicable in dermatopathology and for patient-specific therapeutic options for invasive/metastatic cSCC.

Cutaneous Squamous Cell Carcinoma: From Biology to Therapy

Cutaneous squamous cell carcinoma (CSCC) is the second most frequent cancer in humans and its incidence continues to rise. Although CSCC usually display a benign clinical behavior, it can be both locally invasive and metastatic. The signaling pathways involved in CSCC development have given rise to targetable molecules in recent decades. In addition, the high mutational burden and increased risk of CSCC in patients under immunosuppression were part of the rationale for developing the immunotherapy for CSCC that has changed the therapeutic landscape. This review focuses on the molecular basis of CSCC and the current biology-based approaches of targeted therapies and immune checkpoint inhibitors. Another purpose of this review is to explore the landscape of drugs that may induce or contribute to the development of CSCC. Beginning with the pathogenetic basis of these drug-induced CSCCs, we move on to consider potential therapeutic opportunities for overcoming this adverse effect.

Case Report: Cetuximab use in advanced cutaneous squamous cell carcinoma resistant to chemotherapy

We present the case of a 60-year-old man with unresectable cutaneous squamous cell carcinoma (cSCC) of the sternal area, which was not amenable to radiation therapy (stage III, T3N0M0). The treatment history of this patient is remarkable as the disease had progressed through all lines of conventional therapy established in the literature. The patient was treated with epidermal growth factor receptor (EGFR) inhibitor cetuximab for 35 cycles and restaged after 12 months of therapy with a whole body CT scan, documenting stage IV disease (T3N2bM1). The use of cetuximab as a single agent was effective for a limited time and we decided to initiate combination therapy with cetuximab and nivolumab. Restaging after six months of this combination regimen documented stable disease.

Eicosanoids and HB-EGF/EGFR in cancer

Eicosanoids are bioactive lipids that play crucial roles in various pathophysiological conditions, including inflammation and cancer. They include both the COX-derived prostaglandins and the LOX-derived leukotrienes. Furthermore, the epidermal growth factor receptor (EGFR) pathways family of receptor tyrosine kinases also are known to play a central role in the tumorigenesis. Various antitumor modalities have been approved cancer treatments that target therapeutically the COX-2 and EGFR pathways; these include selective COX-2 inhibitors and EGFR monoclonal antibodies. Research has shown that the COX-2 and epidermal growth factor receptor pathways actively interact with each other in order to orchestrate carcinogenesis. This has been used to justify a targeted combinatorial approach aimed at these two pathways. Although combined therapies have been found to have a greater antitumor effect than the administration of single agent, this does not exempt them from the possible fatal cardiac effects that are associated with COX-2 inhibition. In this review, we delineate the contribution of HB-EGF, an important EGFR ligand, to the cardiac dysfunction related to decreased shedding of HB-EGF after COX-2/PGE2 inhibition. A better understanding of the molecular mechanisms underlying these cardiac side effects will make possible more effective regimens that use the dual-targeting approach.

Identification and validation of COX-2 as a co-target for overcoming cetuximab resistance in colorectal cancer cells

Cetuximab, an epidermal growth factor receptor (EGFR)-blocking antibody, was approved for treatment of metastatic colorectal cancer over a decade ago; however, patients' responses to cetuximab vary substantially due to intrinsic and acquired resistance to cetuximab. Here, we report our findings using Affymetrix HG-U133A array to examine changes in global gene expression between DiFi, a human colorectal cancer cell line that is highly sensitive to cetuximab, and two other cell lines: DiFi5, a DiFi subline with acquired resistance to cetuximab, and DiFi-AG, a DiFi subline with acquired resistance to the EGFR tyrosine kinase inhibitor AG1478 but sensitivity to cetuximab. We identified prostaglandin-endoperoxide synthase 2 (PTGS2), which encodes cyclooxygenase-2 (COX-2), as the gene with the greatest difference between the cetuximab-resistant DiFi5 cells and the cetuximab-sensitive DiFi cells and DiFi-AG cells. Reverse transcription polymerase chain reaction and Western blotting validated upregulation of COX-2 in DiFi5 but not in DiFi or DiFi-AG cells. We developed COX-2 knockdown stable clones from DiFi5 cells and demonstrated that genetic knockdown of COX-2 partially re-sensitized DiFi5 cells to cetuximab. We further confirmed that cetuximab in combination with a COX-2 inhibitor led to cell death via apoptosis or autophagy not only in DiFi5 cells but also in another colorectal cancer cell line naturally resistant to cetuximab. Our findings support further evaluation of the strategy of combining cetuximab and a COX-2 inhibitor for treatment of metastatic colorectal cancer.

Cisplatin and Cetuximab Treatment for Metastatic Cutaneous Squamous Cell Carcinoma: A Systematic Review

BACKGROUND

Cutaneous squamous cell carcinoma (cSCC) is the second most common form of skin cancer and metastasizes in 2% to 5% of cases.

OBJECTIVE

Systematic evaluation of published cases of metastatic cSCC (mSCC) treated with cisplatin or cetuximab from 1989 to 2014.

MATERIALS AND METHODS

A literature search was performed to identify cases of mSCC treated with cisplatin or cetuximab. Patient demographics, tumor characteristics, response rates, and disease-free survivals were extracted.

RESULTS

A total of 60 cases of mSCC treated with cisplatin and 9 cases treated with cetuximab reported in the literature from 1989 to 2014 were included in the analysis. Patients treated with cetuximab obtained a complete response of 67%, an overall response of 78%, and a median disease-free survival of 25 (range 3-48) months. Patients treated with cisplatin obtained a complete response of 22%, an overall response of 45%, and a median disease-free survival of 14.6 (range 3-112) months.

CONCLUSION

Head-to-head prospective clinical studies between cetuximab and cisplatin are needed to determine which is more efficacious. In addition, prospective tumor registries and randomized controlled trials should be developed in order to establish the ideal systemic regimen in cSCC.

Simultaneous blockage of epidermal growth factor receptor and cyclooxygenase-2 in a human xenotransplanted lung cancer model

The effects of erlotinib combined with celecoxib in a lung cancer xenograft model were here explored with a focus on possible mechanisms. A xenotransplanted lung cancer model was established in nude mice using the human lung cancer cell A549 cell line and animals demonstrating tumour growth were randomly divided into four groups: control, erlotinib, celecoxib and combined (erotinib and celecoxib). The tumor major axis and short diameter were measured twice a week and after 40 days tissues were collected for immunohistochemical analyses of Bcl-2 and Bax positive cells and Western-blotting analyses for the epidermal growth factor recepto (EGFR), P-EGFR, and cyclooxygenase-2 (COX-2). Tumor size in the combined group was smaller than in the others (p<0.01) and the percentage of Bcl-2 positive cells was fewer in most cases (p<0.01), while that of Bax positive cells was greater than in the erlotinib and celecoxib groups (P>0.05). Western blotting showed decreased expression of P-EGFR and COX-2 with both erlotinib and celecoxib treatments, but most pronouncedly in the combined group (P<0.05). Simultaneous blockage of the EGFR and COX-2 signal pathways exerted stronger growth effects in our human xenotransplanted lung cancer model than inhibition of either pathway alone. The anti-tumor effects were accompanied by synergetic inhibition of tumor cell apoptosis, activation of p-EGFR and expression of COX-2.

Combined cetuximab and celecoxib treatment exhibits a synergistic anticancer effect on human oral squamous cell carcinoma in vitro and in vivo

The aim of the present study was to evaluate the potency of epidermal growth factor receptor (EGFR) pathway inhibition achieved by combining cetuximab (CET), an anti-EGFR monoclonal antibody, and celecoxib (CXB), a cyclooxygenase-2 (COX-2) inhibitor, in oral squamous cell carcinoma (OSCC) in vitro and in vivo. The OSCC cell line, HSC3, was treated with CET (0-400 µg/ml), CXB (0-40 µM), or a combination of both at a range of concentrations. Cell proliferation, apoptosis, migration and invasion were determined to assess the anticancer effects in vitro. The in vivo effects of CET and CXB on tumor cell growth were examined using an OSCC xenograft nude mouse model. In addition, downstream protein expression levels of EGFR, p-EGFR, PI3K, p-PI3K, AKT and p-Akt were evaluated by western blot analysis. It was found that the combination of low concentrations of CET and CXB significantly suppressed the proliferation, migration and invasion of the HSC3 tumor cells and decreased PEG2 production and VEGF expression in vitro, and inhibited tumor growth in vivo compared to the action of either agent alone. The results also showed that this combination significantly induced apoptosis and increased caspase-3 and caspase-8 activity compared to the action of either agent alone (P<0.01). Furthermore, the combination treatment significantly reduced the expression of p-EGFR, p-PI3K and p-Akt in the HSC3 cell line, which may contribute to the inhibition of tumor growth. Taken together, our findings revealed that the additive combination of CET and CXB is a potential drug candidate for the treatment of OSCC.

Treatment of advanced cutaneous squamous cell carcinomas with epidermal growth factor receptor inhibitors

In advanced cutaneous squamous cell carcinoma (cSCC), efficient medical treatment options are limited in case surgery and radiotherapy failed, particularly since most patients are of higher age and suffer from comorbidities. In many tumor entities, the epidermal growth factor receptor (EGFR) has been established as an important therapeutic target, and blockade of EGFR signaling by monoclonal antibodies or small molecules achieves a therapeutic benefit. EGFR expression is also often dysregulated in cSCC. We report here two patients with advanced cSCC treated with the EGFR inhibitor cetuximab and summarize the current published experience with the use of EGFR inhibitors in cSCC.

Malignant epithelial tumors: Part II. Therapy and prevention

A multitude of surgical and non-surgical therapies are available to treat malignant epithelial tumors of the skin. The article summarizes the current treatment options for basal cell carcinoma, squamous cell carcinoma and keratoacanthoma. Moreover, the possibilities of primary and secondary prevention for high-risk patients are reviewed. The decision about the best therapeutic option depends on location, age, and general health of the patient as well as the risk of tumor recurrence.

Systemic therapy for squamous cell carcinoma of the skin in organ transplant recipients

During the second half of the 20th century, organ transplantation saved thousands of lives. This, unfortunately, also led to unforeseen consequences that need to be addressed to help extend the lives of patients who require these life-saving procedures. Secondary malignancies have been recognized as a potential consequence for decades. One of these malignancies, squamous cell carcinoma of the skin, not only appears more frequently in organ transplant recipients than the general population, but also is more aggressive in organ transplant recipients. It also shows a high propensity to nodal spread and metastasis in transplant patients. Unfortunately, there are no clear guidelines for a chemotherapy in this population, who have an increased need for alternative therapies to surgery given the high recurrence and metastasis rate. In this review, we attempt to describe the characteristics of squamous cell carcinoma of the skin in transplant recipients and discuss what chemotherapeutic options can be used to treat this aggressive malignancy.

Cetuximab in refractory skin cancer treatment

Objectives: Non-melanoma skin cancer is the most common malignancy in US, with an annual incidence of in excess of 1.5 million cases. In the majority of cases, locoregional treatment is curative and systemic therapy is not indicated. Platinum-based chemotherapy regimens have been used most commonly in refractory cases. The use of cetuximab, a monoclonal antibody targeting epidermal growth factor receptor [EGFR], has been reported for skin cancer treatment. This current study evaluated eight cases of locally advanced and refractory basal cell or squamous cell cancers which were treated with cetuximab.

Methods: This is a retrospective study on eight patients who had received cetuximab for treatment of cutaneous carcinoma since 2007 at Southern Illinois University School of Medicine (SIU-SOM) Medical Oncology clinic.

Results: Three of the four patients with basal cell carcinoma and two of the four patients with squamous cell carcinoma maintained remission on treatment.. The main side effect was acneiform rash which required termination of treatment for one patient and dose reduction in another.

Conclusion: The study indicates that cetuximab may have a beneficial role for patients with non-melanoma cutaneous carcinomas that are refractory to standard therapy.

Cetuximab in non-melanoma skin cancer

INTRODUCTION

Non-melanoma skin cancer (NMSC) has become the most common cancer with squamous cell carcinoma (SCC) as the major cause of morbidity and mortality. REVIEW AREAS COVERED: The chimeric human-mouse monoclonal antibody Cetuximab against epidermal growth factor receptor (EGFR) has been approved for advanced head and neck cancer (HNC). Since SCC has been shown to express the EGFR, EGFR-targeted therapy is an option.

METHODOLOGY

A PUBMED research 2000 - 2012 have been conducted using the following items: "Non-melanoma skin cancer AND cetuximab," "cutaneous squamous cell carcinoma AND cetuximab," and "basal cell carcinoma AND cetuximab."

RESULTS

Current evidence of cetuximab efficacy in NMSC results from a Phase II trial and case reports. Cetuximab can be combined with radiotherapy in analogy to HNC. The total response rate is almost 50% in patients with SCC. The combination with radiotherapy resulted in a complete response rate of 50%. Management of adverse reactions in SCC with particular emphasis on cutaneous toxicities is necessary. Further controlled trials are needed.

EXPERT OPINION

EGFR inhibitor cetuximab is an option for recurrent or advanced SCC of skin. The combination with radiotherapy seems to be superior to cetuximab alone.

Effects of epidermal growth factor receptor and insulin-like growth factor 1 receptor inhibition on proliferation and intracellular signaling in cutaneous SCCHN: potential for dual inhibition as a therapeutic modality

BACKGROUND

Combined inhibition of epidermal growth factor receptor (EGFR) and insulin-like growth factor-1 receptor (IGF-1R) has been proposed as a therapy for cutaneous squamous cell carcinoma of the head and neck (SCCHN).

METHODS

Receptor expression and downstream signaling were assessed in cutaneous squamous cell carcinoma (SCC) cell lines and patient samples. EGFR and IGF-1R signaling was inhibited in cutaneous SCC cell lines using erlotinib and/or picropodophyllin.

RESULTS

EGFR and IGF-1R were overexpressed in cutaneous SCCHN specimens relative to normal skin. Dual inhibition of both receptors prevented cell growth and decreased activation of Akt and p42/44 mitogen-activated protein kinase (MAPK) more effectively than either inhibitor alone.

CONCLUSION

Dual inhibition of EGFR and IGF-1R is effective at blocking cell growth, and is correlated with inhibition of Akt and p42/44 MAPK, suggesting that this may be a promising treatment for cutaneous SCCHN.

A phase II study of gefitinib for aggressive cutaneous squamous cell carcinoma of the head and neck

PURPOSE

To determine the disease control rate and toxicity of treating patients with aggressive cutaneous squamous cell carcinoma (CSCC) with neoadjuvant gefitinib.

EXPERIMENTAL DESIGN

A prospective phase II clinical trial evaluating neoadjuvant gefitinib given prior to standard treatment with surgery and/or radiotherapy. Patients with stable disease after one cycle received escalated doses. Patients who responded were given gefitinib during radiation therapy, as well as maintenance therapy after definitive treatment. We analyzed the correlation between epidermal growth factor receptor (EGFR) expression, mutation status, and gene copy number on available tissue samples and clinical response.

RESULTS

Twenty-three patients were accrued and 22 patients were evaluable for response prior to definitive local treatment; complete responses were attained by 18.2% of patients and partial responses by 27.3%. Grades 2 to 3 toxicities were observed in 59.1% of patients experiencing class-specific effects during induction therapy. After induction, 11.8% underwent surgery alone, 17.6% had definitive radiation, 11.8% were treated with radiation and concurrent gefitinib, and 47% had surgery with postoperative radiation and concurrent gefitinib. Median follow-up for the censored observations was 32 months. Two-year overall, disease-specific, and progression-free survival rates were 72.1%, 72.1%, and 63.6%, respectively. No EGFR-activating mutations were identified in tumor samples available from 10 patients. No associations between EGFR correlative studies and patient outcomes were identified.

CONCLUSIONS

Gefitinib, in the neoadjuvant setting, was active and well tolerated in patients with aggressive CSCC and did not interfere with definitive treatment. In view of the 18% complete response rate we observed, EGFR tyrosine kinase inhibitors should be further explored in the treatment of aggressive CSCC.

Update on the management of high-risk squamous cell carcinoma

Cutaneous squamous cell carcinoma (CSCC) is the second most common malignancy occurring in white patients in the United States and incidence rates are increasing. While the majority of the 87,000-760,000 cases that occur yearly in the U.S. are curable, 4% develop lymph node metastases and 1.5% die from the disease. Given the frequency of occurrence of CSCC, it is estimated to cause as many deaths yearly as melanoma, with the majority occurring in patients with high risk tumors or in those at high risk for metastasis due to a variety of host factors, most commonly systemic immunosuppression. There are currently no standardized prognostic or treatment models to assist clinicians in most effectively identifying and managing these patients. Identification of patients at risk for poor outcomes as well as standardization regarding classification, staging, and treatment of high-risk tumors is critical for optimizing patient care. In this article, available literature on the classification and management of high risk CSCC is briefly summarized, emphasizing new information.

Low incidence of EGFR and HRAS mutations in cutaneous squamous cell carcinomas of a German cohort

Epidermal growth factor receptor (EGFR) is highly expressed in squamous cell carcinoma (SCC). The response of patients with lung cancer to EGFR inhibitors is significantly associated with the presence of EGFR mutations. Although these drugs have already been used for the treatment of advanced cutaneous SCC, the knowledge about EGFR mutations in this cancer is limited to one previous study in the US population. We analysed the presence of EGFR and concomitant HRAS mutations in a German cohort of 31 patients with cutaneous SCC by direct sequencing of EGFR and SNaPshot analysis of concomitant RAS mutations. We found a low prevalence of EGFR mutations (1/31; 3%) and HRAS mutations (1/31; 3%). The detected P741L EGFR mutation was proven to be somatic. Our results indicate that both EGFR and HRAS mutations are rare events in the carcinogenesis of cutaneous SCC, and therefore, only a small subgroup of patients will benefit from the screening for EGFR mutations in the run-up to targeted therapies with EGFR inhibitors.

Changing pathology with changing drugs: skin cancer

Today skin cancer is mainly treated by surgical interventions. New findings concerning molecular biology and the signaling pathways in epithelial skin cancers such as basal cell carcinoma, squamous cell carcinoma or melanoma, and mesenchymal skin cancers such as angiosarcoma and dermatofibrosarcoma protuberans (DFSP) have identified new molecular targets for a systemic or local treatment approach. For DFSP there is an opportunity already today to reduce the intensity of surgical procedures by pretreatment with targeted therapy. This article highlights important aspects in several skin cancer types.

Cutaneous lesions of the nose

Skin diseases on the nose are seen in a variety of medical disciplines. Dermatologists, otorhinolaryngologists, general practitioners and general plastic and dermatologic surgeons are regularly consulted regarding cutaneous lesions on the nose. This article is the second part of a review series dealing with cutaneous lesions on the head and face, which are frequently seen in daily practice by a dermatologic surgeon. In this review, we focus on those skin diseases on the nose where surgery or laser therapy is considered a possible treatment option or that can be surgically evaluated.

Cyclooxygenase-2 is a novel transcriptional target of the nuclear EGFR-STAT3 and EGFRvIII-STAT3 signaling axes

Emerging evidence indicates a novel mode of epidermal growth factor receptor (EGFR) signaling, notably, one involves EGFR nuclear translocalization and subsequent gene activation. To date, however, the significance of the nuclear EGFR pathway in glioblastoma (GBM) is unknown. Here, we report that EGFR and its constitutively activated variant EGFRvIII undergo nuclear translocalization in GBM cells, in which the former event requires EGF stimulation and the latter is constitutive. To gain insights into the effect of nuclear EGFR on gene expression in GBM, we created isogenic GBM cell lines, namely, U87MG-vector, U87MG-EGFR, and U87MG-EGFRdNLS that, respectively, express the control vector, EGFR, and nuclear entry-defective EGFR with a deletion of the nuclear localization signal (NLS). Microarray analysis shows that 19 genes, including cyclooxygenase-2 (COX-2), to be activated in U87MG-EGFR cells but not in U87MG-EGFRdNLS and U87MG-vector cells. Subsequent validation studies indicate that COX-2 gene is expressed at higher levels in cells with EGFR and EGFRvIII than those with EGFRdNLS and EGFRvIIIdNLS. Nuclear EGFR and its transcriptional cofactor signal transducer and activator of transcription 3 (STAT3) associate with the COX-2 promoter. Increased expression of EGFR/EGFRvIII and activated STAT3 leads to the synergistic activation of the COX-2 promoter. Promoter mutational analysis identified a proximal STAT3-binding site that is required for EGFR/EGFRvIII-STAT3-mediated COX-2 gene activation. In GBM tumors, an association exists between levels of COX-2, EGFR/EGFRvIII, and activated STAT3. Together, these findings indicate the existence of the nuclear EGFR/EGFRvIII signaling pathway in GBM and its functional interaction with STAT3 to activate COX-2 gene expression, thus linking EGFR-STAT3 and EGFRvIII-STAT3 signaling axes to proinflammatory COX-2 mediated pathway.