Anti-epidermal Growth Factor Receptor Agents Research Articles

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.

Asian ethnicity and survival outcomes in advanced non-small cell lung cancer (NSCLC) patients receiving systemic therapy: A regional Canadian experience.

e18081 Background: Recent studies in advanced NSCLC have identified Asian ethnicity as a favorable survival prognosticator, possibly attributed to the use of antiepidermal growth factor receptor (EGFR) agents. We investigate the validity of this finding in a regional, Canadian population in the anti-EGFR era. Methods: East/Southeast Asian-born patients newly diagnosed with advanced stage IIIB or IV NSCLC from 2002 to 2007 were identified via the Alberta Cancer Registry (Alberta, Canada). Retrospective chart reviews were performed to obtain relevant clinical and histological parameters. A control group consisting of Alberta-born, non-Asian patients was randomly selected and matched for age, gender, stage, and treatment type received. Patients incorrectly classified or who received non-palliative intent therapies were excluded. Statistical analyses were performed using SAS v9.1. Results: 197 Asian patients in total were identified. Of the 67 Asian patients and 67 controls receiving systemic therapy, median overall survival (OS) was significantly longer in the Asian group at 15.9 mo (95% CI: 11.5-20.2) vs 9.7 mo (95% CI: 8.4- 10.9) in the control group (HR = 1.84, 95% CI: 1.27-2.68, p = 0.001). Use of an EGFR tyrosine kinase inhibitor (TKI) during any line of treatment was associated with improved OS in both the Asian and control groups (20.8 mo, 95% CI: 10.3-31.3; vs 12.7 mo, 95% CI: 11.6-13.8), as compared with no EGFR TKI use (7.1 mo, 95% CI: 3.3-10.8; vs 9.0 mo, 95% CI: 8.4-9.6, respectively). On multivariate analysis, use of an EGFR TKI was associated with OS advantage in both groups, especially in the Asian group (HR = 3.90, 95% CI: 1.90-8.02, p = 0.0002). Conclusions: This regional, Canadian study demonstrates a survival advantage associated with Asian ethnicity in advanced NSCLC patients receiving systemic therapy in the anti-EGFR era, particularly associated with EGFR TKI use. These findings likely relate to the higher prevalence of EGFR mutations reported in this population. No significant financial relationships to disclose.

Insulin-like growth factor receptor 1 (IGF1R) expression and survival in surgically resected non-small-cell lung cancer (NSCLC) patients

BackgroundThe purpose of this study is to investigate the prognostic role of insulin-like growth factor receptor 1 (IGF1R) expression in surgically resected non-small-cell lung cancer (NSCLC). Patient characteristics and methodsThis retrospective study was conducted in 369 stage I–II–IIIA, surgically resected, NSCLC patients. Patients exposed to anti-epidermal growth factor receptor (EGFR) agents were excluded. IGF1R expression was evaluated by immunohistochemistry in tissue microarray sections. ResultsA positive IGF1R expression (score≥100) was observed in 282 cases (76.4%) and was significantly associated with squamous cell histology (P=0.04) and with grade III differentiation (P=0.02). No difference in survival was observed between the positive and negative group when score 100 was used as cut-off for discriminating a positive versus a negative IGF1R result (52 versus 48 months, P=0.99) or when median value of IGF1R expression was used (45 versus 55 months, P=0.36). No difference in survival was observed between IGF1R-positive and -negative patients in a subgroup of stage I–II adenocarcinoma (n=137) with known EGFR mutation and copy number status. ConclusionsIGF1R expression does not represent a prognostic factor in resected NSCLC patients. Patients with squamous cell carcinoma overexpress IGF1R more frequently than patients with nonsquamous histology, justifying the different sensitivity to anti-IGF1R agents observed in clinical trials.

Patient-derived xenografts of non-small-cell lung cancer: a pre-clinical model to evaluate adjuvant chemotherapy?☆

Recent trials have evaluated adjuvant chemotherapy in patients with non-small-cell lung cancer (NSCLC). For stage IB to IIIA, a significant improvement of treatment results for platin-based chemotherapy was shown, but only one of the 20 patients treated has a benefit of disease-free and overall 5-year survival. In future the implementation of biomarkers, novel agents and individual selection may contribute to better treatment results in adjuvant therapy. Pre-clinical models are one way to study treatment innovations. We have developed a lung cancer xenograft model. Fresh tumour material of patients with NSCLC was subcutaneously transplanted to immunodeficient mice shortly after surgical resection. In total, 102 samples have been transplanted from which 25 passagable models could be generated. Of the established xenograft lines, 48% were derived from squamous cell carcinomas and 24% from adenocarcinomas. All but one originated from long-term smokers. It could be shown that the early murine passages (maximum 10) were similar to the original tumour with regard to histology and the expression of the surface proteins as E-cadherin, EpCAM or the cell proliferation marker Ki-67. The growth rate of the established xenografts was a unique feature of the different models and not related to patient characteristics or to the histology type. All xenograft models showed a wide variability in response to both classical chemotherapy and targeted anti-epidermal growth factor receptor agents. Response rates were in good accordance with the results of recent clinical studies. In summary, we have developed a panel of patient-derived NSCLC xenografts. These xenograft models could be used for pre-clinical studies to evaluate chemotherapy, novel targeted therapies and expression of potential biomarkers.

Current management of anal canal cancer

Squamous cell carcinoma of the anal canal historically has been treated with abdominoperineal resection, resulting in high rates of morbidity and local recurrence. Pioneering work led to the finding that radiation therapy (RT) combined with 5-fluorouracil (5-FU) and mitomycin results in high rates of local control and disease-free and colostomy-free survival without surgery. Prospective randomized trials from Europe and the United States have shown the superiority of RT, 5-FU, and mitomycin over 1) RT alone, 2) RT with 5-FU, and 3) neoadjuvant cisplatin/5-FU with concurrent radiation, cisplatin, and 5-FU. At present, RT with 5-FU and mitomycin is the standard of care for anal cancer patients. Recent advances include the integration of positron emission tomography into staging, radiation treatment planning and monitoring, and the use of intensity modulated RT. European randomized trials are further evaluating the role of cisplatin in the neoadjuvant, concurrent, and adjuvant settings, as well as radiation dose escalation. Other studies are evaluating the use of capecitabine, oxaliplatin, and the anti-epidermal growth factor receptor agent cetuximab with RT in this malignancy.

Cetuximab in the treatment of metastatic mucoepidermoid carcinoma of the salivary glands: A case report and review of literature

IntroductionPatients with metastatic mucoepidermoid carcinoma of salivary glands have a poor outcome. The epidermal growth factor receptor protein is overexpressed in approximately 70% of mucoepidermoid carcinoma patients and may represent a therapeutic target. However, whether treatment with anti-epidermal growth factor receptor agents is effective is unclear and clinical trials are difficult due to the rarity of the disease. Here we assessed the activity of cetuximab in mucoepidermoid carcinoma on a molecular basis.Case presentationWe present the case of a 40-year old Caucasian man with a mucoepidermoid carcinoma of the major salivary glands who developed distant bone and visceral metastases despite platinum-based chemotherapy. Epidermal growth factor receptor was overexpressed and fluorescence in situ hybridization analysis demonstrated a chromosome 7 polysomy. The patient was treated with the monoclonal antibody cetuximab in combination with cisplatin. After 11 doses of cetuximab, the patient developed brain metastases but evidence of response was documented at all extracranial metastatic sites.ConclusionThis case report indicates that cetuximab can be active in mucoepidermoid carcinoma and may restore sensitivity to cisplatin in platinum-treated patients. Cetuximab does not cross the blood brain barrier and may select a metastatic clone to home the central nervous system while responding at other sites.

Combined effects of bevacizumab with erlotinib and irradiation: a preclinical study on a head and neck cancer orthotopic model.

Clinical benefit has been demonstrated in patients with head and neck tumours receiving an anti-epidermal growth factor receptor (EGFR) agent in combination with radiotherapy (RT). Recent preclinical and clinical studies suggest beneficial effects from combining anti-angiogenic drugs with RT. To investigate the effect of combining these approaches, we evaluated in vivo the anti-tumour efficacy of the anti-angiogenic compound bevacizumab, a highly specific monoclonal antibody directed against the vascular endothelial growth factor (VEGF), erlotinib, an EGFR tyrosine kinase inhibitor, and irradiation given alone and in combination. Investigations were performed using a VEGF-secreting human head and neck tumour cell line, CAL33, with a high EGFR content, injected as orthotopic xenografts into the mouth floor of nude mice. Three days after tumour cell injection, bevacizumab (5 mg kg−1, 5 days a week, i.p.), erlotinib (100 mg kg−1, 5 days a week, orally) and irradiation (6 Gy, 3 days a week) were administered alone and in combination for 10 days. As compared with the control, concomitant administration of drugs produced a marked and significant supra-additive decrease in tumour mass; the addition of irradiation almost completely abolished tumour growth. The drug association markedly reduced the number of metastatic nodes and the triple combination significantly reduced the total number of pathologically positive lymph nodes as compared with controls. The RT-induced proliferation, reflected by Ki67 labelling, was reduced to control level with the triple combination. Radiotherapy induced a strong and very significant increase in tumour angiogenesis, which was no longer observed when combined with erlotinib and bevacizumab. The efficacy of the combination of bevacizumab+erlotinib and RT may be of clinical importance in the management of head and neck cancer patients.

Correlation of KRAS status (wild type [wt] vs. mutant [mt]) with efficacy to first-line cetuximab in a study of cetuximab single agent followed by cetuximab + FOLFIRI in patients (pts) with metastatic colorectal cancer (mCRC)

4129 Background: KRAS mutation status predicts sensitivity to anti-epidermal growth factor receptor (EGFR) agents in pts with refractory mCRC. In order to assess the efficacy of cetuximab alone and in combination with chemotherapy in the first-line setting, we have analyzed the KRAS mutation status in EGFR-expressing mCRC pts participating in a clinical trial comparing weekly versus bi-weekly administration of cetuximab (Tabernero et al. Proc ASCO 2006). Cetuximab was administered as a first-line single agent for 6 weeks, pts were assessed for response and then FOLFIRI chemotherapy was added to all pts. KRAS mutation status was determined in archived tumor material and its correlation with efficacy parameters evaluated. Methods: Blocks of archived tumor material from 50 pts and paraffin- embedded slide sets from 2 pts were assessed for KRAS mutation analysis eligibility. Genomic DNA was isolated from slides with no prior macrodissection. The KRAS mutation status of codons 12/13 was determined by a highly sensitive quantitative polymerase chain reaction- based assay. Independent histopathologic evaluation revealed that 48/52 samples contained tumor tissue. All 48 pts were fully evaluable for efficacy. Response rate (RR) at end of monotherapy, overall RR during the combination phase (cetuximab + FOLFIRI), and progression-free survival (PFS) time for the 48 pts were determined and correlated with the KRAS status of these pts. Results: KRAS mutations were detected in 19 samples (40%) from the KRAS evaluable population. At the end of the monotherapy phase, RR was 27.6% for the KRAS wt population and 0% for the KRAS mt population (p=0.015). During the combination phase this RR increased to 55.2% vs 31.6%, respectively (p=0.144). PFS for cetuximab + FOLFIRI was significantly improved (hazard ratio: 0.47, p=0.0475) for KRAS wt pts vs KRAS mt pts. Conclusions: KRAS mutation status determines efficacy to cetuximab in the first-line setting of pts with mCRC either alone or when subsequently combined with FOLFIRI. Our findings support that KRAS mutation status should be considered in the choice of therapy in the first- line setting of pts with mCRC. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Merck Merck Merck Merck

Biological interaction between anti-epidermal growth factor receptor agent cetuximab and magnesium

Background: Magnesium plays a role in a large number of cellular metabolic reactions. Cetuximab, by the inhibition of epidermal growth factor (EGR), is able to induce hypomagnesaemia by interfering with magnesium transport in the kidney. Objective: To investigate the interactions between magnesium homeostasis and EGF receptor (EGFR) inhibition. Methods: We performed an updated literature search using the MEDLINE database for articles published from 1 January 1966 to 15 February 2008. We comprehensively reviewed all the data published in abstract form during the most significant international meetings (American Society of Clinical Oncology, American Association for Cancer Research, European Society for Medical Oncology and European Cancer Organisation). Results/conclusion: We propose that EGFR inhibition may reduce cancer proliferation and also decrease magnesium levels. These reduced magnesium levels in turn contribute to the inhibition of angiogenesis by directly acting on endothelial cells and indirectly affecting EGFR signalling and the production of angiogenic molecules.

Molecular-targeted therapies in the treatment of squamous cell carcinomas of the head and neck

The present study reviews recent developments of molecular-targeted therapies in the treatment of recurrent and/or metastatic head and neck squamous cell carcinoma. It also highlights ongoing research regarding predictive markers of sensitivity or resistance to anti-epidermal growth factor receptor agents and discusses some promising novel targets in head and neck squamous cell carcinoma, as well as clinical trial design challenges. Phase III randomized studies have brought the proof that cetuximab, an anti-epidermal growth factor receptor agent, is able to improve survival, either in combination with radiation therapy or in first-line treatment for recurrent and/or metastatic head and neck squamous cell carcinoma. In addition, promising results have been obtained with antiangiogenic therapies in phase II trials. Some clinical and molecular markers of resistance to anti-epidermal growth factor receptor agents have been identified, but they have not yet been validated for clinical practice. Other interesting targets, such as insulin-like growth factor 1R or the PI3K/AKT/mTOR pathway, have been shown in vitro to play key roles in head and neck squamous cell carcinoma, and their inhibition warrants further evaluations. Proof of the concept that molecular-targeted therapy is a valid therapeutic approach for head and neck squamous cell carcinoma has emerged with anti-epidermal growth factor receptor agents. Nevertheless, identification of predictive biomarkers of resistance or sensitivity to these therapies remains the main challenge in the optimal selection of patients most likely to benefit from them.

Markers in the epidermal growth factor receptor pathway and skin toxicity during erlotinib treatment

BackgroundSkin toxicity is a common adverse effect of erlotinib and other anti-epidermal growth factor receptor (EGFR) agents. The aim of the study was to explore the relationship between markers in the EGFR pathway and skin rash. Patients and methodsEighteen patients with metastatic breast cancer were treated with daily oral erlotinib at 150 mg. Skin biopsies were obtained at baseline and after 1 month of treatment in 15 patients. EGFR, phosphorylated EGFR (pEGFR), phosphorylated mitogen-activated protein kinase (pMAPK), and phosphorylated Akt (pAkt) or Ki67 were examined quantitatively by immunohistochemistry. Results11 of 18 (61%, 95% confidence interval 35.7% to 82.7%) patients developed skin rash. pAkt at baseline was significantly higher in patients with no rash than those with a grade 1 or 2 rash (18.8±8.3 versus 2.4±1.2 versus 3.3±3.3; P=0.0017 for trend). There was a trend towards a significant increase of pMAPK in skin posttreatment with increasing grade of rash (no rash versus grade 1 versus grade 2 rash: 4.5±2.3 versus 8.4±4.2 versus 19.4±4.6; P=0.036). Other markers were not associated with rash. ConclusionspAkt was significantly associated with not developing a rash and may have a predictive utility for skin toxicity in patients treated with erlotinib and possibly with other anti-EGFR agents.

Protein expression and mutational analysis of epidermal growth factor receptor in renal angiomyolipomas

Renal angiomyolipoma (AML) is a benign but progressive tumor that occasionally requires non-surgical therapy and there appears to be a possibility that epidermal growth factor (EGF) is associated with pathogenesis of renal AML. The response to gefitinib, anti-epidermal growth factor receptor (EGFR) agent and a prime example of target therapy, reportedly has been correlated with the presence of mutations within the tyrosine kinase (TK) domain of EGFR or the expression of its truncated form, EGFR variant III. Therefore the purpose of the present paper was to investigate EGFR protein expression and gene mutations in exons 18, 19 and 21 in 40 renal AML. No EGFR gene mutations of TK domain were detected in any of the 40 cases studied and strong immunostaining was found in 5% of the renal AML cases. The present findings indicate that in renal AML, anti-EGFR treatment may not be promising but that there is a possibility that EGFR is associated with renal AML pathogenesis.

Combined paclitaxel and cetuximab achieved a major response on the skin metastases of a patient with epidermal growth factor receptor-positive, estrogen receptor-negative, progesterone receptor-negative and human epidermal growth factor receptor-2-negative (triple-negative) breast cancer

The epidermal growth factor receptor, a transmembrane receptor tyrosine kinase of the erbB family, is expressed in 15-30% of all breast cancers. Anti-epidermal growth factor receptor agent cetuximab is an IgG1 chimeric monoclonal antibody with a potent antitumor activity. Cetuximab competes with ligand binding to the epidermal growth factor receptor ectodomain, resulting in an efficient blockade of tumor-promoting downstream signaling pathways. Large clinical studies recently demonstrated cetuximab synergy with radiotherapy and chemotherapy agent irinotecan. Studies in human breast cancer xenografts showed cetuximab synergy with paclitaxel, a potent mitosis spindle-cell stabilizer. In this report, combined paclitaxel and cetuximab achieved a major reduction of the skin metastases of a heavily pretreated patient with epidermal growth factor receptor-positive, estrogen receptor-negative, progesterone receptor-negative and human epidermal growth factor receptor-2-negative (triple-negative) invasive ductal breast carcinoma. Treatment was well-tolerated overall and response was not correlated with the appearance of major cetuximab-induced acneiform rash.

The Role of VEGF and EGFR Inhibition: Implications for Combining Anti–VEGF and Anti–EGFR Agents

Multiple cellular pathways influence the growth and metastatic potential of tumors. This creates heterogeneity, redundancy, and the potential for tumors to bypass signaling pathway blockade, resulting in primary or acquired resistance. Combining therapies that inhibit different signaling pathways has the potential to be more effective than inhibition of a single pathway and to overcome tumor resistance. Vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR) inhibitors have become key therapies in several tumor types. Close relationships between these factors exist: VEGF signaling is up-regulated by EGFR expression and, conversely, VEGF up-regulation independent of EGFR signaling seems to contribute to resistance to EGFR inhibition. Therefore, inhibition of both pathways could improve antitumor efficacy and overcome resistance to EGFR inhibition. Preclinical studies have shown that VEGF and EGFR inhibitors can have additive effects and that combined inhibition is effective in EGFR inhibitor-resistant cell lines. Clinical trials have also produced promising data: combining the anti-VEGF monoclonal antibody bevacizumab with the anti-EGFR antibody cetuximab or the EGFR tyrosine kinase inhibitor erlotinib increases benefit compared with either of these anti-EGFR agents alone or combined with chemotherapy. The potential of this novel approach to anticancer therapy will be elucidated by large, ongoing clinical trials.

Epidermal growth factor receptor/angiogenesis dual targeting: preclinical experience

This review aims to critically examine the preclinical background regarding the combination of drugs targeting the epidermal growth factor receptor and anti-angiogenic compounds. There are studies exploring the anti-tumor efficacy of dual inhibitors, such as the compound ZD6474, which combines in the same molecule an anti-tyrosine kinase activity against the epidermal growth factor receptor and the vascular endothelial growth factor receptor. In addition, several studies have investigated the anti-tumor effects of combinations of an anti-epidermal growth factor receptor agent and a vascular endothelial growth factor receptor inhibitor. In general, in these studies, supra-additive anti-tumor efficacy was apparent when combining anti-epidermal growth factor receptor and anti-angiogenic treatments. Beneficial effects were also observed when combining this dual targeted therapy with either conventional chemotherapy or irradiation. Early clinical trials combining the anti-epidermal growth factor receptor drug erlotinib (Tarceva) and the anti-angiogenic agent bevacizumab (Avastin) show acceptable toxicity and promising anti-tumor activity (lung cancer), which need to be confirmed in randomized trials.

Promises and pitfalls in the prediction of antiepidermal growth factor receptor activity

There is a constant examination of the features that may anticipate or predict the likelihood of the clinical benefit that a patient may experience from a given therapy. This is especially true in the case of novel targeted therapies, as proof-of-principle experimental or pilot analyses are increasingly being embedded into clinical protocols. An unprecedented number of significant developments in the field of epidermal growth factor receptor-targeted therapy have occurred in recent months. This is exemplified by the discovery of activating mutations in the catalytic domain of the epidermal growth factor receptor that increase sensitivity to antiepidermal growth factor receptor small-molecule inhibitors. This review discusses the recent advances and controversies of the different approaches to predict the efficacy of antiepidermal growth factor receptor agents and the effectiveness of the tools that we are using to evaluate and predict the efficacy of epidermal growth factor receptor-targeted drugs and their potential pitfalls.

Chemotherapy in patients with resectable liver metastases from colorectal cancer

New chemotherapy drugs and, more recently, targeted therapies have significantly improved the outcome of patients with resected stage III colon cancer (adjuvant chemotherapy) and patients with unresectable metastases (palliative therapy). These advances raise several questions about the place of chemotherapy after and before surgery in patients with resectable liver metastases. To date, only a combined intra-arterial plus systemic fluoropyrimidine-based chemotherapy regimen has clearly demonstrated a relapse-free survival benefit. Yet, this approach is restricted to specialized centers, mainly because of technical difficulties and locoregional toxicities. The role of systemic use of oxaliplatin- and irinotecan-based regimens is currently under investigation. Planned trials will assess the role of anti-angiogenic and anti-epidermal growth factor receptor agents. We review the main trials performed in patients with resectable metastases, and discuss their potent impact on clinical practice.

Antitumor activity of ZD6126, a novel vascular-targeting agent, is enhanced when combined with ZD1839, an epidermal growth factor receptor tyrosine kinase inhibitor, and potentiates the effects of radiation in a human non-small cell lung cancer xenograft model

Targeting the tumor vasculature may offer an alternative or complementary therapeutic approach to targeting growth factor signaling in lung cancer. The aim of these studies was to evaluate the antitumor effects in vivo of the combination of ZD6126, a tumor-selective vascular-targeting agent; ZD1839 (gefitinib, Iressa), an epidermal growth factor receptor tyrosine kinase inhibitor; and ionizing radiation in the treatment of non-small cell lung cancer xenograft model. Athymic nude mice with established flank A549 human non-small cell lung cancer xenograft model xenografts were treated with fractionated radiation therapy, ZD6126, ZD1839, or combinations of each treatment. ZD6126 (150 mg/kg) was given i.p. the day after each course of radiation. Animals treated with ZD1839 received 100 mg/kg per dose per animal, 5 or 7 days/wk for 2 weeks. Immunohistochemistry was done to evaluate the effects on tumor growth using an anti-Ki67 monoclonal antibody. Effects on tumor-induced vascularization were quantified using an anti-factor VIII-related antigen monoclonal antibody. ZD6126 attenuated the growth of human A549 flank xenografts compared with untreated animals. Marked antitumor effects were observed when animals were treated with a combination of ZD6126 and fractionated radiation therapy with protracted tumor regression. ZD6126 + ZD1839 resulted in a greater tumor growth delay than either agent alone. Similar additive effects were seen with ZD1839 + fractionated radiation. Finally, the addition of ZD6126 to ZD1839 and radiation therapy seemed to further improve tumor growth control, with a significant tumor growth delay compared with animals treated with single agent or with double combinations. Immunohistochemistry showed that ZD1839 induced a marked reduction in A549 tumor cell proliferation. Both ZD1839 and ZD6126 treatment substantially reduced tumor-induced angiogenesis. ZD6126 caused marked vessel destruction through loss of endothelial cells and thrombosis, substantially increasing the level of necrosis seen when combined with radiation therapy. The combination of radiation therapy, ZD6126, and ZD1839 induced the greatest effects on tumor growth and angiogenesis. This first report shows that a selective vascular-targeting agent (ZD6126) + an anti-epidermal growth factor receptor agent (ZD1839) and radiation have additive in vivo effects in a human cancer model. Targeting the tumor vasculature offers an excellent strategy to enhance radiation cytotoxicity. Polytargeted therapy with agents that interfere with both growth factor and angiogenic signaling warrants further investigation.

The schedule-dependent enhanced cytotoxic activity of 7-ethyl-10-hydroxy-camptothecin (SN-38) in combination with Gefitinib (Iressa™, ZD1839)

The combination of the topoisomerase I (Topo I) inhibitor CPT-11 with the anti-epidermal growth factor receptor (EGFR) agent Gefitinib (Iressa™, ZD1839) represents a promising medical approach for colorectal cancer patients. In this report, we provide pre-clinical evidences for their optimal combination schedule in HT-29 and LoVo human colon cancer cell lines. We analyzed the different effects that three different combination schedules of SN-38 (the active CPT-11 metabolite) and Gefitinib (Gefitinib before; Gefitinib simultaneously; Gefitinib after SN-38) have on cell growth, cell cycle, apoptosis, and expression/phosphorylation of EGFR, Topo I and some steps of the signal transduction pathway. We first determined the IC 50 of each drug choosing the 5 days exposure for Gefitinib (0.6 and 3.8 μM for LoVo and HT-29 cells, respectively) and 1 day exposure for SN-38 (0.31 and 0.5 μM for LoVo and HT-29 cells, respectively). The different drug combination schedules were tested in various concentrations by using equiactive concentrations of the two drugs. The cytotoxicity of Gefitinib and SN-38 combination was schedule- and concentration-dependent but not cell line-specific. The most synergistic schedule was Gefitinib given after SN-38, with combination indexes (CI) of 0.007 and 0.454 in HT-29 and LoVo, respectively. Analysis of bio-molecular targets showed that Gefitinib was able to modulate SN-38 ability to inhibit Topo I, to accumulate cells in S-phase, and to induce apoptosis. Interestingly, SN-38 was able to activate EGFR and its signal transduction pathway. Confirming preliminary clinical experience of Gefitinib with other cytotoxic drugs, it seems that Gefitinib after SN-38 represents the best cytotoxic combination schedule but the biomolecular basis for this synergism remain to be completely elucidated.

The schedule-dependent enhanced cytotoxic activity of 7-ethyl-10-hydroxy-camptothecin (SN-38) in combination with Gefitinib (Iressa?, ZD1839)

The combination of the topoisomerase I (Topo I) inhibitor CPT-11 with the anti-epidermal growth factor receptor (EGFR) agent Gefitinib (Iressa™, ZD1839) represents a promising medical approach for colorectal cancer patients. In this report, we provide pre-clinical evidences for their optimal combination schedule in HT-29 and LoVo human colon cancer cell lines. We analyzed the different effects that three different combination schedules of SN-38 (the active CPT-11 metabolite) and Gefitinib (Gefitinib before; Gefitinib simultaneously; Gefitinib after SN-38) have on cell growth, cell cycle, apoptosis, and expression/phosphorylation of EGFR, Topo I and some steps of the signal transduction pathway. We first determined the IC50 of each drug choosing the 5 days exposure for Gefitinib (0.6 and 3.8 μM for LoVo and HT-29 cells, respectively) and 1 day exposure for SN-38 (0.31 and 0.5 μM for LoVo and HT-29 cells, respectively). The different drug combination schedules were tested in various concentrations by using equiactive concentrations of the two drugs. The cytotoxicity of Gefitinib and SN-38 combination was schedule- and concentration-dependent but not cell line-specific. The most synergistic schedule was Gefitinib given after SN-38, with combination indexes (CI) of 0.007 and 0.454 in HT-29 and LoVo, respectively. Analysis of bio-molecular targets showed that Gefitinib was able to modulate SN-38 ability to inhibit Topo I, to accumulate cells in S-phase, and to induce apoptosis. Interestingly, SN-38 was able to activate EGFR and its signal transduction pathway. Confirming preliminary clinical experience of Gefitinib with other cytotoxic drugs, it seems that Gefitinib after SN-38 represents the best cytotoxic combination schedule but the biomolecular basis for this synergism remain to be completely elucidated.