Molecular mechanisms underlying the interaction between ZD1839 ('Iressa') and cisplatin/5-fluorouracil

Synthetic lethality in human bladder cancer cells by curcumin via concurrent Aurora A inhibition and autophagy induction

Combination therapies to induce mixed-type cell death and synthetic lethality have the potential to overcome drug resistance in cancer. In this study, we demonstrated that the curcumin-enhanced cytotoxicity of cisplatin/carboplatin in combination with gemcitabine was associated with Aurora A suppression-mediated G2/M arrest, and thus apoptosis, as well as MEK/ERK-mediated autophagy in human bladder cancer cells. Animal study data confirmed that curcumin combined with cisplatin/gemcitabine reduced tumorigenesis of xenograft in mice and this phenomenon was associated with elevated expressions of p-ERK and reduced p-Aurora A in tumors. Gene analyses using data repositories further revealed that reduced Aurora A expression alone did not significantly elevate the sensitivity of human bladder carcinoma cells to these anticancer drugs. Unlike other major cancer types, human bladder urothelial carcinoma tissue coexpressed higher AURKA and lower MAP1LC3B than normal tissue, and reduced Aurora A and induction of autophagy have been clinically associated with a better prognosis in patients with early but not advanced stage bladder cancer. Therefore, our results suggest that treatment strategies can utilize the synthetic lethal pair to concurrently suppress oncogenic Aurora A and induce autophagy by coadministrating curcumin with anticancer drugs for early-stage bladder cancer with high expression of Aurora A.

Pharmacologic Induction of BRCAness in BRCA-Proficient Cancers: Expanding PARP Inhibitor Use

The poly(ADP-ribose) polymerase (PARP) family of proteins has been implicated in numerous cellular processes, including DNA repair, translation, transcription, telomere maintenance, and chromatin remodeling. Best characterized is PARP1, which plays a central role in the repair of single strand DNA damage, thus prompting the development of small molecule PARP inhibitors (PARPi) with the intent of potentiating the genotoxic effects of DNA damaging agents such as chemo- and radiotherapy. However, preclinical studies rapidly uncovered tumor-specific cytotoxicity of PARPi in a subset of cancers carrying mutations in the BReast CAncer 1 and 2 genes (BRCA1/2), which are defective in the homologous recombination (HR) DNA repair pathway, and several PARPi are now FDA-approved for single agent treatment in BRCA-mutated tumors. This phenomenon, termed synthetic lethality, has now been demonstrated in tumors harboring a number of repair gene mutations that produce a BRCA-like impairment of HR (also known as a 'BRCAness' phenotype). However, BRCA mutations or BRCAness is present in only a small subset of cancers, limiting PARPi therapeutic utility. Fortunately, it is now increasingly recognized that many small molecule agents, targeting a variety of molecular pathways, can induce therapeutic BRCAness as a downstream effect of activity. This review will discuss the potential for targeting a broad range of molecular pathways to therapeutically induce BRCAness and PARPi synthetic lethality.

Pterostilbene Sensitizes Cisplatin-Resistant Human Bladder Cancer Cells with Oncogenic HRAS

Simple Summary

RAS oncoproteins are considered undruggable cancer targets. Nearly 15% of cases of bladder cancer have a mutation of HRAS. The active HRAS contributes to the tumor progression and the risk of recurrence. Using our novel gene expression screening platform, pterostilbene was identified to sensitize cisplatin-resistant bladder cancer cells with HRAS alterations via RAS-related autophagy and cell senescence pathways, suggesting a potentially chemotherapeutic role of pterostilbene for cisplatin treatment of human bladder cancer with oncogenic HRAS. Pterostilbene is a safe and readily available food ingredient in edible plants worldwide. Exploiting the principle of combination therapy on pterostilbene-enhanced biosensitivity to identify undruggable molecular targets for cancer therapy may have a great possibility to overcome the cisplatin resistance of bladder cancer. Our data make HRAS a good candidate for modulation by pterostilbene for targeted cancer therapy in combination with conventional chemotherapeutic agents cisplatin plus gemcitabine.

Abstract

Analysis of various public databases revealed that HRAS gene mutation frequency and mRNA expression are higher in bladder urothelial carcinoma. Further analysis revealed the roles of oncogenic HRAS, autophagy, and cell senescence signaling in bladder cancer cells sensitized to the anticancer drug cisplatin using the phytochemical pterostilbene. A T24 cell line with the oncogenic HRAS was chosen for further experiments. Indeed, coadministration of pterostilbene increased stronger cytotoxicity on T24 cells compared to HRAS wild-type E7 cells, which was paralleled by neither elevated apoptosis nor induced cell cycle arrest, but rather a marked elevation of autophagy and cell senescence in T24 cells. Pterostilbene-induced autophagy in T24 cells was paralleled by inhibition of class I PI3K/mTOR/p70S6K as well as activation of MEK/ERK (a RAS target) and class III PI3K pathways. Pterostilbene-induced cell senescence on T24 cells was paralleled by increased pan-RAS and decreased phospho-RB expression. Coadministration of PI3K class III inhibitor 3-methyladenine or MEK inhibitor U0126 suppressed pterostilbene-induced autophagy and reversed pterostilbene-enhanced cytotoxicity, but did not affect pterostilbene-elevated cell senescence in T24 cells. Animal study data confirmed that pterostilbene enhanced cytotoxicity of cisplatin plus gemcitabine. These results suggest a therapeutic application of pterostilbene in cisplatin-resistant bladder cancer with oncogenic HRAS.

Rethink of EGFR in Cancer With Its Kinase Independent Function on Board

The epidermal growth factor receptor (EGFR) is one of most potent oncogenes that are commonly altered in cancers. As a receptor tyrosine kinase, EGFR's kinase activity has been serving as the primary target for developing cancer therapeutics, namely the EGFR inhibitors including small molecules targeting its ATP binding pocket and monoclonal antibodies targeting its ligand binding domains. EGFR inhibitors have produced impressive therapeutic benefits to responsive types of cancers. However, acquired and innate resistances have precluded current anti-EGFR agents from offering sustainable benefits to initially responsive cancers and benefits to EGFR-positive cancers that are innately resistant. Recent years have witnessed a realization that EGFR possesses kinase-independent (KID) pro-survival functions in cancer cells. This new knowledge has offered a different angle of understanding of EGFR in cancer and opened a new avenue of targeting EGFR for cancer therapy. There are already many excellent reviews on the role of EGFR with a focus on its kinase-dependent functions and mechanisms of resistance to EGFR targeted therapies. The present opinion aims to initiate a fresh discussion about the function of EGFR in cancer cells by laying out some unanswered questions pertaining to EGFR in cancer cells, by rethinking the unmet therapeutic challenges from a view of EGFR's KID function, and by proposing novel approaches to target the KID functions of EGFR for cancer treatment.

Dielectrophoretic analysis of treated cancer cells for rapid assessment of treatment efficacy

Whilst personalized medicine (where interventions are precisely tailored to a patient's genotype and phenotype, as well as the nature and state of the disease) is regarded as an optimal form of treatment, the time and cost associated with it means it remains inaccessible to the greater public. A simpler alternative, stratified medicine, identifies groups of patients who are likely to respond to a given treatment. This allows appropriate treatments to be selected at the start of therapy, avoiding the common "trial and error" approach of replacing a therapy only once it is demonstrated to be ineffective in the patient. For stratification to be effective, tests are required that rapidly predict treatment effectiveness. Most tests use genetic analysis to identify drug targets, but these can be expensive and may not detect changes in the phenotype that affect drug sensitivity. An alternative method is to assess the whole-cell phenotype by evaluating drug response using cells from a biopsy. We assessed dielectrophoresis to assess drug efficacy on short timescales and at low cost. To explore the principle of assessing drug efficacy we examined two cell lines (one expressing EGFR, one not) with the drug Iressa. We then further explored the sensitive cells using combinations of chemotherapeutic and radiotherapeutic therapies. Our results compare with known effects of these cell/treatment combination, and offer the additional benefit over methods such as TUNEL of detecting drug effects such as cell cycle arrest, which do not cause cell death.

EGFR targeted therapies and radiation: Optimizing efficacy by appropriate drug scheduling and patient selection

The epidermal growth factor receptor (EGFR) plays an important role in tumor progression and treatment resistance for many types of malignancies including head and neck, colorectal, and nonsmall cell lung cancer. Several EGFR targeted therapies are efficacious as single agents or in combination with chemotherapy. Given the toxicity associated with chemoradiation and poor outcomes seen in several types of cancers, combinations of EGFR targeted agents with or without chemotherapy have been tested in patients receiving radiation. To date, the only FDA approved use of an anti-EGFR therapy in combination with radiation therapy is for locally advanced head and neck cancer. Given the important role EGFR plays in lung and colorectal cancer and the benefit of EGFR inhibition combined with chemotherapy in these disease sites, it is perplexing why EGFR targeted therapies in combination with radiation or chemoradiation have not been more successful. In this review we summarize the clinical findings of EGFR targeted therapies combined with radiation and chemoradiation regimens. We then discuss the interaction between EGFR and radiation including radiation induced EGFR signaling, the effect of EGFR on DNA damage repair, and potential mechanisms of radiosensitization. Finally, we examine the potential pitfalls with scheduling EGFR targeted therapies with chemoradiation and the use of predictive biomarkers to improve patient selection.

Future chemotherapy and radiotherapy options in head and neck cancer

Chemoradiation is a standard approach to advanced unresectable head and neck cancer, although the optimum combination regimen remains controversial. However, in the past few years, chemoradiation has been successfully extended from the treatment of unresectable disease to the postsurgical therapy of high-risk patients and its value as an organ preservation procedure is under evaluation. More recently, molecular-targeted therapies have emerged, which interfere with mechanisms of chemo- and radioresistance, and preliminary data are promising. Their use in the combined treatment of head and neck cancer will hopefully further improve the value of chemoradiation in the clinical setting.

Cadmium modifies the cell cycle and apoptotic profiles of human breast cancer cells treated with 5-fluorouracil

Industrialisation, the proximity of factories to cities, and human work activities have led to a disproportionate use of substances containing heavy metals, such as cadmium (Cd), which may have deleterious effects on human health. Carcinogenic effects of Cd and its relationship with breast cancer, among other tumours, have been reported. 5-Fluorouracil (5-FU) is a fluoropyrimidine anticancer drug used to treat solid tumours of the colon, breast, stomach, liver, and pancreas. The purpose of this work was to study the effects of Cd on cell cycle, apoptosis, and gene and protein expression in MCF-7 breast cancer cells treated with 5-FU. Cd altered the cell cycle profile, and its effects were greater when used either alone or in combination with 5-FU compared with 5-FU alone. Cd significantly suppressed apoptosis of MCF-7 cells pre-treated with 5-FU. Regarding gene and protein expression, bcl2 expression was mainly upregulated by all treatments involving Cd. The expression of caspase 8 and caspase 9 was decreased by most of the treatments and at all times evaluated. C-myc expression was increased by all treatments involving Cd, especially 5-FU plus Cd at the half time of treatment. Cd plus 5-FU decreased cyclin D1 and increased cyclin A1 expression. In conclusion, our results indicate that exposure to Cd blocks the anticancer effects of 5-FU in MCF-7 cells. These results could have important clinical implications in patients treated with 5-FU-based therapies and who are exposed to high levels of Cd.

Cisplatin-Based Chemotherapy Options for Recurrent and/or Metastatic Squamous Cell Cancer of the Head and Neck

Recurrent and/or metastatic head and neck squamous cell carcinoma (R/M HNSCC) is a devastating malignancy with a poor prognosis. Treatment is limited to chemotherapeutic approaches. Cisplatin is an established and effective treatment for R/M HNSCC, and many studies have investigated cisplatin treatment in combination with other agents. Even when being treated with first line therapy (cisplatin + 5-fluorouracil + cetuximab), overall survival is only 10 months, indicating the need for novel chemotherapeutics and treatment regimens. Current research is focused on molecular targeting therapies inhibiting epidermal growth factor receptor, phosphoinositide-3-kinase/Akt/mammalian target of rapamycin, and vascular endothelial growth factor pathways. A variety of clinical trials have been completed and are currently underway with encouraging results. Finally, future directions of cisplatin-based R/M HNSCC treatment may include targeting specific pathways known to induce cisplatin resistance, such as nucleotide excision repair and inhibition of apoptosis, in hopes to enhance response to cisplatin therapy.

The combi-targeting concept: mechanism of action of the pleiotropic combi-molecule RB24 and discovery of a novel cell signaling-based combination principle

RB24 (NSC 741279), a 3-methyltriazene termed "combi-molecule" designed to possess mixed epidermal growth factor receptor (EGFR) targeting and DNA methylating properties showed over a 100-fold greater antiproliferative activity than Temodal(®) (TEM), a 4-fold greater potency than gefitinib and a 5-fold stronger activity than an equi-effective combination of gefitinib+TEM against the O(6)-alkylguanine transferase (AGT)-proficient DU145 cell line that co-expresses EGFR. Investigation of the mechanisms underlying the unique potency of RB24 revealed that cell exposure to TEM was accompanied by activation of p38MAPK and concomitant elevation of the levels of X-ray repair cross-complementing group 1 (XRCC1) protein. Levels of phospho-p38MAPK and XRCC1 were increased by 2-fold in EGF-stimulated cells. In contrast, EGF-stimulation did not alter the status of these proteins in RB24-treated cells and this translated into a 2-fold lower level of XRCC1 when compared with those exposed to TEM+EGF. These effects correlated with significantly delayed DNA repair activity in combi-molecule-treated cells when compared with TEM-exposed ones. Further analysis demonstrated that in contrast to TEM, RB24 could block Bad phosphorylation at serine 136 in a dose-dependent manner and induced significantly higher levels of apoptosis than the former molecule. Tandem depletion of XRCC1 and Bad activation through alternative pathways using the MEK1 inhibitor, PD98059, led to substantial levels of apoptosis in RB24-treated cells. The results in toto indicate that the superior activity of the combi-molecule may be attributed to its ability to down-regulate DNA repair proteins such as XRCC1 and to alleviate anti-apoptotic signaling through blockade of EGFR-mediated signaling while inflicting high levels of DNA lesions to the cells.

cIAP2 upregulated by E6 oncoprotein via epidermal growth factor receptor/phosphatidylinositol 3-kinase/AKT pathway confers resistance to cisplatin in human papillomavirus 16/18-infected lung cancer

PURPOSE

Inhibitors of antiapoptosis protein (IAP) have been implicated in the resistance to cisplatin. Therefore, verifying which pathway is involved in cIAP2 upregulation may be helpful in finding a feasible pathway inhibitor to increase the chemotherapeutic efficacy in human papillomavirus (HPV)-infected lung cancer.

EXPERIMENTAL DESIGN

Specific inhibitors of different pathways were used to verify which pathway is involved in cIAP2 transcription. cIAP2 promoter fragments with various deletions and/or mutations were constructed by site-directed mutagenesis. cIAP2, epidermal growth factor receptor (EGFR), and phospho-AKT (p-AKT) expressions in 136 lung tumors were evaluated by immunohistochemistry.

RESULTS

Our data show that two NF-κB (-209 to -200 and -146 to -137) and one CREB (cyclic AMP-responsive element binding protein; -52 to -42) binding sites in cIAP2 promoter region were responsible for cIAP2 upregulated by E6 in TL-1 cells. Moreover, CREB was phosphorylated by EGFR/phosphatidylinositol 3-kinase (PI3K) pathway. To test the involvement of cIAP2 on cisplatin resistance, IC(50) was lowered to 8.6 μmol/L in TL-1 cells with cIAP2 short hairpin RNA (shRNA) transfection and compared with 39.7 μmol/L in TL-1 cells with nonspecific shRNA. Pretreatment with EGFR or PI3K inhibitor in TL-1 cells diminished the resistance to cisplatin. Among the tumor groups, cIAP2 expression correlated significantly with HPV16/18 E6, EGFR, and p-AKT. We followed up 46 of 136 patients who had tumor recurrence and/or metastasis and underwent chemotherapy. Tumors with cIAP2-positive immunostaining were associated with a poorer tumor response to chemotherapy compared with those with negative immunostaining.

CONCLUSIONS

cIAP2 upregulated by E6 via EGFR/PI3K/AKT cascades may contribute to cisplatin resistance, revealing that the EGFR or PI3K inhibitor combined with cisplatin may improve the chemotherapeutic efficacy in HPV-infected lung cancer.

Phase I trial of liposomal doxorubicin and ZD1839 in patients with refractory gynecological malignancies or metastatic breast cancer

BACKGROUND

Pegylated liposomal doxorubicin has activity in both breast and ovarian cancer. Preclinical data noted that ZD1839 acts synergistically with chemotherapy. Given the lack of cross-resistance between these two agents, a phase I trial was initiated examining the safety and efficacy of the combination of liposomal doxorubicin and ZD1839 in patients with recurrent gynecologic or metastatic breast cancer.

METHODS

Dose-limiting toxicity (DLT) was defined within the first two cycles of treatment. Escalating doses of liposomal doxorubicin were administered every 4 weeks with ZD1839. Pharmacokinetic analysis and correlative studies were performed.

RESULTS

Thirty-five patients were enrolled in this study: six in each cohort. One DLT (febrile neutropenia) was observed in cohort 2. Dose level 3 was determined to be the maximum tolerated dose (MTD), and an additional ten patients were accrued. Serious adverse events (SAEs) included one patient with mental status changes believed secondary to disease progression and two central nervous system (CNS) bleeds believed to be unrelated to the combination of study agents. Toxicities were generally mild except for skin and gastrointestinal toxicity. No cardiac toxicity was observed. The best response to therapy included four partial responses and 20 patients with stable disease.

CONCLUSIONS

Liposomal doxorubicin with ZD1839 is an active regimen but is associated with increased skin toxicity in patients with advanced breast and gynecologic cancer.

Gefitinib induces apoptosis and decreases telomerase activity in MDA-MB-231 human breast cancer cells

Gefitinib is an anti-cancer drug that selectively inhibits epithelial growth factor receptor (EGFR) tyrosine kinase activity and induces apoptosis in many cancer cells. Cancer cells are often protected from apoptotic cell death by telomerase, however the gefitinib-induced telomerase inhibition remains unknown. Here we investigated the effects of gefitinib on telomerase activity in two different breast cancer lines, MCF-7 (low expression of EGFR) and MDA-MB-231 (high expression of EGFR). We observed the inhibition of EGFR phosphorylation that occurred only MDA-MB-231 cells cultured in media containing 10% FBS. Direct cytotoxicity was observed in MDA-MB-231 cells, but not MCF-7 cells when treated with concentrations of gefitinib ranging from 15 to 20 microM. This cytotoxicity was associated with decreased telomerase activity and downregulation of the telomerase subunit, hTERT. c-Myc has previously been shown to activate telomerase activity through transcriptional regulation of hTERT. A decrease in c-myc expression and DNA-binding activity following treatment with gefitinib was observed exclusively in MDA-MB-231 cells. We also demonstrated that gefitinib downregulates the activation of Akt and subsequent hTERT phosphorylation and translocation into the nucleus in MDA-MB-231 cells. These results indicate that gefitinib induces loss of telomerase activity through dephosphorylation of EGFR in MDA-MB-231 cells.

Trichostatin A sensitizes human ovarian cancer cells to TRAIL-induced apoptosis by down-regulation of c-FLIPL via inhibition of EGFR pathway

TRAIL-resistant cancer cells can be sensitized to TRAIL by combination therapy. In this study, we investigated the effect of trichostatin A (TSA), a histone deacetylase inhibitor, to overcome the TRAIL resistance in human ovarian cancer cells. Co-treatment of human ovarian cancer cells with TSA and TRAIL synergistically inhibited cell proliferation and induced apoptosis. The combined treatment of ovarian cancer SKOV3 cells with TSA and TRAIL significantly activated caspase-8 and truncated Bid, resulting in the cytosolic accumulation of cytochrome c as well as the activation of caspase-9 and -3. Moreover, we found that down-regulation of c-FLIP(L) might contribute to TSA-mediated sensitization to TRAIL-induced apoptosis in SKOV3 cells, and this result was supported by showing that down- or up-regulation of c-FLIP(L) with transfection of siRNA or plasmid sensitized or made SKOV3 cells resistant to TRAIL-induced apoptosis, respectively. TSA or co-treatment with TSA alone and TRAIL also resulted in down-regulation of EGFR1/2 and dephosphorylation of its downstream targets, AKT and ERK. Treatment of SKOV3 cells with PKI-166 (EGFR1/2 inhibitor), LY294002 (AKT inhibitor), and PD98059 (ERK inhibitor) decreased c-FLIP(L) expression and co-treatment with TRAIL further reduced the level of c-FLIP(L,) respectively, as did TSA. Collectively, our data suggest that TSA-mediated sensitization of ovarian cancer cells to TRAIL is closely correlated with down-regulation of c-FLIP(L) via inhibition of EGFR pathway, involving caspase-dependent mitochondrial apoptosis, and combination of TSA and TRAIL may be an effective strategy for treating TRAIL-resistant human ovarian cancer cells.

The efficacy and toxicity of EGFR in the settings of radiotherapy: Focus on published clinical trials

Basic research in solid malignant tumours has led to a wealth of knowledge about this disease process and about novel ways to more effectively target our therapies. Laboratory research continues to identify novel therapeutic targets and moreover, clinical research is identifying effective new treatment regimens. Many preclinical studies in this area have targeted the epidermal growth factor receptor (EGFR) signalling pathway to increase radiosensitivity. The in vitro rationale for targeting EGFR and concurrent ionising radiation is well established, but to date, rare clinical data could provide proof-of-principle. Here we report all the different published clinical trials focusing on efficacy and toxicity in order to clarify and to summarise the present state-of-the-art of this particularly promising combination in solid tumour management.

Gefitinib radiosensitizes non-small cell lung cancer cells by suppressing cellular DNA repair capacity

PURPOSE

Overexpression of the epidermal growth factor receptor (EGFR) promotes unregulated growth, inhibits apoptosis, and likely contributes to clinical radiation resistance of non-small cell lung cancer (NSCLC). Molecular blockade of EGFR signaling is an attractive therapeutic strategy for enhancing the cytotoxic effects of radiotherapy that is currently under investigation in preclinical and clinical studies. In the present study, we have investigated the mechanism by which gefitinib, a selective EGFR tyrosine kinase inhibitor, restores the radiosensitivity of NSCLC cells.

EXPERIMENTAL DESIGN

Two NSCLC cell lines, A549 and H1299, were treated with 1 micromol/L gefitinib for 24 h before irradiation and then tested for clonogenic survival and capacity for repairing DNA double strand breaks (DSB). Four different repair assays were used: host cell reactivation, detection of gamma-H2AX and pNBS1 repair foci using immunofluorescence microscopy, the neutral comet assay, and pulsed-field gel electrophoresis.

RESULTS

In clonogenic survival experiments, gefitinib had significant radiosensitizing effects on both cell lines. Results from all four DNA damage repair analyses in cultured A549 and H1299 cells showed that gefitinib had a strong inhibitory effect on the repair of DSBs after ionizing radiation. The presence of DSBs was especially prolonged during the first 2 h of repair compared with controls. Immunoblot analysis of selected repair proteins indicated that pNBS1 activation was prolonged by gefitinib correlating with its effect on pNBS1-labeled repair foci.

CONCLUSIONS

Overall, we conclude that gefitinib enhances the radioresponse of NSCLC cells by suppressing cellular DNA repair capacity, thereby prolonging the presence of radiation-induced DSBs.

Epidermal growth factor receptor inhibitors enhance susceptibility to Fas-mediated apoptosis in oral squamous cell carcinoma cells

Molecular inhibition of epidermal growth factor receptor (EGFR) signaling is a promising cancer treatment strategy. We examined whether inhibition of EGFR signaling would affect the susceptibility of oral squamous cell carcinoma (OSCC) cells to Fas-mediated apoptosis. Treatment of OSCC cells with an anti-EGFR monoclonal antibody, C225, and an EGFR tyrosine kinase inhibitor, AG1478, which target the extracellular and intracellular domains of the receptor, respectively, inhibited phosphorylation of EGFR and its downstream effector molecule Akt and amplified the induction of Fas-mediated apoptosis. In OSCC cells treated with EGFR inhibitors, Fas-mediated apoptosis was accompanied by caspase-8 activation but not Bid cleavage. Caspase-3 and -8 inhibitors reduced the effect of EGFR inhibitors on Fas-mediated apoptosis in OSCC cells, but a caspase-9 inhibitor did not. These results indicate that the pro-apoptotic activity of EGFR inhibitors in OSCC cells depends on the extrinsic pathway of the caspase cascade. Although EGFR inhibitors did not affect the expression of Fas, the Fas-associated death domain protein, or procaspase-8 in OSCC cells, the inhibition downregulated cellular FLICE-inhibitory protein (c-FLIP). Moreover, knockdown of c-FLIP in HSC-2 cells with a small interfering RNA strongly enhanced Fas-mediated apoptosis. These results suggest that the EGFR signaling pathway may, in part, regulate Fas-mediated apoptosis in OSCC cells through c-FLIP expression.

Preclinical study of a "tailor-made" combination of NK4-expressing gene therapy and gefitinib (ZD1839, Iressa) for disseminated peritoneal scirrhous gastric cancer

We evaluated the effect of a "tailor-made" chemo-gene therapy in scirrhous gastric cancer (SGC)-bearing nude mice. For this tailor-made approach, we first selected gefitinib (epidermal growth factor receptor-tyrosine kinase inhibitor)-sensitive SGC cell lines, and 5/8 cell lines demonstrated various degrees of gefitinib-sensitivity. In the highly gefitinib-sensitive NUGC-4, the biological response to NK4 (HGF antagonist/angiogenesis inhibitor) was examined. Subsequently, the composition of an NK4-expressing ternary complex (cationic lipid/nucleic acid/HMG-1, 2 protein) was optimized for maximum transfection activity in NUGC-4. Finally, mice were peritoneally coinoculated with NUGC-4 and scirrhous-associated gastric fibroblasts, NF22, on day 0. Animal models were orally administrated gefitinib (50 mg/kg/day, on days 7-28), and peritoneally NK4-expressing ternary complex (on days 14, 21 and 28). NK4-expression suppressed the gefitinib-resistance induced by the interaction between fibroblasts and SGC, and eventually, this tailor-made combination synergistically decelerated the disease progression by inhibiting proliferative, angiogenic and antiapoptotic effects in tumor tissues. On day 28, both the hemoglobin concentration (g/dl) (control (n = 8), 11.9; treated (n = 8), 17.3; p = 0.0014) and the numbers of mice in good condition (control, 2; treated, 8; p = 0.0012) were significantly greater, and the abdominal girth (mm) (control, 81.1; treated, 70.3; p = 0.0036) was significantly reduced. The median points of bloody ascite-free survival time (days) (control, 22; treated, 44; p < 0.0001) and time to euthanasia (days) (control, 36.5; treated, 56; p < 0.0001) were also significantly prolonged. This combination is a potentially useful approach to the treatment of peritoneal gefitinib-sensitive SGC dissemination.

Induction of apoptosis by an inhibitor of EGFR in neuroblastoma cells

We aimed to examine the expression of EGFR in neuroblastoma tissues and to investigate the antitumor activity of a selective EGFR-tyrosine kinase inhibitor, gefitinib, on neuroblastoma. The expression of EGFR was detected in each of two tumor tissues by immunohistochemistry and eight of 10 cell lines by Western blotting. Gefitinib inhibited EGFR-phosphorylation and in vitro cell growth (IC(50): approximately 1.2 microM), and a high concentration of gefitinib (20-30 microM) induced apoptosis in vitro. This is the first report that EGFR protein is expressed on the cell surface in neuroblastoma tissues and in cell lines. We also demonstrated an EGFR inhibitor induced apoptosis on neuroblastoma cells. Our results suggest the feasibility of targeting EGFR as a novel strategy against neuroblastoma.

Dose scheduling of the dual VEGFR and EGFR tyrosine kinase inhibitor vandetanib (ZD6474, Zactima) in combination with radiotherapy in EGFR-positive and EGFR-null human head and neck tumor xenografts

PURPOSE

Vandetanib (ZD6474, Zactima) is a novel, orally available inhibitor of vascular endothelial growth factor receptor-2 (VEGFR2) tyrosine kinase activity with additional activity against epidermal growth factor receptor (EGFR) tyrosine kinase. Vandetanib has demonstrated enhanced efficacy in combination with radiation therapy (RT) in human tumor models. This study aimed to evaluate the schedule-dependent interaction of clinically relevant dosing of vandetanib with RT in human head and neck cancer models that had been characterized as EGFR positive (EGFR+) or negative (EGFR-) in order to begin differentiating vandetanib and RT interactions at the level of antitumor (EGFR) or antivascular (VEGFR2) activities.

METHODS

The human head and neck squamous cell carcinoma (HNSCC) cell lines UMSCC2 (EGFR+) and UMSCC10 (EGFR(-)) are sensitive and resistant to EGFR inhibitors, respectively, while having similar sensitivity to ionizing radiation. Nude mice with UMSCC2 or UMSCC10 tumor xenografts were treated with vandetanib or RT alone, or with combinations of concomitant and sequential therapy. Vandetanib was dosed at 30 mg kg(-1) day(-1) based on pharmacokinetic studies in nude mice showing that this dose results in drug exposure similar to that seen in humans at clinical doses. RT was dosed at 3 Gy twice a week for two consecutive weeks for a total dose of 12 Gy.

RESULTS

Vandetanib alone caused regression in EGFR+ but not EGFR- tumors and RT therapy alone was similar in both tumor types. Combinations of vandetanib and RT showed concomitant use of vandetanib and RT was superior to RT followed by vandetanib or visa versa in EGFR- tumors. Therapeutic response of EGFR+ tumors was similar regardless of treatment sequencing.

CONCLUSIONS

The combination of vandetanib and RT is active in both EGFR+ and EGFR- HNSCC tumor xenografts, however, vandetanib alone is only active in EGFR+ xenografts. EGFR+ tumor response to vandetanib and RT was independent of treatment sequencing, but concomitant treatment was superior to sequencing in EGFR- tumors. These results suggest that the anti-VEGFR2 antitumor activity of vandetanib is enhanced by RT as presumably the activity seen in EGFR- tumors is due to antiangiogenic activity, whereas the anti-EGFR antitumor activity dominates in EGFR+ tumors such that RT enhancement is not observed.

Tumor inhibitory effect of gefitinib (ZD1839, Iressa) and taxane combination therapy in EGFR-overexpressing breast cancer cell lines (MCF7/ADR, MDA-MB-231)

Some kinds of breast cancer cell lines, similar to several types of solid tumors, express epidermal growth factor receptor (EGFR). However, gefitinib, an EGFR tyrosine kinase inhibitor, is not effective for all these cell lines. Similarly, taxane is effective for many of the cell lines, although some, such as the multidrug-resistant MCF7/ADR cell line, show taxane-resistance. Here, we examined the growth inhibitory effect of combination treatment with gefitinib and taxane on the breast cancer cell lines MDA-MB-231 (EGFR-positive) and MCF7/ADR (EGFR- and HER2-positive). To estimate the combined effect, a Combination Index was calculated for each cell line. The combination of gefitinib and taxane showed a strong synergistic effect on MCF7/ADR cells, but an invitro additive-antagonistic effect on MDA-MB-231 cells. Similarly, the combination treatment showed a significantly increased tumor inhibitory effect on MCF7/ADR xenografts, but not on MDA-MB-231 xenografts. Regarding the mechanism of the synergistic effect, Western blotting analysis revealed that taxane activated the EGFR-Akt pathway in MCF7/ADR cells but not in MDA-MB-231. To determine the optimal sequential administration of gefitinib and taxane for MCF7/ADR cells, we used flow cytometry to analyze the cell cycle and apoptosis; finding that taxane treatment followed by gefitinib produced a higher rate of G2 arrest and apoptosis than gefitinib treatment followed by taxane. These results suggest gefitinib overcomes the drug-resistance of these cells, thereby increasing the effects of taxane on MCF7/ADR cells. Further, activation of the EGFR-Akt pathway by taxane is related to this synergistic effect.

Combined Treatment of Bladder Cancer Cell Lines with Lapatinib and Varying Chemotherapy Regimens—Evidence of Schedule-Dependent Synergy

OBJECTIVES

ErbB family members present an attractive target for therapeutic manipulation in bladder cancer. Lapatinib is an oral, small molecule, reversible dual inhibitor of ErbB1 (epidermal growth factor receptor) and ErbB2 (HER2) tyrosine kinases. Cisplatin-based combination chemotherapy has proven benefit in palliating symptoms and prolonging survival in patients with metastatic bladder cancer. In this study, we investigated the potential utility of lapatinib as an adjunct to chemotherapy in human bladder cancer cell lines. We also assessed whether these interactions were schedule dependent and synergistic.

METHODS

We chose two bladder cancer cell lines, one (RT112) with high expression of ErbB1 and ErbB2 and one (J82) with low expression of these receptors. These cell lines were used to determine the growth inhibitory effects of lapatinib and the clinically relevant combination of gemcitabine and cisplatin (GC) chemotherapy. Four different schedules were assessed: GC alone (no lapatinib); lapatinib before and during GC; lapatinib concomitant with GC; and lapatinib after GC.

RESULTS

Lapatinib reduced cell viability in both cell lines in a dose-dependent fashion. The values for the 50% inhibitory concentration for RT112 and J82 cells after lapatinib were similar. In both cell lines, the addition of lapatinib to GC potentiated the efficacy. The optimal sequence consisted of lapatinib before and during GC. Using this schedule, cooperation was synergistic.

CONCLUSIONS

Our data present evidence that lapatinib cooperates with clinically relevant cytotoxic agents and may have therapeutic utility in the management of chemotherapy-naive metastatic bladder cancer. Lapatinib may also enable reduced-dose chemotherapy, a potential toxicity-sparing strategy.

Integration of EGFR inhibitors with radiochemotherapy

Laboratory studies that led to the development of epidermal growth factor receptor (EGFR) inhibitors indicated that such inhibitors would be effective when given to patients with tumours that are driven by activated EGFR. However, initial clinical studies have shown modest responses to EGFR inhibitors when used alone, and it has not yet been possible to clearly identify which tumours will respond to this therapy. As a result, EGFR inhibitors are now used in combination with radiation therapy, chemotherapy and, more recently, with concurrent radiochemotherapy. In general, these clinical trials have been designed without much preclinical data. What do we need to know to make these combinations successful in the clinic?

Blockage of Epidermal Growth Factor Receptor-Phosphatidylinositol 3-Kinase-AKT Signaling Increases Radiosensitivity of K-RAS Mutated Human Tumor Cells In vitro by Affecting DNA Repair

PURPOSE

It is known that blockage of epidermal growth factor receptor (EGFR)/phosphatidylinositol 3-kinase (PI3K) activity enhances radiation sensitivity of human tumor cells presenting a K-RAS mutation. In the present study, we investigated whether impaired repair of DNA double-strand breaks (DSB) is responsible for the radiosensitizing effect of EGFR and PI3K inhibition in K-RAS mutated (K-RAS(mt)) cells.

EXPERIMENTAL DESIGN

The effect of the EGFR tyrosine kinase inhibitor BIBX1382BS (BIBX) on cellular radiosensitivity was determined in K-RAS(mt) (A549) and K-RAS(wt) (FaDu) cell lines by clonogenic survival assay. Radiation-induced phosphorylation of H2AX (Ser139), ATM (Ser1981), and DNA-dependent protein kinase catalytic subunit (DNA-PKcs; Thr2609) was analyzed by immunoblotting. Twenty-four hours after irradiation, residual DSBs were quantified by identification of gammaH2AX foci and frequency of micronuclei.

RESULTS

BIBX reduced clonogenic survival of K-RAS(mt)-A549 cells, but not of K-RAS(wt)-FaDu cells, after single-dose irradiation. Analysis of the radiation-induced H2AX phosphorylation revealed that BIBX, as well as the PI3K inhibitor LY294002, leads to a marked reduction of P-H2AX in K-RAS(mt)-A549 and MDA-MB-231 cells, but not in K-RAS(wt)-FaDu and HH4ded cells. Likewise, radiation-induced autophosphorylation of DNA-PKcs at Thr2609 was only blocked in A549 cells by these two inhibitors and AKT1 small interfering RNA transfection. However, neither in K-RAS(mt) nor in K-RAS(wt) cells the inhibitors did affect radiation-induced ATM phosphorylation. As a consequence of inhibitor treatment, a significant enhancement of both residual DSBs and frequency of micronuclei was apparent only in A549 but not in FaDu cells following radiation.

CONCLUSION

Targeting of the EGFR-dependent PI3K-AKT pathway in K-RAS-mutated A549 cells significantly affects postradiation survival by affecting the activation of DNA-PKcs, resulting in a decreased DSB repair capacity.

Targeting of EGFR tyrosine kinase by ZD1839 ("Iressa") in androgen-responsive prostate cancer in vitro

EGFR, highly expressed in a variety of human malignancies, is correlated with poor tumour differentiation, high tumour growth and metastatic rate. EGF and several other ligands, such as transforming growth factor-alpha, amphiregulin, heparin-binding EGF, and betacellulin, activate Ras/Raf mitogen-activated protein kinases (MAPKs) and phosphatidyl inositol 3'-kinase (PI3K)/Akt signalling pathways. Therefore, EGFR can regulate multiple processes, i.e., gene expression, cellular proliferation, angiogenesis, and inhibition of apoptosis, which contribute to the development of malignancy. In this review, we discuss the inhibition of EGFR by the specific tyrosine kinase inhibitor Iressa (ZD1839) focusing on its effects in prostate cancer.

Interaction of the epidermal growth factor receptor and the DNA-dependent protein kinase pathway following gefitinib treatment

The epidermal growth factor receptor (EGFR) is an important target for cancer therapy. We previously showed that the EGFR inhibitor gefitinib modulated repair of DNA damage following exposure to cisplatin and etoposide involving the DNA-dependent protein kinase (DNA-PK) pathway. In this study, we specifically investigated the effect of EGFR inhibition by gefitinib on functional activity of DNA-PK in cancer cell lines and the interaction between EGFR and DNA-PK. The effects of DNA-PK inhibition by wortmannin and small interfering RNA to the catalytic subunit of DNA-PK (DNA-PK(CS)) on cell proliferation and DNA interstrand cross-link repair were investigated in the human MCF-7 breast cancer cell line and compared with the effects of gefitinib. DNA-PK activity was quantitated and expression measured by immunoblotting following gefitinib treatment. Immunoprecipitation experiments were done with and without gefitinib in MCF-7 cells, the AR42J pancreas cell line with high EGFR, and the human MDA-453 breast cancer cell line expressing low EGFR. Nuclear and cytoplasmic extracts were immunoblotted with antibody to DNA-PK(CS) to determine if gefitinib treatment altered cellular expression. Reduction of DNA-PK activity by wortmannin and expression by small interfering RNA to DNA-PK(CS) sensitized cells to cisplatin and inhibited repair of cisplatin-induced interstrand cross-links. Gefitinib treatment reduced DNA-PK activity in MCF-7 and AR42J but not MDA-453 cells. Immunoprecipitation experiments showed interaction between EGFR and DNA-PK(CS) in a dose-dependent and time-dependent manner following gefitinib treatment in MCF-7 and AR42J but not MDA-453 cells. Gefitinib treatment reduced nuclear expression and increased cytosolic expression of DNA-PK(CS) in MCF-7 and AR42J but not MDA-453 cells. Treatment with gefitinib modulates association of EGFR and DNA-PK(CS). This is correlated with decreased function of DNA-PK(CS). Inhibition of DNA-PK(CS) may be an important factor in sensitization to chemotherapy and radiation following treatment with inhibitors of the EGFR pathway.

ZD6474 inhibits proliferation and invasion of human hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is characterized by hypervascularization, neoangiogenesis formation and blood vessel invasion. Recently, it has been demonstrated that an inhibitor of the vascular endothelial growth factor (VEGF) receptor, ZD6474, may directly inhibit the growth of tumor cells. ZD6474 effectiveness was investigated on cell growth, apoptosis, adhesion, migration and invasion and related to the drug-dependent modulation of main molecular targets on HCC cells. ZD6474 inhibited HCC cell proliferation, however, such effect was reverted by Laminin-5 (Ln-5) but not by other extracellular matrix proteins (ECM). ZD6474 also inhibited HCC cell adhesion, migration and invasion, whereas the simultaneous treatment with the drug and Ln-5 strongly recovered those effects. Under the same experimental conditions, ZD6474 inhibited the expression of phosphorylated EGFR in all cell lines while the effect on p-Erk1/2 was dependent on cellular invasive characteristics. Nonetheless, co-incubation with Ln-5 completely recovered this effect. Our results support the hypothesis that ZD6474 could represent an interesting therapeutic opportunity for patients with HCC scarcely expressing the ECM protein, Ln-5.

Epidermal growth factor receptor inhibitor (PD168393) potentiates cytotoxic effects of paclitaxel against androgen-independent prostate cancer cells

Recent data showed that epidermal growth factor receptor (EGFR) inhibitors, such as ZD1839, alone or in combination with chemotherapeutic agents for androgen-independent prostate cancer (AIPC) did not produce promising results in clinical settings. More effective regimens involving novel stronger inhibitor of EGFR and better combinations are needed. The anti-tumor activity of PD168393, an irreversible EGFR inhibitor, with or without chemotherapeutic agents for the treatment of AIPC was investigated in vitro. In results, both the androgen-independent cell lines PC-3 and DU145 expressed higher levels of EGFR than the androgen-dependent MDA PCa 2b and androgen-responsive LNCaP cells by Western blotting. DU145 was much more sensitive to PD168393 and ZD1839 than MDA PCa 2b. PD168393, but not ZD1839, significantly potentiated paclitaxel cytotoxicity against DU145 by MTT assay and median-effect analysis. The combination of PD168393 or ZD1839 with other cytotoxic agents including docetaxel and 5-fluorouracil, however, was either additive or antagonistic. Compared to paclitaxel alone, PD168393 significantly enhanced paclitaxel-induced DNA fragmentation, sub-G1 fraction accumulation, mitochondrial membrane dysfunction, cytochrome C release, caspase-3 activation and eventually apoptosis. These molecular events were accompanied by Bad up-regulation, p53 and p21Waf1/Cip1 induction, ERK1/2 inactivation and inhibition of EGFR phosphorylation in the presence of PD168393. These effects did not involve significant alteration in the Akt1/2 and STAT3 signaling pathway. In conclusion, the combination of paclitaxel and PD168393 produced a profound synergistic growth inhibition of AIPC cells. Combining PD168393 with paclitaxel may have clinical benefits and warrants further investigation.

Update on clinical radiobiology

Radiation therapy is an important local cytotoxic modality for cancer treatment whose aim is to control the disease while minimising damage to normal tissue. The combination of different treatment modalities offers a more effective cure and reduction in normal tissue toxicity. However, the differences in genetic profiles can cause diverse treatment outcomes. Multidisciplinary research, where technologies and knowledge from different areas are integrated, is necessary to design the optimal regimen for individualised cancer treatment. This paper offers an overview of some new cancer treatment strategies; the impact of molecular imaging on radiation oncology; and a computer simulation model to optimise treatment planning based on patient information. It briefly discusses molecular targeted therapy, tumour microenvironment and bioreductive agents, and evidence for making individualised medicine a reality. Using DNA microarrays and proteomic technologies, information on defined molecular targets and genetic profiling for individual patients can be obtained and new algorithms for radiation oncology-related diagnosis, treatment response and prognosis can be developed.

Response of endothelial cells to a dual tyrosine kinase receptor inhibition combined with irradiation

Recent studies suggest the possibility of a direct antiangiogenic effect of anti-epidermal growth factor receptor (EGFR) drugs due to the presence of EGFR on endothelial cells. The aim of this study was to analyze the direct effect on endothelial cells of associating EGFR targeting, vascular endothelial growth factor receptor (VEGFR)-2 targeting, and irradiation. We examined both the cytotoxic effects and the effect on molecular markers resulting from the combined action of gefitinib (Iressa; anti-EGFR), ZM317450 [VEGFR tyrosine kinase inhibitor (VTKI); anti-VEGFR-2], and irradiation (radiation therapy) on HMME7 cells, an immortalized microvascular endothelial cell of human origin. The presence of a functional EGFR pathway sensitive to gefitinib was shown in HMME7 cells (gefitinib-induced decrease in phospho-EGFR, phospho-p42/p44, and phospho-Akt). The stimulation of VEGFR-2 pathway led to an increase in Akt phosphorylation that was inhibited by VTKI. Of note, a post-radiation therapy induction of phospho-p42/p44 was observed on HMME7 cells, and this effect was inhibited by a pretreatment with gefitinib. Based on combination indexes (Chou and Talalay analyses), the associations gefitinib-radiation therapy, VTKI-radiation therapy, VTKI-gefitinib, and gefitinib-VTKI-radiation therapy were found to be additive, slightly synergistic, and markedly synergistic, respectively, for the cytotoxicity on HMME7 cells. Among molecular explanatory factors that were examined, the combination gefitinib-radiation therapy totally abolishes DNA-dependent protein kinase expression, and gefitinib attenuates the radiation therapy-induced enhancement of ERCC1 and augments the VTKI-induced CD95 enhancement. The existence of a radiation therapy-dependent neoangiogenesis may be related to the induction of EGFR pathway in endothelial cells, a phenomenon that can be attenuated by anti-EGFR drugs like gefitinib. In complement to the direct antitumor effects of radiation therapy and anti-EGFR drugs, a strong antiangiogenic effect may be obtained with therapeutic strategies combining radiation therapy with EGFR and VEGFR-2 targeting agents.

Phase I study of gefitinib, oxaliplatin, 5-fluorouracil, and leucovorin (IFOX) in patients with advanced solid malignancies

PURPOSE

Aphase 1 study of gefitinib in combination with oxaliplatin, 5-fluorouracil and leucovorin (IFOX)was conducted to evaluate the safety and feasibility of this regimen.

PATIENTS AND METHODS

Patients with advanced solid malignancies were treated with escalating doses of gefitinib (250 mg or 500 mg once daily) in combination with FOLFOX (oxaliplatin, 5-fluorouracil, and leucovorin). The initial dose of oxaliplatin was 70 mg/m2 with sequential dose escalation to 85 mg/m2.

RESULTS

Sixteen patients received a total of 138 14-day courses of daily gefitinib in combination with FOLFOX. Escalation of gefitinib from 250 mg/d to 500 mg/d with FOLFOX was well-tolerated. In addition, no severe toxicities precluded subsequent dose escalation of oxaliplatin from 70 mg/m2 to 85 mg/m2 at which no dose-limiting toxicity was seen. No further dose escalation was performed as this represented the oxaliplatin dose administered in the standard FOLFOX-4 regimen. The most predominant toxicity was diarrhea, which was well controlled with oral antidiarrheal agents. Four partial remissions occurred in patients with metastatic colorectal cancer.

CONCLUSIONS

Gefitinib as a 500 mg daily continuous dose was well tolerated in combination with full doses of FOLFOX-4.

ZD1839 (Gefitinib, ‘Iressa’), an epidermal growth factor receptor-tyrosine kinase inhibitor, enhances the anti-cancer effects of TRAIL in human esophageal squamous cell carcinoma

The EGF (epidermal growth factor) receptor-tyrosine kinase inhibitor ZD1839 (Gefitinib, 'Iressa') blocks the cell signaling pathways involved in cell proliferation, survival, and angiogenesis in various cancer cells. TNF-related death apoptosis inducing ligand (TRAIL) acts as an anticancer agent. We investigated the antitumor effects of ZD1839 alone or in combination with TRAIL against human esophageal squamous cell cancer (ESCC) lines. Although all ESCC cells expressed EGF receptor at a protein level, the effect of ZD1839 on cell growth did not correlate with the level of EGFR expression and phosphorylation of EGF receptor protein in ESCC lines. ZD1839 caused a dose-dependent growth arrest at G0-G1 phase associated with increased p27 expression. As TE8 cells are resistant to TRAIL, we tested whether ZD1839 combined with TRAIL induced apoptosis of TE8 cells via the inhibition of EGF receptor signaling by ZD1839. ZD1839 inhibited the phosphorylation of Akt, and enhanced TRAIL-induced apoptosis via activation of caspase-3 and caspase-9, and inactivation of Bcl-xL. Our results indicated that ZD1839 has anti-cancer properties against human esophageal cancer cells. ZD1839 also augmented the anti-cancer activity of TRAIL, even in TRAIL-resistant tumors. These results suggest that treatment with ZD1839 and TRAIL may have potential in the treatment of ESCC patients.

Prognostic impact of the epidermal growth factor receptor levels for patients with larynx and hypopharynx cancer

The aim of this study was to analyse prognostic factors for disease free interval (DFI) and overall survival (OS) among patients with larynx and hypopharynx cancer requiring a total laryngectomy. Three groups of patients were studied according to the type of treatment they received. Fifty-eight patients had total laryngectomy, 71 patients had organ preservation treatment including induction chemotherapy followed by exclusive radiotherapy, 26 patients received induction chemotherapy followed by salvage total laryngectomy. The studied potential prognostic factors were age, gender, performans status, primary tumor localization, T status, N status, tumor volume and tumoral EGFR level (fmol/mg protein). The multivariate analysis showed that both N status and tumor volume were significant for DFI and OS. EGFR level was significant only for patients treated by induction chemotherapy and exclusive radiotherapy (p = 0.05 and 0.05 for DFI and OS length, respectively). Among this group, patients with tumor EGFR levels lower and higher than 100 fmol/mg protein had 53% versus 22% and 51% versus 18% 5-year of DFI and OS rates, respectively (Log rank test: p = 0.001 and 0.0001). EGFR determination appears to be a powerful prognostic parameter for patients treated by induction chemotherapy followed by exclusive radiotherapy. Laryngectomy seems to erase the prognostic impact of EGFR expression. These results profile the use of EGFR targeting therapy for this category of patients.

Modulation of survival signaling pathways and persistence of the genotoxic stress as a basis for the synergistic interaction between the atypical retinoid ST1926 and the epidermal growth factor receptor inhibitor ZD1839

Strategies targeting apoptotic pathways may have relevance to improve the efficacy of antitumor therapy. Because synthetic atypical retinoids are potent inducers of apoptosis, there is an increasing interest in exploiting their potential in novel therapeutic approaches. In the present study, we have investigated the cellular effects of the combination of a novel atypical retinoid, ST1926, and the epidermal growth factor receptor inhibitor ZD1839. The results indicated a synergistic interaction between the two drugs associated with a dramatic enhancement of apoptotic response, up-regulation of the cell death receptor DR5, and caspase 8 activation. Other molecular events induced by the cotreatment included (a) a stabilization of the ST1926-induced genotoxic stress detected by formation of phosphorylated gamma-H2AX foci and (b) a complete inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation associated with activation of the proapoptotic protein BAD (i.e., inhibition of phosphorylation on Ser112). In addition, ZD1839 itself inhibited survival pathways by causing a partial dephosphorylation of Akt and a marked down-regulation of survivin. The role of ERK-mediated survival pathways in the cellular response to the drug combination was further supported by the counteracting effect of stimulation of survival pathways by an alternative receptor tyrosine kinase and by the use of a specific inhibitor of the ERK pathway. In conclusion, the results support that the survival pathways activated by epidermal growth factor receptor are determinants of the cell susceptibility to ST1926-induced apoptosis and lowering survival signals may increase the cellular sensitivity to the atypical retinoid. The favorable pharmacologic profiles of both ST1926 and ZD1839 suggest that the combination of these well-tolerated agents may have therapeutic potential.

The effect of ZD1839 (Iressa), an epidermal growth factor receptor tyrosine kinase inhibitor, in combination with cisplatin, on apoptosis in SCC-15 cells

The aim of this study was to determine the effect of ZD1839 on growth and apoptosis in SCC-15 (a human head and neck cancer cell line) lone, or in combination with cisplatin. High expression of the epidermal growth factor receptor has been implicated in the development of squamous cell carcinomas of head and neck. ZD1839 ('Iressa') is an orally active, selective epidermal growth factor receptor tyrosine kinase inhibitor that blocks signal transduction pathways implicated in proliferation and survival of cancer cells, and other host-dependent processes promoting cancer growth. Here, growth arrest was observed with 3.64 microm ZD1839. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (sMTT) viability assay revealed a significant decrease (P < 0.001) in the percentage of surviving cells upon treatment with ZD1839 and cisplatin compared with cisplatin or ZD1839 on their own. Combined therapy of 3.64 microm ZD1839 for 24 h, prior to administration of 100 microm cisplatin, significantly (P < 0.001) and additively increased the cytotoxicity effect of cisplatin. p53-independent apoptosis was seen with cisplatin treatment, a novel finding. These data support the use of ZD1839 in anti-cancer therapy, and particularly in combination therapy. Cisplatin may induce p53-independent apoptosis. Over-expression of Bcl-2 in head and neck squamous cell carcinoma tumour cell lines is unlikely to be a general mechanism to protect these cells from apoptosis.

HER1/EGFR-targeted agents: predicting the future for patients with unpredictable outcomes to therapy

Therapeutic agents that target the epidermal growth factor receptor (HER1/EGFR) signal pathway, such as small-molecule tyrosine kinase inhibitors and monoclonal antibodies are now advanced in clinical development and two are already licensed for use. Complete/ongoing phase II studies with these agents clearly demonstrate that a small, but significant proportion of patients respond to HER1/EGFR inhibition. However, with our current understanding of tumour biology and genetics, we cannot explain why some patients respond well and others less so or not at all. These differences may be a result of many factors, such as patients' genotype and phenotype, pharmacological and pharmacokinetic differences between agents or the inherent molecular heterogeneity of tumours. In this article, we explore current strategies to identify patients who respond differently and ways to maximise the clinical benefit of these therapies. This includes defining optimal dose and dosing schedules, identifying appropriate combination partners and finding predictive and surrogate markers of response. The association between HER1/EGFR gene mutations in non-small cell lung cancer (NSCLC) tumours and response to HER1/EGFR-targeted agents is also discussed. This may help us to preselect responsive patients, tailor the dose according to the individual's tolerability, or monitor these agents to optimise/interrupt therapy at an early stage.

Plattenepithelkarzinome des Kopf-Hals-Bereichs

Biologic therapies able to induce or up-regulate anti-tumor immune responses could represent a complementary approach to improve the conventional treatment of squamous cell carcinomas of the head and neck (SCCHN). Patients with SCCHN are frequently immunocompromised due to the elimination and dysfunction of critical immune effector cells. Therefore, it might be necessary to restore these immune functions to allow for the generation of effective anti-tumor host responses. Simultaneously, to prevent tumor escape from immunological recognition and destruction, it might also be necessary to alter antigenic and immunogenic attributes of the malignant cells. The present overview summarizes general aspects, historical data, and recent advances in the field of immunotherapy of SCCHN, including non-specific immune stimulation, transfer of immunocompetent cells, gene therapy, use of monoclonal antibodies, and anti-cancer vaccines.

Le récepteur à l'EGF et les cancers des voies aérodigestives supérieures

EGFR is overexpressed and is associated with a poor prognosis in head and neck cancer. Among the biological and cellular effects resulting from EGFR targeting in head and neck cancer there is the capacity to restore apoptotic capacities. Other experimental results put into evidence that DNA-repair activity was reduced by the application of EGFR targeting agents. This context was in favor of a research oriented towards combination between anti-EGFR drugs and cytotoxic agents, particularly irradiation. Supra-additive cytotoxic effects have been observed at the experimental level when combining anti-EGFR drugs with irradiation in head and neck cancer. These experimental data were recently confirmed at the clinical level in locally advanced head and neck cancer.

Molecular therapy of head and neck cancer

Aberrant expression of growth factor receptor systems and dysregulation of the downstream cell signalling molecules have been reported in a wide range of epithelial tumours including head and neck cancer. In some cases, such alterations have been associated with a poor prognosis. In the past 25 years, several antigen specific monoclonal antibodies (mAbs, mouse, chimeric, humanized and human versions), and small molecule kinase inhibitors have been developed that are at different stages of preclinical and clinical developments. Some of these agents (e.g. Herceptin, Iressa, cetuximab, avastin) have already been approved for the treatment of epithelial tumours and may also have potential in the treatment of head and neck cancer patients. This review discusses, the development and potential of these antigen specific agents, in particular the human epidermal growth factor receptor (EGFR) inhibitors, either as a single agent or in combination with other EGFR inhibitors, biological agents (e.g. inhibitors of cycloogenase-2, angiogenesis, insulin like growth factor-I receptor and others), and conventional forms of therapy in the prevention and treatment of head and neck cancer. From preclinical and clinical studies with some of these compounds, it is evident that further detailed studies of biopsies from cancer patients are needed in order to identify markers that can be used not only in the selection of the specific population of cancer patients who would benefit from such antigen specific therapeutic strategies, but also those factors which are responsible for the poor response and the development of a phenotype resistance to such inhibitors. The results of such studies could in turn facilitate the widespread use of such agents in the treatment of a wide range of human cancers including head and neck cancer.

Apoptotic Pathways and Therapy Resistance in Human Malignancies

Apoptosis and necrosis are two morphologically distinct forms of cell death that are important for maintaining of cellular homeostasis. Almost all agents can provoke either response when applied to cells; however, the duration of treatment and the dose of the used agents determine which type of death (apoptosis or necrosis) is initiated. The response of tumors to chemo-, radio-, and hormone therapy or to treatment with biologically active agents may depend at least in part on the propensity of these tumors to undergo cell death. Some tumors, e.g., leukemias, small cell lung cancer, and seminomas, respond quickly to first-line therapy; this fast response is thought to result from induction of apoptosis. Solid tumors, on the other hand, usually respond slowly and less effectively, with cell death characterized not only by apoptosis but also by necrosis, or mitotic catastrophe. It is likely that resistance of tumors to treatment might be associated with defects in, or dysregulation of, different steps of the apoptotic pathways. Several attempts were undertaken to use the knowledge of these defects to design new drugs, which might either activate or re-activate the apoptotic machinery of tumor cells. Here we discuss the apoptotic pathways and their role in therapy resistance of human malignancies. Although such studies are still in progress, they offer great promise for future cancer therapy. We hope that some of these agents will turn out to be valuable additions to the future therapeutic arsenal, which will most probably include a combination of conventional cytotoxic drugs and molecular target-based pro-apoptotic drugs.

Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor Does Not Improve Paclitaxel Effect in an Orthotopic Mouse Model of Lung Cancer

PURPOSE

The purpose is to evaluate whether inhibition of epidermal growth factor receptor (EGFR) activation by PKI166, an EGFR-tyrosine kinase inhibitor, affects growth of human lung cancer implanted orthotopically into the lungs of nude mice.

EXPERIMENTAL DESIGN

Lungs of mice were injected with NCI-H358 human bronchioloalveolar cancer cells. In three experiments, groups of mice (n = 10 per group) were randomized 7 days after tumor implantation to receive one of the following treatments: i.p. paclitaxel 100 or 200 microg (4 or 8 mg/kg) once per week, oral PKI166 100 or 200 mg/kg three times per week, paclitaxel plus PKI166, or i.p. saline and oral PKI166-vehicle (control) for 5 weeks. Mice were killed 6.5 to 8 weeks after tumor implantation. The experiments were repeated with PC14PE6 human lung adenocarcinoma cells to assess effect on survival.

RESULTS

Immunohistochemical analyses revealed the expression and phosphorylation of EGFR in the growing tumors. Treatment with PKI166 alone or in combination with paclitaxel diminished activation of EGFR on tumor cells, yet maximal therapeutic effect was observed in mice treated with paclitaxel alone. Activated mitogen-activated protein kinase and basic fibroblast growth factor expression were similar in all treatment groups. Survival in mice treated with the combination of paclitaxel and PKI166 was shorter than in those treated with paclitaxel alone.

CONCLUSIONS

Our results suggest that concurrent administration of EGFR-tyrosine kinase inhibitor and chemotherapy is equivalent and may indeed be inferior to chemotherapy alone, even if EGFR is functional and its phosphorylation effectively inhibited. Our data show that the interaction of EGFR-TKIs and chemotherapy is complex and suggest that other growth factors may activate the downstream signaling events.

Anti-REGF et radiothérapie

EGF-receptor (EGFR) is a transmembrane protein, which was implicated in the progression of many epithelial cancer types. Its activation induce some transduction pathways inside the cell, and contribute to many cellular processes as cell proliferation, inhibition of apoptosis and angiogenesis. Monoclonal antibodies directed against EGFR or small molecules inhibiting its tyrosine-kinase function could block all these pathways. By modulating these cellular functions, these molecules enhance the antitumor activity of ionizing radiation. Several mechanisms have been discussed (alteration od DNA damage repair, facilitation of apoptosis, inhibition of tumour repopulation) and justify the current clinical trials combining these drugs and radiotherapy.