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PubMed2006

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.

Androstadienes↗
PubMed2006

A review of the benefit-risk profile of gefitinib in Asian patients with advanced non-small-cell lung cancer.

BACKGROUND: Improvements in first-line therapy of advanced non-small-cell lung cancer (NSCLC) have increased the need for effective second-line treatment options. In a Phase II trial of the anticancer drug gefitinib (IRESSA), greater efficacy was observed in Japanese compared with non-Japanese patients. Furthermore, results from a placebo-controlled Phase III trial (IRESSA Survival Evaluation in Lung cancer [ISEL]) showed that treatment with gefitinib was not associated with a statistically significant improvement in survival in either the overall or adenocarcinoma co-primary populations, although there was marked heterogeneity in survival outcomes between patient groups, with patients of Asian origin achieving a significant survival benefit with gefitinib compared with placebo. OBJECTIVE: To review the benefit:risk profile of gefitinib in Asian patients with advanced NSCLC. RESEARCH DESIGN AND METHODS: We identified and reviewed 31 reports (each with >or= 25 patients) of clinical experience with gefitinib 250 mg/day in Asia involving a total of > 2000 patients with refractory NSCLC in Japan, China, Korea and Taiwan by searching EMBASE and Medline databases for publications between 1 January 2003 and 1 July 2005. RESULTS AND DISCUSSION: In the majority of these reports, objective response rates of > 25% and disease control rates of > 60% have been described. Treatment with gefitinib resulted in a median time to progression of > 3 months and a median survival time of > 6 months in most studies. These 31 reports also demonstrated the efficacy of gefitinib in patients with secondary brain metastases, those with poor performance status (PS) and in patients receiving the drug as first-line treatment. Female gender, adenocarcinoma histology, non-smoking history, good PS and the presence of multiple lung metastases are associated with improved responsiveness to gefitinib. Reflecting the results of previous clinical trials, the reports indicate that gefitinib is generally well tolerated by Asian patients. The incidence of interstitial lung disease appears to be higher in Japanese than non-Japanese patients, although the reasons for this are not clear. Recent findings regarding cellular and genetic factors that may underlie the increased responsiveness to gefitinib among Asian patients are discussed.

Antineoplastic Agents↗
PubMed2003

Pilot trial of the epidermal growth factor receptor tyrosine kinase inhibitor gefitinib plus carboplatin and paclitaxel in patients with stage IIIB or IV non-small-cell lung cancer.

PURPOSE: Gefitinib is an oral agent that inhibits the tyrosine kinase of the epidermal growth factor receptor. In phase I trials gefitinib was well tolerated and antitumor activity was seen in pretreated non-small-cell lung cancer (NSCLC) patients. Preclinical studies indicated enhanced effects when gefitnib was added to carboplatin or paclitaxel. This pilot trial combined gefitinib with carboplatin and paclitaxel to define the toxicities of the combination and assess drug-drug interactions in untreated advanced NSCLC patients. PATIENTS AND METHODS: Initially (part 1) patients were randomly assigned to receive intermittent gefitinib with cycle 1 or 2 of chemotherapy. Thereafter (part 2), the highest dose of gefitinib that was given without dose-limiting toxicity (DLT) from part 1 was administered continuously beginning with the first cycle of chemotherapy. Three sequentially enrolled cohorts received gefitinib 250 and 500 mg (intermittently) and 500 mg (continuously). RESULTS: We treated 24 patients; nine patients with 250 mg and 15 patients with 500 mg (nine patients continuous). Two occurrences of DLT were observed. One patient (500 mg, part 1) developed grade 3 rash and another patient (part 2) developed prolonged neutropenia. Steady-state gefitinib levels did not affect exposure to chemotherapy. In a limited sample, chemotherapy modestly increased the gefitinib area under concentration-time curve at steady-state and minimum steady-state trough concentration. Partial responses were observed in five of 24 patients. The median survival was 8 months. CONCLUSION: The gefitinib with carboplatin and paclitaxel regimen was generally well tolerated and no unanticipated toxicities or clinically relevant pharmacokinetic interactions were observed. Both doses of gefitinib were believed to be safe for further study with chemotherapy. This regimen was thus tested in a completed randomized phase III trial.

Adult↗
PubMed2005

Mutations of the epidermal growth factor receptor gene predict prolonged survival after gefitinib treatment in patients with non-small-cell lung cancer with postoperative recurrence.

PURPOSE: To evaluate the relationship between mutations of the epidermal growth factor receptor (EGFR) gene and the effectiveness of gefitinib treatment in patients with recurrent lung cancer after pulmonary resection. PATIENTS AND METHODS: We sequenced exons 18-21 of the EGFR gene using total RNA extracted from 59 patients with lung cancer who were treated with gefitinib for recurrent lung cancer. Gefitinib effectiveness was evaluated by both imaging studies and change in serum carcinoembryonic antigen (CEA) levels. RESULTS: EGFR mutations were found in 33 patients (56%). Of these mutations, 17 were deletions around codons 746-750 and 15 were point mutations (12 at codon 858, three at other codons), and one was an insertion. EGFR mutations were significantly more prevalent in females, adenocarcinoma, and never-smokers. Gefitinib treatment resulted in tumor shrinkage and/or CEA decrease to less than half of the baseline level in 26 patients, tumor growth and/or CEA elevation in 24 patients, and gefitinib effect was not assessable in nine patients. Female, never-smoking patients with adenocarcinoma tended to respond better to gefitinib treatment. Gefitinib was effective in 24 of 29 patients with EGFR mutations, compared with two of 21 patients without mutations (P < .0001). Of note, del746-750 might be superior to L858R mutations for prediction of gefitinib response. Patients with EGFR mutations survived for a longer period than those without the mutations after initiation of gefitinib treatment (P = .0053). CONCLUSION: EGFR mutations were a good predictor of clinical benefit of gefitinib in this setting.

Adult↗
PubMed2003

EGFR tyrosine kinase inhibitor "gefitinib (Iressa)" for cancer therapy.

Many malignant tumors including non-small cell lung cancer (NSCLC) express or over-express EGFR that have shown correlations with rapid growth, metastases, resistance to conventional chemotherapy or radiotherapy, and poor prognosis. Gefitinib is a potent and selective inhibitor of EGFR tyrosine kinase (EGFRTK). Gefitinib specifically inhibited EGF-stimulated cell proliferation in vitro and it also exhibited a broad anti-tumor spectrum against NSCLC, prostate, colorectal, and ovarian cancers in vivo. Gefitinib showed dose-dependent and reversible reduction of c-fos mRNA level and decreased Ki67 significantly in tumors in vivo. In in vitro studies, gefitinib arrested the cell cycle at G1 phase by inducing intrinsic cyclin-dependent kinase (cdk) inhibitors and following inhibition of cdk2. Apoptosis was also seen in gefitinib-treated tumor cells and skin biopsy samples from clinical study. Gefitinib inhibited VEGF production in tumor cells through inhibition of EGFR signaling, leading to suppression of angiogenesis. In clinical studies, gefitinib demonstrated therapeutic benefit in patients who failed conventional chemotherapy. No correlation has been established between the anti-tumor activity of gefitinib and EGFR expression level, whilst sensitivity factors to gefitinib are yet to be elucidated. Identification of sensitivity factors will be a key for effective use of EGFRTK inhibitors including gefitinib for cancer treatment.

Animals↗
PubMed2004

Cell growth after withdrawal of gefitinib ("Iressa", ZD1839) in human lung cancer cells.

Gefitinib ("Iressa", ZD1839) is a selective epidermal growth factor receptor-tyrosine kinase inhibitor, which blocks signal transduction pathways implicated in proliferation and survival of cancer cells. However, in vitro and in vivo studies concerning cell growth after withdrawal of gefitinib are limited. To determine whether cancer cells would resume proliferation upon removal of gefitinib, an in vitro study was undertaken using 4 human non-small cell lung cancer cell lines. With immunocytochemical staining and Western blot analysis, we confirmed positive expression of EGFR in these cell lines. We next evaluated growth inhibition before and after withdrawal of gefitinib. After incubation with 0-100 microM gefitinib for 24 h, medium containing gefitinib was removed, followed by addition of fresh growth medium to cell cultures. MTT assays were performed daily over a 6-day time course. Even at very low levels of gefitinib (<1 microM), these 4 TKB cells had 1-10% growth inhibition, respectively. With these levels of gefitinib, continued inhibitory effects after withdrawal of getitinib were observed in 3 of the 4 cell lines. Furthermore, none of the 4 cell lines, including the cell line which had abolished growth inhibition, showed accelerated re-growth rate after the withdrawal of gefitinib even in these exposure conditions. Based on our in vitro experiments, additional in vivo studies, which can compare the pre- and post-treatment growth rate, will be necessary to help better understand the mechanisms behind cell growth recovery after temporary gefitinib treatment.

Antineoplastic Agents↗
PubMed2004

[Recurrence of non-small cell lung cancer after successful treatment with gefitinib--report of three cases].

Gefitinib, a first epidermal growth factor receptor (EGFR) inhibitor has been reported to be effective in chemotherapy-resistant non-small cell lung cancer. Gefitinib was also reported, however, to produce severe adverse effects, such as interstitial lung disease. Thus, clinical evaluation of gefitinib is still controversial and further studies are needed. We present 3 cases of non-small cell lung cancer (stage IV adeno-carcinoma) that showed recurrence after successful gefitinib treatment. Symptoms of all patients ameliorated in a week after the therapy, and radiograph and laboratory data improved. However, all showed recurrence in 3 to 7 months. After recurrence, patient 1 was re-treated with gefitinib at the request of the patient. Patient 2 has been on gefitinib. Patient 3 was treated with gefitinib, which was later replaced by another chemotherapy agent. After recurrence, however, no effective response was obtained in any of the 3 cases. There have been several reports of good response to gefitinib therapy at the first time in patients with advanced non-small cell lung cancer, but few reports of recurrence in patients after successful therapy with this agent. This report is thought to be important for the clinical evaluation of gefitinib and useful in terms of information about the resistance of gefitinib.

Adenocarcinoma↗
PubMed2006

Activated Src and Ras induce gefitinib resistance by activation of signaling pathways downstream of epidermal growth factor receptor in human gallbladder adenocarcinoma cells.

PURPOSE: Although gefitinib, a selective inhibitor of epidermal growth factor receptor (EGFR) tyrosine kinase, has been demonstrated to exhibit its antitumor activity by the blockade of EGF receptor, the role of signaling pathways downstream of EGFR in gefitinib sensitivity remains unknown. In this study, we investigated the mechanistic role of Src and Ras, major oncogene products implicated in the pathogenesis of many human cancers in gefitinib sensitivity. METHODS: Using parental and v-src- or c-H-ras-transfected HAG-1 human gallbladder adenocarcinoma cell lines, effects of gefitinib on cytotoxicity, cell cycle purtubation and apoptosis, and tyrosine phosphorylation of EGFR, Akt, and Erk were determined by WST-1 assay, flow cytometry, and Western blots, respectively. RESULTS: Activated Ras and Src conferred a strong resistance to gefitinib by nearly 30-fold and 200-fold, respectively. Gefitinib induced accumulation of cells in the G0/G1 phase of the cell cycle at 24-h, with progressive expansion of apoptotic cell population in parental HAG-1 cells, but these effects were completely abolished in v-src- or c-H-ras-transfected cell line. Upon gefitinib treatment, EGFR activation and subsequent downstream activation through Erk and Akt were significantly inhibited in HAG-1 cells. By contrast, gefinitib failed to inhibit the activation of both Akt and Erk in v-src-transfected cells and Erk, but not Akt in c-H-ras-transfected cells, despite the blockade of EGFR activation in these respective cell lines. Treatment of v-src-transfected cells with herbimycin A, a Src tyrosine kinase inhibitor, partially reversed the gefitinib resistance, with concomitant inhibition of Akt and Erk. CONCLUSION: Our results suggest that activated Ras and Src could induce gefitinib resistance by activating either or both of Akt and Erk signaling pathways, thus providing a strategic rationale for assessment of these specific signaling molecules downstream of EGFR to customize treatment.

Antineoplastic Agents↗
PubMed2006

Elevation of soluble interleukin-2 receptor in patients with non-small cell lung cancer treated with gefitinib.

PURPOSE: We previously reported that plasma thromboxan B(2), soluble P-selectin, and serum regulated on activation, normal T-cell expressed and secreted (RANTES) were elevated after gefitinib treatment. We hypothesized that gefitinib could activate T-lymphocytes via activated platelets, and so we measured serum levels of soluble interleukin-2 receptor (sIL-2R) in patients medicated with gefitinib. METHODS: Twenty-one patients with non-small cell lung cancer (NSCLC) were entered into this study. All patients received gefitinib over 2 weeks without severe adverse effects. Blood samples were withdrawn from all patients before and after the administration of gefitinib and plasma soluble P-selectin, serum RANTES, and serum sIL-2R were measured by enzyme-linked immunosolvent assay. In addition, we carried out the basic study of the interleukin-2 receptor (IL-2R) expression on CD4(+) lymphocytes by RANTES. RESULTS: Plasma soluble P-selectin, serum RANTES, and serum sIL-2R levels increased significantly in patients receiving gefitinib treatment for 1 and 2 weeks. RANTES did not induce the expression of IL-2R on CD4(+) lymphocyte. However, the anti-CD3 monoclonal antibody-induced expression of IL-2R was enhanced by the addition of RANTES. CONCLUSION: Our finding indicated that lymphocytes were activated by gefitinib treatment. We think that sIL-2R elevation after gefitinib administration may be a factor positively effecting patients with NSCLC. It is deemed possible that the effect of gefitinib is induced not only by its blocking of the tyrosine kinase of epidermal growth factor receptor but also by antitumor immunity via its activation of T-cells.

Adult↗
PubMed2003

Gefitinib (Iressa) trials in non-small cell lung cancer.

Gefitinib (Iressa) is a synthetic anilinoquinazoline capable of inhibiting the epidermal growth factor receptor tyrosine kinase in vitro at nanomolar concentrations. In phase I trials, gefitinib was well tolerated at doses above that required to induce antitumor effects in vitro. Notably, antitumor activity was observed in lung cancer patients. These findings resulted in the initiation of phase II trials employing gefitinib monotherapy in patients with recurrent non-small cell lung cancer (the so-called IDEAL trials). Study participants were randomized to 250 mg or 500 mg of gefitinib per day. Objective response rates between 10 and 20% were achieved with minimal host related toxicity (mainly acne like rash and mild diarrhea). Median survivals ranged between 6 and 8 months. Subsequently, phase III trials (the so-called INTACT trials) combined gefitinib and chemotherapy in chemonaive patients with advanced non-small cell lung cancer. These trials failed to demonstrate a survival advantage with the addition of gefitinib to standard platinum-based chemotherapy regimens. However, overall host related toxicities were not substantially worsened with the addition of gefitinib to chemotherapy. Further studies employing single agent gefitinib as well as regimens employing a different sequencing of chemotherapy and gefitinib are planned in recurrent and previously untreated lung cancer patients.

Aged↗
PubMed2004

Activating mutations in the epidermal growth factor receptor underlying responsiveness of non-small-cell lung cancer to gefitinib.

BACKGROUND: Most patients with non-small-cell lung cancer have no response to the tyrosine kinase inhibitor gefitinib, which targets the epidermal growth factor receptor (EGFR). However, about 10 percent of patients have a rapid and often dramatic clinical response. The molecular mechanisms underlying sensitivity to gefitinib are unknown. METHODS: We searched for mutations in the EGFR gene in primary tumors from patients with non-small-cell lung cancer who had a response to gefitinib, those who did not have a response, and those who had not been exposed to gefitinib. The functional consequences of identified mutations were evaluated after the mutant proteins were expressed in cultured cells. RESULTS: Somatic mutations were identified in the tyrosine kinase domain of the EGFR gene in eight of nine patients with gefitinib-responsive lung cancer, as compared with none of the seven patients with no response (P<0.001). Mutations were either small, in-frame deletions or amino acid substitutions clustered around the ATP-binding pocket of the tyrosine kinase domain. Similar mutations were detected in tumors from 2 of 25 patients with primary non-small-cell lung cancer who had not been exposed to gefitinib (8 percent). All mutations were heterozygous, and identical mutations were observed in multiple patients, suggesting an additive specific gain of function. In vitro, EGFR mutants demonstrated enhanced tyrosine kinase activity in response to epidermal growth factor and increased sensitivity to inhibition by gefitinib. CONCLUSIONS: A subgroup of patients with non-small-cell lung cancer have specific mutations in the EGFR gene, which correlate with clinical responsiveness to the tyrosine kinase inhibitor gefitinib. These mutations lead to increased growth factor signaling and confer susceptibility to the inhibitor. Screening for such mutations in lung cancers may identify patients who will have a response to gefitinib.

Adenocarcinoma↗
PubMed2005

Gefitinib ("Iressa", ZD1839), an epidermal growth factor receptor tyrosine kinase inhibitor, reverses breast cancer resistance protein/ABCG2-mediated drug resistance.

Gefitinib ("Iressa", ZD1839) is an orally active, selective epidermal growth factor receptor tyrosine kinase inhibitor, and the single agent is clinically effective in non-small cell lung cancer. Although gefitinib combined with various cytotoxic agents has been reported to enhance cytotoxicity in vitro and in mouse models, the mechanism remains undetermined. Here, to explore the mechanism with topoisomerase I inhibitors, we focused on the efflux pump of the breast cancer resistance protein (BCRP/ABCG2), and then examined whether gefitinib restored drug sensitivity in multidrug-resistant cancer cells overexpressing BCRP. We used PC-6 human small cell lung cancer cells and multidrug-resistant PC-6/SN2-5H cells selected with SN-38 of the active metabolite of irinotecan, and BCRP-overexpressing MCF-7/MX cells selected with mitoxantrone and BCRP cDNA transfectant MCF-7/clone 8 cells. Drug sensitivity against anticancer drugs was determined by tetrazolium dye assay, and intracellular topotecan accumulation by FACScan. The topotecan transport study was done using the plasma membrane vesicles of PC-6/SN2-5H cells. The resistant PC-6/SN2-5H cells overexpressed BCRP but not epidermal growth factor receptor mRNA. Ten micromoles of gefitinib reversed topotecan, SN-38, and mitoxantrone resistance, and increased the intracellular topotecan accumulation in the resistant cells but not in the parental cells. Furthermore, gefitinib inhibited the topotecan transport into the vesicles, and the K(i) value was 1.01 +/- 0.09 micromol/L in the Dixon plot analysis, indicating direct inhibition of BCRP by gefitinib. However, gefitinib was not transported into the vesicles with the high-performance liquid chromatography method. These results indicate that gefitinib reverses BCRP-mediated drug resistance by direct inhibition other than competitive inhibition as a BCRP substrate. Combination of gefitinib and topoisomerase I inhibitors could be clinically effective in cancers expressing BCRP.

ATP Binding Cassette Transporter, Subfamily G, Mem↗
PubMed2006

Synergistic effects of gemcitabine and gefitinib in the treatment of head and neck carcinoma.

Although the combination of gemcitabine and radiation produces a high frequency of complete responses in the treatment of locally advanced head and neck cancer, substantial toxicity suggests that an improvement in the therapeutic index is required. The purpose of this study was to determine if gefitinib could improve the efficacy of gemcitabine and if drug schedule is important. We hypothesized that gemcitabine followed by gefitinib would be superior to the opposite order because of both cell cycle and growth factor signaling interactions. Using UMSCC-1 cells in vitro, we confirmed that gefitinib arrested cells in G(1) and suppressed phospho-epidermal growth factor receptor (p(Y845)EGFR) and that gemcitabine arrested cells in S phase and stimulated p(Y845)EGFR. The schedule of gemcitabine followed by gefitinib caused arrest of cells in S phase. Gefitinib suppressed gemcitabine-mediated p(Y845)EGFR stimulation. This schedule caused decreased p(S473)AKT, increased poly(ADP-ribose) polymerase cleavage, and increased apoptosis compared with gemcitabine alone. The schedule of gefitinib followed by gemcitabine also caused suppression of p(Y845)EGFR but arrested cells in G(1). This schedule in which gefitinib was used first was associated with stable levels of p(S473)AKT and minimal poly(ADP-ribose) polymerase cleavage and apoptosis. These results were reflected in experiments in nude mice bearing UMSCC-1 xenografts, in which there was greater tumor regression and apoptosis when animals received gemcitabine followed by gefitinib during the first week of therapy. These findings suggest that the schedule of gemcitabine followed by gefitinib may increase the therapeutic index over gemcitabine alone and, combined with clinical data, encourage exploration of combination of gemcitabine, EGFR inhibitors, and radiation.

Antibiotics, Antineoplastic↗
PubMed2006

Transforming growth factor alpha expression drives constitutive epidermal growth factor receptor pathway activation and sensitivity to gefitinib (Iressa) in human pancreatic cancer cell lines.

The epidermal growth factor receptor (EGFR) is considered an important therapeutic target in pancreatic cancer, but it is currently impossible to identify those patients who are most likely to benefit from EGFR-directed therapy. We examined the biological effects of the EGFR tyrosine kinase inhibitor gefitinib (ZD1839, Iressa) in a panel of nine human pancreatic cancer cell lines. The drug strongly inhibited DNA synthesis and induced low levels of apoptosis at clinically relevant concentrations in a subset of three of the lines (L3.6pl, BxPC3, and Cfpac1). Sensitivity to gefitinib correlated directly with ligand [transforming growth factor-alpha (TGF-alpha)] expression (r(2) = 0.71, P = 0.004) but not with surface EGFR expression. The gefitinib-sensitive cells displayed constitutive baseline EGFR phosphorylation, whereas the gefitinib-resistant cells did not. Exposure to gefitinib or a small interfering RNA construct specific for TGF-alpha reversed the constitutive EGFR phosphorylation and downstream target [extracellular signal-regulated kinases (ERK), AKT] phosphorylation in the gefitinib-sensitive cells but had no effects on ERK or AKT phosphorylation in gefitinib-resistant cells. Baseline EGFR phosphorylation was lower in a subclone of L3.6pl selected for low TGF-alpha expression, and these cells were also resistant to gefitinib-mediated growth inhibition. Gefitinib blocked the growth of tumor xenografts derived from L3.6pl cells but had no effect on the growth of tumors derived from EGFR-independent MiaPaCa-2 cells. Together, our data show that TGF-alpha expression identifies a subset of human pancreatic cancer cells that is dependent on EGFR signaling in vitro and in vivo. Quantification of TGF-alpha expression may therefore represent an effective means of identifying EGFR-responsive primary tumors.

Animals↗
PubMed2004

Antitumor activity of gefitinib in malignant rhabdoid tumor cells in vitro and in vivo.

PURPOSE: Malignant rhabdoid tumor (MRT) is a rare and highly aggressive neoplasm of young children. Current treatments have had only limited success. Epidermal growth factor receptor (EGFR) was found recently to be expressed on MRT cell lines. Gefitinib (trade name Iressa) is an oral and selective EGFR-tyrosine kinase inhibitor and has been demonstrated to be effective in inhibiting the proliferation of cancer cells in vivo as well as in clinical trials. This encouraged us to examine the antitumor effects of gefitinib on MRT cells in vitro and in vivo. EXPERIMENTAL DESIGN: The expression of EGFR in two MRT tumors and two MRT cell lines (MP-MRT-AN and KP-MRT-NS), established from these two tumor tissues, was examined by immunohistochemistry, immunofluorescence, and immunoblot. The effect of gefitinib on EGFR phosphorylation was examined by immunoblot. The effects of gefitinib on cell growth and apoptosis were examined by cell growth assay and terminal deoxynucleotidyl transferase-mediated nick end labeling assay. The in vivo effect of gefitinib was assessed in athymic mice that had been xenografted with MRT cells. RESULTS: The expression of EGFR was detected in both tumor tissues and cell lines. Gefitinib inhibited EGFR-phosphorylation (IC(50) < 0.1 micromol/L) and in vitro cell growth (IC(50) = approximately 10-12 micromol/L), and a high concentration of gefitinib (20 micromol/L) induced apoptosis in vitro (MP-MRT-AN, 42.9% and KP-MRT-NS, 47.2%). Furthermore, gefitinib at 150 mg/kg had a cytostatic effect on established MRT xenografts (MP-MRT-AN, P = 0.039 and 0.0014; and KP-MRT-NS, P = 0.048 and 0.0086). CONCLUSIONS: Our results demonstrate that gefitinib has antitumor effects in MRT cells in vitro and in vivo and, thus, has promise as a novel and therapeutic strategy for MRT.

Animals↗
PubMed2004

Dominant papillary subtype is a significant predictor of the response to gefitinib in adenocarcinoma of the lung.

PURPOSE: Gefitinib (IRESSA; AstraZeneca, Osaka, Japan) shows excellent antitumor activity against advanced non-small-cell lung cancer, especially for the treatment of adenocarcinoma. However, the predictive factors for the response to gefitinib are still controversial. The aim of this study was to identify the clinicopathological and immunohistochemical features that are favorable to the use of gefitinib in adenocarcinoma patients. EXPERIMENTAL DESIGN: Between June 2002 and October 2003, 36 adenocarcinoma patients who experienced a relapse after surgical resection were treated with gefitinib at our hospital. The histologic patterns of the tumors were divided into four distinctive subtypes according to the revised World Health Organization histologic classification, and the dominant histologic subtype for the maximum cut surface of each resected specimen was documented. Association between the response to gefitinib and the clinicopathological features or immunohistochemical expression of epidermal growth factor receptor (EGFR), phosphorylated EGFR, or c-erbB-2 were then investigated. RESULTS: A significant association between the response to gefitinib and dominant papillary subtype findings was observed (P = 0.0021); the survival time of papillary subtype patients was also significantly prolonged compared with that of non-papillary subtype patients (P = 0.03). No other clinicopathological features or the expression of EGFR, phosphorylated EGFR, or c-erbB-2 were associated with the response to gefitinib. CONCLUSIONS: The results of the present study indicate that dominant papillary subtype findings of lung adenocarcinomas can be an important predictor of the response to gefitinib. Thus, this type of adenocarcinoma might be susceptible to postoperative adjuvant treatment with gefitinib.

Adenocarcinoma↗
PubMed2006

Radiosensitivity enhancement by combined treatment of celecoxib and gefitinib on human lung cancer cells.

PURPOSE: To characterize the radiation-enhancing effects and underlying mechanisms of combined treatment with celecoxib, a cyclooxygenase-2 selective inhibitor, and gefitinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, in human lung cancer cells. EXPERIMENTAL DESIGN: Clonogenic cytotoxicity assays and clonogenic radiation survival assays after treatments with celecoxib and gefitinib with or without radiation were done on three human lung cancer cell lines. Synergisms after combined treatment with celecoxib, gefitinib, and radiation were investigated using isobologram and statistical analyses according to an independent action model. Alterations in apoptosis and cell cycle were measured to identify the mechanisms underlying the cell killing or radiation-enhancing effects of celecoxib and gefitinib combination treatment. Western blots for phosphorylated EGFR, EGFR, cyclooxygenase-2, and G(2) checkpoint molecules were conducted after treatment with celecoxib and/or gefitinib with or without radiation. RESULTS: Combination celecoxib, gefitinib, and radiation treatments were shown to be synergistic in causing clonogenic cell deaths in all cell lines tested, but the nature of synergism was cell type specific. The combined drug treatments induced apoptosis in an additive manner in A549 cells and in a synergistic manner in NCI-H460 and VMRC-LCD cells. Celecoxib or gefitinib attenuated radiation-induced G(2)-M arrest, and combined drug treatment additively attenuated radiation-induced G(2)-M arrest in all cell lines. Radiation-induced checkpoint kinase (Chk) 1 and Chk2 phosphorylation were inhibited by celecoxib and gefitinib treatment, respectively. CONCLUSIONS: Combined celecoxib and gefitinib treatments were shown to synergistically enhance the effect of radiation on lung cancer cells. The mechanisms underlying these synergistic effects seem to involve the synergistic enhancement of apoptosis and cooperative attenuation of radiation-induced G(2)-M arrest, possibly via Chk1 and Chk2 inhibition, by the combined drug treatments.

Animals↗
PubMed2005

Gefitinib treatment is highly effective in non-small-cell lung cancer patients failing previous chemotherapy in Taiwan: a prospective phase II study.

Gefitinib has shown activity in the treatment of non-small-cell lung cancer (NSCLC) patients who failed previous platinum-based combination chemotherapy and/or taxane treatment. Recently, gefitinib was documented to be more effective in an East Asian population, as well. Thus, we performed a gefitinib trial in Taiwanese patients to assess the efficacy of this regimen. Treatment consisted of gefitinib 250 mg one tablet daily until disease progression. Thirty-six patients were enrolled from January 2003 to September 2004. Gefitinib was second-line treatment in 10, third-line in 15, fourth-line in 9, and fifth-line in 2. All patients were evaluable for toxicity profile and response rate. After 8 weeks of treatment, three patients had a complete response (CR) and nine had a partial response (PR), with an overall response rate of 33.3% (95% confidence interval 17.9%-48.7%). All treatment-related toxicities were few and mild in severity, except that one patient suffered from reversible grade 3 interstitial pneumonitis. The median time to disease progression was 4.7 months, and the median survival was 9.5 months. The one-year survival rate was 45.1%. Survival was significantly better in those who responded to treatment (CR and PR) than in those who did not (median 20.1 vs. 4.7 months, p=0.0002). Survival was also better in those who demonstrated disease control using gefitinib (CR, PR, and stable disease) than in those who did not (14.1 vs. 1.4 months, p<0.0001). The authors conclude that daily gefitinib treatment has high activity, is well tolerated, and provides very good survival in Taiwanese NSCLC patients who have failed previous chemotherapy, especially in those who responded to gefitinib treatment or those whose disease was controlled by gefitinib treatment.

Adult↗