Effect of Vandetanib on Lung Tumorigenesis in Transgenic Mice Carrying an Activating Egfr Gene Mutation.

Vandetanib (ZactimaTM) is a novel, orally available inhibitor of both vascular endothelial growth factor receptor-2 (VEGFR-2) and epidermal growth factor receptor (EGFR) tyrosine kinase. In the present study, a line of transgenic mice with a mouse Egfr gene mutation (delE748-A752) corresponding to a human EGFR mutation (delE746-A750) was established. The transgenic mice developed atypical adenomatous hyperplasia to adenocarcinoma of the lung at around 5 weeks of age and died of lung tumors at approximately 17 weeks of age. In the mice treated with vandetanib (6mg/kg/day), these lung tumors disappeared and the phosphorylations of EGFR and VEGFR-2 were reduced in lung tissues to levels comparable to those of non-transgenic control mice. The median overall survival time of the transgenic mice was 28 weeks in the vandetanib-treated group and 17 weeks in the vehicle-treated group. Vandetanib significantly prolonged the survival of the transgenic mice (log-rank test, p＜ 0.01); resistance to vandetanib occurred at 20 weeks of age and the animals died from their lung tumors at about 28 weeks of age. These data suggest that vandetanib could suppress the progression of tumors harboring an activating EGFR mutation.

Lower gefitinib dose led to earlier resistance acquisition before emergence of T790M mutation in epidermal growth factor receptor-mutated lung cancer model.

Non-small-cell lung cancers with epidermal growth factor receptor (EGFR) mutations are sensitive to EGFR tyrosine kinase inhibitors (TKIs); however, unlike cytotoxic agents, it is generally accepted that minimal doses of drugs inhibiting target molecules are sufficient when molecular-targeted agents, including EGFR-TKIs, are used. Thus, any utility of higher doses remains unclear. We compared low-dose (15 mg/kg) gefitinib therapy with high-dose (50 mg/kg) therapy using an EGFR-mutated lung cancer xenograft model. Both gefitinib doses induced tumor shrinkage, but tumors regrew in the low-dose group within 1 month, whereas tumors in the high-dose group did not. Neither the T790M mutation nor MET amplification was apparent in regrown tumors. We also compared outcomes after two doses of gefitinib (5 and 25 mg/kg) in a transgenic EGFR-mutated lung cancer mouse model. In line with the results obtained using the xenograft model, both gefitinib doses completely inhibited tumor growth, but tumors treated with the lower dose of gefitinib developed earlier drug resistance. In conclusion, a low gefitinib dose caused tumors to become drug-resistant prior to acquisition of the T790M mutation or MET amplification in EGFR-mutated models of lung cancer. This suggests that it is important to optimize the EGFR-TKI dose for treatment of EGFR mutation-associated lung cancer. Gefitinib may need to be given at a dose greater than the minimum required for inhibition of target molecules.

JAK2-related pathway induces acquired erlotinib resistance in lung cancer cells harboring an epidermal growth factor receptor-activating mutation.

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors, such as gefitinib and erlotinib, are effective for non-small cell lung cancer with activating EGFR mutations. However, even in patients with an initial dramatic response to such a drug, acquired resistance develops after 6-12 months. A secondary mutation of T790M in EGFR and amplification of the MET gene account for this resistance; however, the mechanism(s) of approximately 30% of acquired resistance cases remain unknown. We established an erlotinib-resistant lung cancer cell line named PC-9/ER3 that harbors an EGFR mutation after continuously exposing PC-9 cells to erlotinib. PC-9/ER3 cells were 136-fold more resistant to erlotinib than the parental cells. Although the PC-9/ER3 cells did not carry the T790M mutation or MET amplification and had similar levels of phosphorylated (p) STAT3, pJAK2 increased in the resistant cells. It was found in the present study that 3-12 h of exposure to erlotinib in both cell lines did not affect pJAK2 expression, but did result in increased pSTAT3 expression. pAkt in PC-9/ER3 cells was less suppressed than in PC-9 cells, although pEGFR and pMAPK were markedly suppressed in both cell lines. The combined treatment of erlotinib plus a JAK2 inhibitor (JSI-124) suppressed pAkt in PC-9/ER3 cells. Similarly, the combination of erlotinib plus JSI-124 or siRNA against JAK2 restored sensitivity to erlotinib in PC-9/ER3 cells. The combination of erlotinib plus JSI-124 was also effective for reducing PC-9/ER3 tumors in a murine xenograft model. Our results suggest that the activation of JAK2 partially accounts for acquired erlotinib resistance.

Phase II study of irinotecan and amrubicin in patients with relapsed non-small cell lung cancer: Okayama Lung Cancer Study Group Trial 0402.

BACKGROUND: The survival advantage achieved by existing anti-cancer agents as second-line therapy for relapsed non-small cell lung cancer (NSCLC) is modest and further improvement of treatment outcome is desired. Combination chemotherapy with irinotecan and amrubicin for advanced NSCLC has not been fully evaluated. METHODS: The primary endpoint of this phase II clinical trial was objective response. Patients with NSCLC who had been treated previously with one or two chemotherapy agents were enrolled. Irinotecan and amrubicin were both administered on Days 1 and 8 of a 21-day cycle, at doses of 100 mg/m(2) and 40 mg/m(2), respectively. RESULTS: Between 2004 and 2006, 31 patients received a total of 101 courses; the median number of courses administered was three (range, one to six). Objective response was obtained in nine of the 31 patients (29.0% response rate; 95% confidence interval (CI), 12.1-46.0%). With a median follow-up time of 43.9 months, median survival time and the median progression-free survival time were 14.2 and 4.0 months, respectively. Myelosuppression was the most frequently observed adverse event, with grade 3/4 neutropenia in 51% of patients. Febrile neutropenia developed after nine courses (9%) and resulted in one treatment-related death. Cardiac toxicity and diarrhea, possibly specific for both agents, were infrequent and manageable. CONCLUSION: Combination chemotherapy with irinotecan and amrubicin is effective in patients with NSCLC but showed moderate toxicities in second- or third-line settings.

STAT3 expression in activating EGFR-driven adenocarcinoma of the lung.

Bronchioloalveolar carcinoma (BAC) pattern is often seen at the margin of invasive adenocarcinomas. We investigated EGFR signaling abnormalities involved in the progression of adenocarcinoma. Fifty tumors were obtained from patients who underwent surgery for lung adenocarcinoma seen as dense areas in ground glass opacity on computed tomography. Six, 18, and 26 tumors <1cm, 1-2 cm, and ≥2 cm in diameter, respectively, were analyzed. Of the 24 tumors ≤2 cm in diameter, nine were preinvasive and 15 were invasive. EGFR, pAKT, and pMAPK were overexpressed in the center of the adenocarcinoma compared to the BAC component (p<0.01) by immunohistochemistry, while pSTAT3 expression was reversed (p=0.017). In the tumors ≤2 cm in diameter, pSTAT3 expression in the central area was higher in preinvasive tumors than in invasive tumors (p=0.005). pSTAT3 was identified in the BAC component of 88% of the EGFR mutant (n=17) and 82% of the wild-type tumors (n=33). Transgenic mice expressing delE748-A752 EGFR and two lung cancer cell lines (PC-9 mutant and A549 wild-type EGFR) were also investigated. In transgenic mice, pSTAT3 was overexpressed in the BAC component around the adenocarcinoma center. Two lung cancer cell lines that overexpressed pSTAT3 were equally sensitive to a JAK2/STAT3 inhibitor (JSI-124). The role of STAT3 in the progression of adenocarcinoma should be further pursued.

A phase I study of S-1 with concurrent thoracic radiotherapy in elderly patients with localized advanced non-small cell lung cancer.

S-1, an oral 5-fluorouracil derivative, is effective against advanced non-small cell lung cancer (NSCLC) with mild toxicity and synergistic effects with radiation in preclinical trials. In this phase I study, we evaluated the dose-limiting toxicity and recommended dose of S-1 for a future phase II study when administered concurrently with thoracic radiation (total dose of 60 Gy at 2 Gy per daily fraction) in elderly patients (>75 years old) with localized advanced NSCLC. S-1 was administered on days 1-14 and 29-42 at the following dosages: 60, 70, and 80 mg/m(2)/day. Twenty-two previously untreated patients were enrolled in this study. Dose-limiting toxicity included febrile neutropenia, thrombocytopenia, stomatitis, and pneumonitis. One patient had grade 5 radiation pneumonitis. No other patient experienced radiation pneumonitis or esophagitis exceeding grade 2. The recommended dose for S-1 was determined to be 80 mg/m(2)/day, which produced an overall response rate of 75% (n=12). The median progression-free survival time was 11.5 months (95% confidence interval: 7.1-15.8 months) with a median follow-up time of 27.9 months. These results indicate that concurrent treatment with S-1 and thoracic radiation is a feasible option for NSCLC in the elderly. A phase II study is currently under way.

Immunohistochemical detection of neuroendocrine differentiation in non-small-cell lung cancer and its clinical implications.

PURPOSE: The purpose of this study was to prospectively assess the clinical implications of neuroendocrine (NE) differentiation in non-small-cell lung cancer (NSCLC) tumors. METHODS: This study accrued subjects suspected to have lung cancer who underwent diagnostic bronchoscopy. Bronchoscopically-biopsied specimens were subjected to routine pathologic examination, and immunohistochemical studies were then performed if lung cancer was diagnosed. Chromogranin-A, synaptophysin, neural cell adhesion molecule, and Leu7 were used to demonstrate NE differentiation. RESULTS: A total of 280 subjects were accrued to this study over a period of 2 years. Among them, 149 subjects were assessable for this study, and 130 were diagnosed as having NSCLC tumors (55 adenocarcinomas, 50 squamous cell carcinomas, 24 NSCLCs not otherwise specified, and 1 typical carcinoid). Large cell NE carcinoma was not observed in this study. Immunohistochemically, NE differentiation was detected in 16% of NSCLC tumors excluding typical carcinoid. By status of NE differentiation of NSCLC tumors, progression-free survivals were similar in 73 patients undergoing non-surgical treatment (positive, n = 10; negative, n = 63) and 43 patients undergoing surgical resection (positive, n = 8; negative, n = 35), respectively. Overall survival of patients with NE-positive tumors appeared to be favorable both for those undergoing non-surgical treatment and those undergoing surgical resection, though the differences in survival were not significant (P = 0.11 and 0.35, respectively). CONCLUSIONS: NE differentiation was detected in 16% of NSCLC tumors in our study. However, the prognostic implications of the presence of this feature could not be clearly determined in this study.

A phase I study of combination S-1 plus cisplatin chemotherapy with concurrent thoracic radiation for locally advanced non-small cell lung cancer.

A combination of S-1, a newly developed oral 5-fluorouracil derivative, and cisplatin is reported to show anti-tumour activity against advanced non-small cell lung cancer (NSCLC). Because S-1 shows synergistic effects with radiation, we conducted a phase I study to evaluate the maximum tolerated doses (MTDs), recommended doses (RDs), and dose-limiting toxicities (DLTs) of cisplatin and S-1 when combined with concurrent thoracic radiation (total dose of 60 Gy with 2 Gy per daily fraction) in patients with locally advanced NSCLC. Chemotherapy consisted of two 4-week cycles of cisplatin administered on days 1 and 8, and S-1 administered on days 1-14. S-1/cisplatin dosages (mg/m(2)/day) were escalated as follows: 60/30, 60/40, 70/40, 80/40 and 80/50. Twenty-two previously untreated patients were enrolled. The MTDs and RDs for S-1/cisplatin were 80/50 and 80/40, respectively. DLTs included febrile neutropaenia, thrombocytopaenia, bacterial pneumonia and delayed second cycle of chemotherapy. No patient experienced radiation pneumonitis>grade 2 and only one patient experienced grade 3 radiation oesophagitis. The overall response rate was 86.4% with a median survival time of 24.4 months. These results indicate that combination cisplatin-S-1 chemotherapy with concurrent thoracic radiation would be a feasible treatment option and a phase II study is currently under way.

Combination of SN-38 with gefitinib or imatinib overcomes SN-38-resistant small-cell lung cancer cells.

Irinotecan is one of the effective anticancer agents for small-cell lung cancer (SCLC) and 7-ethyl-10-hydroxy-campthothecin (SN-38) is an active metabolite of irinotecan. Gefitinib and imatinib are tyrosine kinase inhibitors which have clinical activities in several malignancies and they are also potent inhibitors of breast cancer resistance protein (BCRP) transporter, which confers the resistance of topoisomerase I inhibitors including SN-38 and topotecan. The cytotoxicity of SN-38, gefitinib and imatinib for the SN-38-resistant cells (SBC-3/SN-38) from human SCLC cells, SBC-3, was evaluated using AlamarBlue assay. The drug concentration required to inhibit the growth of tumor cells by 50% (IC50) for 96-h exposure was used to evaluate the cytotoxicity. BCRP expression was determined by Western blotting and immunofluorescence staining. Intracellular topotecan accumulation was evaluated by flow cytometry. No differences were observed in the IC50 values (mean +/- SD) of the tyrosine kinase inhibitors between the SBC-3 cells and the SBC-3/SN-38 cells: 15+/-1.6 and 12+/-2.8 microM of gefitinib, respectively; 15+/-0.51 and 14+/-3.9 microM of imatinib, respectively. The SBC-3/SN-38 was 9.5-fold more resistant to SN-38 than the parental SBC-3. The SBC-3/SN-38 restored sensitivity to SN-38 when combined with 8 microM gefitinib or 8 microM imatinib, even though the IC50 values of SN-38 combined with gefitinib or imatinib in the SBC-3 cells did not change. BCRP was equally overexpressed in the SBC-3/SN-38 with and without gefitinib or imatinib. In addition, the BCRP expression on the SBC-3/SN-38 cell membrane with and without gefitinib seemed to be equal. Gefitinib increased intracellular accumulation of topotecan in the SBC-3/SN-38 cells. Gefitinib or imatinib reversed SN-38-resistance in these SCLC cells, possibly due to intracellular accumulation of SN-38 without any change in BCRP quantity. Irinotecan with gefitinib or imatinib might be effective for SCLC refractory to irinotecan.