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Keywords:

  • NK012;
  • drug-delivery system;
  • lung cancer;
  • lung adenocarcinoma;
  • 7-ethyl-10-hydroxycamptothecin;
  • SN-38;
  • micelles;
  • bevacizumab

Abstract

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. Acknowledgements
  7. CONFLICT OF INTEREST DISCLOSURES
  8. REFERENCES

BACKGROUND:

It has been demonstrated that NK012, a novel 7-ethyl-10-hydroxycamptothecin (SN-38)-incorporating polymeric micelle, exerts significantly more potent antitumor activity against various human tumor xenografts than irinotecan (CPT-11) (a water-soluble prodrug of SN-38). Combination therapy of anticancer agents with bevacizumab (Bv), an anti-vascualr endothelial growth factor humanized monoclonal antibody, has more potently inhibited tumor growth than either agent alone. In the current study, the authors examined the antitumor effect of NK012 in combination with Bv against human lung cancer.

METHODS:

Nude mice bearing lung adenocarcinoma (PC-14 or A549 xenografts) were administered NK012 at SN-38-equivalent doses of 5 mg/kg or 30 mg/kg in combination with or without Bv at 5 mg/kg. CPT-11 at a dose of 66.7 mg/kg was administered with or without Bv at a dose of 5 mg/kg in the same experimental model. To evaluate interaction with Bv, the pharmacokinetics and microvessel density in tumors that were treated on each regimen were analyzed.

RESULT:

In vitro, the growth-inhibitory effect of NK012 was 50-fold more potent than that of CPT-11 and was almost equivalent to that of SN-38. In vivo studies revealed that the combination of NK012 plus Bv had significantly greater antitumor activity against human lung cancer xenografts compared with NK012 alone (PC-14, P = .0261; A549, P < .001). The pharmacokinetic profile of NK012 revealed that coadministration of Bv did not interfere with the accumulation of NK012.

CONCLUSIONS:

In this study, significant antitumor activity was noted with NK012 in combination with Bv against lung cancer cells. The current results warrant the clinical evaluation of NK012 in lung cancer. Cancer 2010. © 2010 American Cancer Society.

Lung cancer is the leading cause of cancer-related deaths worldwide, and nonsmall cell lung cancer (NSCLC), including adenocarcinoma, accounts for 75% to 80% of lung cancer cases.1 Currently, cisplatin (CDDP)-based chemotherapy is the recommended first-line treatment for patients with advanced NSCLC.2, 3 Despite recent advances in the treatment of lung cancer, the prognosis for patients with NSCLC remains relatively poor, so attention currently is focused on finding novel agents, including new cytotoxic agents.

Irinotecan (CPT-11), a prodrug of 7-ethyl-10-hydroxycamptothecin (SN-38) (the active metabolite of irinotecan), which is a topoisomerase-I inhibitor, appears to be an effective agent against NSCLC when used as monotherapy or in combination with cisplatin.4, 5 Bevacizumab (Bv) is an antivascular endothelial growth factor (anti-VEGF) humanized monoclonal antibody. Bv reportedly is effective in various cancers, including colorectal cancer,6 renal cell cancer,7 and breast cancer.8 Sandler et al reported that the addition of Bv to paclitaxel plus carboplatin in the treatment of NSCLC had a significant survival benefit.9 In addition, Reck et al reported that the addition of Bv to gemcitabine plus cisplatin also had a significant clinical benefit in NSCLC.10

NK012 is an SN-38-incorporating polymeric micelle and is categorized as a drug-delivery system. We previously demonstrated that NK012 accumulates more efficiently in various human tumor xenografts by using leaky tumor vessels and exerts significantly more potent antitumor activity against various human tumor xenografts compared with CPT-11.11-17 Since the greater antitumor effect of NK012 may be attributed to its greater accumulation in the tumor using the leaky tumor vasculature, the addition of Bv to NK012 may hinder the efficient accumulation of NK012 in tumors because the permeability of tumor vasculature caused by VEGF is inhibited by Bv. In the current study, we evaluated the antitumor activity of NK012 administered in combination with Bv in experimental models.

MATERIALS AND METHODS

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. Acknowledgements
  7. CONFLICT OF INTEREST DISCLOSURES
  8. REFERENCES

Drugs and Cells

NK012, an SN-38-incorporating polymeric micelle, and SN-38 were obtained from Nippon Kayaku Company, Ltd. (Tokyo, Japan), CPT-11 was purchased from Yakult Honsha Company, Ltd. (Tokyo, Japan), and Bv was purchased from Chugai Seiyaku Company, Ltd. (Tokyo, Japan). The human lung adenocarcinoma cell lines PC-14 and PC-9 kindly were provided by Dr. Y. Hayata (Tokyo Medical University, Tokyo, Japan). Human lung adenocarcinoma cell lines A549, NCI-H23, and NCI-H1975 were purchased from the American Type Culture Collection (Manassas, Va). These cell lines were maintained in RPMI 1640 supplemented with 10% fetal bovine serum (Cell Culture Technologies, Gaggenau-Hoerden, Germany), penicillin (100 U/mL), streptomycin (100 μg/mL), and amphotericin B (25 μg/mL; all from Sigma, St. Louis, Mo) in a humidified, 5% CO2 atmosphere at 37°C.

In Vitro Growth-Inhibition Assay

PC-14, A549, NCI-H23, and NCI-H1975 cells were seeded in 96-well plates at a density of 10,000 cells per well in a final volume of 100 μL. Twenty-four hours after seeding, the medium was removed, and a graded concentration of SN38, NK012, and CPT-11 was added to the wells. Cultures were maintained in a CO2 incubator for an additional 72 hours. Then, cell growth inhibition was measured by using a tetrazolium salt-based proliferation assay (WST assay; Wako Chemicals, Osaka, Japan). After removal of the medium, WST-8 solution (10 μL) and medium (90 μL) were added to the wells, and the plates were incubated at 37°C for 1 hour. The absorbance of the formazan product formed was detected at 450 nm in a 96-well spectrophotometric plate reader. Cell viability was measured and compared with that of the control cells. Each experiment was carried out in triplicate. Data were averaged and normalized against the nontreated controls to generate dose-response curves.

In Vivo Growth-Inhibition Assay

The animal experimental protocols were approved by the Committee for Ethics of Animal Experimentation, and the experiments were conducted in accordance with the Guidelines for Animal Experiments from the National Cancer Center.

Female BALB/c mice, 6 weeks old, were obtained from SLC Japan (Shizuoka, Japan). These mice were maintained in a laminar air-flow cabinet and were inoculated subcutaneously with 5 × 106 PC-14 cells or with 5 × 106 A549 cells in the flank region. When tumor volumes (TVs) reached approximately 100 mm3, the mice were divided randomly into test groups of 5 mice per group (Day 0). The length (a) and width (b) of the tumor mass were measured twice weekly, and the TV was calculated as follows: TV = (a × b2)/2. The relative TV (RTV) at Day n was calculated as follows: RTV = TVn/TV0, where TVn is the TV at Day n, and TV0 is the TV at Day 0.

Experiment 1: Evaluation of the Antitumor Effect of NK012 and CPT-11

By comparing the data between NK012 and CPT-11, we evaluated their effects as single agents against PC-14 or A549 xenografts. The maximum tolerated dose (MTD) of NK012 (30 mg/kg)11 or the MTD of CPT-11 (66.7 mg/kg)18 was administered by intravenous injection into the tail vein on Days 0, 4, and 8.

Experiment 2: Evaluation of the Antitumor Effect of NK012 Alone and NK012 With Bv

By comparing the data between NK012 alone and NK012 plus Bv, we evaluated the combined effect of NK012 plus Bv against PC-14 xenografts. NK012 at a dose of 5 mg/kg was administered intravenously into the tail vein on Days 0, 4, and 8 with or without Bv. In addition, we evaluated the combined effects against A549 xenografts (NK012 [30 mg/kg intravenously] with Bv). When Bv was coadministered with each anticancer agent, Bv was administered intraperitoneally at a dose of 5 mg/kg on Days 0, 4, and 8.

Distribution Studies of Free SN-38, CPT-11, and NK012 in Tumors by High-Performance Liquid Chromatography

When the PC-14 TV reached approximately 100 mm3, NK012 (30 mg/kg) or CPT-11 (66.7 mg/kg) was administered intravenously with or without Bv (5 mg/kg intraperitoneally). Twenty-four hours after the injection of NK012 or CPT-11, each tumor was excised under anesthesia. In other experiments, NK012 (5 mg/kg) was administered intravenously with or without Bv (5 mg/kg intraperitoneally), and each tumor was excised under anesthesia at 12 hours, 24 hours, 3 days, 7 days, 10 days, and 14 days after the injection of NK012. The tumor tissues were rinsed with physiologic saline; mixed with 0.1 M glycine-HCl buffer, pH 3.0, in methanol at 5% (weight/weight); and homogenized. To detect free SN-38 and CPT-11, the tumor samples (100 μL) were mixed with 20 μL 1 mM phosphoric acid in methanol (1:1) and 40 μL ultrapure water, and camptothecin was used as the internal standard (10 ng/mL for free SN-38, 12 ng/mL for CPT-11). The samples were vortexed vigorously for 10 seconds and filtered through an Ultrafree-MC centrifugal filter device (Millipore, Bedford, Mass). Reverse-phase high-performance liquid chromatography (HPLC) was conducted at 35°C on a Mightysil RP-18 GP column (150 × 4.6 mm; Kanto Chemical, Tokyo, Japan). Then, the samples were injected into an Alliance Water 2795 HPLC system (Waters, Milford, Mass) equipped with a Waters 2475 multi-λ fluorescence detector. Fluorescence originating from SN-38 was detected at 540 nm with an excitation wavelength of 365 nm.

For the detection of polymer-bound SN-38, SN-38 was released from the polymer as described previously.11 In brief, 100-μL tissue samples were diluted with 20 μL methanol (50% [weight/weight]) and 20 μL NaOH (0.7 M). The samples were incubated for 15 minutes at room temperature. After incubation, 20 μL HCl (0.7 M) and 60 μL of internal standard solution were added to the samples and the hydrolysate was filtered. The filtrate was applied to the HPLC system. Polymer-bound SN-38 was determined by subtraction of nonpolymer-bound SN-38 from the total SN-38 in the hydrolysate.

Immunofluorescence Study

At Day 14 after the injection of saline, Bv, NK012, or NK012 plus Bv, the PC-14 tumors were excised under anesthesia. Frozen sections of these tumors (10 μm) were fixed with 4% paraformaldehyde and washed with phosphate-buffered saline (PBS). After blocking with 5% skim milk (BD, Franklin Lakes, NJ) in PBS, the slides were incubated with anti-cluster of differentiation molecule 31 (anti-CD31) monoclonal antibody (1:100 dilution; PharMingen, San Diego, Calif) and anti-NG2 monoclonal antibody (1:1000 dilution; Chemicon, Temecula, Calif) for 1 hour. After washing with PBS, the slides were stained with Alexa 555-, Alexa 647-conjugated secondary antibodies, antirat (red) and antirabbit immunoglobulin G (green; 1:100 dilution; Invitrogen, Carlsbad, Calif), and 4′,6-diamidino-2-phenylindole (DAPI) for nuclear staining. Five areas were chosen randomly from each mouse (n = 2), and the fluorescence intensity was measured and analyzed with BZ-II ANALYZER software (Keyence, Osaka, Japan) for histologic quantification under fluorescence microscopy at 20-fold magnification.

Statistical Analysis

One-way fractional analyses of variance and multiple comparison tests (Scheffe and Bonferroni/Dunn) conducted with StatView software (version 5.0; SAS Institute, Inc., Cary, NC) were used to compare the different treatment groups of xenografts. Data were expressed as the mean ± standard deviation. Data were analyzed with the Student t test when the groups had equal variance (F test) or with the Welch test when they had unequal variance (F test). P values <.05 were regarded as statistically significant. All statistical tests were 2-sided.

RESULTS

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. Acknowledgements
  7. CONFLICT OF INTEREST DISCLOSURES
  8. REFERENCES

Sensitivity of Lung Cancer Cells to SN-38, NK012, and CPT-11

The 50% inhibitory concentration values of NK012 for the cell lines ranged from 0.059 μmol/L to 0.88 μmol/L. The growth-inhibitory effect of NK012 was 50-fold more potent than that of CPT-11 and was almost equivalent to that of SN-38 (Table 1).

Table 1. Fifty Percent Inhibitory Concentration Values of 7-Ethyl-10-Hydroxycamptothecin (SN-38), the SN-38–Incorporating Polymeric Micelle NK012, and Irinotecan in Various Human Lung Adenocarcinoma Cell Lines
 IC50 (μmol/L)a
Cell LineSN-38NK012CPT-11
  • IC50 indicates 50% inhibitory concentration; CPT-11, irinotecan.

  • a

    All values shown are the mean values±standard deviation.

PC-140.050±0.0030.053±0.0029.688±1.187
A5490.506±0.0290.883±0.84048.153±4.641
PC-90.028±0.0110.059±0.00521.782±2.145
NCI-H230.025±0.0050.060±0.0025.223±1.586
NCI-H19750.047±0.0840.082±0.0026.330±0.432

Histologic Examination of PC-14 and A549 Xenografts

Hematoxylin and eosin staining of the tumors from PC-14 xenografts revealed that the tumors were poor in stroma, whereas the tumors from A549 xenografts appeared to be stroma-rich. Immunostaining of both tumor tissues with CD31 and NG2 indicated that vasculatures covered with pericytes were more abundant in the A549 xenografts than in the PC-14 xenografts (Fig. 1).

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Figure 1. These photomicrographs are from the histologic examination of excised tumors from PC-14 and A549 xenografts that were stained with hematoxylin and eosin (H.E.) or analyzed by immunohistochemistry for cluster of differentiation molecule 31 (CD31) (also called platelet endothelial cell adhesion molecule 1) (red) for the chondroitin sulfate proteoglycan NG2 (green) and for 4′,6-diamidino-2-phenylindole (DAPI) (blue). Scale bars = 100 μm.

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Antitumor Activity of NK012 and CPT-11 on Subcutaneous PC-14 and A549 Xenografts

Experiment 1: Comparison of the antitumor effect of NK012 and CPT-11

In PC-14 xenografts that were treated with NK012 at 30 mg/kg, the tumors started to shrink on Day 4, the tumors disappeared completely by Day 14, and there was no relapse during observation until 60 days after treatment (Fig. 2A). Comparison of the relative TV revealed that the antitumor activity of NK012 was significantly greater than that of CPT-11 (P = .0267). Conversely, the TV did not shrink in A549 tumor-bearing mice that were treated with NK012 (Fig. 2B). Although the antitumor activity of NK012 did not differ significantly from that of CPT-11 in A549 xenografts (P = .0869), a trend toward a superior antitumor effect against A549 tumors was observed in the NK012 treatment group.

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Figure 2. These graphs illustrate (A) the antitumor effects of the novel 7-ethyl-10-hydroxycamptothecin (SN-38)-incorporating polymeric micelle NK012 alone (5 mg/kg daily), bevacizumab (Bv) alone (5 mg/kg daily), and combined NK012 (5 mg/kg daily) plus Bv (5 mg/kg daily) against PC-14 tumor-bearing mice and (B) the effects of NK012 alone (30 mg/kg daily) and combined NK012 (30 mg/kg daily) plus Bv (5 mg/kg daily) against A549 tumor-bearing mice. Squares indicate NK012; open triangles, Bv; solid triangles, NK012 plus Bv; saline, circles. NK012 was administered intravenously (i.v.), and Bv was administered intraperitoneally (i.p.) on Days 0, 4, and 8. Each group included 5 mice. Points indicate mean values; bars, standard deviation.

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Experiment 2: Comparison of the antitumor effect of NK012 alone and NK012 plus Bv

In PC-14 xenografts, the combination of 5 mg/kg NK012 with 5 mg/kg Bv resulted in a significantly greater inhibition of tumor growth compared with NK012 5 mg/kg alone (P = .0261) (Fig. 3A). Also in A549 xenografts, the combination of 30 mg/kg NK012 with 5 mg/kg Bv resulted in significant inhibition of tumor growth compared with NK012 30 mg/kg alone (P < .0001) (Fig. 3B).

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Figure 3. These graphs illustrate the antitumor effects of the novel 7-ethyl-10-hydroxycamptothecin (SN-38)-incorporating polymeric micelle NK012 alone or irinotecan (CPT-11) alone against (A) PC-14 (B) and A549 tumor-bearing mice. The treatment was initiated 11 days after PC-14 inoculation and 13 days after A549 inoculation. NK012 (30 mg/kg daily) (squares), CPT-11 (66.7 mg/kg daily) (triangles), or saline (circles) was administered intravenously (i.v.) on Days 0, 4, and 8. Each group included 5 mice. Points indicate mean values; bars, standard deviation.

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Distribution Studies of Free SN-38, CPT-11, and NK012 in Tumors Using HPLC

In tumors that were obtained 24 hours after the injection of CPT-11 or NK012, the level of free SN-38 released from NK012 was significantly greater than the level of SN-38 converted from CPT-11 (P = .003) (Fig. 4A). Conversely, the level of free SN-38 released from treatment with NK012 plus Bv did not differ significantly from the level released from treatment with NK012 alone. The intratumor concentrations of polymer-bound SN-38 did not differ between NK012 plus Bv and NK012 alone (Fig. 4B). At only 12 hours after injection, intratumor concentrations of polymer-bound SN-38 were significantly greater with NK012 alone than with NK012 plus Bv (P = .015). At this time point, however, there was no difference in the intratumor concentration of free SN-38 between treatment with NK012 alone and treatment with NK012 plus Bv. Thereafter, the intratumor concentrations of both polymer-bound SN-38 and free SN-38 did not differ between treatment with NK012 alone and treatment with NK012 plus Bv (Fig. 4C,D).

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Figure 4. These charts illustrate pharmacokinetics in PC-14 tumor-bearing mice. (A) Polymer-unbound 7-ethyl-10-hydroxycamptothecin (free SN-38) in tumor was quantified by high-performance liquid chromatography (HPLC) 24 hours after the injection of irinotecan (CPT-11) (66.7 mg/kg), combined CPT-11 (66.7 mg/kg) plus bevacizumab (Bv) (5 mg/kg), the SN-38-incorporating micelle NK012 (30 mg/kg), or combined NK012 (30 mg/kg) plus Bv (5 mg/kg). (B) Polymer-bound SN-38 in tumor also was quantified by HPLC 24 hours after the injection of NK012 (30 mg/kg) or combined NK012 (30 mg/kg) plus Bv (5 mg/kg). Free SN-38 (C) and polymer-bound SN-38 (D) in tumor was quantified by HPLC at 12 hours, 24 hours, 3 days, 7 days, 10 days, and 14 days after the injection of NK012 (5 mg/kg daily) (squares) or combined NK012 (5 mg/kg daily) plus Bv (5 mg/kg daily) (triangles). Each group included 3 mice. Points indicate mean values; bars, standard deviation; asterisk, P < .01.

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Immunofluorescence Staining to Clarify the Antivascular Effect of Bv

Treatment with Bv in combination with or without NK012 significantly reduced the area of CD31-positive proliferating endothelial cells in the tumors compared with controls on Day 14 (P < .01) (Fig. 5A,B). Conversely, the area of NG2-positive pericytes was not significantly different between the groups (Fig. 5A,C).

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Figure 5. These photomicrographs reveal immunofluorescence staining of cluster of differentiation molecule 31 (CD31)-positive endothelial cells and the chondroitin sulfate proteoglycan NG2-positive pericytes. (A) Fourteen days after the injection of saline, bevacizumab (Bv), the novel 7-ethyl-10-hydroxycamptothecin (SN-38)-incorporating polymeric micelle NK012, or combined NK012 plus Bv, all tumors were excised from the mice. Frozen sections from these tumors (10 μm) were stained with anti-CD31 monoclonal antibody (red), anti-NG2 antibody (green), and 4′,6-diamidino-2-phenylindole (DAPI) (blue). Scale Bars = 100 μm. Histologic quantification under fluorescence microscopy at 20-fold magnification was performed (B) for CD31-positive areas and (C) for NG2-positive areas. Bars indicate standard deviation; asterisks, P < .01 compared with control.

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DISCUSSION

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. Acknowledgements
  7. CONFLICT OF INTEREST DISCLOSURES
  8. REFERENCES

The size of NK012 is approximately 20 nm in diameter, and NK012 is sufficiently large to avoid renal secretion. NK012 can evade nonspecific capture by the reticuloendothelial system in various organs, because the outer shell of NK012 is covered with polyethyleneglycol. Therefore, NK012 is expected to achieve a long plasma half-life, which permits large amounts of SN-38 to reach the tumor site through the enhanced permeability and retention effect.19

To date, we have reported that NK012 has significantly greater antitumor activity against various human tumor xenografts including, small cell lung cancer,11, 17 colorectal cancer,14 renal cancer,13 pancreatic cancer,12 gastric cancer,15 and malignant glioma,16 compared with CPT-11. In the current study, NK012 also appeared to eradicate PC-14 xenografts completely, but not A549 xenografts. This difference may be because of differences in the sensitivity of each cell line to NK012 and in pericyte coverage on vasculatures. Less pericyte coverage reportedly to results in more leakiness of plasma substances; therefore, the degree of NK012 accumulation may be associated inversely with the degree of pericyte coverage.20, 21

Angiogenesis, which permits tumors to grow and metastasize, plays a pivotal role in several pathologic disorders.22 VEGF is 1 of the most potent positive regulators of angiogenesis23 and is recognized as an attractive target in cancer therapy. Unlike normal vasculature, the microvessels of tumors are hyperpermeable to several substances, including macromolecules and nanoparticles. The permeability, interstitial fluid pressure, and numbers of microvessels are increased by VEGF-induced angiogenesis.24, 25 Anti-VEGF antibody administered in combination with chemotherapeutic agents, including doxorubicin,26 topotecan,27, 28 paclitaxel,29 and docetaxel,30 resulted in more potent inhibition of tumor growth than either agent alone. However, it has not been clarified whether anti-VEGF antibody administered in combination with drug-incorporating polymeric micelles has an additive effect. In the current study, we demonstrated that the combination of NK012 plus Bv had significantly greater antitumor activity against human lung adenocarcinoma cells (PC-14 and A549) compared with NK012 alone. The concentrations of either polymer-bound SN-38 or free SN-38 after the administration of NK012 plus Bv did not clearly differ from the concentrations after NK012 alone. In addition, after treatment with Bv, the area of vascular endothelial cells stained with CD31 was decreased significantly compared with controls. These results suggest that VEGF inhibition may not disturb NK012 accumulation in the tumors and that the direct effect of NK012 plus Bv produced an additional antitumor effect.

In the current study, we demonstrated that NK012 has significantly greater antitumor activity against human lung adenocarcinoma cells (PC-14 and A549) compared with CPT-11. Therefore, we believe that NK012 is a promising oncologic treatment for patients with NSCLC. In 2 individual phase 1 trials that were conducted in Japan and the United States, the toxic profile of NK012 was favorable, and the dose-limiting toxicity was neutropenia.31, 32 Diarrhea was mild; that is, even the worst diarrhea was grade 2 in the phase 1 setting.

In conclusion, the current study demonstrated the superior antitumor activity of NK012 against NSCLC cells compared with CPT-11. In patients with NSCLC, clinical trials of the combination of NK012 plus Bv may be warranted.

Acknowledgements

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. Acknowledgements
  7. CONFLICT OF INTEREST DISCLOSURES
  8. REFERENCES

We thank Ms. N. Mie and Ms. M. Ohtsu for technical assistance and Ms. K. Shiina and Ms. K. Abe for secretarial assistance.

CONFLICT OF INTEREST DISCLOSURES

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. Acknowledgements
  7. CONFLICT OF INTEREST DISCLOSURES
  8. REFERENCES

Supported by a Grant-in-Aid from the Third Term Comprehensive Control Research for Cancer; by Ministry of Health, Labor, and Welfare grant H19-025 (to K. Goto, Y. Nishiwaki, and Y. Matsumura); by Ministry of Education, Culture, Sports, Science, and Technology Scientific Research on Priority Areas grant 17016087 (to Y. Matsumura); by the Japanese Foundation for Multidisciplinary Treatment of Cancer (to Y. Matsumura); and by the Princess Takamatsu Cancer Research Fund (07-23908).

REFERENCES

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. Acknowledgements
  7. CONFLICT OF INTEREST DISCLOSURES
  8. REFERENCES
  • 1
    Jemal A, Thun MJ, Ries LA, et al. Annual report to the nation on the status of cancer, 1975-2005, featuring trends in lung cancer, tobacco use, and tobacco control. J Natl Cancer Inst. 2008; 100: 1672-1694.
  • 2
    [No authors listed] Chemotherapy in non-small cell lung cancer: a meta-analysis using updated data on individual patients from 52 randomised clinical trials. Non-small Cell Lung Cancer Collaborative Group. BMJ. 1995; 311: 899-909.
  • 3
    Ardizzoni A, Boni L, Tiseo M, et al. Cisplatin- versus carboplatin-based chemotherapy in first-line treatment of advanced non-small-cell lung cancer: an individual patient data meta-analysis. J Natl Cancer Inst. 2007; 99: 847-857.
  • 4
    Fukuoka M, Niitani H, Suzuki A, et al. A phase II study of CPT-11, a new derivative of camptothecin, for previously untreated non-small-cell lung cancer. J Clin Oncol. 1992; 10: 16-20.
  • 5
    Ohe Y, Ohashi Y, Kubota K, et al. Randomized phase III study of cisplatin plus irinotecan versus carboplatin plus paclitaxel, cisplatin plus gemcitabine, and cisplatin plus vinorelbine for advanced non-small-cell lung cancer: Four-Arm Cooperative Study in Japan. Ann Oncol. 2007; 18: 317-323.
  • 6
    Hurwitz H, Fehrenbacher L, Novotny W, et al. Bevacizumab plus irinotecan, fluorouracil, and leucovorin for metastatic colorectal cancer. N Engl J Med. 2004; 350: 2335-2342.
  • 7
    Yang JC, Haworth L, Sherry RM, et al. A randomized trial of bevacizumab, an anti-vascular endothelial growth factor antibody, for metastatic renal cancer. N Engl J Med. 2003; 349: 427-434.
  • 8
    Miller K, Wang M, Gralow J, et al. Paclitaxel plus bevacizumab versus paclitaxel alone for metastatic breast cancer. N Engl J Med. 2007; 357: 2666-2676.
  • 9
    Sandler A, Gray R, Perry MC, et al. Paclitaxel-carboplatin alone or with bevacizumab for non-small-cell lung cancer. N Engl J Med. 2006; 355: 2542-2550.
  • 10
    Reck M, von Pawel J, Zatloukal P, et al. Phase III trial of cisplatin plus gemcitabine with either placebo or bevacizumab as first-line therapy for nonsquamous non-small-cell lung cancer: AVAil. J Clin Oncol. 2009; 27: 1227-1234.
  • 11
    Koizumi F, Kitagawa M, Negishi T, et al. Novel SN-38-incorporating polymeric micelles, NK012, eradicate vascular endothelial growth factor-secreting bulky tumors. Cancer Res. 2006; 66: 10048-10056.
  • 12
    Saito Y, Yasunaga M, Kuroda J, Koga Y, Matsumura Y. Enhanced distribution of NK012, a polymeric micelle-encapsulated SN-38, and sustained release of SN-38 within tumors can beat a hypovascular tumor. Cancer Sci. 2008; 99: 1258-1264.
  • 13
    Sumitomo M, Koizumi F, Asano T, et al. Novel SN-38-incorporated polymeric micelle, NK012, strongly suppresses renal cancer progression. Cancer Res. 2008; 68: 1631-1635.
  • 14
    Nakajima TE, Yasunaga M, Kano Y, et al. Synergistic antitumor activity of the novel SN-38-incorporating polymeric micelles, NK012, combined with 5-fluorouracil in a mouse model of colorectal cancer, as compared with that of irinotecan plus 5-fluorouracil. Int J Cancer. 2008; 122: 2148-2153.
  • 15
    Nakajima TE, Yanagihara K, Takigahira M, et al. Antitumor effect of SN-38-releasing polymeric micelles, NK012, on spontaneous peritoneal metastases from orthotopic gastric cancer in mice compared with irinotecan. Cancer Res. 2008; 68: 9318-9322.
  • 16
    Kuroda J, Kuratsu J, Yasunaga M, Koga Y, Saito Y, Matsumura Y. Potent antitumor effect of SN-38-incorporating polymeric micelle, NK012, against malignant glioma. Int J Cancer. 2009; 124: 2505-2511.
  • 17
    Nagano T, Yasunaga M, Goto K, et al. Antitumor activity of NK012 combined with cisplatin against small cell lung cancer and intestinal mucosal changes in tumor-bearing mouse after treatment. Clin Cancer Res. 2009; 15: 4348-4355.
  • 18
    Kawato Y, Furuta T, Aonuma M, Yasuoka M, Yokokura T, Matsumoto K. Antitumor activity of a camptothecin derivative, CPT-11, against human tumor xenografts in nude mice. Cancer Chemother Pharmacol. 1991; 28: 192-198.
  • 19
    Matsumura Y, Maeda H. A new concept for macromolecular therapeutics in cancer chemotherapy: mechanism of tumoritropic accumulation of proteins and the antitumor agent smancs. Cancer Res. 1986; 46: 6387-6392.
  • 20
    Abramsson A, Lindblom P, Betsholtz C. Endothelial and nonendothelial sources of PDGF-B regulate pericyte recruitment and influence vascular pattern formation in tumors. J Clin Invest. 2003; 112: 1142-1151.
  • 21
    Kano MR, Komuta Y, Iwata C, et al. Comparison of the effects of the kinase inhibitors imatinib, sorafenib, and transforming growth factor-beta receptor inhibitor on extravasation of nanoparticles from neovasculature. Cancer Sci. 2009; 100: 173-180.
  • 22
    Folkman J. Seminars in Medicine of the Beth Israel Hospital, Boston Clinical applications of research on angiogenesis. N Engl J Med. 1995; 333: 1757-1763.
  • 23
    Ferrara N. Vascular endothelial growth factor: basic science and clinical progress. Endocr Rev. 2004; 25: 581-611.
  • 24
    Gerber HP, Ferrara N. Pharmacology and pharmacodynamics of bevacizumab as monotherapy or in combination with cytotoxic therapy in preclinical studies. Cancer Res. 2005; 65: 671-680.
  • 25
    Jain RK. Normalization of tumor vasculature: an emerging concept in antiangiogenic therapy. Science. 2005; 307: 58-62.
  • 26
    Borgstrom P, Gold DP, Hillan KJ, Ferrara N. Importance of VEGF for breast cancer angiogenesis in vivo: implications from intravital microscopy of combination treatments with an anti-VEGF neutralizing monoclonal antibody and doxorubicin. Anticancer Res. 1999; 19: 4203-4214.
  • 27
    Soffer SZ, Moore JT, Kim E, et al. Combination antiangiogenic therapy: increased efficacy in a murine model of Wilms tumor. J Pediatr Surg. 2001; 36: 1177-1181.
  • 28
    Kim ES, Soffer SZ, Huang J, et al. Distinct response of experimental neuroblastoma to combination antiangiogenic strategies. J Pediatr Surg. 2002; 37: 518-522.
  • 29
    Fox WD, Higgins B, Maiese KM, et al. Antibody to vascular endothelial growth factor slows growth of an androgen-independent xenograft model of prostate cancer. Clin Cancer Res. 2002; 8: 3226-3231.
  • 30
    Sweeney CJ, Miller KD, Sissons SE, et al. The antiangiogenic property of docetaxel is synergistic with a recombinant humanized monoclonal antibody against vascular endothelial growth factor or 2-methoxyestradiol but antagonized by endothelial growth factors. Cancer Res. 2001; 61: 3369-3372.
  • 31
    Kato K, Hamaguchi T, Shirao K, et al. Interim analysis of phase I study of NK012, polymer micelle SN-38, in patients with advanced cancer [abstract]. Paper presented at: 2008 Gastrointestinal Cancers Symposium; January 25-26, 2008; Orlando, Fla. Abstract 485.
  • 32
    Burris HA, III, Infante JR, Spigel DR, et al. A phase I dose-escalation study of NK012 [abstract]. J Clin Oncol. 2008; 26( May 20 suppl). Abstract 2538.