Development of a novel in vitro human tissue-based angiogenesis assay to evaluate the effect of antiangiogenic drugs

Randomised phase II trial of weekly ixabepilone ± biweekly bevacizumab for platinum-resistant or refractory ovarian/fallopian tube/primary peritoneal cancer

BACKGROUND

This multi-center RP2 study assessed activity/safety of ixabepilone + bevacizumab compared to ixabepilone in platinum-resistant/refractory ovarian/fallopian tube/primary peritoneal cancer. Additional objectives were to examine the role of prior bevacizumab and taxanes, and explore class III-ß-tubulin (TUBB3) as a predictive biomarker.

METHODS

Participants were randomised to receive ixabepilone 20 mg/m2 days 1, 8, 15 with (IXA + BEV) or without (IXA) bevacizumab 10 mg/kg days 1, 15 every 28 days. Patients were stratified by prior BEV. The primary endpoint was PFS. OS, safety, and ORR served as secondary endpoints.

RESULTS

Among 76 evaluable patients who received IXA + BEV (n = 39) compared to IXA (n = 37), the ORR was 33% (n = 13) versus 8% (n = 3)(P = 0.004), durable at 6 months in 37% (n = 14) and 3% (n = 1) (P < 0.001). BEV significantly improved PFS (median:5.5 vs 2.2 months, HR = 0.33, 95%CI 0.19-0.55, P < 0.001) and OS (median:10.0 vs 6.0 months, HR = 0.52, 95%CI 0.31-0.87, P = 0.006). Both regimens were well-tolerated. TUBB3 expression did not predict response. Subgroup analyses revealed minimal effect of prior BEV or taxane resistant/refractory status on response to IXA + BEV.

CONCLUSIONS

IXA + BEV is a well-tolerated, effective combination for platinum/taxane-resistant ovarian cancer that extends PFS and likely OS relative to IXA monotherapy. Prior receipt of BEV should not preclude the use of IXA + BEV. TUBB3 is not a predictive biomarker.

CLINICAL TRIAL REGISTRATION

NCT3093155.

Treatment of neuroblastoma and rhabdomyosarcoma using RGD-modified liposomal formulations of patupilone (EPO906)

Background

Patupilone (EPO906) is a microtubule stabilizer with a potent antitumor effect. Integrin αVβ3-binding (RGD) liposomes were loaded with EPO906, and their antitumor efficacy was evaluated in two pediatric tumor models, ie, neuroblastoma and rhabdomyosarcoma.

Methods

Integrin αVβ3 gene expression, RGD-liposome cellular association, and the effect of EPO906 and liposomal formulations of EPO906 on cell viability were assessed in vitro in human umbilical vein endothelial cells (HUVEC), in the RH-30 rhabdomyosarcoma cell line, and in the Kelly neuroblastoma cell line. In vivo, mice bearing neuroblastoma or rhabdomyosarcoma tumors were treated with EPO906, EPO906-liposomes, or EPO906-RGD-liposomes. Tumor growth, cumulative survival, and toxicity were monitored.

Results

Integrin αVβ3 was highly expressed in HUVEC and RH-30, but not in Kelly cells. Accordingly, RGD-liposomes were highly associated with HUVEC and RH-30 cells in vitro, but not with the Kelly cells. EPO906 and its liposomal formulations inhibited HUVEC, RH-30, and Kelly cell viability to the same extent. In vivo, EPO906 1.5 mg/kg and liposomal EPO906 potently inhibited tumor growth in both xenograft models without triggering major toxicity. At this dose, liposomal EPO906 did not enhance the antitumor effect of EPO906 in neuroblastoma, but tended to have an increased antitumor effect in rhabdomyosarcoma. Using a lower dose of EPO906-RGD-liposomes significantly enhanced cumulative survival in rhabdomyosarcoma compared with EPO906 alone.

Conclusion

EPO906 shows a strong antitumor effect in neuroblastoma and rhabdomyosarcoma, without triggering major side effects. Its liposomal encapsulation does not alter its activity, and enhances cumulative survival when EPO906-RGD-liposomes are used at low dose in rhabdomyosarcoma.

Use of epothilone B (patupilone) in refractory lymphoma and advanced solid tumors in dogs

BACKGROUND

The epothilones are microtubule-stabilizing agents with promising antitumor effect in refractory and metastatic tumors in humans. The toxicity profile is considered more favorable than in taxanes. The safety of epothilone B (patupilone) has not been evaluated in tumor-bearing dogs.

OBJECTIVES

To evaluate the inhibition of proliferation in canine tumor cells after patupilone treatment. To assess toxicity profile and maximally tolerated dose of patupilone in dogs with refractory tumors.

ANIMALS

Twenty client-owned dogs with various malignancies.

METHODS

Prospective clinical study. The inhibition of proliferation was assessed with a proliferation assay in vitro in canine hemangiosarcoma and lymphoma cell lines. Dogs received patupilone IV once a week for 2 treatments (= 1 treatment cycle). Dose was escalated with 3 dogs per cohort and 20% increments. Adverse effects were graded according to the VCOG-CTCAE v1.0.

RESULTS

Both canine cell lines were sensitive to patupilone with approximately 50% decrease in proliferative activity at 0.2-1 nM. In vivo, dose-limiting adverse effects occurred at 3.3 mg/m(2); main adverse effects were diarrhea, anorexia, vomiting, and nausea. Neither neutropenia nor peripheral neuropathy was observed. Maximally tolerated dose for 2 patupilone administrations once weekly IV is 2.76 mg/m(2). Three per 11 dogs receiving more than 1 treatment cycle showed partial remission in the short period of observation.

CONCLUSIONS AND CLINICAL IMPORTANCE

Canine tumor cells show inhibition of proliferation to patupilone in vitro. Clinically, a dose of 2.76 mg/m(2) IV is well tolerated in dogs with spontaneously occurring tumors.

Anti-angiogenic activity of Herba Epimedii on zebrafish embryos in vivo and HUVECs in vitro

Herba Epimedii, an herb commonly used in East Asian medicine, is commonly used for treatment of impotence, osteoporosis and many inflammatory conditions in traditional Chinese medicine. Recent studies revealed that Herba Epimedii also has anti-tumor or anti-cancer activities, which may possibly be mediated through anti-angiogenesis. This study aims to examine and confirm the anti-angiogenic activity in the herb using both in vivo and in vitro approaches. The 95% ethanol extract and four subsequent fractions (n-hexane, ethyl acetate (EA), n-butanol and aqueous fractions) of Herba Epimedii were tested on the zebrafish model by the quantitative assay for endogenous alkaline phosphatase; then, the active fraction was further tested on Tg(fli1a:EGFP)y1 zebrafish embryos and human umbilical vein endothelial cells (HUVECs) for the anti-angiogenic effects. In addition, the action mechanism of Herba Epimedii was further investigated on wild-type zebrafish embryos and HUVECs. The EA fraction showed anti-angiogenic effects in both in vivo and in vitro models. Further experiments demonstrated that it might affect angiogenesis by acting on multiple molecular targets in zebrafish embryos and ERK signaling pathway in HUVECs. In conclusion, Herba Epimedii can inhibit angiogenesis, which may be the mechanism for its anti-inflammatory, anti-tumor and anti-cancer actions.

Radiosensitizing effect of epothilone B on human epithelial cancer cells

BACKGROUND

A combined modality treatment employing radiation and chemotherapy plays a central role in the management of solid tumors. In our study, we examined the cytotoxic and radiosensitive effect of the microtubule stabilizer epothilone B on two human epithelial tumor cell lines in vitro and its influence on the microtubule assembly.

METHODS

Cancer cells were treated with epothilone B in proliferation assays and in combination with radiation in colony-forming assays. For the analysis of ionizing radiation-induced DNA damage and the influence of the drug on its repair a γH2AX foci assay was used. To determine the effect of epothilone B on the microtubule assembly in cells and on purified tubulin, immunofluorescence staining and tubulin polymerization assay, respectively, were conducted.

RESULTS

Epothilone B induced a concentration- and application-dependent antiproliferative effect on the cells, with IC(50) values in the low nanomolar range. Colony forming assays showed a synergistic radiosensitive effect on both cell lines which was dependent on incubation time and applied concentration of epothilone B. The γH2AX assays demonstrated that ionizing radiation combined with the drug resulted in a concentration-dependent increase in the number of double-strand breaks and suggested a reduction in DNA repair capacity. Epothilone B produced enhanced microtubule bundling and abnormal spindle formation as revealed by immunofluorescence microscopy and caused microtubule formation from purified tubulin.

CONCLUSION

The results of this study showed that epothilone B displays cytotoxic antitumor activity at low nanomolar concentrations and also enhances the radiation response in the tumor cells tested; this may be induced by a reduced DNA repair capacity triggered by epothilone B. It was also demonstrated that epothilone B in fact targets microtubules in a more effective manner than paclitaxel.

Pharmacokinetic pilot study of the antiangiogenic activity of standardized platycodi radix

INTRODUCTION

Platycodi radix is a radish used in food, such as Korean kimchi, and has been shown to cause weight loss in rodents. Platycodin D is considered its active ingredient and has been shown to inhibit lipases. The authors hypothesized that platycodi radix and the platycodin D it contains inhibit angiogenesis; another mechanism for weight loss.

METHODS

This study tested platycodi radix extract, platycodin D, and an extract of platycodi radix standardized to platycodin D for their ability to inhibit angiogenesis in a human adipose tissue assay. This study treated five healthy volunteers, orally, with platycodi radix extract standardized to 414 mg of platycodin D. Three volunteers were treated under fasting conditions, one volunteer with a 400 kcal meal, and one volunteer treated with a placebo. Blood was drawn over 5 hours to compare serum inhibition of the human adipose tissue angiogenesis.

RESULTS

Platycodin radix extract, platycodin D, and platycodi radix extract standardized to platycodin D all inhibited angiogenesis. The three volunteers who consumed platycodi radix extract standardized to 414 mg of platycodin D had a 25.76% reduction in angiogenesis from baseline at 60 minutes (P<0.002), and had a statistically significant reduction in angiogenesis from 30 to 240 minutes (P<0.05 to P<0.002). The placebo decreased angiogenesis by 5.6% between 30 and 240 minutes, compared with 17.8% by the extract. The meal delayed absorption by approximately 3.5 hours.

CONCLUSION

Platycodi radix extract standardized to platycodin D inhibited angiogenesis in human volunteers, and paves the way for a dose-response study and a human clinical obesity trial.

The role of angiogenesis in neuroendocrine tumors

The first studies to assess in vitro angiogenesis in neuroendocrine tumors used animal-based assays to study the antiangiogenic properties of somatostatin analogs. Current technologies enable investigators to directly appraise the in vitro angiogenic response of an individual's neuroendocrine tumor with and without potential antiangiogenic reagents. This article describes the evolution of methods to assess in vitro angiogenesis in neuroendocrine tumors and describes some of the clinical data.

Metronomic dosing enhances the anti-angiogenic effect of epothilone B

BACKGROUND

High doses (10 nM) of epothilone B, a microtubule stabilizer, will inhibit the development of human tumor-derived angiogenesis following short (14 d) drug exposure times. Metronomic dosing regimes use lower drug doses and prolonged drug exposure times in an attempt to decrease toxicity compared with standard dosing schedules. We hypothesized that epothilone B would be an effective anti-angiogenic agent when administered at very low doses over an extended period of time.

METHODS

Fragments of four fresh human tumors were cultured in a fibrin-thrombin matrix and maintained in nutrient media plus 20% fetal bovine serum (FBS) for 56 d. Tumor fragments (n=40-60 per group) were exposed to weekly doses of epothilone B at concentrations of 10, 5, 1, 0.5, or 0.1 nM. All of these concentrations are clinically achievable. Tumor angiogenesis was assessed weekly on d 14-56 using a validated visual grading system. This system rates neovessel growth, density, and length on a 0-16 scale [angiogenic index, (AI)]. The average change in AI between d 14 and 56 was calculated for all samples and used to evaluate the metronomic response.

RESULTS

Epothilone B produced a dose-dependent anti-angiogenic response in all tumors. Two of the four tumors demonstrated a clear and significant metronomic anti-angiogenic effect over time.

CONCLUSIONS

Epothilone B, when dosed by a metronomic schedule may have a significant anti-angiogenic effect on human solid tumors. This study provides evidence for the potential use of epothilone B on a metronomic dosing schedule.

Isolation of human fetal liver progenitors and their enhanced proliferation by three-dimensional coculture with endothelial cells

Liver progenitor cells, characterized by the coexpression of biliary and hepatocyte lineage markers and the ability to form colonies in culture, were isolated by flow cytometry from primary human fetal livers. These prospectively isolated liver progenitor cells supported hepatitis D virus infection, expressed, and produced albumin and alpha-fetoprotein, as tracked by albumin- and alpha-fetoprotein-driven lentiviral promoter reporter constructs and measured by ELISA, respectively. Coculture in three-dimensional (3D) fibrin gel with endothelial cells resulted in the formation of vascular structures by the endothelial cells and increased proliferation of liver progenitors. The enhanced proliferation of liver progenitors that was observed when liver progenitors and endothelial cells were cultured in direct contact was not achieved when liver progenitors and endothelial cells were cultured on adjacent but separate matrices and when they were cultured across transwell membranes. In conclusion, coculture of liver progenitors and endothelial cells in three-dimensional matrix resulted in enhanced liver progenitor proliferation and function. This coculture methodology offers a novel coculture system that could be applied for the development of engineered liver tissues.

Isolation of human fetal liver progenitors and their enhanced proliferation by three-dimensional coculture with endothelial cells

Liver progenitor cells, characterized by the coexpression of biliary and hepatocyte lineage markers and the ability to form colonies in culture, were isolated by flow cytometry from primary human fetal livers. These prospectively isolated liver progenitor cells supported hepatitis D virus infection, expressed, and produced albumin and alpha-fetoprotein, as tracked by albumin- and alpha-fetoprotein-driven lentiviral promoter reporter constructs and measured by ELISA, respectively. Coculture in three-dimensional (3D) fibrin gel with endothelial cells resulted in the formation of vascular structures by the endothelial cells and increased proliferation of liver progenitors. The enhanced proliferation of liver progenitors that was observed when liver progenitors and endothelial cells were cultured in direct contact was not achieved when liver progenitors and endothelial cells were cultured on adjacent but separate matrices and when they were cultured across transwell membranes. In conclusion, coculture of liver progenitors and endothelial cells in three-dimensional matrix resulted in enhanced liver progenitor proliferation and function. This coculture methodology offers a novel coculture system that could be applied for the development of engineered liver tissues.

An assay to measure angiogenesis in human fat tissue

BACKGROUND

Inhibition of angiogenesis reverses rodent obesity. A validated assay in human fat tissue is needed to study the role of angiogenesis in human obesity.

METHODS

Human fat tissue fragments from surgery were placed in 96-well plates, embedded in fibrin thrombin clot and overlaid with cell culture media containing 20% fetal bovine serum. After 15 days, the clots were examined by histology and electron microscopy. The effect of taxol, cobalt chloride and a heparin-steroid combination was tested in the fat tissue assay and compared to the validated human placental vein angiogenesis model (HPVAM).

RESULTS

Blood vessels initiated growth and elongated from the fat tissue fragments over 15 days. Presence of blood vessels was confirmed with histology and electron microscopy. Taxol at 10(-6) and 10(-7) M completely inhibited angiogenesis, while Taxol 10(-8) and 10(-9) M and the heparin-steroid partially inhibited angiogenesis. The response to taxol and heparin-steroid was similar to that of the HPVAM, a validated angiogenesis assay. Cobalt chloride, a stimulator of vascular endothelial growth factor (VEGF) stimulated angiogenesis initiation at 10(-9) M in fat tissue and the HPVAM, but at 10(-10) M blood vessel growth was stimulated only in the fat assay.

CONCLUSION

This angiogenesis assay based on human fat tissue uses three-dimensionally intact human tissue. The vessels are derived from quiescient vessels within the fat. These properties allow the angiogenic switch to be evaluated in an in vitro setting. The angiogenic response of fat tissue is not identical to placental tissue. This assay allows exploration of angiogenesis in fat tissue.

Microtubule-targeting agents inhibit angiogenesis at subtoxic concentrations, a process associated with inhibition of Rac1 and Cdc42 activity and changes in the endothelial cytoskeleton

Conventional anticancer agents may display antiangiogenic effects, but the underlying mechanism is poorly understood. We determined the antiangiogenic properties of cisplatin, doxorubicin, and the microtubule-targeting agents docetaxel, epothilone B, and vinblastine at concentrations not affecting cell proliferation. We also assessed tubulin and actin morphology and the activity of two key molecules in cell motility, the small Rho GTPases Cdc42 and Rac1. The highest non-toxic concentration (HNTC) of each drug was defined as the concentration inhibiting a maximum of 10% human umbilical vein endothelial cell growth on a 1-hour drug exposure, being for cisplatin 10 micromol/L, doxorubicin 100 nmol/L, docetaxel 10 nmol/L, epothilone B 1 nmol/L, and vinblastine 10 nmol/L. Comparative endothelial cell functional assays using HNTCs for an exposure time of 1 hour indicated that endothelial cell migration in the wound assay, endothelial cell invasion in a transwell invasion system, and endothelial cell formation into tubelike structures on a layer of Matrigel were significantly inhibited by docetaxel, epothilone B, and vinblastine (P < 0.05), but not by cisplatin and doxorubicin. Docetaxel was slightly more efficient in the inhibition of endothelial cell motility than epothilone B and vinblastine. Fluorescence microscopy revealed that only the microtubule-targeting agents affected the integrity of the tubulin and F-actin cytoskeleton, which showed disturbed microtubule structures, less F-actin stress fiber formation, and appearance of nuclear F-actin rings. These observations were associated with early inhibition of Rac1 and Cdc42 activity. In conclusion, HNTCs of microtubule-targeting agents efficiently reduce endothelial cell motility by interference with microtubule dynamics preventing the activation of Rac1/Cdc42 and disorganizing the actin cytoskeleton.

Patupilone induced vascular disruption in orthotopic rodent tumor models detected by magnetic resonance imaging and interstitial fluid pressure

PURPOSE

Evaluation of vascular disruptive activity in orthotopic models as potential surrogate biomarkers of tumor response to the microtubule-stabilizing agent patupilone.

EXPERIMENTAL DESIGN

Mice bearing metastatic B16/BL6 melanoma and rats bearing mammary BN472 tumors received vehicle or efficacious patupilone doses (4 and 0.8-1.5 mg/kg i.v., respectively). Tumor vascularity assessment by dynamic contrast-enhanced or dynamic susceptibility contrast magnetic resonance imaging and interstitial fluid pressure (IFP) occurred at baseline, 2 days (mice and rats), and 6 days (rats) after treatment and were compared with histologic measurements and correlated with tumor response.

RESULTS

In B16/BL6 metastases, patupilone (4 mg/kg) induced a 21 +/- 5% decrease (P < 0.001) in tumor blood volume and a 32 +/- 15% decrease (P = 0.02) in IFP after 2 days and reduced tumor growth and vessel density (>42%) after 2 weeks (P < or = 0.014). Patupilone dose-dependently inhibited BN472 tumor growth (day 6) and reduced IFP on days 2 and 6 (-21% to -70%), and the percentage change in IFP correlated (P < 0.01) with the change in tumor volume. In both models, histology and vascular casts confirmed decreases in tumor blood volume. One patupilone (0.8 mg/kg) administration decreased (P < 0.01) tumor IFP (54 +/- 4%), tumor blood volume (50 +/- 6%), and vessel diameter (40 +/- 11%) by day 6 but not the apparent diffusion coefficient, whereas histology showed that apoptosis was increased 2.4-fold and necrosis was unchanged. Apoptosis correlated negatively (P < 0.001) with IFP, tumor blood volume, and tumor volume, whereas tumor blood volume and IFP were correlated positively (P = 0.0005).

CONCLUSIONS

Vascular disruptive effects of patupilone were detected in situ using dynamic contrast-enhanced or dynamic susceptibility contrast magnetic resonance imaging and IFP. Changes in IFP preceded and correlated with tumor response, suggesting that IFP may be a surrogate biomarker for patupilone efficacy.

Surgical treatment of advanced-stage carcinoid tumors: lessons learned

OBJECTIVE

To evaluate clinical outcomes in a large group of advanced-stage carcinoid patients (stage IV) following multimodal surgical therapy.

SUMMARY BACKGROUND DATA

Patients with advanced-stage carcinoid have traditionally experienced poor 5-year survival (18%-30%). Few recent series have evaluated a large number of patients treated with aggressive surgical rescue therapy.

METHODS

This single-center retrospective review analyzes the records of 82 consecutive carcinoid patients treated by the same 2 surgeons, from August 1998 through August 2004 with a 3- to 72-month follow-up.

RESULTS

Surprisingly, one third of 26 (32%) patients were found to have intestinal obstructions; 10 being moribund at presentation. Mesenteric encasement with intestinal ischemia was successfully relieved in 10 of 12 cases. Five of eighty-two "terminal" patients were rendered free of macroscopic disease. Karnofsky performance scores improved from 65 to 85 (P < 0.0001). Two- and four-year survival for patients with no or unilateral liver metastases (n = 23) was 89%, while 2- and 4-year survival for patients with bilateral liver disease (n = 59) was 68% and 52% (P = 0.072), respectively.

CONCLUSION

We think that all patients with advanced-stage carcinoid should be evaluated for possible multimodal surgical therapy. Primary tumors should be resected, even in the presence of distant metastases to prevent future intestinal obstruction. The "wait and see" method of management of this slow-growing cancer no longer has merit. We offer an algorithm for the surgical evaluation and management of these patients.

Colchicine and 2-methoxyestradiol Inhibit Human Angiogenesis

BACKGROUND

Angiogenesis is a critical determinant of tumor growth and the development of metastases. Tubulin inhibitors have been shown to be effective inhibitors of angiogenesis. We hypothesized that colchicine, a well-know tubulin inhibitor and 2-methoxyestradiol (2 MeOH), a novel tubulin inhibitor, would limit the initiation of a human angiogenic response and would limit subsequent neovessel growth in a dose-dependent manner.

METHODS

To test this hypothesis, we cultured full-thickness human placental vein discs from three placentas in a fibrin-thrombin clot model. Both colchicine and 2 MeOH were tested over a wide range of concentrations (10(-6) to 10(-12) M) to determine their effect on the percent of wells that initiated an angiogenic response (%I) and the subsequent growth (Angiogenic Index, 0-16 range) of vein-derived neovessels.

RESULTS

Colchicine at doses of 10(-6) and 10(-8) M completely inhibited the angiogenic response (CI: 95%, P < 0.0001) but lower (10(-10) to 10(-12) M) doses did not significantly inhibit angiogenesis (P = NS). Effective in vitro colchicine levels far exceed achievable non-toxic human plasma levels. In contrast, 2-methoxyestradiol decreased initiation and angiogenic growth significantly at 10(-6) M (CI: 95%, P < 0.0001), but did not significantly decrease angiogenesis at doses of 10(-8), 10(-10), or 10(-12) M. In contrast to colchicine, human plasma levels of 10(-6) M 2 MeOH are achievable clinically with little or no associated toxicity.

CONCLUSIONS

Effective in vitro drug levels of 2 MeOH can be achieved in vivo, suggesting that 2 MeOH may have a role in the clinical treatment of angiogenesis-dependent diseases.