Vascular endothelial growth factor immunoneutralization plus Paclitaxel markedly reduces tumor burden and ascites in athymic mouse model of ovarian cancer

Anti-tumor effects of adenovirus containing human growth hormone sequences in a mouse model of human ovarian cancer

Women with ovarian cancer have a low survival rate and develop resistance to chemotherapy, so new approaches to treatment are needed. We unexpectedly found administration of a replication-deficient adenovirus containing human growth hormone sequences (AdXGH) was beneficial in a mouse model of human ovarian cancer. Intraperitoneal injections of AdXGH prolonged median survival from a mean of 31 ± 1.2 to 40 ± 1.4 days in immunodeficient SCID mice given SKOV3.ip1 human ovarian cancer cells in the peritoneal cavity. Adenovirus containing human prolactin or del32-71growth hormone sequences had no effect. Repeated injection of growth hormone or implantation of tablets with sustained growth hormone release did not increase survival. Control mice had overlapping tumors throughout the peritoneal cavity and liver and frequent lung metastases 24 days after tumor cell injection. Mice that received two injections of AdXGH had no lung metastases. Mice that received four injections had no lung or liver metastases and peritoneal fibrosis. They did not survive longer than mice that received two injections, but they had enlarged livers with hepatocellular changes, indicating that a limitation of increasing the dose is liver toxicity.

Phage display peptide probes for imaging early response to bevacizumab treatment

Early evaluation of cancer response to a therapeutic regimen can help increase the effectiveness of treatment schemes and, by enabling early termination of ineffective treatments, minimize toxicity, and reduce expenses. Biomarkers that provide early indication of tumor therapy response are urgently needed. Solid tumors require blood vessels for growth, and new anti-angiogenic agents can act by preventing the development of a suitable blood supply to sustain tumor growth. The purpose of this study is to develop a class of novel molecular imaging probes that will predict tumor early response to an anti-angiogenic regimen with the humanized vascular endothelial growth factor antibody bevacizumab. Using a bevacizumab-sensitive LS174T colorectal cancer model and a 12-mer bacteriophage (phage) display peptide library, a bevacizumab-responsive peptide (BRP) was identified after six rounds of biopanning and tested in vitro and in vivo. This 12-mer peptide was metabolically stable and had low toxicity to both endothelial cells and tumor cells. Near-infrared dye IRDye800-labeled BRP phage showed strong binding to bevacizumab-treated tumors, but not to untreated control LS174T tumors. In addition, both IRDye800- and (18)F-labeled BRP peptide had significantly higher uptake in tumors treated with bevacizumab than in controls treated with phosphate-buffered saline. Ex vivo histopathology confirmed the specificity of the BRP peptide to bevacizumab-treated tumor vasculature. In summary, a novel 12-mer peptide BRP selected using phage display techniques allowed non-invasive visualization of early responses to anti-angiogenic treatment. Suitably labeled BRP peptide may be potentially useful pre-clinically and clinically for monitoring treatment response.

Role of vascular endothelial growth factor inhibitors in the treatment of gynecologic malignancies

This article reviews the history and current status of vascular endothelial growth factor targeted therapy for the most common gynecologic malignancies - epithelial ovarian, endometrial and cervical cancers. The biologic rationale for targeting vascular endothelial growth factor (VEGF) for these disease sites is well-founded, and pre-clinical studies have supported the development of anti-VEGF agents. Their classification, known mechanisms of action, unique toxicities and clinical development are herein explored, the latter including issues related to study design, disease site and disease setting.

Targeting pericytes with a PDGF-B aptamer in human ovarian carcinoma models

PURPOSE

On the basis of the known role of platelet-derived growth factor (PDGF)-BB/PDGF receptor (PDGFR) beta in pericyte regulation, highly specific inhibitors of this target are needed. We tested the efficacy of a highly selective aptamer against PDGF-B with or without anti-VEGF therapy in ovarian cancer models.

RESULTS

Bevacizumab inhibited tumor growth by 45% and 48% in the HeyA8 and SKOV3ip1 models, respectively. AX102 had minimal effect on the HeyA8 model, but increased tumor growth in the SKOV3ip1 model. However, bevacizumab plus AX102 was more effective than bevacizumab alone, and resulted in 76-88% inhibition of tumor growth in both models. A longitudinal study in the HeyA8 model using bioluminescence imaging showed that combination of bevacizumab, AX102 and paclitaxel caused tumor reduction by 65% (based on bioluminescence imaging). In the HeyA8 model, MVD and PCNA counts were significantly reduced in the bevacizumab treatment groups, and pericyte coverage was significantly decreased in the AX102 treatment groups. In the SKOV3ip1 model, MVD and PCNA was significantly reduced in the bevacizumab treatment group, and even lower in the bevacizumab and AX102 combination treatment group.

EXPERIMENTAL DESIGN

The therapeutic efficacy of targeting endothelial cells (bevacizumab) and/or pericytes (PDGF-aptamer, AX102) was examined using HeyA8 and SKOV3ip1 orthotopic models of ovarian cancer metastasis. Following therapy, tumors were examined for microvessel density (MVD), proliferating cell nuclear antigen (PCNA) and vascular maturation (pericyte coverage).

CONCLUSIONS

Dual targeting of endothelial cells and pericytes holds potential as an anti-vascular therapeutic approach in ovarian carcinoma.

What is the benefit of bevacizumab combined with chemotherapy in patients with recurrent ovarian, fallopian tube or primary peritoneal malignancies?

The aim of this retrospective analysis was to investigate the efficacy and adverse effects of the monoclonal antivascular endothelial growth factor antibody bevacizumab (Avastin(R)) combined with chemotherapeutic agents in non-protocol patients with recurrent ovarian, fallopian tube, or primary peritoneal malignancies. Using our databases, we identified patients treated with bevacizumab combination therapy since June 2005. Responses were evaluated with Response evaluation Criteria in Solid tumors and serum CA125 Rustin criteria. Toxicity was assessed according to the Common toxicity Criteria (CTC) v.3.0. Data from 64 patients were included. The median patient age was 58 years, and they had undergone a median of 4.5 (range, 1-10) prior cytotoxic chemotherapy regimens. The median length of follow-up was 8 months (range, 2-29). The most commonly used combinations were bevacizumab plus taxanes (26.6%) and plus cyclophosphamide (26.6%). A median of 4 cycles of therapy with a median bevacizumab dose of 3,600 mg (range, 500-18,240) were administered. An overall response rate of 21.3% was observed in 13 patients with partial response, and another 42.6% of patients had stable disease. Among the patients with elevated pretreatment serum CA125 concentration, an overall response rate of 46.3% (25/54) was observed according to modification of the Rustin criteria. Fifteen (23.4%) patients had grades 3 or 4 adverse events. Gastrointestinal perforations occurred in 2 (3.1%) patients. Seventeen (26.6%) patients had improved performance status scores. Bevacizumab combined with chemotherapy showed promising clinical benefits, with significant response of serum CA125 concentration and moderate adverse effects.

Biodistribution of humanized anti-VEGF monoclonal antibody/bevacizumab on peritoneal metastatic models with subcutaneous xenograft of gastric cancer in mice

PURPOSE

Vascular endothelial growth factor (VEGF) is correlated with peritoneal metastasis of gastric cancer, increasing vascular permeability accompanied by accumulation of ascites. The aim of the current study is to investigate the biodistribution of bevacizumab in a peritoneal metastatic model of gastric cancer and to clarify which is more suited to treatment of peritoneal metastasis, systemic or regional therapy.

METHODS

A highly peritoneal-seeding cell line of gastric cancer, OCUM-2MD3, which exhibited high production and release of VEGF was used in this study. The biodistribution of bevacizumab was investigated using peritoneal metastatic models together with subcutaneous xenografts, and (125)I-radiolabelled bevacizumab was administrated to these models subcutaneously (s.c.) or intraperitoneally (i.p.), respectively. In addition, the anti-tumor response of bevacizumab and paclitaxel was assessed as single agents or in combination using peritoneal metastatic models.

RESULTS

In the analysis of biodistribution, (125)I-bevacizumab administrated i.p. indicated low peritoneal clearance. On the other hand, s.c. administration of (125)I-bevacizumab showed preferential accumulation in subcutaneous tumors and peritoneal nodules, with a high blood concentration. In peritoneal metastatic models, the effects of bevacizumab were found for both the growth inhibition of peritoneal nodules (P < 0.01) and the reduction of ascites (P < 0.05). These effects were more prominent by s.c. administration compared with i.p. administration and were increased in combination with i.p. paclitaxel.

CONCLUSION

Bevacizumab should be administrated systemically compared to regionally, and the combination with i.p. paclitaxel has a potential to be useful for patients with peritoneal metastasis of gastric cancer.

Combined anti-angiogenic therapy against VEGF and integrin alphaVbeta3 in an orthotopic model of ovarian cancer

PURPOSE

We tested the efficacy of dual targeting of vascular endothelial growth factor (VEGF) and the alpha(V)beta(3) integrin in orthotopic mouse models of ovarian cancer.

RESULTS

In the SKOV3ip1 model, both single-agent bevacizumab and etaracizumab reduced tumor growth by 52-63% (p < 0.05), while combined therapy reduced growth by 63-74% compared to either agent alone (p < 0.05). Furthermore, bevacizumab/paclitaxel was superior to paclitaxel alone (weight reduction by 53%, p < 0.05), but etaracizumab/paclitaxel was not. Combining all three agents was more effective than either agent with paclitaxel (p < 0.05). Significantly, both bevacizumab and etaracizumab each sensitized the taxane-resistant SKOV3TRip2 cells to paclitaxel, reducing growth by 56-73% (p < 0.05). Both agents decreased proliferation and microvessel density, and increased apoptosis, alone and in combination with paclitaxel. In the HeyA8 model, there was significantly reduced growth with bevacizumab treatment, but not with etaracizumab, and combination therapy was not superior to bevacizumab alone.

EXPERIMENTAL DESIGN

In vivo therapy experiments were conducted in chemo-sensitive (SKOV3ip1, HeyA8) and -resistant (SKOV3TRip2) ovarian cancer models. VEGF was targeted with bevacizumab and alpha(V)beta(3) with etaracizumab. Mice were treated with each agent alone, together, or in combination with paclitaxel for assessment of tumor growth. Tumor specimens were tested for proliferative index, microvessel density and apoptosis.

CONCLUSIONS

Bevacizumab and etaracizumab are more effective in combination than individually in some ovarian cancer models, but not all. Both can sensitize taxane-resistant ovarian cancer cells to paclitaxel, though bevacizumab was superior to etaracizumab in this regard. Further study of this dual anti-angiogenic therapy is warranted.

Intraperitoneal VEGF inhibition using bevacizumab: a potential approach for the symptomatic treatment of malignant ascites?

Despite overall improvements in oncological care in the palliative setting, symptomatic malignant ascites remains a severe clinical problem. This form of effusion is known to be widely resistant to established modes of systemic therapy. Accordingly, frequent paracentesis often represents the only effective way for symptom relief in patients with advanced cancer. This invasive mode of therapy, however, is often very burdensome for the patient who is already severely distressed by the underlying malignancy. Recently, the trifunctional monoclonal antibody catumaxomab given i.p. has shown symptom relief in patients with ovarian cancer and malignant ascites. On another front, the release of vascular endothelial growth factor (VEGF) by tumor cells has been identified as a main factor promoting the i.p. secretion of fluid. Accordingly, recent evidence suggests that targeting VEGF may have the potential to suspend the ascites production resulting from peritoneal metastasis. Here, we review preclinical and clinical data supporting this hypothesis. We show current evidence suggesting that the i.p. application of the anti-VEGF antibody bevacizumab, which is already in use as an i.v. therapeutic drug for a variety of tumors, might represent an effective way to prevent local fluid accumulation. Because such an effect would result in significant relief for patients, future clinical studies should stringently assess the effectiveness of this targeted therapy for the treatment of malignant i.p. effusions.

Dissemination of intraperitoneal ovarian cancer: Discussion of mechanisms and demonstration of lymphatic spreading in ovarian cancer model

Ovarian cancer is often accompanied by severe ascites. This complication aggravates the disease per se and the chances for its successful treatment. The etiology of ascites is not well understood nor are efficient therapies for ascites available. These empirical observations support the view that ascites might be caused by blocking of lymphatic vessels. Furthermore, it suggests that cancer cells might be the blocking agent and could use lymphatic vessels for metastatic spreading. To test this hypothesis, we used labeled cancer cells in an immuno-competent animal model of ovarian cancer and followed their dissemination. These NuTu-19 cells are ovarian cancer cells derived from normal rat ovarian epithelial cells, the origin of the most frequent ovarian cancer. Thus studying NuTu-19 cell behavior in an animal model is likely to reflect the progression of the human disease. To unambiguously document the migration of NuTu-19 cells from the peritoneum to remote organs, we generated EGFP expressing NuTu-19 cells by transduction with EGFP-lentiviral vectors. The EGFP positive NuTu-19 cells were injected intraperitoneally into immuno-competent FISHER 344 rats, and the metastatic spreading was monitored. Metastases were observed on the peritoneum, the omentum and in the parathymus. This clearly demonstrates that systemic spreading of NuTu-19 ovarian cancer cells is conducted by lymphatic ways. Animals die 7 weeks after injection, with severe ascites, which suggests that blockage of lymphatic drainage by the cancer cell growth is an important complication of the disease.

VEGFR-2 silencing by small interference RNA (siRNA) suppresses LPA-induced epithelial ovarian cancer (EOC) invasion

BACKGROUND

The VEGF-VEGF receptor (VEGFR) signaling axis has emerged as a promising target for cancer therapy, attributing to its vital role in tumor angiogenesis and growth. We have previously reported the regulation of epithelial ovarian cancer (EOC) invasion and migration by VEGF and the implication of VEGF-VEGFR-2 axis in lysophosphatidic acid (LPA)-induced EOC invasion. However, the expression profile of VEGF and VEGFRs in EOC, their association with tumor aggressiveness, and their regulation by LPA remain unclear.

OBJECTIVES AND METHODS

In this study, we examined the expression of VEGFR-1, VEGFR-2, neuropilin-1 (NRP-1), NRP-2, VEGF(121), and VEGF(165) in established EOC cell lines and assessed their correlation with cell invasiveness. Moreover, using an ovarian cancer tissue qPCR array, we analyzed VEGFR-2 expression across a panel of 48 tissues with different disease stages and histological grades. We also tested the effect of LPA on VEGF and VEGFR-2 expression and examined whether blocking VEGFR-2 by RNA interference (RNAi) affects LPA-induced EOC invasion.

RESULTS

We show that VEGF and VEGFR-2 expression correlates with cell invasiveness and VEGFR-2 expression in ovarian cancer tissues correlate with tumor grade. In addition, LPA, at 20 muM, significantly induced the expression of VEGF(121), VEGF(165), and VEGFR-2 in SKOV3 and DOV13 cells (P<0.05). VEGFR-2 small interference RNA (siRNA) transfection remarkably decreased LPA's invasion-promoting effect (P<0.001) in SKOV3 cells without significantly decreasing SKOV3 cells' basal invasiveness. In DOV13 cells, VEGFR-2 silencing significantly decreases both the basal level cell invasion and LPA's invasion promoting effect (P<0.001).

CONCLUSION

These results suggest that decreasing VEGFR-2 expression by RNAi may prove to be an effective method to reduce the metastatic potential of EOC cells exposed to elevated levels of LPA.

Inhibition of cell proliferation, vascular endothelial growth factor and tumor growth by albendazole

Vascular endothelial growth factor (VEGF) is the key molecule mediating tumor growth and malignant ascites formation. We recently reported that, in an end stage OVCAR-3 xenograft model, albendazole (ABZ) suppresses ascites formation, but not tumor growth. Hence, in the present study, we assessed the effect of ABZ on in vitro OVCAR-3 cell proliferation plus in vivo tumor growth, however, initiating ABZ treatment at mid stage (3 weeks post cell inoculation) rather than end stage disease. Here, ABZ treatment led to potent inhibition of cell proliferation, VEGF suppression, complete inhibition of ascites formation and most strikingly arrest of tumor growth.

Beyond chemotherapy: targeted therapies in ovarian cancer

Ovarian cancer is the leading cause of death from gynaecological malignancies in the Western world. Despite the evolution of surgical techniques and meticulously designed chemotherapy regimens, relapse remains almost inevitable in patients with advanced disease. In an age when great advances have been made in understanding the genetics and molecular biology of this heterogeneous disease, it is likely that the introduction of novel targeted therapies will have a major impact on the management of ovarian cancer. Importantly, such strategies might allow selection of treatments based on the molecular characteristics of tumours and bring us closer to an era of personalized medicine.

Use of an anti-vascular endothelial growth factor antibody in a pharmacokinetic strategy to increase the efficacy of intraperitoneal chemotherapy

The efficacy of intraperitoneal chemotherapy for ovarian cancers is limited by poor penetration of drug into peritoneal tumors. Based on pharmacokinetic theory that suggests that penetration depth is primarily determined by the rate of drug removal via tumor capillaries, we have hypothesized that co-administration of antiangiogenic therapy will allow for decreased drug removal, increased drug concentrations in tumor, and increased efficacy of intraperitoneal chemotherapy. Pharmacokinetic modeling was conducted to simulate the effect of tumor blood flow on tumor concentrations of topotecan. Simulations predicted that tumor blood flow reductions, as potentially achieved by antiangiogenic therapy, would lead to substantial increases in tumor concentrations after intraperitoneal chemotherapy but would lead to a slight decrease after systemic chemotherapy. Pharmacokinetic studies performed using the A2780 xenograft tumor model showed that animals receiving combined intraperitoneal topotecan and an anti-vascular endothelial growth factor (VEGF) monoclonal antibody had approximately 6.5-fold higher (p = 0.0015) tumor topotecan concentrations compared with animals receiving intraperitoneal topotecan alone, whereas there was no significant (p = 0.16) difference for systemic topotecan. Therapeutic studies conducted with two different drugs, topotecan and cisplatin, showed that animals receiving combined intraperitoneal chemotherapy and anti-VEGF therapy displayed superior survival relative to animals treated with chemotherapy alone (i.e., cisplatin or topotecan), anti-VEGF alone, or intravenous chemotherapy with concomitant anti-VEGF therapy. Combined intraperitoneal topotecan and anti-VEGF resulted in the complete cure of four of 11 mice. The proposed combination of antiangiogenic therapy and intraperitoneal chemotherapy, which was predicted to be beneficial by pharmacokinetic simulations, may provide substantial benefit to patients with peritoneal malignancies.

Preclinical studies and clinical utilization of monoclonal antibodies in epithelial ovarian cancer

OBJECTIVE

To present an overview of selected monoclonal antibodies (mAbs) that have been studied in epithelial ovarian cancer with a focus on combination treatment with conventional chemotherapy.

METHODS

The authors perform a narrative review of the literature. Preclinical studies that provided rationale for mAb use are examined, and selected clinical trials that evaluated efficacy and tolerability are reviewed.

RESULTS

Numerous mAbs have been utilized in epithelial ovarian cancer, including bevacizumab (anti-vascular endothelial growth factor), trastuzumab (anti-human epidermal growth factor-2), cetuximab (anti-epidermal growth factor receptor), and oregovomab (anti-CA125). Favorable preclinical results have lead to the development of a number of clinical trials. Side-effects have been minimal and combination therapy has been well-tolerated. Efficacy has been variable in the clinical trials.

CONCLUSIONS

Targeted treatment with mAbs in conjunction with cytotoxic chemotherapy has been an important research area during the last decade. This therapeutic approach holds promise for improved outcomes in patients with ovarian cancer.

Maintenance treatment with bevacizumab prolongs survival in an in vivo ovarian cancer model

PURPOSE

Vascular endothelial growth factor (VEGF) plays a central role in tumor angiogenesis and is regarded as a promising therapeutic target. We hypothesized that treatment with bevacizumab, a humanized recombinant anti-VEGF monoclonal antibody, could enhance antitumor response to cisplatin and prolong survival in a murine ovarian cancer model.

EXPERIMENTAL DESIGN

We conducted an MTS assay to examine the effect of bevacizumab on proliferation of the VEGF producing human ovarian cancer cell lines in vitro. Next, the antiangiogenic activity of bevacizumab was investigated by in vivo angiogenesis and wound healing assays. We then determined the toxicity and antitumor response of bevacizumab and cisplatin as single agents or in combination in xenograft models of ovarian cancer. Finally, using the same xenograft model, we examined the effect of these regimens, as well as bevacizumab maintenance therapy, on survival.

RESULTS

Bevacizumab had no effect on the proliferation of ovarian cancer cells in vitro but significantly inhibited angiogenesis and delayed wound healing in vivo. Bevacizumab inhibited i.p. tumor growth and ascites production in the nu/nu mouse xenograft model and enhanced the therapeutic efficacy of cisplatin. Combination therapy with bevacizumab and cisplatin for 3 weeks was associated with complete disappearance of all macroscopic evidence of disease. Moreover, maintenance treatment with bevacizumab after 3 weeks of induction combination therapy inhibited recurrence and significantly prolonged survival.

CONCLUSIONS

Bevacizumab has significant antitumor activity not only as a single agent or in combination with cisplatin but may also prolong survival when used as maintenance therapy after a complete response to cisplatin-based chemotherapy.

New therapeutic agents in ovarian cancer

PURPOSE OF REVIEW

Despite advances in management over recent years, epithelial ovarian cancer remains the most lethal gynaecological malignancy. Methods of early detection, as well as improved therapeutic options, are urgently needed.

RECENT FINDINGS

Currently, a number of targeted therapies, including vascular endothelial growth factor inhibitors, poly-ADP-ribose polymerase inhibitors and folate receptor inhibitors look promising in this arena and this article will review a number of these drugs and the evidence pertaining to their use.

SUMMARY

Much further research is required to define if, when and how best to integrate these novel therapies, and also to define associated biomarkers that predict toxicity and select patients most likely to derive benefit. Individualized therapy is not an impossible dream, but there is still a long way to go.

Autocrine VEGF-A/KDR loop protects epithelial ovarian carcinoma cells from anoikis

Epithelial ovarian carcinoma (EOC) patients are usually diagnosed at an advanced stage, characterized by interperitoneal carcinomatosis and production of large volumes of ascites. Vascular endothelial growth factor-A (VEGF-A) and its main signaling receptor VEGFR2 (KDR) are coexpressed in primary ovarian tumors, ascitic cells and metastases, suggesting the existence of an autocrine VEGF-A/KDR loop in EOC cells. In the present study, we examined this possibility and explored the role of this autocrine loop in protecting EOC cells from apoptosis under anchorage free growth conditions (anoikis). We found that 3 different EOC cell lines (Caov3, OVCAR3, SKOV3) express both VEGF-A and its receptors, including KDR. In these cells, KDR is constitutively phosphorylated and is detected both in the cell plasma membrane and in the nucleus. Treating EOC cells with specific internal inhibitors of KDR kinase activity or a VEGF-A neutralizing antibody abolished KDR autophosphorylation and resulted in significant increase in apoptosis when cells were grown in single-cell, anchorage-free conditions. By contrast, these blocking reagents had no effect on cell viability when EOC cells were grown in adhesive monolayers. In summary, our results indicate that an autocrine VEGF-A/KDR loop exists in EOC cells and that it plays a role in protecting the cells from anoikis. Our results imply that treating EOC patients with VEGF blocking agents may potentially reduce peritoneal dissemination by decreasing vascular permeability as well as inducing apoptosis of shed ovarian cancer cells in ascites.

Mining the ovarian cancer ascites proteome for potential ovarian cancer biomarkers

Current ovarian cancer biomarkers are inadequate because of their relatively low diagnostic sensitivity and specificity. There is a need to discover and validate novel ovarian cancer biomarkers that are suitable for early diagnosis, monitoring, and prediction of therapeutic response. We performed an in-depth proteomics analysis of ovarian cancer ascites fluid. Size exclusion chromatography and ultrafiltration were used to remove high abundance proteins with molecular mass >/=30 kDa. After trypsin digestion, the subproteome (</=30 kDa) of ascites fluid was determined by two-dimensional liquid chromatography-tandem mass spectrometry. Filtering criteria were used to select potential ovarian cancer biomarker candidates. By combining data from different size exclusion and ultrafiltration fractionation protocols, we identified 445 proteins from the soluble ascites fraction using a two-dimensional linear ion trap mass spectrometer. Among these were 25 proteins previously identified as ovarian cancer biomarkers. After applying a set of filtering criteria to reduce the number of potential biomarker candidates, we identified 52 proteins for which further clinical validation is warranted. Our proteomics approach for discovering novel ovarian cancer biomarkers appears to be highly efficient because it was able to identify 25 known biomarkers and 52 new candidate biomarkers that warrant further validation.

VEGF inhibition: insights from preclinical and clinical studies

Angiogenesis, the growth of new blood vessels, is required for a variety of normal proliferative processes. Furthermore, angiogenesis is well established as also playing an important role in neoplastic growth and metastasis. Numerous regulators of angiogenesis have been identified and characterized over the last few decades. Among these, vascular endothelial growth factor (VEGF)-A appears especially important in several pathophysiological processes. Several VEGF inhibitors have been approved, by the US Food and Drug Administration, for the treatment of tumors or age-releted macular degeneration. This review examines the various mouse tumor models in which VEGF inhibitors have been tested and the lessons learned from these studies.

Vascular endothelial growth factor stimulates organ-specific host matrix metalloproteinase-9 expression and ovarian cancer invasion

Vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMP) regulate each other, contributing to tumor progression. We have previously reported that MMP9 induces the release of tumor VEGF, promoting ascites formation in human ovarian carcinoma xenografts. The aim of this study was to investigate whether tumor-derived VEGF regulated the expression of gelatinase by the stroma, influencing the invasive properties of ovarian tumors. Tumor variants derived from 1A9 human ovarian carcinoma, stably expressing VEGF(121) in the sense (1A9-VS-1) and antisense orientations (1A9-VAS-3), were used. In vivo, zymographic analysis of tumors from 1A9-VS-1 implanted in the peritoneal cavity of nude mice showed higher levels of gelatinases, particularly murine MMP9, indicating that VEGF stimulates host expression of the matrix-degrading enzyme. Murine MMP9 expression was also high in the ovaries of mice bearing 1A9-VS-1 tumors. The effect on host MMP9 activity was organ-specific. The levels of host pro-MMP9 in ovaries correlated with the plasma levels of tumor VEGF and with the selective invasion of the ovaries. Induction of host MMP9 expression in tumors and ovaries was independent of the site of tumor growth as it was seen in mice carrying both intraperitoneal and subcutaneous tumors. The anti-VEGF antibody bevacizumab (Avastin) inhibited MMP9 expression and tumor invasion in the ovaries of mice bearing 1A9-VS-1 tumors. These findings point to a complex cross-talk between VEGF and MMPs in the progression of ovarian tumor and suggest the possibility of using VEGF inhibitors to affect MMP-dependent tumor invasion.

Potential role of multi-targeted tyrosine kinase inhibitors in non-small-cell lung cancer

Treatment outcomes for patients with metastatic non-small-cell lung cancer (NSCLC) are poor with chemotherapy. In recent years, novel agents that target specific, aberrant molecular pathways in NSCLC have been under evaluation in clinical trials. To date, just two targeted agents have impacted the natural history of the disease--erlotinib and bevacizumab--each of which targets a single molecule in a signalling pathway involved in NSCLC. While modest, the activity of these single-target agents results in improved clinical outcomes, highlighting the potential of agents that target biological pathways in patients with NSCLC. However, as NSCLC is a highly heterogeneous disease, it is likely that agents with multiple targets (e.g. sunitinib, sorafenib, ZD6474, AZD2171 and AMG 706) may have greater activity than those with single-target activity through inhibition of other pathways that may act as salvage or escape mechanisms for malignant cells. New multi-targeted therapeutic agents currently undergoing clinical evaluation have shown promise as single agents, and preclinical studies have indicated that this efficacy may be due at least in part to the inhibition of multiple pathways that may result in a synergistic antitumour effect.

Targeting vasculature in urologic tumors: mechanistic and therapeutic significance

Recent advances toward understanding the molecular mechanisms regulating cancer initiation and progression provide new insights into the therapeutic value of targeting tumor vascularity by interfering with angiogenic signaling pathways. The functional contribution of key angiogenic factors toward increased vascularity characterizing metastatic tumors and their therapeutic exploitation is considered in three major urologic malignancies, renal, bladder, and prostate cancer. With the realization that the success of the therapeutic efficacy of the various anti-angiogenic approaches for the treatment of urologic tumors has yet to be proven clinically, the challenge remains to select critical angiogenesis pathways that can be targeted for an individual tumor. Here we discuss the major mechanisms that support formation of vasculature in renal, bladder, and prostate tumors and the current results of targeting of specific molecules/regulators for therapeutic intervention against metastastic disease.

Intraperitoneal bevacizumab for the palliation of malignant ascites in refractory ovarian cancer

BACKGROUND

Malignant ascites often has a profound impact on the quality of life of patients with refractory ovarian cancer. Current treatments, including dietary, medical, and procedural are often temporary and unsatisfactory options in patients approaching the end of life.

CASE

We present a case of an 88 year-old receiving home hospice care with refractory ovarian cancer and severe symptomatic ascites. We performed a paracentesis and treated her with intraperitoneal bevacizumab with dramatic improvement in her ascites and the quality of her final weeks of life.

CONCLUSION

Intraperitoneal bevacizumab may be a useful tool in the palliation of malignant ascites and is worthy of further study.

New therapies for ovarian cancer: cytotoxics and molecularly targeted agents

Ovarian cancer, although a chemo-sensitive disease, is associated with high morbidity and mortality due to its often-late presentation. Platinums and taxanes have improved the prognosis over recent years but median overall survival is still unacceptably low (24-60 months). Apart from the manipulation of doses, schedules, mode of delivery, and combinations of existing drugs, new cytotoxics and molecularly targeted agents with different mechanisms of action must be evaluated in this patient population. This article will review the most recent clinical trials data pertaining to these new cytotoxic drugs including patupilone, telcyta, and trabectedin, as well as those of small molecules and inhibitors of the EGFR and VEGF receptor families. It will also discuss other potential signal transduction targets worthy of further evaluation in future trials.

Anti-tumor activity and tumor vessel normalization by the vascular endothelial growth factor receptor tyrosine kinase inhibitor KRN951 in a rat peritoneal disseminated tumor model

We assessed the antitumor efficacy of KRN951, a novel tyrosine kinase inhibitor of vascular endothelial growth factor receptors, using a rat colon cancer RCN-9 syngeneic model in which the tumor cells are transplanted into the peritoneal cavity of F344 rats. KRN951 treatments that commenced 4 days after tumor transplantation (day 4) significantly inhibited tumor-induced angiogenesis, the formation of tumor nodules in the mesenteric windows, and the accumulation of malignant ascites. Moreover, KRN951 treatments initiated on day 14, by which time angiogenesis and malignant ascites have already been well established, resulted in the regression of newly formed tumor vasculatures with aberrant structures and also in the apparent loss of malignant ascites by the end of the study period. Quantitative analysis of the vessel architecture on mesenteric windows revealed that KRN951 not only regressed, but also normalized the tumor-induced neovasculature. Continuous daily treatments with KRN951 significantly prolonged the survival of rats bearing both early stage and more advanced-stage tumors, compared with the vehicle-treated animals. The results of our current study thus show that KRN951 inhibits colon carcinoma progression in the peritoneal cavity by blocking tumor angiogenesis, ascites formation, and tumor spread, thereby prolonging survival. Moreover, these studies clearly demonstrate the therapeutic effects of KRN951 against established tumors in the peritoneal cavity, including the regression and normalization of the tumor neovasculature. Our findings therefore suggest that KRN951 has significant potential as a future therapeutic agent in the treatment of peritoneal cancers with ascites.

Chapter 6. Mouse models to investigate anti-cancer effects of VEGF inhibitors

Angiogenesis, the growth of new blood vessels, is required for a variety of normal proliferative processes. Furthermore, it is well established that angiogenesis plays an important role also in neoplastic growth and metastasis. Numerous regulators of angiogenesis have been identified and characterized over the last decades. Among these, vascular endothelial growth factor (VEGF)-A appears especially important in several pathophysiological processes. Several VEGF inhibitors have been approved by the Food and Drug Administration for the treatment of tumors or age-related macular degeneration. This chapter examines the various mouse tumor models in which VEGF inhibitors have been tested and the lessons learned from these studies.

Phase II trial of bevacizumab in persistent or recurrent epithelial ovarian cancer or primary peritoneal cancer: a Gynecologic Oncology Group Study

PURPOSE

Vascular endothelial growth factor (VEGF) seems to be a promoter of tumor progression for epithelial ovarian cancer (EOC) and primary peritoneal cancer (PPC). We conducted a phase II trial to assess the efficacy and tolerability of single-agent bevacizumab, an anti-VEGF monoclonal antibody.

PATIENTS AND METHODS

Eligible patients had persistent or recurrent EOC/PPC after one to two prior cytotoxic regimens, measurable disease, and Gynecologic Oncology Group performance status of at least 2. Treatment consisted of bevacizumab 15 mg/kg intravenously every 21 days until disease progression or prohibitive toxicity. Primary end points were progression-free survival (PFS) at 6 months and clinical response.

RESULTS

The study consisted of 62 eligible and assessable patients, median age 57 years, 41 (66.1%) having received two prior regimens and 36 (58.1%) [CORRECTED] considered platinum resistant. Grade 3 adverse events at least possibly related to bevacizumab were hematologic (1), GI (3), hypertension (6), thromboembolism (1), allergy (2), hepatic (1), pain (3), coagulation (1), constitutional (1), and dyspnea (1). Grade 4 adverse events included pulmonary embolus (1), vomiting and constipation (1), and proteinuria (1). Thirteen patients (21.0%) experienced clinical responses (two complete, 11 partial; median response duration, 10 months), and 25 (40.3%) survived progression free for at least 6 months. Median PFS and overall survival were 4.7 and 17 months, respectively. There was no significant association of prior platinum sensitivity, age, number of prior chemotherapeutic regimens, or performance status with the hazard of progression or death.

CONCLUSION

Bevacizumab seems to be well tolerated and active in the second- and third-line treatment of patients with EOC/PPC and merits phase III investigation.

Nursing Considerations of Bevacizumab Use in Multiple Tumor Types

PURPOSE/OBJECTIVES

To update information concerning the antiangiogenic agent bevacizumab, discuss side effects, and provide information on nursing management of the side effects.

DATA SOURCES

Published articles, abstracts, and research data.

DATA SYNTHESIS

In clinical trials, the addition of bevacizumab to standard chemotherapy increased survival in patients with metastatic colorectal cancer and advanced non-small cell lung cancer and increased progression-free survival in patients with metastatic breast cancer. Bevacizumab also is being evaluated in combination with other targeted agents in various tumor types. Commonly reported side effects associated with bevacizumab include hypertension, proteinuria, and minor bleeding.

CONCLUSIONS

The value of bevacizumab in treating metastatic colorectal cancer has long been established. Clinical trial data have demonstrated the benefit of using bevacizumab in combination with standard chemotherapy in the treatment of non-small cell lung cancer and metastatic breast cancer. Because of bevacizumab's expanding role in cancer treatment, nurses need to know how to use it, be aware of possible side effects, and anticipate interventions.

IMPLICATIONS FOR NURSING

Nurses play an important role in the identification and management of adverse events associated with bevacizumab.

The role of VEGF and EGFR inhibition: implications for combining anti-VEGF and anti-EGFR agents

Multiple cellular pathways influence the growth and metastatic potential of tumors. This creates heterogeneity, redundancy, and the potential for tumors to bypass signaling pathway blockade, resulting in primary or acquired resistance. Combining therapies that inhibit different signaling pathways has the potential to be more effective than inhibition of a single pathway and to overcome tumor resistance. Vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR) inhibitors have become key therapies in several tumor types. Close relationships between these factors exist: VEGF signaling is up-regulated by EGFR expression and, conversely, VEGF up-regulation independent of EGFR signaling seems to contribute to resistance to EGFR inhibition. Therefore, inhibition of both pathways could improve antitumor efficacy and overcome resistance to EGFR inhibition. Preclinical studies have shown that VEGF and EGFR inhibitors can have additive effects and that combined inhibition is effective in EGFR inhibitor-resistant cell lines. Clinical trials have also produced promising data: combining the anti-VEGF monoclonal antibody bevacizumab with the anti-EGFR antibody cetuximab or the EGFR tyrosine kinase inhibitor erlotinib increases benefit compared with either of these anti-EGFR agents alone or combined with chemotherapy. The potential of this novel approach to anticancer therapy will be elucidated by large, ongoing clinical trials.

Bevacizumab, a humanized anti-angiogenic monoclonal antibody for the treatment of colorectal cancer

Angiogenesis is the process by which new blood vessels are created from pre-existing vessels. It is essential for the growth and development of normal cells and tissues during embryonic and neonatal development and of tumour cells. Solid tumours rely on having an extensive network of blood vessels for growth and survival. The key mediator of angiogenesis, vascular endothelial growth factor-A (VEGF-A), is critical for the growth of tumours and their subsequent metastasis and is known to initiate angiogenesis. Bevacizumab is a humanized immunoglobulin G monoclonal antibody that binds to VEGF with high specificity, thereby blocking VEGF-mediated signalling pathways and thus angiogenesis. Clinical trials have shown that bevacizumab is effective in prolonging survival in patients with metastatic colorectal cancer (CRC) when combined with standard chemotherapy. Consequently, bevacizumab has been approved in combination with 5-fluorouracil-based chemotherapy for first-line treatment of patients with metastatic CRC. Bevacizumab is generally well tolerated in most patients and does not exacerbate the adverse events associated with conventional chemotherapy. Bevacizumab-related side effects are generally manageable; however, monitoring for hypertension, gastrointestinal perforation, bleeding, proteinuria and thromboembolism is advised, especially in patients with predisposing factors. In addition to demonstrated survival benefits, the convenient dosing schedule and lack of interactions should ensure the successful integration of this novel agent into clinical practice.

Viral serpin, Serp-1, inhibits endogenous angiogenesis in the chicken chorioallantoic membrane model

BACKGROUND

Angiogenesis is a critical factor in the development of malignant tumors, in arthritic joints, and in cardiovascular disease. In cardiovascular disease, angiogenesis is recognised both as a potential therapy and as a complicating factor in atherosclerotic plaque rupture and thrombotic obstruction. Serine proteases regulate thrombosis, inflammation, and cell invasion, events that trigger various stages of angiogenesis and are in turn regulated by inhibitors, termed serpins. Serp-1 is a secreted anti-inflammatory viral serpin that profoundly inhibits early mononuclear cell invasion, and the development of atherosclerosis, transplant vasculopathy, and arthritis in a range of animal models.

METHODS

The capacity of Serp-1 to alter angiogenesis was evaluated in the chicken chorioallantoic membrane (CAM) model using morphometric analysis of vascular changes and RT-PCR to explore alterations in gene expression.

RESULTS

Serp-1 inhibited endogenous angiogenesis in a dose-dependent manner, with associated altered expression of laminin and vascular endothelial growth factor (VEGF). Serp-1 was ineffective in CAMs no longer in the rapid growth phase. Similar inhibition of angiogenesis was detected after inhibition of VEGF, but not after treatment with the inactivated reactive center loop mutant of Serp-1.

CONCLUSIONS

The angiogenic process can be controlled using Serp-1, an anti-inflammatory agent that is effective at low concentrations with rapid reversibility, targets endothelial cells, and reduces the availability of VEGF. These properties may be especially important in cardiovascular disease, reducing plaque destabilization. It is likely that the anti-angiogenic activity of Serp-1 contributes to the observed anti-inflammatory and anti-atherogenic actions with potential importance in this therapeutic setting.

Bevacizumab for Advanced Breast Cancer

Tumor angiogenesis is essential for the growth and metastasis of solid tumors. In breast cancer, increased levels of vascular endothelial growth factor (VEGF) have been associated with poor prognosis in lymph node-positive and lymph node-negative patients. In addition to its prognostic significance, VEGF is now a validated target in the treatment of breast cancer. Bevacizumab, an anti-VEGF antibody, has demonstrated significant clinical benefit in several solid tumors. In this article the authors discuss the data pertaining to bevacizumab and other antiangiogenic agents for the treatment of patients who have advanced breast cancer.

Challenges for patient selection with VEGF inhibitors

As targeted therapies for cancer become increasingly integrated into standard practice, appropriate selection of the patients most likely to benefit from these therapies is now receiving critical scrutiny. Early experience with therapies directed at targets that are definitively overactive (e.g. the bcr-abl tyrosine kinase targeted by imatinib) or over-expressed [e.g. the human epidermal growth factor receptor 2 (HER2) targeted by trastuzumab] has generated the perception that pre-treatment target assessment is a pre-requisite for therapy with all targeted agents. However, emerging evidence suggests that this is not presently feasible for anti-angiogenic agents. Despite considerable evidence for the association of intratumoral and/or plasma vascular endothelial growth factor (VEGF) levels with tumor progression and/or poor prognosis, pre-treatment VEGF levels do not appear to be predictive of response to anti-angiogenic therapy. This may possibly be due to the complexity of the angiogenic pathways and the limitations associated with current methods of VEGF detection and quantification; e.g. low assay sensitivity and lack of standardized methods could prevent detection of very small increases in VEGF, which may be clinically important in patients with tumors that are highly dependent on this growth factor. In addition to a general lack of agreement as to the relative clinical relevance of circulating versus tumor VEGF levels, the absence of a 'gold standard' VEGF detection assay and the lack of a predefined, clinically relevant cut-off pose a significant hindrance to the clinical utility of VEGF measurements for therapy selection. Given the fundamental importance of angiogenesis for tumor growth and progression, and the key role of VEGF in these processes, presently it seems appropriate to view anti-VEGF agents such as bevacizumab (Avastin) as having potential utility, independently of pre-treatment screening. Further research is needed to define the relationship between potential surrogate markers of VEGF pathway activity and clinical outcomes.

c-Met overexpression is a prognostic factor in ovarian cancer and an effective target for inhibition of peritoneal dissemination and invasion

The hepatocyte growth factor receptor c-Met is a receptor tyrosine kinase that plays an important role in tumor growth by activating mitogenic signaling pathways. The goal of this study was to evaluate the role of c-Met in the biology of ovarian cancer and to determine its potential as a therapeutic target. c-Met protein expression was detected by immunohistochemistry in 138 advanced-stage ovarian cancers using a tissue microarray annotated with disease-specific patient follow-up. Fifteen of 138 (11%) tissues had c-Met overexpression. Median survival for patients with high c-Met levels was 17 months versus 32 months (P = 0.001) for patients with low c-Met expression. Infection of SKOV-3ip1 cells with an adenovirus expressing a small interfering RNA (siRNA) against c-Met efficiently inhibited c-Met protein and mRNA expression as well as extracellular signal-regulated kinase and phosphatidylinositol 3-kinase signaling. It also inhibited adhesion to different extracellular matrix components, human primary mesothelial cells, and full-thickness human peritoneum and, in vivo, to mouse peritoneum. This was paralleled by a significant reduction in alpha(5) and beta(1) integrin protein and mRNA expression as well as a reduction of urokinase and matrix metalloproteinase (MMP)-2/MMP-9 activity. In SKOV-3ip1 ovarian cancer xenografts, i.p. treatment with the c-Met siRNA significantly reduced tumor burden, ascites formation, protease activity, and the number of peritoneal implants but not tumor size or angiogenesis. These results suggest that c-Met overexpression is a prognostic factor in ovarian cancer and that targeting c-Met in vivo inhibits peritoneal dissemination and invasion through an alpha(5)beta(1) integrin-dependent mechanism. Therefore, c-Met should be explored further as a therapeutic target in ovarian cancer.

Mice expressing a humanized form of VEGF-A may provide insights into the safety and efficacy of anti-VEGF antibodies

VEGF-A is important in tumor angiogenesis, and a humanized anti-VEGF-A monoclonal antibody (bevacizumab) has been approved by the FDA as a treatment for metastatic colorectal and nonsquamous, non-small-cell lung cancer in combination with chemotherapy. However, contributions of both tumor- and stromal-cell derived VEGF-A to vascularization of human tumors grown in immunodeficient mice hindered direct comparison between the pharmacological effects of anti-VEGF antibodies with different abilities to block host VEGF. Therefore, by gene replacement technology, we engineered mice to express a humanized form of VEGF-A (hum-X VEGF) that is recognized by many anti-VEGF antibodies and has biochemical and biological properties comparable with WT mouse and human VEGF-A. The hum-X VEGF mouse model was then used to compare the activity and safety of a panel of VEGF Mabs with different affinities for VEGF-A. Although in vitro studies clearly showed a correlation between binding affinity and potency at blocking endothelial cell proliferation stimulated by VEGF, in vivo experiments failed to document any consistent correlation between antibody affinity and the ability to inhibit tumor growth and angiogenesis in most animal models. However, higher-affinity antibodies were more likely to result in glomerulosclerosis during long-term treatment.

Angiogenesis inhibition with bevacizumab and the surgical management of colorectal cancer

BACKGROUND

Bevacizumab is an angiogenesis inhibitor and a new therapy for the treatment of colorectal cancer. It is a humanized monoclonal antibody that targets vascular endothelial growth factor.

METHODS

This review is based on a literature search of Medline, Pubmed, ISI web of knowledge and other published work for original articles, reviews and abstracts relevant to the surgical management of colorectal cancer with bevacizumab.

RESULTS AND CONCLUSION

Combined with current chemotherapy regimens, bevacizumab offers a significant survival advantage, making it likely to see widespread use. Despite being generally well tolerated, serious toxicities, including wound complications and gastrointestinal perforation, have been reported that affect surgical management. Consideration should be given to the timing of surgical and adjuvant intervention when using this drug.

Pathophysiologic Effects of Vascular-Targeting Agents and the Implications for Combination with Conventional Therapies

A functional vascular supply is critical for the continued growth and development of solid tumors. It also plays a major role in metastatic spread of tumor cells. This importance has led to the concept of targeting the vasculature of the tumor as a form of cancer therapy. Two major types of vascular-targeting agent (VTA) have now emerged: those that prevent the angiogenic development of the neovasculature of the tumor and those that specifically damage the already established tumor vascular supply. When used alone neither approach readily leads to tumor control, and so, for VTAs to be most successful in the clinic they will need to be combined with more conventional therapies. However, by affecting the tumor vascular supply, these VTAs should induce pathophysiologic changes in variables, such as blood flow, pH, and oxygenation. Such changes could have negative or positive influences on the tumor response to more conventional therapies. This review aims to discuss the pathophysiologic changes induced by VTAs and the implications of these effects on the potential use of VTAs in combined modality therapy.

Combretastatin A-1 phosphate potentiates the antitumor activity of carboplatin and paclitaxel in a severe combined immunodeficiency disease (SCID) mouse model of human ovarian carcinoma

In search for new therapeutic modalities to target epithelial ovarian carcinomas, we investigated the effect of the antiangiogenic drug combretastatin A-1 phosphate (CA1P) as a single treatment or in combination with established therapy, ie, carboplatin and paclitaxel. Five different human epithelial ovarian carcinoma cell lines were inoculated subcutaneously into FOX CHASE CB-77 severe combined immunodeficiency disease (SCID) mice. When tumors reached a volume of approximately 100 mm(3), the treatment was initiated. All drugs were given intraperitoneally at weekly doses. CA1P was more effective as an antitumor agent than combretastatin A-4 phosphate as a single-drug treatment or in combination with carboplatin and paclitaxel. CA1P had a strong tumor outgrowth inhibiting effect on four out of five tumors included in this study. Comparing animals receiving CA1P with animals receiving a combination of carboplatin and paclitaxel, CA1P was more effective on two out of three tested tumors, whereas carboplatin and paclitaxel were more effective on one out of three of the tumors. We show that treatment of human ovarian carcinomas with CA1P in the SCID mouse model results in a strong antitumor effect both as a single-drug treatment and as an enhancement of the therapeutic effect in a combination treatment protocol with carboplatin and paclitaxel.

Paracrine VEGF/VE-cadherin action on ovarian cancer permeability

Ascites formation associated with neoplasms is most likely due to increased vascular permeability, a process in which vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) plays a pivotal role. We hypothesized that tumor-derived VEGF/VPF modulates ascites formation through a paracrine effect on both tumor and peritoneal vessels. We investigated human vascular endothelial permeability using a newly developed dual-chamber permeability assay by co-culturing human umbilical vein cells with and without ovarian cancer cell lines (OVCAR-3, Hey-A8, and OCC-1) in the presence or absence of a human VEGF monoclonal antibody and VE-cadherin function-blocking antibody. This method permits determination of mechanisms by which substances released from neoplasms and other sources of vascular endothelial cell secretagogues modulate vascular permeability and likely other pathologic states.

Albendazole: a potent inhibitor of vascular endothelial growth factor and malignant ascites formation in OVCAR-3 tumor-bearing nude mice

PURPOSE

Angiogenesis and vessel hyperpermeability are the two factors leading to the formation of ascites. Vascular endothelial growth factor (VEGF) plays a pivotal role in malignant ascites formation. We have recently shown that albendazole inhibits peritoneal growth of human colorectal cancer cells (HT-29). The present study was designed to find out if albendazole can suppress ascites formation in ascites-producing peritoneal carcinomatosis.

EXPERIMENTAL DESIGN

Female nude mice bearing peritoneal tumors of human ovarian cancer cells (OVCAR-3) were treated with albendazole. Following i.p. inoculation and ascites development, mice were given i.p. albendazole (150 mg/kg) or the vehicle x 3 weekly for 4 weeks.

RESULTS

Whereas vehicle-treated mice developed overt ascites requiring repeated aspiration, ascites formation in the albendazole-treated mice was markedly suppressed. As a result of this, 7 of 10 mice from the control group had to be euthanized before the course of treatment was over. Suppressed ascites production and reduced tumor vascularity observed was a result of dramatic reduction in tumor VEGF production as revealed by profoundly lower VEGF ascites fluid and plasma levels. In vitro, incubation of SKOV-3 cells with various concentrations of albendazole led to significant dose-dependent inhibition of VEGF secretion. Examination of floating tumor cells collected from the peritoneal wash revealed profound down-regulation of VEGF mRNA in albendazole-treated mice.

CONCLUSIONS

These findings suggest for the first time that in nude mice bearing OVCAR-3 peritoneal tumors, by inhibiting VEGF production, albendazole abolishes tumor angiogenesis and ascites formation.

The use of bevacizumab to palliate symptomatic ascites in patients with refractory ovarian carcinoma

OBJECTIVE

To evaluate our experience with the use of bevacizumab in patients with heavily pretreated recurrent ovarian carcinoma who have symptomatic ascites.

METHODS

Four patients were identified who were previously heavily pretreated for recurrent ovarian carcinoma. Each had symptomatic ascites and required frequent therapeutic paracenteses. Each was treated with bevacizumab with the intent to palliate symptomatic ascites. Clinical data including demographic data and clinicopathologic variables was abstracted.

RESULTS

The four patients demonstrated symptomatic relief of ascites. Toxicity was manageable in all patients with no grade 3/4 toxicity observed. In addition to symptomatic relief of ascites, no therapeutic paracenteses were required after initiation of therapy with bevacizumab.

CONCLUSIONS

Bevacizumab may be a viable palliative option in patients with end stage ovarian carcinoma who have symptomatic ascites.

Bevacizumab combination therapy in recurrent, platinum-refractory, epithelial ovarian carcinoma: A retrospective analysis

BACKGROUND

The study was undertaken to determine the safety and efficacy of the monoclonal, antivascular endothelial growth factor antibody bevacizumab in combination with cytotoxic chemotherapy for women with platinum-refractory ovarian cancer.

METHODS

A retrospective analysis of women who received bevacizumab in combination with a cytotoxic agent was performed. Response was determined by measurable disease or assessment of serial cancer antigen (CA) 125 measurements.

RESULTS

Twenty-three patients were identified. The patients were heavily pretreated with a median of 7 prior regimens including a median of 3 prior platinum regimens. The combination regimen included cyclophosphamide in 15 (65%), 5-fluorouracil (5-FU) in 6 (26%), docetaxel in 1 (4%), and gemcitibine/liposomal doxorubicin in 1 (4%). Two (9%) women developed chylous ascites during treatment. CTC Grade 4-5 toxicities occurred in 4 (17%) subjects. Gastrointestinal perforation occurred in 2 (9%) patients. Measurable disease was present in 22. The overall best response rate was 35% and all 8 were partial responses (PRs). Stable disease was found in a further 10 (44%) women, whereas progressive disease was observed in 5 (22%). The median time to progression was 5.6 months in patients with a PR and 2.3 months in subjects with stable disease. Three (13%) women experienced a progression-free interval (PFI) of >6 months. At last follow-up, 8 (35%) subjects had died of disease, whereas 15 (65%) women were alive with disease.

CONCLUSIONS

Combination bevacizumab therapy demonstrated activity in heavily pretreated women with ovarian cancer. Gastrointestinal perforations were identified in 9%. Despite the toxicity of the regimen, prospective studies, particularly in less heavily pretreated patients, are warranted.

Molecular determinants of response to RTK-targeting agents in nonsmall cell lung cancer

Receptor tyrosine kinases (RTKs) are essential components of the cellular signaling apparatus and are often mutated or otherwise deregulated in nonsmall cell lung cancer (NSCLC). These receptors are not solely expressed by cancer cells but also by multiple other cell types, including stromal cells that, in turn, may modulate cancer cell functions by various direct and indirect interactions. Recently, clinical studies have successfully evaluated the inhibition of RTKs by specific RTK-targeting agents, including tyrosine kinase inhibitors (TKIs). Although the response was impressive in some studies, only a limited proportion of patients benefit from these new drugs. Therefore, an intensive search for markers has started to determine which patients and tumor types are most likely to respond favorably to this new kind of treatment. Considerable attention has been focused onto molecular changes in cancer cells such as receptor expression, gene amplification, changes in intracellular signaling and receptor mutations. In this article, we explore the current data regarding molecular alterations as surrogate markers of response to specific RTK-targeting agents in NSCLC. Defined alterations may serve as key markers helping to preselect NSCLC patients for an individualized therapeutic approach in the future.

The effects of the oral, pan-VEGF-R kinase inhibitor CEP-7055 and chemotherapy in orthotopic models of glioblastoma and colon carcinoma in mice

CEP-7055, a fully synthetic, orally active N,N-dimethylglycine ester of CEP-5214, a C3-(isopropylmethoxy)-fused pyrrolocarbazole with potent pan-vascular endothelial growth factor receptor (VEGFR) kinase inhibitory activity, has recently completed phase I clinical trials in cancer patients. These studies evaluated the antitumor efficacy of CEP-7055 using orthotopic models of glioblastoma and colon carcinoma in combination with temozolomide, and irinotecan and oxaliplatin, respectively, for their effects on primary and metastatic tumor burden and median survival. Chronic administration of CEP-7055 (23.8 mg/kg/dose) and temozolomide resulted in improvement of median survival of nude mice bearing orthotopic human glioblastoma xenografts compared with temozolomide alone (261 versus 192 days, respectively; P < or = 0.02). Reductions in neurologic dysfunction, brain edema, hemorrhage, and intratumoral microvessel density (CD34 staining) were observed in glioma-bearing mice receiving CEP-7055 alone, temozolomide alone, and the combination of CEP-7055 and temozolomide relative to vehicle and to temozolomide monotherapy. The administration of CEP-7055 in combination with irinotecan (20 mg/kg/dose i.p. x 5 days), and to a lesser degree with oxaliplatin (10 mg/kg/dose i.v.), showed reductions on primary colon carcinoma and hepatic metastatic burden in the CT-26 tumor model relative to that achieved by irinotecan and oxaliplatin monotherapy. These data show the significant efficacy and tolerability of optimal efficacious doses of CEP-7055 when given in combination with temozolomide and irinotecan relative to monotherapy with these cytotoxic agents in preclinical orthotopic glioma and colon carcinoma models and lend support for the use of these treatment regimens in a clinical setting in patients with glioblastoma and colon carcinoma.

Systemic therapy for ovarian cancer: current status and new treatments

Current systemic therapy for ovarian cancer consists of a combination of carboplatin and paclitaxel. While the majority of patients achieve clinical complete remission after six cycles of chemotherapy, the relapse rate stands at over 50%. Median survival time for patients after recurrence is approximately 2 years. New treatment approaches for patients with advanced ovarian cancer include consolidation and maintenance therapy, intraperitoneal administration of cytotoxic agents, new combination chemotherapy regimens, the development of new cytotoxic agents, and molecular-targeted therapies. These agents will be evaluated either singularly or with chemotherapy. Currently, the Gynecologic Oncology Group is evaluating a combination of bevacizumab together with paclitaxel and carboplatin in previously untreated patients with advanced ovarian cancer. This trial is based on phase II data that suggest that bevacizumab as a single agent has significant activity in patients with recurrent ovarian cancer. In addition, the Gynecologic Oncology Group will be conducting phase II trials of different combinations of intraperitoneal chemotherapy in an effort to decrease toxicity associated with current intraperitoneal regimens that have shown an improvement in survival in patients with small-volume stage III disease. The Gynecologic Oncology Group will also be conducting a trial of maintenance therapy in patients who enter clinical complete remission with paclitaxel plus carboplatin, comparing observation with monthly paclitaxel or monthly paclitaxel poliglumex. Novel new cytotoxic and biologic agents are also being evaluated as single agents in phase II trials in patients with recurrent ovarian cancer.

HSulf-1 Inhibits Angiogenesis and TumorigenesisIn vivo

We previously identified HSulf-1 as a down-regulated gene in several tumor types including ovarian, breast, and hepatocellular carcinomas. Loss of HSulf-1, which selectively removes 6-O-sulfate from heparan sulfate, up-regulates heparin-binding growth factor signaling and confers resistance to chemotherapy-induced apoptosis. Here we report that HSulf-1 expression in MDA-MB-468 breast carcinoma clonal lines leads to reduced proliferation in vitro and reduced tumor burden in athymic nude mice in vivo. Additionally, xenografts derived from HSulf-1-expressing stable clones of carcinoma cells showed reduced vessel density, marked necrosis, and apoptosis, indicative of inhibition of angiogenesis. Consistent with this observation, HSulf-1-expressing clonal lines showed reduced staining with the endothelial marker CD31 in Matrigel plug assay, indicating that HSulf-1 expression inhibits angiogenesis. More importantly, HSulf-1 expression in the xenografts was associated with a reduced ability of vascular endothelial cell heparan sulfate to participate in a complex with fibroblast growth factor 2 (FGF-2) and its receptor tyrosine kinase FGF receptor 1c. In vitro, short hairpin RNA-mediated down-regulation of HSulf-1 in human umbilical vein endothelial cells (HUVEC) resulted in an increased proliferation mediated by heparan sulfate-dependent FGF-2, hepatocyte growth factor, and vascular endothelial growth factor 165 (VEGF165) but not by heparan sulfate-independent VEGF121. HSulf-1 down-regulation also enhanced downstream signaling through the extracellular signal-regulated kinase pathway compared with untreated cells. Consistent with the role of heparan sulfate glycosaminoglycan sulfation in VEGF-mediated signaling, treatment of HUVEC cells with chlorate, which inhibits heparan sulfate glycosaminoglycan sulfation and therefore mimics HSulf-1 overexpression, led to an attenuated VEGF-mediated signaling. Collectively, these observations provide the first evidence of a novel mechanism by which HSulf-1 modulates the function of heparan sulfate binding VEGF165 in proliferation and angiogenesis.

Bevacizumab and weekly taxane chemotherapy demonstrates activity in refractory ovarian cancer

OBJECTIVE

To determine the ability of patients to be treated with biweekly bevacizumab and weekly taxane chemotherapy in women with advanced, refractory ovarian cancer.

METHODS

Ten patients with advanced, recurrent, and refractory ovarian cancer who were treated with biweekly bevacizumab (10 mg/kg) and weekly taxane (paclitaxel or docetaxel) chemotherapy days 1, 8, 15, and 22 every 28 days were identified retrospectively. All patients were followed with serial CA125 measurements prior to each cycle of therapy; cross-sectional imaging was not used to follow response to therapy. Toxicities were assessed prior to each cycle of treatment.

RESULTS

Of the 10 patients treated with weekly taxane and biweekly bevacizumab therapy, all 9 that were evaluable had a decrease in CA125. Five patients have had an increase in CA125 after therapy after a median of three cycles (range 1-4), while 3 patients experienced normalization of CA125 and another with continued improvement in CA125. All symptomatic patients experienced rapid palliation of pain, nausea, and ascites. Side effects have been mild, with no grade 3 or 4 toxicities noted. No treatment delays or discontinuations have been necessary.

CONCLUSION

Treatment of advanced, recurrent, refractory epithelial ovarian cancer with bevacizumab and weekly taxane chemotherapy leads to significant, albeit temporary, improvement in the cancer-related symptoms in women treated on this regimen, and short-term exposure to these agents is not associated with significant toxicity. Thus, continued investigation of bevacizumab with weekly scheduling of cytotoxic chemotherapy is imperative.