The Role of Angiogenesis Inhibitors in Prostate Cancer

Luteolin, ellagic acid and punicic acid are natural products that inhibit prostate cancer metastasis

Prostate cancer (PCa) is the second cause of cancer deaths in men in the USA. When the cancer recurs, early stages can be controlled with hormone ablation therapy to delay the rate of cancer progression but, over time, the cancer overcomes its hormone dependence, becomes highly aggressive and metastasizes. Clinical trials have shown that pomegranate juice (PJ) inhibits PCa progression. We have previously shown that the PJ components luteolin (L), ellagic acid (E) and punicic acid (P) together inhibit growth of hormone-dependent and -independent PCa cells and inhibit their migration and chemotaxis towards CXCL12, a chemokine that is important in PCa metastasis. On the basis of these findings, we hypothesized that L+E+P inhibit PCa metastasis in vivo. To test this possibility, we used a severe combined immunodeficiency mouse model in which luciferase-expressing human PCa cells were injected subcutaneously near the prostate. Tumor progression was monitored with bioluminescence imaging weekly. We found that L+E+P inhibits PC-3M-luc primary tumor growth, inhibits the CXCL12/CXCR4 axis for metastasis and none of the tumors metastasized. In addition, L+E+P significantly inhibits growth and metastasis of highly invasive Pten (-/-) ;K-ras (G12D) prostate tumors. Furthermore, L+E+P inhibits angiogenesis in vivo, prevents human endothelial cell (EC) tube formation in culture and disrupts preformed EC tubes, indicating inhibition of EC adhesion to each other. L+E+P also inhibits the angiogenic factors interleukin-8 and vascular endothelial growth factor as well as their induced signaling pathways in ECs. In conclusion, these results show that L+E+P inhibits PCa progression and metastasis.

Bevacizumab and wound-healing complications: mechanisms of action, clinical evidence, and management recommendations for the plastic surgeon

Reflecting the growing understanding of vascular endothelial growth factor (VEGF) in cancer survival and growth, the anti-VEGF antibody bevacizumab (Avastin) is increasingly used to treat advanced malignancy. However, because VEGF also mediates proper wound healing, bevacizumab may lead to potentially severe wound-healing complications (WHCs). Because bevacizumab expands in use, the plastic surgeon will increasingly be entrusted to manage such WHCs successfully. Therefore, this review summarizes the pathophysiological evidence, systematically reviews the available clinical evidence, and provides management guidelines for bevacizumab-related WHCs. Bevacizumab produces WHCs by disrupting vasodilation, increased vascular permeability, and angiogenesis. Current clinical evidence suggests that bevacizumab may increase WHC risk. This risk seems higher with neoadjuvant than adjuvant bevacizumab use and may be decreased by extending the bevacizumab-surgery interval. Further research is required to quantify the exact bevacizumab-related WHC incidence and optimize the bevacizumab-surgery interval. We propose management guidelines for bevacizumab-related WHCs by indication that should be integrated with clinical judgment, input from the oncology team, and patient wishes when making therapeutic decisions.

Targeted antivascular therapy with the apolipoprotein(a) kringle V, rhLK8, inhibits the growth and metastasis of human prostate cancer in an orthotopic nude mouse model

Antivascular therapy has emerged as a rational strategy to improve the treatment of androgen-independent prostate cancer owing to the necessity of establishing a vascular network for the growth and progression of the primary and metastatic tumor. We determined whether recombinant human apolipoprotein(a) kringle V, rhLK8, produces therapeutic efficacy in an orthotopic human prostate cancer animal model. Fifty thousand androgen-independent human prostate cancer cells (PC-3MM2) were injected into the prostate of nude mice. After 3 days, these mice were randomized to receive the vehicle solution (intraperitoneally [i.p.], daily), paclitaxel (8 mg/kg i.p., weekly), rhLK8 (50 mg/kg i.p., daily), or a combination of paclitaxel and rhLK8 for 4 weeks. Treatment with paclitaxel or rhLK8 alone did not show significant therapeutic effects on tumor incidence or on tumor size compared with the control group. The combination of rhLK8 and paclitaxel significantly reduced tumor size and incidence of lymph node metastasis. Significant reduction in microvessel density and cellular proliferation and induction of apoptosis of tumor cells, and tumor-associated endothelial cells, were also achieved. Similarly, PC-3MM2 tumors growing in the tibia showed significant suppression of tumor growth and lymph node metastasis by the combination treatment with rhLK8 and paclitaxel. The integrity of the bone was significantly preserved, and apoptosis of tumor cells and tumor-associated endothelial cells was increased. In conclusion, these results suggest that targeting the tumor microenvironment with the antivascular effect of rhLK8 combined with conventional cytotoxic chemotherapy could be a new and effective approach in the treatment of androgen-independent prostate cancer and their metastases.

Immunomodulatory drugs and active immunotherapy for chronic lymphocytic leukemia

BACKGROUND

The last decade witnessed the emergence of several therapeutic options for patients with chronic lymphocytic leukemia (CLL) for first-line and relapsed settings. The vast majority of patients with relapsed or refractory CLL carry poor prognostic features, which are strong predictors of shorter overall survival and resistance to first-line treatment, particularly fludarabine-based regimens.

METHODS

This article highlights the current role of immunomodulatory drugs (IMiDs) and active immunotherapy as treatment options for this select group. The rationale of using IMiDs is discussed from the perspective of lenalidomide as a novel active agent. Relevant clinical trials using IMiDs alone or in combinations are discussed. New immunotherapeutic experimental approaches are also described.

RESULTS

As a single agent, lenalidomide offers an overall response rate of 32% to 47% in patients with relapsed/refractory disease. Recent studies have shown promising activity as a single agent in treatment-naive patients. The combination of lenalidomide with immunotherapy (rituximab and ofatumumab) has also shown clinical responses. Encouraging preclinical and early clinical data have been observed with different immunotherapeutic approaches.

CONCLUSIONS

The use of IMiDs alone or in combination with immunotherapy represents a treatment option for relapsed/refractory or treatment-naive patients. Mature data and further studies are needed to validate overall and progression-free survival. The toxicity profile of lenalidomide might limit its use and delay further studies. Immunotherapy offers another potential alternative, but further understanding of the immunogenicity of CLL cells and the mechanisms of tumor fl are reaction is needed to improve the outcomes in this field.

Thalidomide attenuates mammary cancer associated-inflammation, angiogenesis and tumor growth in mice

Thalidomide has proven to exert anti-inflammatory, anti-proliferative and anti-angiogenic activities in both neoplastic and non-neoplastic conditions. We investigated the effects of this compound on key components (blood vessel formation, inflammatory cell recruitment/activation, cytokine production) of 4T1 mammary tumor in mice. In addition, tumor growth and lung metastasis were evaluated. 4T1 cells were injected subcutaneously into Balb/c mice. After tumor engraftment (5days), thalidomide (150mg/kg) was administered to the treated group for 7days. Tumors of control (saline) and treated groups were sized regularly, removed 12days after inoculation and processed for biochemical and immunohistological parameters to assess neovascularization, inflammation and proliferative activity. Daily oral dose of thalidomide was able to reduce in 46% the tumor volume. The number of metastasis in the lungs was less in the thalidomide-treated group compared with the control animals. Assessment of tumor vascularization revealed a significant decrease in blood vessels formation by thalidomide. Likewise, the expression of FGF-1 showed weaker cytoplasmic positivity in the group treated with thalidomide compared with the control group. The levels of two cytokines, VEGF (pro-angiogenic) and TNF-α (pro-inflammatory) were decreased in tumor samples of thalidomide-treated group compared with the control group. Accumulation of neutrophils or macrophages in the 4T1 tumor measured by the activities of inflammatory enzymes, myeloperoxidase (MPO) for neutrophils and N-acetyl-β-D-glucosaminidase (NAG) for macrophages was inhibited by the treatment. By targeting key components of 4T1 tumor simultaneously, thalidomide was effective in attenuating tumor growth and metastasis. This approach, suppression of inflammation and angiogenesis may provide further insights for both prevention and treatment of cancer.

Pathways of chemotherapy resistance in castration-resistant prostate cancer

Chemotherapy remains the major treatment option for castration-resistant prostate cancer (CRPC) and limited cytotoxic options are available. Inherent chemotherapy resistance occurs in half of all patients and inevitably develops even in those who initially respond. Docetaxel has been the mainstay of therapy for 6 years, providing a small survival benefit at the cost of significant toxicity. Cabazitaxel is a promising second-line agent; however, it is no less toxic, whereas mitoxantrone provides only symptomatic benefit. Multiple cellular pathways involving apoptosis, inflammation, angiogenesis, signalling intermediaries, drug efflux pumps and tubulin are implicated in the development of chemoresistance. A thorough understanding of these pathways is needed to identify biomarkers that predict chemotherapy resistance with the aim to avoid unwarranted toxicities in patients who will not benefit from treatment. Until recently, the search for predictive biomarkers has been disappointing; however, the recent discovery of macrophage inhibitory cytokine 1 as a marker of chemoresistance may herald a new era of biomarker discovery in CRPC. Understanding the interface between this complex array of chemoresistance pathways rather than their study in isolation will be required to effectively predict response and target the late stages of advanced disease. The pre-clinical evidence for these resistance pathways and their progress through clinical trials as therapeutic targets is reviewed in this study.

Treatment strategies for high-risk locally advanced prostate cancer

High-risk prostate cancer can be defined by the assessment of pretreatment prognostic factors such as clinical stage, Gleason score, and PSA level. High-risk features include PSA >20 ng/ml, Gleason score 8-10, and stage T3 tumors. Patients with adverse prognostic factors have historically fared poorly with monotherapeutic approaches. Multimodal treatment utilizing combined androgen suppression and radiotherapy has improved survival rates for patients with high-risk prostate cancer. In addition, multiple randomized trials in patients treated with primary radical prostatectomy have demonstrated improved outcomes with the addition of adjuvant radiotherapy. Improved radiotherapy techniques that allow for dose escalation, and new systemic therapy approaches such as adjuvant chemotherapy, present promising future therapeutic alternatives for patients with high-risk prostate cancer.

Rosuvastatin, identified from a zebrafish chemical genetic screen for antiangiogenic compounds, suppresses the growth of prostate cancer

BACKGROUND

Prostate cancer (PCa) is the most common malignancy in males in Western countries. Despite improvements in standard treatments such as surgery, radiotherapy, and chemotherapy, many patients still progress to advanced stages. Recent clinical trials have shown encouraging results regarding the application of angiogenic inhibitors in the treatment of angiogenesis-dependent diseases, paving the way for novel PCa therapies.

OBJECTIVE

To identify new antiangiogenic compounds and examine their therapeutic potential in models of PCa.

DESIGN, SETTING, AND PARTICIPANTS

We performed a chemical genetic screen in developing zebrafish embryos to identify small molecules inhibiting zebrafish angiogenesis. Transgenic Tg(flk1:EGFP) zebrafish embryos were used in the screening of the Spectrum Collection compound library. Subsequently, the antiangiogenic mechanism of an identified lead compound, rosuvastatin, was studied by conducting endothelial cell function assays and examining antitumor efficacy in a PCa xenograft mouse model. MEASUREMENTS, RESULTS AND LIMITATIONS: Seven lead compounds, including isorotenone, dihydromunduletone, aristolochic acid, simvastatin, mevastatin, lovastatin, and rosuvastatin, were identified to inhibit the growth of the zebrafish intersegmental vessels. Of these seven leads, rosuvastatin was further evaluated for its antiangiogenic mechanism and anticancer efficacy. Rosuvastatin decreased the viability of the human umbilical endothelial cells (HUVECs) (one-half inhibitory concentration: 5.87 microM) by inducing G(1) phase arrest and promoting apoptosis. Moreover, rosuvastatin remarkably inhibited the migration of HUVECs and dose-dependently inhibited the HUVEC capillary-like tube formation in vitro. Furthermore, we demonstrated that rosuvastatin suppressed xenografted PPC-1 prostate tumors in nonobese diabetic severe combined immunodeficiency (NOD-SCID) mice associated with decreased microvessel density (MVD) and tumor cell apoptosis.

CONCLUSIONS

Collectively, our data suggest that rosuvastatin possesses antiangiogenic and antitumor activities and has therapeutic potential for the treatment of PCa. This study represents the first zebrafish antiangiogenic chemical genetic screen to identify a lead compound that targets cancer angiogenesis.

Targeted therapy in biliary tract cancer: 2009 update

Biliary tract cancers (BTCs) include cholangiocarcinoma (intrahepatic, perihilar and extrahepatic), carcinoma of the gall bladder and ampullary carcinoma. In patients with advanced disease the prognosis is poor. There is not a consensus regarding treatment strategy. Chemotherapy has only limited efficacy. This review summarizes the new approaches for BTC patients and the rationale for targeted therapies. The prognostic factors and the molecular features of BTC are analyzed. The clinical trials evaluating the targeted agents are accurately described, especially those assessing the role of anti-EGFR and antiangiogenic drugs. The ongoing trials are also analyzed. In fact, only the results of these trials will establish which is the most effective agent or combination for this setting.

Inositol hexaphosphate suppresses growth and induces apoptosis in prostate carcinoma cells in culture and nude mouse xenograft: PI3K-Akt pathway as potential target

Constitutive activation of phosphoinositide 3-kinase (PI3K)-Akt pathway transmits growth-regulatory signals that play a central role in promoting survival, proliferation, and angiogenesis in human prostate cancer cells. Here, we assessed the efficacy of inositol hexaphosphate (IP6) against invasive human prostate cancer PC-3 and C4-2B cells and regulation of PI3K-Akt pathway. IP6 treatment of cells suppressed proliferation, induced apoptosis along with caspase-3 and poly(ADP-ribose) polymerase (PARP) cleavage, and inhibited constitutive activation of Akt and its upstream regulators PI3K, phosphoinositide-dependent kinase-1 and integrin-linked kinase-1 (ILK1). Downstream of Akt, IP6 inhibited the phosphorylation of glycogen synthase kinase-3alpha/beta at Ser(21/9) and consequently reduced cyclin D1 expression. Efficacy studies employing PC-3 tumor xenograft growth in nude mice showed that 2% (w/v) IP6 feeding in drinking water inhibits tumor growth and weight by 52% to 59% (P < 0.001). Immunohistochemical analysis of xenografts showed that IP6 significantly reduces the expression of molecules associated with cell survival/proliferation (ILK1, phosphorylated Akt, cyclin D1, and proliferating cell nuclear antigen) and angiogenesis (platelet endothelial cell adhesion molecule-1 or CD31, vascular endothelial growth factor, endothelial nitric oxide synthase, and hypoxia-inducible factor-1alpha) together with an increase in apoptotic markers (cleaved caspase-3 and PARP). These findings suggest that, by targeting the PI3K-ILK1-Akt pathway, IP6 suppresses cell survival, proliferation, and angiogenesis but induces death in prostate cancer cells, which might have translational potential in preventing and controlling the growth of advanced and aggressive prostate cancer for which conventional chemotherapy is not effective.

FGF-8b induces growth and rich vascularization in an orthotopic PC-3 model of prostate cancer

Fibroblast growth factor 8 (FGF-8) is expressed at an increased level in a high proportion of prostate cancers and it is associated with a poor prognosis of the disease. Our aim was to study the effects of FGF-8b on proliferation of PC-3 prostate cancer cells and growth of PC-3 tumors, and to identify FGF-8b-associated molecular targets. Expression of ectopic FGF-8b in PC-3 cells caused a 1.5-fold increase in cell proliferation in vitro and a four- to fivefold increase in the size of subcutaneous and orthotopic prostate tumors in nude mice. Tumors expressing FGF-8b showed a characteristic morphology with a very rich network of capillaries. This was associated with increased spread of the cancer cells to the lungs as measured by RT-qPCR of FGF-8b mRNA. Microarray analyses revealed significantly altered, up- and downregulated, genes in PC-3 cell cultures (169 genes) and in orthotopic PC-3 tumors (61 genes). IPA network analysis of the upregulated genes showed the strongest association with development, cell proliferation (CRIP1, SHC1), angiogenesis (CCL2, DDAH2), bone metastasis (SPP1), cell-to-cell signaling and energy production, and the downregulated genes associated with differentiation (DKK-1, VDR) and cell death (CYCS). The changes in gene expression were confirmed by RT-qPCR. In conclusion, our results demonstrate that FGF-8b increases the growth and angiogenesis of orthotopic prostate tumors. The associated gene expression signature suggests potential mediators for FGF-8b actions on prostate cancer progression and metastasis.

Open-label, clinical phase I studies of tasquinimod in patients with castration-resistant prostate cancer

BACKGROUND

Tasquinimod is a quinoline-3-carboxamide derivative with anti-angiogenic activity. Two open-label phase I clinical trials in patients were conducted to evaluate the safety and tolerability of tasquinimod, with additional pharmacokinetic and efficacy assessments.

METHODS

Patients with castration-resistant prostate cancer with no previous chemotherapy were enrolled in this study. The patients received tasquinimod up to 1 year either at fixed doses of 0.5 or 1.0 mg per day or at an initial dose of 0.25 mg per day that escalated to 1.0 mg per day.

RESULTS

A total of 32 patients were enrolled; 21 patients were maintained for >or=4 months. The maximum tolerated dose was determined to be 0.5 mg per day; but when using stepwise intra-patient dose escalation, a dose of 1.0 mg per day was well tolerated. The dose-limiting toxicity was sinus tachycardia and asymptomatic elevation in amylase. Common treatment-emergent adverse events included transient laboratory abnormalities, anaemia, nausea, fatigue, myalgia and pain. A serum prostate-specific antigen (PSA) decline of >or=50% was noted in two patients. The median time to PSA progression (>25%) was 19 weeks. Only 3 out of 15 patients (median time on study: 34 weeks) developed new bone lesions.

CONCLUSION

Long-term continuous oral administration of tasquinimod seems to be safe, and the overall efficacy results indicate that tasquinimod might delay disease progression.

Phase II study of sunitinib in men with advanced prostate cancer

BACKGROUND

This study explored the efficacy and tolerability of sunitinib, an inhibitor of tyrosine kinase receptors, in men with castration-resistant prostate cancer (CRPC).

METHODS

Men with no prior chemotherapy (group A) and men with docetaxel (Taxotere)-resistant prostate cancer (group B) were treated with sunitinib. The primary end point was confirmed 50% prostate-specific antigen (PSA) decline. Secondary end points included objective response rate and safety. Serum-soluble biomarkers were measured.

RESULTS

Seventeen men were enrolled in each group. One confirmed PSA response was observed in each group, and an additional eight men and seven men had stable PSA at week 12 in groups A and B, respectively. Improvements in imaging were observed in the absence of post-treatment PSA declines. Common adverse effects included fatigue, nausea, diarrhea, myelosuppression and transaminase elevation. Significant changes following sunitinib treatment were observed in serum-soluble biomarkers including soluble vascular endothelial growth factor receptor-2, platelet-derived growth factor aa, placental growth factor and leptin.

CONCLUSIONS

Sunitinib monotherapy resulted in few confirmed 50% post-treatment declines in PSA in men with CRPC. Serum markers of angiogenesis confirmed on-target effects of sunitinib. Assessments of radiographic disease status were often discordant with changes in PSA, indicating that alternate end points are important in future trials.

A review on bevacizumab and surgical wound healing: an important warning to all surgeons

Bevacizumab (Avastin, Genentech, Inc, San Francisco, CA), a humanized monoclonal antibody against vascular endothelial growth factor, was recently approved for the treatment of metastatic breast cancer.A PubMed and OVID search was performed using keywords: bevacizumab, Avastin, wound healing, VEGF, angiogenesis, and colorectal cancer. Our objective was to review the current literature in regard to bevacizumab and its adverse effects on surgical wound healing.Bevacizumab has been associated with multiple complications in regard to wound healing, such as dehiscence, ecchymosis, surgical site bleeding, and wound infection. Current literature suggests patients should wait at least 6 to 8 weeks (>40 days) after cessation to have surgery (half-life = 20 days). In addition, postoperative reinitiation of bevacizumab must wait > or =28 days to prevent an increased risk of wound healing complications, and the surgical incision should be fully healed.The adverse effects of bevacizumab in regard to wound healing must be considered in all surgical patients.

The involvement of altered corticotropin releasing factor receptor 2 expression in prostate cancer due to alteration of anti-angiogenic signaling pathways

BACKGROUND

Expression of urocortin (Ucn) in the human benign prostate and prostate cancer has been reported recently. Ucn binds and activates corticotropin releasing factor (CRF) receptor 1 (CRFR1) and 2 (CRFR2). Activation of CRFR2 has been shown to inhibit tumor growth by regulation of proliferation and apoptosis as well as suppression of vascularization. However, there is no report demonstrating expression profile of CRFR2 in normal prostate versus prostate cancer.

METHODS

CRFR2 mRNA expression was assessed in human normal prostate and prostate cancer by reverse transcriptase PCR. CRFR2 expression on protein level has been performed using double staining immunofluorescence (IF) of tissue microarrays of 32 cases of prostatic adenocarcioma with corresponding normal tissues. Confocal microscopy was carried out to visualize the immunostaining.

RESULTS

PCR of normal prostate lysates exhibited specific signals for CRFR2 mRNA. However PCR of lysates of prostate cancer exhibited no signal for CRFR2 mRNA. IF study exhibited that smooth muscle components of the stroma and endothelial cells of blood vessels express an extensive staining for CRFR2. In a lesser extend vascular smooth muscle cells expressed CRFR2. The tumoral neovascular system and stroma exhibited no immunopositivity for CRFR2.

CONCLUSIONS

The present study demonstrates for the first time that human benign prostate tissue and prostate cancer specimen differentially express CRFR2. While Ucn expression in prostate cancer has been shown to be identical to non-malignant prostate tissues, we hypothesize that expression loss of CRFR2 in prostate cancer and its neovascularization contributes to prostate tumorigenesis, progression, and neoangiogenesis.

Targeted medical therapy of biliary tract cancer: recent advances and future perspectives

The limited efficacy of cytotoxic therapy for advanced biliary tract and gallbladder cancers emphasizes the need for novel and more effective medical treatment options. A better understanding of the specific biological features of these neoplasms led to the development of new targeted therapies, which take the abundant expression of several growth factors and cognate tyrosine kinase receptors into account. This review will briefly summarize the status and future perspectives of antiangiogenic and growth factor receptor-based pharmacological approaches for the treatment of biliary tract and gallbladder cancers. In view of multiple novel targeted approaches, the rationale for innovative therapies, such as combinations of growth factor (receptor)-targeting agents with cytotoxic drugs or with other novel anticancer drugs will be highlighted.