Neutralizing anti-vascular endothelial growth factor antibody completely inhibits angiogenesis and growth of human prostate carcinoma micro tumors in vivo

Tumor promoting effect of spheroids in an orthotopic prostate cancer mouse model

In this study, we aimed to establish a technique for intraprostatic implantation of prostate cancer (PCa) spheroids and to identify the impact of three-dimensional organization of PCa cells on tumor progression and metastasis in a representative in vivo model. 40,000 LNCaP cells were implanted into the prostate of immunodeficient SCID mice either as single cells (n = 8) or as preformed 3D spheroids (n = 8). For a follow up of 20 weeks, tumor growth was monitored by serum PSA and high-resolution 3D ultrasonography. Eventually, animals were sacrificed and autopsied. The organ dissects were analyzed for the presence of metastases by histology (H&E) and immunohistochemistry (AMACR, AR, Ki-67, CK5, CK8, E-Cadherin, Vimentin). Solid intraprostatic tumors developed in 50% of mice after spheroid implantation and in 50% of mice after implantation of a single cells. Primary tumors of LNCaP spheroids evolved earlier, exhibiting a shorter tumor doubling time whilst developing larger tumor volumes, which was reflected by a higher immunohistochemical expression of Ki-67 and AR, too. Spheroid tumors established lung and lymph node metastases in 75% of mice, in contrast to 50% of mice after single cell implantation. Our technique enables a variety of studies regarding the influence of the tumor microenvironment on PCa progression.

Xenografts on nude mouse diaphragm of human DU145 prostate carcinoma cells: mesothelium removal by outgrowths and angiogenesis

Human prostate carcinoma DU145 cells, androgen-independent malignant cells, implanted in the athymic nu/nu male mouse, developed numerous tumors on peritoneal and retro-peritoneal organs whose growth aspects and vascular supply have yet to be investigated with fine structure techniques. A series of necropsies from moribund implanted mice diaphragms were examined with light, scanning, and transmission electron microscopy. DU145 xenografts installations, far away from the implanted site, were described as the smallest installation to large diaphragm outgrowths in moribund mice. Carcinomas did not show extracellular matrix and, reaching more than 0.15 mm in thickness, they revealed new structures in these outgrowths. Voids to be gland-like structures with mediocre secretion and, unexpectedly, intercellular spaces connected with fascicles of elongated DU145 cells that merged with a vascular supply originated from either the tumor cells and/or some perimysium vessels. In the largest carcinomas, most important vascular invasions coincidently accompanied the mouse lethality, similarly to human cancers. This androgen-independent model would be useful to study tumor outgrowth's changes related to testing anticancer strategy, including anti-angiogenic therapies involving toxicity, simultaneously with those of other vital organs with combined biomolecular and fine structure techniques.

Vascular endothelial growth factor (VEGF) targeting therapy for persistent, recurrent, or metastatic cervical cancer

BACKGROUND

Cervical cancer ranks as the fourth leading cause of death from cancer in women. Historically, women with metastatic or recurrent cervical cancer have had limited treatment options. New anti-angiogenesis therapies, such as vascular endothelial growth factor (VEGF) targeting agents, offer an alternative strategy to conventional chemotherapy; they act by inhibiting the growth of new blood vessels, thereby restricting tumour growth by blocking the blood supply.

OBJECTIVES

To assess the benefits and harms of VEGF targeting agents in the management of persistent, recurrent, or metastatic cervical cancer.

SEARCH METHODS

We performed searches of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, online registers of clinical trials, and abstracts of scientific meetings up until 27 May 2020.

SELECTION CRITERIA

We examined randomised controlled trials (RCTs) that evaluated the use of VEGF targeting agents alone or in combination with conventional chemotherapy or other VEGF targeting agents.

DATA COLLECTION AND ANALYSIS

Three review authors independently screened the results of search strategies, extracted data, assessed risk of bias, and analysed data according to the standard methods expected by Cochrane. The certainty of evidence was assessed via the GRADE approach.

MAIN RESULTS

A total of 1634 records were identified. From these, we identified four studies with a total of 808 participants for inclusion. We also identified two studies that were awaiting classification and nine ongoing studies. Bevacizumab plus chemotherapy versus chemotherapy Treatment with bevacizumab plus chemotherapy may result in lower risk of death compared to chemotherapy alone (hazard ratio (HR) 0.77, 95% confidence interval (CI) 0.62 to 0.95; 1 study, 452 participants; low-certainty evidence). However, there are probably more specific adverse events when compared to chemotherapy alone, including gastrointestinal perforations or fistulae (risk ratio (RR) 18.00, 95% CI 2.42 to 133.67; 1 study, 440 participants; moderate-certainty evidence); serious thromboembolic events (RR 4.5, 95% CI 1.55 to 13.08; 1 study, 440 participants; moderate-certainty evidence); and hypertension (RR 13.75, 95% CI 5.07 to 37.29; 1 study, 440 participants; moderate-certainty evidence). There may also be a higher incidence of serious haemorrhage (RR 5.00, 95% CI 1.11 to 22.56; 1 study, 440 participants; low-certainty evidence). In addition, the incidence of serious adverse events is probably higher (RR 1.44, 95% CI 1.16 to 1.79; 1 study, 439 participants; moderate-certainty evidence). The incremental cost-effectiveness ratio was USD 295,164 per quality-adjusted life-year (1 study, 452 participants; low-certainty evidence). Cediranib plus chemotherapy versus chemotherapy Treatment with cediranib plus chemotherapy may or may not result in similar risk of death when compared to chemotherapy alone (HR 0.94, 95% CI 0.53 to 1.65; 1 study, 69 participants; low-certainty evidence). We found very uncertain results for the incidences of specific adverse events, including gastrointestinal perforations or fistulae (RR 3.27, 95% CI 0.14 to 77.57; 1 study, 67 participants; very low-certainty evidence); serious haemorrhage (RR 5.45, 95% CI 0.27 to 109.49; 1 study, 67 participants; very low-certainty evidence); serious thromboembolic events (RR 3.41, 95% CI 0.14 to 80.59; 1 study, 60 participants; very low-certainty evidence); and serious hypertension (RR 0.36, 95% CI 0.02 to 8.62; 1 study, 67 participants; very low-certainty evidence). In addition, there may or may not be a similar incidence of serious adverse events compared to chemotherapy alone (RR 1.15, 95% CI 0.75 to 1.78; 1 study, 67 participants; low-certainty evidence). Apatinib plus chemotherapy or chemotherapy/brachytherapy versus chemotherapy or chemotherapy/brachytherapy Treatment with apatinib plus chemotherapy or chemotherapy/brachytherapy may or may not result in similar risk of death compared to chemotherapy alone or chemotherapy/brachytherapy alone (HR 0.90, 95% CI 0.51 to 1.60; 1 study, 52 participants; low-certainty evidence). However, hypertension events may occur at a higher incidence as compared to chemotherapy alone or chemotherapy/brachytherapy alone (RR 5.14, 95% CI 1.28 to 20.73; 1 study, 52 participants; low-certainty evidence). Pazopanib plus lapatinib versus lapatinib Treatment with pazopanib plus lapatinib may result in higher risk of death compared to lapatinib alone (HR 2.71, 95% CI 1.16 to 6.31; 1 study, 117 participants; low-certainty evidence). We found very uncertain results for the incidences of specific adverse events, including gastrointestinal perforations or fistulae (RR 2.00, 95% CI 0.19 to 21.59; 1 study, 152 participants; very low-certainty evidence); haemorrhage (RR 2.00, 95% CI 0.72 to 5.58; 1 study, 152 participants; very low-certainty evidence); and thromboembolic events (RR 3.00, 95% CI 0.12 to 72.50; 1 study, 152 participants; very low-certainty evidence). In addition, the incidence of hypertension events is probably higher (RR 12.00, 95% CI 2.94 to 49.01; 1 study, 152 participants; moderate-certainty evidence). There may or may not be a similar incidence of serious adverse events as compared to lapatinib alone (RR 1.45, 95% CI 0.94 to 2.26; 1 study, 152 participants; low-certainty evidence). Pazopanib versus lapatinib Treatment with pazopanib may or may not result in similar risk of death as compared to lapatinib (HR 0.96, 95% CI 0.67 to 1.38; 1 study, 152 participants; low-certainty evidence). We found very uncertain results for the incidences of specific adverse events, including gastrointestinal perforations or fistulae (RR 1.03, 95% CI 0.07 to 16.12; 1 study, 150 participants; very low-certainty evidence); haemorrhage (RR 1.03, 95% CI 0.31 to 3.40; 1 study, 150 participants; very low-certainty evidence); and thromboembolic events (RR 3.08, 95% CI 0.13 to 74.42; 1 study, 150 participants; very low-certainty evidence). In addition, the incidence of hypertension events is probably higher (RR 11.81, 95% CI 2.89 to 48.33; 1 study, 150 participants; moderate-certainty evidence). The risk of serious adverse events may or may not be similar as compared to lapatinib (RR 1.31, 95% CI 0.83 to 2.07; 1 study, 150 participants; low-certainty evidence).

AUTHORS' CONCLUSIONS

We found low-certainty evidence in favour of the use of bevacizumab plus chemotherapy. However, bevacizumab probably increases specific adverse events (gastrointestinal perforations or fistulae, thromboembolic events, hypertension) and serious adverse events. We found low-certainty evidence that does not support the use of cediranib plus chemotherapy, apatinib plus chemotherapy, apatinib plus chemotherapy/brachytherapy, or pazopanib monotherapy. We found low-certainty evidence suggesting that pazopanib plus lapatinib worsens outcomes. The VEGF inhibitors apatinib and pazopanib may increase the probability of hypertension events.

Why we do what we do. A brief analysis of cancer therapies

The goal of all medical activity is to preserve health in fit people, and to restore the sick into a state of complete physical, mental and social wellbeing. In an effort to determine whether we are achieving this last goal in oncology, herein we review the biological and clinical framework that has led to the foundations of the current anticancer treatment paradigm. Currently, cancer therapy is still based on the ancient axiom that states that the complete eradication of the tumor burden is the only way to achieve a cure. This strategy has led to a substantial improvement in survival rates as cancer mortality rates have dropped in an unprecedented way. Despite this progress, more than 9 million people still die from cancer every year, indicating that the current treatment strategy is not leading to a cancer cure, but to a cancer remission, that is "the temporary absence of manifestations of a particular disease"; after months or years of remission, in most patients, cancer will inevitably recur. Our critical analysis indicates that it is time to discuss about the new key challenges and future directions in clinical oncology. We need to generate novel treatment strategies more suited to the current clinical reality.

Three-Dimensional Cell Cultures as an In Vitro Tool for Prostate Cancer Modeling and Drug Discovery

In the last decade, three-dimensional (3D) cell culture technology has gained a lot of interest due to its ability to better recapitulate the in vivo organization and microenvironment of in vitro cultured cancer cells. In particular, 3D tumor models have demonstrated several different characteristics compared with traditional two-dimensional (2D) cultures and have provided an interesting link between the latter and animal experiments. Indeed, 3D cell cultures represent a useful platform for the identification of the biological features of cancer cells as well as for the screening of novel antitumor agents. The present review is aimed at summarizing the most common 3D cell culture methods and applications, with a focus on prostate cancer modeling and drug discovery.

Resistance to Anti-angiogenic Therapies: A Mechanism Depending on the Time of Exposure to the Drugs

Angiogenesis, the formation of new blood vessels from preexisting one, represents a critical process for oxygen and nutrient supply to proliferating cells, therefore promoting tumor growth and metastasis. The Vascular Endothelial Growth Factor (VEGF) pathway is one of the key mediators of angiogenesis in cancer. Therefore, several therapies including monoclonal antibodies or tyrosine kinase inhibitors target this axis. Although preclinical studies demonstrated strong antitumor activity, clinical studies were disappointing. Antiangiogenic drugs, used to treat metastatic patients suffering of different types of cancers, prolonged survival to different extents but are not curative. In this review, we focused on different mechanisms involved in resistance to antiangiogenic therapies from early stage resistance involving mainly tumor cells to late stages related to the adaptation of the microenvironment.

Cytokines and Chemokines as Mediators of Prostate Cancer Metastasis

The consequences of prostate cancer metastasis remain severe, with huge impact on the mortality and overall quality of life of affected patients. Despite the convoluted interplay and cross talk between various cell types and secreted factors in the metastatic process, cytokine and chemokines, along with their receptors and signaling axis, constitute important factors that help drive the sequence of events that lead to metastasis of prostate cancer. These proteins are involved in extracellular matrix remodeling, epithelial-mesenchymal-transition, angiogenesis, tumor invasion, premetastatic niche creation, extravasation, re-establishment of tumor cells in secondary organs as well as the remodeling of the metastatic tumor microenvironment. This review presents an overview of the main cytokines/chemokines, including IL-6, CXCL12, TGFβ, CXCL8, VEGF, RANKL, CCL2, CX3CL1, IL-1, IL-7, CXCL1, and CXCL16, that exert modulatory roles in prostate cancer metastasis. We also provide extensive description of their aberrant expression patterns in both advanced disease states and metastatic sites, as well as their functional involvement in the various stages of the prostate cancer metastatic process.

[18F]FET PET is a useful tool for treatment evaluation and prognosis prediction of anti-angiogenic drug in an orthotopic glioblastoma mouse model

O-2-¹⁸F-fluoroethyl-l-tyrosine ([¹⁸F]FET) has been widely used for glioblastomas (GBM) in clinical practice, although evaluation of its applicability in non-clinical research is still lacking. The objective of this study was to examine the value of [¹⁸F]FET for treatment evaluation and prognosis prediction of anti-angiogenic drug in an orthotopic mouse model of GBM. Human U87MG cells were implanted into nude mice and then bevacizumab, a representative anti-angiogenic drug, was administered. We monitored the effect of anti-angiogenic agents using multiple imaging modalities, including bioluminescence imaging (BLI), magnetic resonance imaging (MRI), and positron emission tomography-computed tomography (PET/CT). Among these imaging methods analyzed, only [¹⁸F]FET uptake showed a statistically significant decrease in the treatment group compared to the control group (P=0.02 and P=0.03 at 5 and 20 mg/kg, respectively). This indicates that [¹⁸F]FET PET is a sensitive method to monitor the response of GBM bearing mice to anti-angiogenic drug. Moreover, [¹⁸F]FET uptake was confirmed to be a significant parameter for predicting the prognosis of anti-angiogenic drug (P=0.041 and P=0.007, on Days 7 and 12, respectively, on Pearson's correlation; P=0.048 and P=0.030, on Days 7 and 12, respectively, on Cox regression analysis). However, results of BLI or MRI were not significantly associated with survival time. In conclusion, this study suggests that [¹⁸F]FET PET imaging is a pertinent imaging modality for sensitive monitoring and accurate prediction of treatment response to anti-angiogenic agents in an orthotopic model of GBM.

Linking microsomal prostaglandin E Synthase-1/PGE-2 pathway with miR-15a and -186 expression: Novel mechanism of VEGF modulation in prostate cancer

Prostaglandin E-2 (PGE-2) promotes tumor angiogenesis via paracrine secretion of pro-angiogenic growth factors, such as vascular endothelial growth factor (VEGF). Since miRNAs regulate several cell processes, including angiogenesis, we sought to determine whether they would influence PGE-2-induced VEGF. We compared DU145 and PC3 prostate cancer cells bearing the mPGES-1 enzyme (mPGES-1+/+) and producing PGE-2, with those in which the enzyme was silenced or deleted (mPGES-1-/-). We demonstrated that mPGES-1/PGE-2 signaling decreased Dicer expression and miRNA biogenesis. Genome-wide sequencing of miRNAs revealed that miR-15a and miR-186, associated with expression of VEGF and hypoxia inducible factor-1α (HIF-1α), were down-regulated in mPGES-1+/+ cells. As a consequence, mPGES-1+/+ tumor cells expressed high levels of VEGF and HIF-1α, induced endothelial cells activation and formed highly vascularized tumors. Mir-186 mimic inhibited VEGF expression in mPGES-1+/+ tumor xenografts and reduced tumor growth. In human prostate cancer specimens, mPGES-1 was over-expressed in tumors with high Gleason score, elevated expression of VEGF and HIF-1α, high microvessel density and decreased expression of Dicer, miR15a and miR-186. Thus, clear evidence for regulating miRNA processing and VEGF output by intrinsic PGE-2 production provides a means to distinguish between aggressive and indolent prostate tumors and suggests a potential target for controlling tumor progression.

MicroRNA-34a: A Key Regulator in the Hallmarks of Renal Cell Carcinoma

Renal cell carcinoma (RCC) incidence has increased over the past two decades. Recent studies reported microRNAs as promising biomarkers for early cancer detection, accurate prognosis, and molecular targets for future treatment. This study aimed to evaluate the expression levels of miR-34a and 11 of its bioinformatically selected target genes and proteins to test their potential dysregulation in RCC. Quantitative real-time PCR for miR-34a and its targets; MET oncogene; gene-regulating apoptosis (TP53INP2 and DFFA); cell proliferation (E2F3); and cell differentiation (SOX2 and TGFB3) as well as immunohistochemical assay for VEGFA, TP53, Bcl2, TGFB1, and Ki67 protein expression have been performed in 85 FFPE RCC tumor specimens. Clinicopathological parameter correlation and in silico network analysis have also implicated. We found RCC tissues displayed significantly higher miR-34a expression level than their corresponding noncancerous tissues, particularly in chromophobic subtype. MET and E2F3 were significantly upregulated, while TP53INP2 and SOX2 were downregulated. ROC analysis showed high diagnostic performance of miR-34a (AUC = 0.854), MET (AUC = 0.765), and E2F3 (AUC = 0.761). The advanced pathological grade was associated with strong TGFB1, VEGFA, and Ki67 protein expression and absent Tp53 staining. These findings indicate miR-34a along with its putative target genes could play a role in RCC tumorigenesis and progression.

The Role of CC-Chemokines in the Regulation of Angiogenesis

Angiogenesis, the formation of new blood vessels, is critical for survival and in the regenerative response to tissue injury or ischemia. However, in diseases such as cancer and atherosclerosis, inflammation can cause unregulated angiogenesis leading to excessive neovascularization, which exacerbates disease. Current anti-angiogenic therapies cause complete inhibition of both inflammatory and ischemia driven angiogenesis causing a range of side effects in patients. Specific inhibition of inflammation-driven angiogenesis would therefore be immensely valuable. Increasing evidence suggests that the CC-chemokine class promotes inflammation-driven angiogenesis, whilst there is little evidence for a role in ischemia-mediated angiogenesis. The differential regulation of angiogenesis by CC-chemokines suggests it may provide an alternate strategy to treat angiogenesis associated pathological diseases. The focus of this review is to highlight the significant role of the CC-chemokine class in inflammation, versus ischemia driven angiogenesis, and to discuss the related pathologies including atherosclerosis, cancer, and rheumatoid arthritis. We examine the pros and cons of anti-angiogenic therapies currently in clinical trials. We also reveal novel therapeutic strategies that cause broad-spectrum inhibition of the CC-chemokine class that may have future potential for the specific inhibition of inflammatory angiogenesis.

[Safety of Neoadjuvant Bevacizumab plus Pemetrexed and Carboplatin in Patients with IIIa Lung Adenocarcinoma]

背景与目的

贝伐珠单抗联合化疗在晚期肺腺癌治疗中已取得较好疗效，本研究探讨贝伐珠单抗联合培美曲塞加卡铂方案作为Ⅲa期肺腺癌患者的新辅助方案对手术安全性的影响。

方法

选择在中山大学肿瘤防治中心应用贝伐珠单抗联合培美曲塞加卡铂方案进行新辅助化疗的Ⅲa期肺腺癌患者25例，所有病例均在新辅助化疗2周期后，接受肺叶或者全肺叶切除加纵隔淋巴结清扫术。分析患者在化疗期间的毒性反应以及患者在围手术期间的并发症。

结果

与新辅助化疗相关的3级-4级的不良事件包括3例疲劳事件、3例嗜中性白血球减少症和1例高血压。认为与贝伐珠单抗相关的不良事件包括2例鼻出血（1例1级、1例2级）和3例高血压（2例1级、1例3级）。在围手术期出现的并发症包括肺炎（2例）、支气管残端瘘（1例）、肺不张（2例）和心律失常（1例）。围手术期没有观察到既往贝伐珠单抗联合化疗中常见的出血事件、血栓事件以及伤口愈合问题的发生。

结论

贝伐珠单抗联合培美曲塞加卡铂作为新辅助化疗方案是对于Ⅲa期肺腺癌患者来说是安全的，可以耐受的。

MTA family of proteins in prostate cancer: biology, significance, and therapeutic opportunities

This review summarizes our current understanding of the role of MTA family members, particularly MTA1, with a special emphasis on prostate cancer. The interest for the role of MTA1 in prostate cancer was boosted from our initial findings of MTA1 as a component of "vicious cycle" and a member of bone metastatic signature. Analysis of human prostate tissues, xenograft and transgenic mouse models of prostate cancer, and prostate cancer cell lines has provided support for the role of MTA1 in advanced disease and its potential role in initial stages of prostate tumor progression. Recent discoveries have highlighted a critical role for MTA1 in inflammation-triggered prostate tumorigenesis, epithelial-to-mesenchymal transition, prostate cancer survival pathways, and site metastasis. Evidence for MTA1 as an upstream negative regulator of tumor suppressor genes such as p53 and PTEN has also emerged. MTA1 is involved in prostate tumor angiogenesis by regulating several pro-angiogenic factors. Evidence for MTA1 as a prognostic marker for aggressive prostate cancer and disease recurrence has been described. Importantly, pharmacological dietary agents, namely resveratrol and its analogs, are potentially applicable to prostate cancer prevention, treatment, and control of cancer progression due to their potent inhibitory effects on MTA proteins.

Targeting angiogenesis in advanced cervical cancer

Patients with advanced stage or recurrent cervical cancer represent a population with limited chemotherapeutic options. More specifically, patients with recurrent disease have a poor salvage rate, with a 5-year survival rate of less than 10%. This year, the first prospective phase III clinical trial exploring the anti-angiogenic agent, bevacizumab, was published, meeting its primary endpoint, with a significant improvement in overall survival. As such, a review of anti-angiogenic therapy in the treatment of this disease is warranted.

Limitations of the dorsal skinfold window chamber model in evaluating anti-angiogenic therapy during early phase of angiogenesis

Background

Angiogenesis is an essential process during tumor development and growth. The murine dorsal skinfold window chamber model has been used for the study of both tumor microvasculature and other vascular diseases, including the study of anti-angiogenic agents in cancer therapy. Hyperspectral imaging of oxygen status of the microvasculature has not been widely used to evaluate response to inhibition of angiogenesis in early tumor cell induced vascular development. This study demonstrates the use of two different classes of anti-angiogenic agents, one targeting the Vascular Endothelial Growth Factor (VEGF) pathway involved with vessel sprouting and the other targeting the Angiopoietin/Tie2 pathway involved in vascular destabilization. Studies evaluated the tumor microvascular response to anti-angiogenic inhibitors in the highly angiogenic renal cell carcinoma induced angiogenesis model.

Methods

Human renal cell carcinoma, Caki-2 cells, were implanted in the murine skinfold window chamber. Mice were treated with either VEGF pathway targeted small molecule inhibitor Sunitinib (100 mg/kg) or with an anti-Ang-2 monoclonal antibody (10 mg/kg) beginning the day of window chamber surgery and tumor cell implantation. Hyperspectral imaging of hemoglobin saturation was used to evaluate both the development and oxygenation of the tumor microvasculature. Tumor volume over time was also assessed over an 11-day period post surgery.

Results

The window chamber model was useful to demonstrate the inhibition of angiogenesis using the VEGF pathway targeted agent Sunitinib. Results show impairment of tumor microvascular development, reduced oxygenation of tumor-associated vasculature and impairment of tumor volume growth compared to control. On the other hand, this model failed to demonstrate the anti-angiogenic effect of the Ang-2 targeted agent. Follow up experiments suggest that the initial surgery of the window chamber model may interfere with such an agent thus skewing the actual effects on angiogenesis.

Conclusions

Results show that this model has great potential to evaluate anti-VEGF, or comparable, targeted agents; however the mere protocol of the window chamber model interferes with proper evaluation of Ang-2 targeted agents. The limitations of this in vivo model in evaluating the response of tumor vasculature to anti-angiogenic agents are discussed.

Pilot study of (89)Zr-bevacizumab positron emission tomography in patients with advanced non-small cell lung cancer

BACKGROUND

The aim of this pilot study was to evaluate whether the uptake of (89)Zr-bevacizumab in non-small cell lung cancer (NSCLC) tumors could be visualized and quantified. The correlation between tumor (89)Zr-bevacizumab uptake and tumor response to antitumor therapy with a bevacizumab-based regimen was explored.

METHODS

Seven NSCLC patients underwent static PET scans at days 4 and 7 after injection of 36.4 ± 0.9 MBq (mean ± SD) (89)Zr-bevacizumab, prior to commencing carboplatin-paclitaxel-bevacizumab chemotherapy (CPB). Overall survival (OS) and progression-free survival (PFS) to CPB followed by bevacizumab maintenance therapy was correlated to tumor tracer uptake, quantified using peak standardized uptake values (SUVpeak).

RESULTS

Zr-bevacizumab uptake (SUVpeak) was approximately four times higher in tumor tissues (primary tumor and metastases) than in non-tumor tissues (healthy muscle, lung, and fat) on days 4 and 7. A positive trend but no significant correlation could be found between SUVpeak and OS or PFS.

CONCLUSIONS

This pilot study shows that (89)Zr-bevacizumab PET imaging in NSCLC is feasible. Further investigation to validate this technique as a predictive biomarker for selecting patients for bevacizumab treatment is warranted.

Incorporation of anti-angiogenesis therapy in the management of advanced ovarian carcinoma--mechanistics, review of phase III randomized clinical trials, and regulatory implications

Despite survival gains achieved nearly two decades ago with combination platinum- and taxane-based intravenous chemotherapy, overall survival curves have remained relatively unchanged during the 21st century using newer cytotoxic agents. Although combined intravenous-intraperitoneal (IV-IP) chemotherapy is promising, tolerability remains a significant issue. An emphasis has been placed on exploring dose dense schedules and targeted agents. Vascular endothelial growth factor (VEGF) has emerged as an important therapeutic target in several solid tumors including ovarian carcinoma. The monoclonal antibody, bevacizumab, binds VEGF, thus preventing activation of the VEGF receptor (VEGFR) leading to inhibition of tumor angiogenesis. To date eight phase 3 randomized controlled trials incorporating anti-angiogenesis therapy in the treatment of newly diagnosed and recurrent ovarian carcinoma have met their primary endpoints. Four of these trials included bevacizumab and were reported from 2010 to 2012. During 2013, the other four studies were reported, each studying one of the following novel anti-angiogenesis agents: pazopanib, cediranib, trebananib, and nintedanib. Importantly, none of these drugs have been approved by the United States Food and Drug Administration (US FDA) for the treatment of ovarian cancer. The purpose of this review will be to highlight both VEGF-dependent and non-VEGF dependent angiogenic pathways in ovarian cancer and discuss the phase 3 experiences and regulatory implications of targeting the tumor microenviroment with anti-angiogenesis therapy.

Anti-VEGFA Therapy Reduces Tumor Growth and Extends Survival in a Murine Model of Ovarian Granulosa Cell Tumor

Although angiogenesis has been proposed as a therapeutic target for the treatment of ovarian granulosa cell tumor (GCT), its potential has not been evaluated in controlled studies. To do so, we used the Pten (tm1Hwu/tm1Hwu); Ctnnb1 (tm1Mmt/+);Amhr2 (tm3(cre)Bhr/+) (PCA) mouse model, which develops GCTs that mimic the advanced disease in women. A monoclonal anti-vascular endothelial growth factor A (VEGFA) antibody was administered weekly to PCA mice beginning at 3 weeks of age. By 6 weeks of age, anti-VEGFA therapy significantly decreased tumor weights relative to controls (P < .05) and increased survival, with all treated animals but none of the controls surviving to 8 weeks of age. Analyses of PCA tumors showed that anti-VEGFA treatment resulted in significant decreases in tumor cell proliferation and microvessel density relative to controls (P < .05). However, treatment did not have a significant effect on apoptosis or tumor necrosis. The VEGFA receptor 2 (VEGFR2) signaling effector p44/p42 mitogen-activated protein kinase (MAPK), whose activity is associated with cell proliferation, was significantly less phosphorylated (i.e., activated) in tumors from the treated group (P < .05). Conversely, no significant difference was found in the activation of protein kinase B, a VEGFR2 signaling effector associated with cell survival. Together, these results suggest that anti-VEGFA therapy is effective at inhibiting GCT growth in the PCA model and acts by reducing microvascular density and cell proliferation through inhibition of the VEGFR2-MAPK pathway. Findings from this preclinical model therefore support the investigation of targeting VEGFA for the adjuvant treatment of GCT in women.

Measures of biosimilarity in monoclonal antibodies in oncology: the case of bevacizumab

Biosimilars have been available on the European market since 2006 and experience with their use is increasing. The next wave of biopharmaceuticals that are about to lose patent protection consists of more-complicated products, including many monoclonal antibodies. Guidance has been released on the particulars of a biosimilarity exercise involving these products. Considerable challenges exist to establish biosimilarity for anticancer products. An especially challenging product is bevacizumab (Avastin(®)). On the basis of data available for the innovator product (bevacizumab) we will discuss strengths and weaknesses of preclinical and clinical models and explore the application of novel endpoints to the biosimilar comparability exercise.

G protein-coupled receptor FPR1 as a pharmacologic target in inflammation and human glioblastoma

Formylpeptide receptor1 (FPR1) is a G protein-coupled receptor (GPCR) originally identified in phagocytic leucocytes and mediates cell chemotaxis and activation in response to bacterial formylated chemotactic peptides. However, FPR1 also participates in a signal relay which regulates the infiltration of phagocytes, in particular neutrophils, to inflammatory sites in response to tissue-derived chemoattractant ligands. In addition to participating in innate immune responses, recently, FPR1 has been shown to be expressed by highly malignant glioblastoma (GBM) cells. Upon activation by an endogenous agonist Annexin 1 (Anx A1) released by necrotic glioma cells, FPR1 transactivates the receptor for epithelial growth factor (EGFR) and consequently to promote glioma cell chemotaxis, invasion, growth and production of angiogenic factors. The observations demonstrate that FPR1, as a multifunctional GPCR with pattern recognition properties, is not only involved in innate immune responses but also in the progression of GBM. Thus, FPR1 is an immunopharmacologic target for development of novel therapies.

Finding the place of histone deacetylase inhibitors in prostate cancer therapy

Histone deacetylase inhibitors (HDACIs) are showing promise as therapeutic agents for hematological malignancies and solid tumors. In the case of prostate cancer, HDACIs are effective at inhibiting proliferation and inducing apoptosis in a range of in vitro and in vivo experimental models. Recent studies have revealed that the actions of HDACIs in prostate cancer cells extend beyond regulation of histone acetylation and affect proteins involved in maintaining cellular homeostasis and tumor progression, including the androgen receptor, p21(WAF1) and VEGF. The broad spectrum of HDACI targets has allowed rational design of combinations with other therapeutic agents to target multiple pathways involved in prostate cancer progression, including angiogenesis and androgen signaling. In particular, synergistic inhibition of prostate cancer cell growth has been demonstrated using HDACIs in combination with radio- and chemo-therapy, Apo2L/TRAIL, angiogenesis inhibitors, heat-shock protein 90 inhibitors and androgen receptor antagonists. This review examines the current understanding of the actions of HDACIs in prostate cancer cells, both in a laboratory and a clinical context and discusses the potential utility of combination strategies for the treatment of prostate cancer.

Phase I study of bevacizumab, everolimus, and panobinostat (LBH-589) in advanced solid tumors

PURPOSE

To define the maximum tolerated dose, clinical toxicities, and pharmacodynamics of bevacizumab, everolimus, and panobinostat (LBH-589) when administered in combination to patients with advanced solid tumor malignancies.

EXPERIMENT DESIGN

Subjects received 10 mg of panobinostat three times weekly, 5 or 10 mg everolimus daily, and bevacizumab at 10 mg/kg every 2 weeks. Dose-limiting toxicities (DLTs) were assessed in cycle 1; toxicity evaluation was closely monitored throughout treatment. Treatment continued until disease progression or undesirable toxicity. Protein acetylation was assessed in peripheral blood mononuclear cells (PBMC) both at baseline and on treatment.

RESULTS

Twelve subjects were evaluable for toxicity and nine subjects for response. DLTs in cohort 1 included grade 2 esophagitis and grade 3 oral mucositis; DLTs in cohort -1 were grade 2 ventricular arrhythmia and grade 2 intolerable skin rash. Common adverse events were diarrhea (50 %), headache (33 %), mucositis/stomatitis (25 %), hyperlipidemia (25 %), and thrombocytopenia (25 %). There was 1 partial response; an additional 2 subjects had stable disease as best response. No consistent changes in protein acetylation in PBMC were observed in samples available from eight patients on treatment compared with baseline.

CONCLUSIONS

Bevacizumab, everolimus, and panobinostat in combination at the lowest proposed doses did not have an acceptable safety and tolerability profile and did not consistently inhibit HDAC activity; therefore, we do not recommend further evaluation.

[Targeted therapy and breast cancer: state of the art]

CONTEXT

Scientific advances in molecular biology and understanding of oncogenesis have lead to anticancer molecular targeted therapies. They encompass monoclonal antibodies binding to active membrane epitopes and small molecules interfering with enzymatic reactions essential to cancer cell survival (oncogene addiction). These pathways may be optimal targets. Clinical benefits achieved using these targeted agents have been outstanding both in localized and metastatic disease.

METHOD

We conducted a survey of literature analyzing activity and safety of targeted agents approved by FDA and/or FDA for the treatment of patients with breast cancer: anti-HER2 and antiangiogenic agents.

RESULTS

Activity and main toxicities of these targeted agents are described according to signaling pathway targeted as well as stage of breast cancer.

CONCLUSIONS

Availability of these targeted therapies has indeed transformed the outcome of subgroups of breast cancer to the expense of acceptable and manageable side effects, as compared to classical cytotoxics to which they are nevertheless combined.

Recent developments in treatments targeting castration-resistant prostate cancer bone metastases

BACKGROUND

Prostate cancer is the most common male cancer and one of the top causes of male cancer-related death. Most patients with prostate cancer respond to initial androgen deprivation therapy before progressing to castration-resistant prostate cancer (CRPC) and eventually developing bone metastases. Growth of prostate cancer metastases in the bone microenvironment produces numerous factors that disrupt the dynamic equilibrium of osteogenesis and osteolysis existing in healthy bone, leading to progressive morbidity, poor quality of life, and increased treatment costs.

MATERIALS AND METHODS

Relevant studies of CRPC and targeted therapies were identified from literature and clinical trial databases, websites, and conference abstracts.

RESULTS

Available data on agents potentially targeting bone metastatic CRPC or the bone microenvironment in patients with CRPC are discussed, including inhibitors of tumor growth/survival and bone turnover (SRC family kinase inhibitors, endothelin-1 inhibitors, MET inhibitors, and thalidomide and its derivatives), inhibitors of bone turnover (bisphosphonates and receptor activator of nuclear factor-kB ligand inhibitors), antiangiogenic agents (vascular endothelial growth factor receptor and platelet-derived growth factor blockers), prostate cancer vaccines, and bone-directed radiopharmaceuticals.

CONCLUSIONS

With increasing data availability demonstrating tumor-bone microenvironment interactions and routine incorporation of bone-related end points into CRPC trials, bone microenvironment-targeted agents are likely to become an increasingly important component of CRPC treatment.

Bevacizumab-based therapies in the first-line treatment of metastatic colorectal cancer

Since its approval for the first-line treatment of metastatic colorectal cancer (mCRC), bevacizumab has become a standard treatment option in combination with chemotherapy for patients with mCRC. Bevacizumab has demonstrated efficacy in combination with a number of different backbone chemotherapy regimens, and its widespread use has introduced several important questions regarding the selection and optimization of bevacizumab-based treatment regimens, its use in various patient populations, and the identification of associated adverse events. This review discusses the results of several phase II and phase III clinical trials, as well as large observational studies, to address the use of bevacizumab in the treatment of patients with mCRC in the first-line setting.

Progress of molecular targeted therapies for prostate cancers

Prostate cancer remains the most commonly diagnosed malignancy and the second leading cause of cancer-related deaths in men in the United States. The current standard of care consists of prostatectomy and radiation therapy, which may often be supplemented with hormonal therapies. Recurrence is common, and many develop metastatic prostate cancer for which chemotherapy is only moderately effective. It is clear that novel therapies are needed for the treatment of the malignant forms of prostate cancer that recur after initial therapies, such as hormone refractory (HRPC) or castration resistant prostate cancer (CRPC). With advances in understanding of the molecular mechanisms of cancer, we have witnessed unprecedented progress in developing new forms of targeted therapy. Several targeted therapeutic agents have been developed and clinically used for the treatment of solid tumors such as breast cancer, non-small cell lung cancer, and renal cancer. Some of these reagents modulate growth factors and/or their receptors, which are abundant in cancer cells. Other reagents target the downstream signal transduction, survival pathways, and angiogenesis pathways that are abnormally activated in transformed cells or metastatic tumors. We will review current developments in this field, focusing specifically on treatments that can be applied to prostate cancers. Finally we will describe aspects of the future direction of the field with respect to discovering biomarkers to aid in identifying responsive prostate cancer patients.

Anatomic closure of the premature patent ductus arteriosus: The role of CD14+/CD163+ mononuclear cells and VEGF in neointimal mound formation

Permanent closure of the newborn ductus arteriosus requires the development of neointimal mounds to completely occlude its lumen. VEGF is required for neointimal mound formation. The size of the neointimal mounds (composed of proliferating endothelial and migrating smooth muscle cells) is directly related to the number of VLA4 mononuclear cells that adhere to the ductus lumen after birth. We hypothesized that VEGF plays a crucial role in attracting CD14/CD163 mononuclear cells (expressing VLA4) to the ductus lumen and that CD14/CD163 cell adhesion to the ductus lumen is important for neointimal growth. We used neutralizing antibodies against VEGF and VLA-4 to determine their respective roles in remodeling the ductus of premature newborn baboons. Anti-VEGF treatment blocked CD14/CD163 cell adhesion to the ductus lumen and prevented neointimal growth. Anti-VLA-4 treatment blocked CD14/CD163 cell adhesion to the ductus lumen, decreased the expression of PDGF-B (which promotes smooth muscle migration), and blocked smooth muscle influx into the neointimal subendothelial space (despite the presence of increased VEGF in the ductus wall). We conclude that VEGF is necessary for CD14/CD163 cell adhesion to the ductus lumen and that CD14/CD163 cell adhesion is essential for VEGF-induced expansion of the neointimal subendothelial zone.

Bevacizumab and weekly docetaxel in patients with metastatic castrate-resistant prostate cancer previously exposed to docetaxel

Background. The aim of this paper was to evaluate the activity and tolerability of docetaxel (D) and bevacizumab (Bev) in patients with metastatic castrate-resistant prostate cancer (CRPC) previously exposed to D. Methods. Treatment consisted of D 30 mg/m(2) i.v. for four consecutive weekly administrations followed by a 2-week rest interval, in addition to Bev 5 mg/kg i.v. every 2 weeks. Results. Forty-three patients were enrolled: a PSA response was observed in 27 patients (62.7%, 95% CI: 0.41 to 0.91), and a palliative response was achieved in 31 patients (72.1%, 95%CI: 0.48 to 1.02). After a median followup of 11.3 months, only five patients had died. The regimen was generally well tolerated. Conclusion. Weekly D + biweekly Bev seems to be an effective and well-tolerated treatment option for patients with metastatic CRPC previously exposed to D-based chemotherapy.

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.

The VEGF family in cancer and antibody-based strategies for their inhibition

Angiogenesis is required in normal physiological processes, but is also involved in tumor growth, progression and metastasis. Vascular endothelial growth factor (VEGF), a primary mediator of angiogenesis in normal physiology and in disease, and other VEGF family members and their receptors provide targets that have been explored extensively for cancer therapy. Small molecule inhibitors and antibody/protein-based strategies that target the VEGF pathway have been studied in multiple types of cancer. This review will focus on VEGF pathway targeting antibodies that are currently being evaluated in pre-clinical and clinical studies.

Disease Course Patterns After Discontinuation of Bevacizumab: Pooled Analysis of Randomized Phase III Trials

Purpose

Preclinical studies have suggested accelerated tumor growth, local invasion, and distant metastasis after withdrawal of treatment with some antiangiogenic agents. To investigate whether discontinuation of bevacizumab treatment is associated with accelerated disease progression or increased mortality, we retrospectively analyzed five randomized, placebo-controlled phase III studies in 4,205 patients with breast, colorectal, renal, and pancreatic cancer.

Methods

Time from treatment discontinuation to progressive disease or death was analyzed in patients discontinuing bevacizumab/placebo as a result of adverse events (AEs). Mortality rates were assessed at 30, 60, 90, 120, 150, 180, and 210 days after the last bevacizumab/placebo dose in the following two groups: patients discontinuing bevacizumab/placebo as a result of AEs and patients discontinuing bevacizumab/placebo for any reason. In the same groups, time from treatment discontinuation to death was analyzed. Data on disease progression pattern were available and analyzed in four of the five studies.

Results

In the pooled analysis, median time from discontinuation as a result of AEs to progression/death was 3.0 months (95% CI, 2.6 to 3.8 months) for placebo and 4.0 months (95% CI, 3.4 to 4.6 months) for bevacizumab (hazard ratio, 0.93; 95% CI, 0.79 to 1.10). Mortality rates from 30 days to 210 days after treatment discontinuation and time from discontinuation to death were similar in bevacizumab- and placebo-treated patients. In addition, similar patterns of disease progression were seen in bevacizumab- and placebo-treated patients.

Conclusion

This retrospective analysis of five placebo-controlled clinical trials does not support a decreased time to disease progression, increased mortality, or altered disease progression pattern after cessation of bevacizumab therapy.

Clinical applications of VEGF-trap (aflibercept) in cancer treatment

Angiogenesis is one of the key acquired characteristics or "hallmarks" essential for the growth and development of all solid tumor types. The antiangiogenic agent vascular endothelial growth factor-Trap (VEGF-Trap) (aflibercept), which is a composite decoy receptor based on VEGF receptor-1 and VEGF receptor-2 fused to an Fc segment of immunoglobulin G1 that binds specifically to VEGF, has demonstrated preclinical efficacy in a range of different tumor types. VEGF-Trap exerts its antiangiogenic effects through regression of tumor vasculature, remolding or normalization of surviving vasculature, and inhibition of new tumor vessel growth. Preclinical and clinical studies have reported that VEGF-Trap can be combined effectively with both chemotherapy and radiotherapy. This review examines the main effects of VEGF-Trap on tumor vasculature and on different types of solid tumors, and explores the preclinical and clinical benefits of incorporating VEGF-Trap into anticancer treatment strategies.

Betulinic acid induces apoptosis and inhibits hedgehog signalling in rhabdomyosarcoma

Background:

Rhabdomyosarcoma (RMS) is the most common soft-tissue sarcoma in childhood with the ability to resist apoptosis by the activation of survival promoting and anti-apoptotic proteins.

Methods:

Efficacy of the apoptosis-inducing agent betulinic acid (BA) was determined in RMS cell cultures and in vivo by measuring cell viability, survival, apoptosis, hedgehog signalling activity, and neovascularisation.

Results:

Betulinic acid had a strong cytotoxic effect on RMS cells in a dose-dependent manner. The BA treatment caused a massive induction of apoptosis mediated by the intrinsic mitochondrial pathway, which could be inhibited by the broad-range caspase inhibitor zVAD.fmk. Exposure of hedgehog-activated RMS-13 cells to BA resulted in a strong decrease in GLI1, GLI2, PTCH1, and IGF2 expression as well as hedgehog-responsive luciferase activity. Intraperitoneal injection of 20 mg BA per kg per day significantly retarded growth of RMS-13 xenografts in association with markedly higher counts of apoptotic cells and down-regulation of GLI1 expression compared with control tumours, while leaving microvascular density, cell proliferation, and myogenic differentiation unaffected.

Conclusion:

Our data show that induction of apoptosis and inhibition of hedgehog signalling are important features of the anti-tumourigenic effect of BA in RMS and advices this compound for the use in a multimodal therapy of this highly aggressive paediatric tumour.

VEGF inhibitors and prostate cancer therapy

Prostate cancer remains the most common non-cutaneous malignancy among American men. Since the advent of PSA testing, most men are diagnosed with localized disease, but a proportion of men will be diagnosed with metastatic disease, many will eventually receive chemotherapy with docetaxel and prednisone. However, responses are not durable and all men will ultimately progress on this treatment. As such, continued efforts are geared towards the discovery of new agents and mechanisms of targeting prostate cancer. Angiogenesis has been shown to play an important role in tumorigenesis, proliferation and metastasis in prostate cancer. Here we discuss the major angiogenic signaling pathway involving VEGF in prostate cancer progression and the role of various promising agents that targets this pathway. This includes bevacizumab, thalidomide and its analogues, tyrosine kinase inhibitors sorafenib and AZD2171, and other inhibitors of angiogenic signaling pathways. Results of key clinical trials associated with the use of these agents and future directions are discussed herein.

Angiogenesis inhibition in cancer therapy: platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) and their receptors: biological functions and role in malignancy

Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen in vitro and an angiogenic inducer in a variety of in vivo models. VEGF gene transcription is induced in particular in hypoxic cells. In developmental angiogenesis, the role of VEGF is demonstrated by the finding that the loss of a single VEGF allele results in defective vascularization and early embryonic lethality. Substantial evidence also implicates VEGF as a mediator of pathological angiogenesis. In situ hybridization studies demonstrate expression of VEGF mRNA in the majority of human tumors. Platelet-derived growth factor (PDGF) is mainly believed to be an important mitogen for connective tissue, and also has important roles during embryonal development. Its overexpression has been linked to different types of malignancies. Thus, it is important to understand the physiology of VEGF and PDGF and their receptors as well as their roles in malignancies in order to develop antiangiogenic strategies for the treatment of malignant disease.

Bevacizumab (Avastin)

Bevacizumab is a humanized monoclonal antibody that was the first FDA approved therapy designed to inhibit angiogenesis. This paper will review the mechanism of action and clinical role of this antiangiogenic agent.

Targeting the Vascular Endothelial Growth Factor Pathway in the Treatment of Human Malignancy

Over 30 years ago, it was proposed that blocking new blood vessel formation would significantly inhibit solid tumor growth and hence, limit cancer progression. Efforts guided by this philosophy have resulted in a better understanding of the molecular basis of tumor angiogenesis. The first successful therapeutic to emerge from this work, an antibody (bevacizumab) targeting the vascular endothelial growth factor (VEGF), was recently approved for the treatment of colorectal cancer. Additional positive clinical data with bevacizumab in the treatment of breast and lung carcinoma have also been reported. These clinical achievements have validated the approach of anti-angiogenesis therapy for cancer and provided further confirmation for antibodies as a therapeutic class in this disease. Nevertheless, important unanswered questions with regard to preclinical and clinical results of VEGF pathway inhibitors remain. For example, preclinical models with a number of VEGF pathway inhibitors suggest that these agents would have significant clinical activity on their own; yet, clinical activity in patients with bevacizumab or other VEGF pathway inhibitors as monotherapy have been disappointing. Moreover, while bevacizumab is approved for the treatment of colorectal cancer in combination with cytotoxics, the mechanism for the benefits of this combination are still poorly understood, with a number of viable mechanisms under active experimental evaluation. The 3-8-month survival benefit in colorectal cancer patients treated with bevacizumab is a positive step forward. However, improving our understanding of the mechanism for these effects, as well as the mechanism underlying the inability as yet to achieve greater effects, is needed in order to follow up on the positive clinical results with improved strategies. This review discusses the experimental results surrounding the current status of our understanding of the mechanism of action of VEGF signaling inhibitors, and the potential for utilizing these agents in the future so that clinical benefits will be measured in years rather than months.

A HIF-1alpha-dependent autocrine feedback loop promotes survival of serum-deprived prostate cancer cells

BACKGROUND

We previously reported that normoxic, serum-deprived prostate cancer (PCa) cells upregulate hypoxia-inducible factor-1alpha (HIF-1alpha) protein, which promotes survival during serum deprivation via insulin-like growth factor-2 (IGF-2) upregulation. This study investigated the molecular mechanism of autocrine regulation of HIF-1alpha, IGF-2 and cell survival in serum-deprived PC-3 and LNCaP PCa cells.

METHODS

Cell viability was assessed by trypan blue assay. PI3K activity was inhibited with LY294002, and PTEN overexpression. mRNA was assessed by RT-PCR, and IGF-2 protein by ELISA. Activated insulin-like growth factor-I receptor (IGF-IR) was detected by probing immunoprecipitated IGF-IR for phospho-tyrosine. IGF-IR activity was inhibited with IGF-2 neutralizing antibody and IGF-IR-specific siRNA. HIF-1alpha, phospho-Akt, total-Akt and IGF-IR protein was assessed by immunoblots. HIF-1alpha was suppressed with siRNA.

RESULTS

We detected a time-dependent increase in Akt activation during serum deprivation, and inhibition of Akt activation attenuated the serum deprivation-mediated increase in HIF-1alpha and cell survival. Importantly, IGF-2 secretion significantly increased during serum deprivation, and was accompanied by increased activation of its receptor, IGF-IR. Additionally, inhibition of IGF-2 activity markedly attenuated the serum deprivation-mediated increase in IGF-IR and Akt activation, HIF-1alpha expression, and also its own transcription, suggesting autocrine regulation of HIF-1alpha expression via IGF-2. Cross-talk between IGF-2/ IGF-IR system and PI3K-Akt pathway was further demonstrated by findings wherein IGF-IR suppression inhibited Akt activation, and IGF-IR activation was inhibited following PI3K inhibition. Furthermore, HIF-1alpha suppression attenuated the serum deprivation-mediated increase in Akt and IGF-IR activation.

CONCLUSION

Collectively, our study demonstrates existence of a pro-survival HIF-1alpha-dependent autocrine feedback loop in normoxic, serum-deprived PCa cells.

Phase I dose escalation study of telatinib (BAY 57-9352) in patients with advanced solid tumours

Telatinib (BAY 57-9352) is an orally available, small-molecule inhibitor of vascular endothelial growth factor receptors 2 and 3 (VEGFR-2/-3) and platelet-derived growth factor receptor beta tyrosine kinases. In this multicentre phase I dose escalation study, 71 patients with refractory solid tumours were enroled into 14 days on/7 days off (noncontinuous dosing) or continuous dosing groups to receive telatinib two times daily (BID). Hypertension (23%) and diarrhoea (7%) were the most frequent study drug-related adverse events of CTC grade 3. The maximum-tolerated dose was not reached up to a dose of 1500 mg BID continuous dosing. Telatinib was rapidly absorbed with median t(max) of 3 hours or less. Geometric mean C(max) and AUC(0-12) increased in a less than dose-proportional manner and plateaued in the 900-1500 mg BID dose range. Two renal cell carcinoma patients reached a partial response. Tumour blood flow measured by contrast-enhanced magnetic resonance imaging and sVEGFR-2 plasma levels decreased with increasing AUC(0-12) of telatinib. Telatinib is safe and well tolerated up to a dose of 1500 mg BID continuous dosing. Based on pharmacokinetic and pharmacodynamic criteria, 900 mg telatinib BID continuously administered was selected as the recommended phase II dose.

HIF-1 alpha: a key survival factor for serum-deprived prostate cancer cells

BACKGROUND

Hypoxia-inducible factor-1 alpha (HIF-1 alpha) is commonly overexpressed in prostate cancer (PCa) cells. As PCa cells are known to survive serum deprivation, we investigated the effect of prolonged serum deprivation on HIF-1 alpha expression, and the function of HIF-1 alpha in regulating the survival of normoxic serum-deprived PCa cells.

METHODS

HIF-1 alpha protein was assessed by immunoblots. Cell viability and proliferation were assessed by trypan blue assay and flow cytometric analysis. Transcriptional activity was assessed by luciferase reporter assay and RT-PCR. HIF-1 alpha expression was suppressed with siRNA. Activities of HIF-1 alpha-target genes were inhibited with neutralizing antibody.

RESULTS

Prolonged serum deprivation is a potent inducer of HIF-1 alpha in PC-3 and LNCaP PCa cells, despite normal oxygen conditions. In contrast, cells grown in the presence of serum did not show HIF-1 alpha protein accumulation. Moreover, HIF-1 alpha protein increase during serum deprivation correlated with increased cell survival, while suppression of HIF-1 alpha expression significantly decreased PCa cell viability. Our results further demonstrate that HIF-1 alpha protein increase is due to increased HIF-1 alpha protein synthesis. First, there was no significant increase in HIF-1 alpha mRNA. Secondly, cycloheximide, a protein synthesis inhibitor, prevented HIF-1 alpha protein increase in serum-deprived PCa cells. Moreover, the expression of HIF-1 alpha-target genes, VEGF and IGF-2, was concomitantly increased in serum-deprived PCa cells, while suppression of HIF-1 alpha expression significantly inhibited their induction. Furthermore, inhibition of IGF-2 activity resulted in a significant decline in PCa cell survival.

CONCLUSION

PCa cells counteract the stress of prolonged serum deprivation by upregulating HIF-1 alpha protein which increases IGF-2 expression to promote cell survival.

Endothelial cells support the growth of prostate tissue in vivo

INTRODUCTION

The contribution of vascular endothelial cells to prostate growth has not been investigated. We examined whether endothelial cells support growth of prostate tissue when co-inoculated with prostate epithelial cells under the renal capsule.

METHODS

Vascular endothelial cells were isolated from mice and co-inoculated under the renal capsule with a prostate luminal or basal epithelial cell line. After 60 days, kidneys were examined for growth of prostate tissue. Prostatic tissues were examined by immunohistochemistry for expression of cytokeratins 5 and 8, and vascular density was determined. To determine if increased expression of VEGF-A would increase prostatic growth, transfected endothelial cells overexpressing VEGF-A were co-inoculated with the prostate luminal or basal epithelial lines.

RESULTS

Co-inoculation of endothelial cells and prostate luminal or basal epithelial cells resulted in significant growth of prostatic tissue, whereas inoculation of any of the cell lines alone resulted in little growth. The growths from co-inoculation of endothelial cells and luminal epithelial cells contained duct-like structures that stained with antibodies to cytokeratin 8, whereas those from co-inoculation of endothelial cells and basal epithelial cells contained cords of cells that stained with antibodies to cytokeratin 5. Overexpression of VEGF-A had no effect on growth of the prostatic tissues.

CONCLUSION

Endothelial cells contribute to the growth of prostatic epithelial cells.

Monoclonal antibody therapy for prostate cancer

Early detection of prostate cancer (PCa) and advances in hormonal and chemotherapy treatments have provided great clinical benefits to patients with early stages of the disease. However, a significant proportion of patients still progress to advanced, metastatic disease, for which no effective therapies are available. Therefore, there is a critical need for new treatment modalities, ideally targeted specifically to prostate cancer cells. The recent clinical and commercial successes of monoclonal antibodies (MAbs) have made them the most rapidly expanding class of therapeutics being developed for many disease indications, including cancer. PCa is well suited for antibody-based therapy due to the size and location of recurrent and metastatic tumors, and the lack of necessity to avoid targeting the normal prostate, a nonessential organ. These properties have fostered interest in the development and clinical evaluation of therapeutic MAbs directed to both well established and newly discovered targets in PCa. MAbs directed to established targets include those approved for other solid tumors, including anti-human epidermal growth factor receptor-2 (HER2) MAb trastuzumab, anti-epidermal growth factor receptor (EGFR) MAbs cetuximab and panitumumab, and the antivascular endothelial growth factor (VEGF) MAb bevacizumab. Genomics efforts have yielded a large number of novel, clinically relevant targets in PCa with the desirable expression profiling in tumor and normal tissues, and with an implicated role in tumor growth and spread. Growing efforts are directed to the development of naked or payload-conjugated therapeutic antibodies to these targets, and a variety of MAb products are currently progressing through preclinical and various stages of clinical development. The clinical experience with some of the commercialized MAb products points out specific challenges in conducting clinical trials with targeted therapy in PCa.