Phase II study of recombinant human endostatin in patients with advanced neuroendocrine tumors

Recombinant human endostatin as a potential anti-angiogenic agent: therapeutic perspective and current status

Angiogenesis is the physiological process that results in the formation of new blood vessels develop from pre-existing vasculature and plays a significant role in several physiological and pathological processes. Inhibiting angiogenesis, a crucial mechanism in the growth and metastasis of cancer, has been proposed as a potential anticancer therapy. Different studies showed the beneficial effects of angiogenesis inhibitors either in patients suffering from different cancers, alone or in combination with conventional therapies. Even though there are currently a number of efficient anti-angiogenic drugs, including monoclonal antibodies and kinase inhibitors, the associated toxicity profile and their affordability constraints are prompting researchers to search for a safe and affordable angiostatic agent for cancer treatment. Endostatin is one of the endogenous anti-angiogenic candidates that have been extensively pursued for the treatment of cancer, but even over three decades after its discovery, we have not made much advancement in employing it as an anticancer therapeutic despite of its remarkable anti-angiogenic effect with low toxicity profile. A recombinant human endostatin (rh-Es) variant for non-small cell lung cancer was approved by China in 2006 and has since been used effectively. Several other successful clinical trials related to endostatin for various malignancies are either ongoing or have already been completed with promising results. Thus, in this review, we have provided an overview of existing anti-angiogenic drugs developed for cancer therapy, with a summary of tumour angiogenesis in the context of Endostatin, and clinical status of rh-Es in cancer treatment. Furthermore, we briefly discuss the various strategies to improve endostatin features (poor pharmacokinetic properties) for developing rh-Es as a safe and effective agent for cancer treatment.

Treating radiation‑related nasopharyngeal necrosis with endostar in patient with nasopharyngeal carcinoma: A report of two cases and a literature review

Radiation-related nasopharyngeal necrosis (RRNN) is a rare and often fatal complication in patients with nasopharyngeal carcinoma (NPC). Currently, no standard treatments are recommended for RRNN. The effects of traditional conservative treatments are suboptimal, and surgery for RRNN cannot be performed by inexperienced doctors. In the present study, the use of Endostar in two patients with RRNN was evaluated. Two patients with RRNN were treated at the Department of Oncology, Panyu Central Hospital (Guangzhou, China). Endostar was administrated (15 mg/day from day 1 to day 7, every three weeks) intravenously for four and seven cycles in a male and a female patient, respectively. The effects of Endostar were assessed using magnetic resonance imaging (MRI) and a nasopharyngoscope. The symptoms of RRNN in both patients were relieved after treatment with Endostar. MRI and nasopharyngoscope analysis revealed that necrosis of the nasopharynx was substantially decreased and nasopharyngeal ulcers were healed. Endostar has the potential to be a novel, effective therapy for the treatment of patients with RRNN. However, clinical trials are required to confirm the results of the present study.

Golden Syrian Hamster Models for Cancer Research

The golden Syrian hamster (Mesocricetus auratus) has long been a valuable rodent model of human diseases, especially infectious and metabolic diseases. Hamsters have also been valuable models of several chemically induced cancers such as the DMBA-induced oral cheek pouch cancer model. Recently, with the application of CRISPR/Cas9 genetic engineering technology, hamsters can now be gene targeted as readily as mouse models. This review describes the phenotypes of three gene-targeted knockout (KO) hamster cancer models, TP53, KCNQ1, and IL2RG. Notably, these hamster models demonstrate cancer phenotypes not observed in mouse KOs. In some cases, the cancers that arise in the KO hamster are similar to cancers that arise in humans, in contrast with KO mice that do not develop the cancers. An example is the development of aggressive acute myelogenous leukemia (AML) in TP53 KO hamsters. The review also presents a discussion of the relative strengths and weaknesses of mouse cancer models and hamster cancer models and argues that there are no perfect rodent models of cancer and that the genetically engineered hamster cancer models can complement mouse models and expand the suite of animal cancer models available for the development of new cancer therapies.

Tolerance and Pharmacokinetics of Recombinant Human Endostatin Administered as Single-Dose or Multiple-Dose Infusions in Patients With Advanced Solid Tumors: A Phase I Clinical Trial

Objective: This study aimed to investigate the tolerance and pharmacokinetic characteristics of recombinant human endostatin (rh-endostatin) administered as single-dose or multiple-dose infusions in patients with advanced solid tumors. Methods: This phase I trial was designed as a single-center, single-arm, nonrandomized, open-label, dose-escalation study. The trial consisted of 2 parts: a single-dose part and a multiple-dose part, each with 3 dose comparison groups. Rh-endostatin was administered as an intravenous injection only once at a dose of 5 mg/m², 7.5 mg/m², or 10 mg/m² in the single-dose part and as a daily intravenous injection for 14 days at the same doses in the multiple-dose part. The serum pharmacokinetics, toxicity and immunogenicity of rh-endostatin were evaluated. Results: Dose-limiting toxicity (DLT) was not observed in any group. A few patients developed cardiotoxicity, such as QT prolongation or narrow arrhythmia. Other adverse events were slight coagulation abnormalities and haematological abnormalities. For rh-endostatin doses of 5 mg/m², 7.5 mg/m², and 10 mg/m², the mean C_max values in the single-dose part were 344 ± 38.7 ng/mL, 524 ± 157 ng/mL, and 800 ± 201 ng/mL, respectively, and the average AUC_0-t values were 3290 ± 3790 ng•h/mL, 4940 ± 4380 ng•h/mL, and 5050 ± 3980 ng•h/mL, respectively. The C_{max ss} values of the 3 doses in the multiple-dose part were 575 ± 270 ng/mL, 531 ± 106 ng/mL, and 864 ± 166 ng/mL, respectively, and the AUC_0-τ values were 3610 ± 1040 ng•h/mL, 3290 ± 1090 ng•h/mL, and 5180 ± 1210 ng•h/mL, respectively. The C_max of a single-dose regimen showed linear kinetic characteristics. The patients in the single-dose group were negative for serum antibodies against rh-endostatin, while one patient in the multiple-dose group was positive. Conclusions: Rh-endostatin as a daily intravenous injection for 14 days in patients with advanced solid tumors is safe and well tolerated, without DLT, at doses of 5 mg/m², 7.5 mg/m², and 10 mg/m². Serum antibodies against rh-endostatin were very low after multiple infusions. For phase II trials, the recommended rh-endostatin dose is 10 mg/m² as a daily intravenous injection for 14 days.

Inhibition of Vasculogenic Mimicry and Angiogenesis by an Anti-EGFR IgG1-Human Endostatin-P125A Fusion Protein Reduces Triple Negative Breast Cancer Metastases

Triple negative breast cancer (TNBC) is an aggressive breast cancer subtype with limited therapeutic options. Metastasis is the major cause of TNBC mortality. Angiogenesis facilitates TNBC metastases. Many TNBCs also form vascular channels lined by tumor cells rather than endothelial cells, known as ‘vasculogenic mimicry’ (VM). VM has been linked to metastatic TNBC behavior and resistance to anti-angiogenic agents. Epidermal growth factor receptor (EGFR) is frequently expressed on TNBC, but anti-EGFR antibodies have limited efficacy. We synthesized an anti-EGFR antibody–endostatin fusion protein, αEGFR IgG1-huEndo-P125A (αEGFR-E-P125A), designed to deliver a mutant endostatin, huEndo-P125A (E-P125A), to EGFR expressing tumors, and tested its effects on angiogenesis, TNBC VM, and motility in vitro, and on the growth and metastasis of two independent human TNBC xenograft models in vivo. αEGFR-E-P125A completely inhibited the ability of human umbilical vein endothelial cells to form capillary-like structures (CLS) and of TNBC cells to engage in VM and form tubes in vitro. αEGFR-E-P125A treatment reduced endothelial and TNBC motility in vitro more effectively than E-P125A or cetuximab, delivered alone or in combination. Treatment of TNBC with αEGFR-E-P125A was associated with a reduction in cytoplasmic and nuclear β-catenin and reduced phosphorylation of vimentin. αEGFR-E-P125A treatment of TNBC xenografts in vivo inhibited angiogenesis and VM, reduced primary tumor growth and lung metastasis of orthotopically implanted MDA-MB-468 TNBC cells, and markedly decreased lung metastases following intravenous injection of MDA-MB-231-4175 lung-tropic TNBC cells. Combined inhibition of angiogenesis, VM, and TNBC motility mediated by αEGFR-E-P125A is a promising strategy for the prevention of TNBC metastases.

Angiogenesis Inhibitors for Head and Neck Squamous Cell Carcinoma Treatment: Is There Still Hope?

Background

Head and neck squamous cell carcinoma (HNSCC) carries poor survival outcomes despite recent progress in cancer treatment in general. Angiogenesis is crucial for tumour survival and progression. Therefore, several agents targeting the pathways that mediate angiogenesis have been developed. We conducted a systematic review to summarise the current clinical trial data examining angiogenesis inhibitors in HNSCC.

Methods

We carried out a literature search on three angiogenesis inhibitor categories—bevacizumab, tyrosine kinase inhibitors and endostatin—from Ovid MEDLINE, Cochrane Library, Scopus and ClinicalTrials.gov database.

Results

Here, we analysed 38 clinical trials, total of 1670 patients, investigating 12 angiogenesis inhibitors. All trials were in phase I or II, except one study in phase III on bevacizumab. Angiogenesis inhibitors were used as mono- and combination therapies together with radio-, chemo-, targeted- or immunotherapy. Among 12 angiogenesis inhibitors, bevacizumab was the most studied drug, included in 13 trials. Although bevacizumab appeared effective in various combinations, it associated with high toxicity levels. Endostatin and lenvatinib were well-tolerated and their anticancer effects appeared promising.

Conclusions

Most studies did not show benefit of angiogenesis inhibitors in HNSCC treatment. Additionally, angiogenesis inhibitors were associated with considerable toxicity. However, some results appear encouraging, suggesting that further investigations of angiogenesis inhibitors, particularly in combination therapies, for HNSCC patients are warranted.

Systematic Review Registration

PROSPERO (https://www.crd.york.ac.uk/prospero/), identifier CRD42020157144.

Development of Molecules Antagonizing Heparan Sulfate Proteoglycans

Heparan sulfate proteoglycans (HSPGs) occur in almost every tissue of the human body and consist of a protein core, with covalently attached glycosaminoglycan polysaccharide chains. These glycosaminoglycans are characterized by their polyanionic nature, due to sulfate and carboxyl groups, which are distributed along the chain. These chains can be modified by different enzymes at varying positions, which leads to huge diversity of possible structures with the complexity further increased by varying chain lengths. According to their location, HSPGs are divided into different families, the membrane bound, the secreted extracellular matrix, and the secretory vesicle family. As members of the extracellular matrix, they take part in cell-cell communication processes on many levels and with different degrees of involvement. Of particular therapeutic interest is their role in cancer and inflammation as well as in infectious diseases. In this review, we give an overview of the current status of medical approaches to antagonize HSPG function in pathology.

Integrated human organ-on-a-chip model for predictive studies of anti-tumor drug efficacy and cardiac safety

Traditional drug screening models are often unable to faithfully recapitulate human physiology in health and disease, motivating the development of microfluidic organs-on-a-chip (OOC) platforms that can mimic many aspects of human physiology and in the process alleviate many of the discrepancies between preclinical studies and clinical trials outcomes. Linsitinib, a novel anti-cancer drug, showed promising results in pre-clinical models of Ewing Sarcoma (ES), where it suppressed tumor growth. However, a Phase II clinical trial in several European centers with patients showed relapsed and/or refractory ES. We report an integrated, open setting, imaging and sampling accessible, polysulfone-based platform, featuring minimal hydrophobic compound binding. Two bioengineered human tissues - bone ES tumor and heart muscle - were cultured either in isolation or in the integrated platform and subjected to a clinically used linsitinib dosage. The measured anti-tumor efficacy and cardiotoxicity were compared with the results observed in the clinical trial. Only the engineered tumor tissues, and not monolayers, recapitulated the bone microenvironment pathways targeted by linsitinib, and the clinically-relevant differences in drug responses between non-metastatic and metastatic ES tumors. The responses of non-metastatic ES tumor tissues and heart muscle to linsitinib were much closer to those observed in the clinical trial for tissues cultured in an integrated setting than for tissues cultured in isolation. Drug treatment of isolated tissues resulted in significant decreases in tumor viability and cardiac function. Meanwhile, drug treatment in an integrated setting showed poor tumor response and less cardiotoxicity, which matched the results of the clinical trial. Overall, the integration of engineered human tumor and cardiac tissues in the integrated platform improved the predictive accuracy for both the direct and off-target effects of linsitinib. The proposed approach could be readily extended to other drugs and tissue systems.

Survival analysis of patients with medium and advanced hepatocellular carcinoma treated by TACE combined with Endostar

To explore the effects of two different administration routes of Endostar on the survival of patients with medium and advanced hepatocellular carcinoma (HCC) and underwent trans-arterial chemoembolization (TACE). Seventy-two patients with medium and advanced HCC were enrolled. Among them, 42 patients underwent the hepatic arterial infusion of Endostar combined with TACE (infusion therapy group); and the remaining 30 patients underwent the hepatic treatment of TACE combined with the intravenous application of Endostar (intravenous therapy group). All patients underwent regular examinations of CT (or MRI) and DSA to observe the conditions of tumor recurrence or metastasis, and to determine the existence of tumor angiogenesis. The response rate of treatment in the Endostar hepatic arterial infusion group was higher than that in the control group, and the difference was statistically significant (31/42:14/30, X2 = 5.501, p < 0.05). In addition, median progression free-survival time of the two groups were 8.67 months and 6.67 months, respectively ( p = 0.046); and the difference was statistically significant. The hepatic arterial infusion of Endostar combined with TACE can significantly improve recent clinical efficacy and mPFS in the treatment of medium and advanced HCC. However, improvement on the overall survival of long-term efficacy is not significant.

Clinical Performance of (1,3) Beta-D Glucan for the Diagnosis of Pneumocystis Pneumonia (PCP) in Cancer Patients Tested With PCP Polymerase Chain Reaction

BACKGROUND

Serum (1,3)-beta-D glucan (BDG) is increasingly used to guide the management of suspected Pneumocystis pneumonia (PCP). BDG lacks specificity for PCP, and its clinical performance in high-risk cancer patients has not been fully assessed. Polymerase chain reaction (PCR) for PCP detection is highly sensitive, but cannot differentiate between colonization and infection. We evaluated the diagnostic performance of serum BDG in conjunction with PCP PCR on respiratory samples in patients with cancer and unexplained lung infiltrates.

METHODS

We performed a retrospective analysis of adult patients evaluated for PCP at our institution from 2012 to 2015, using serum BDG and PCP PCR. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the serum BDG at different thresholds were evaluated using PCP PCR alone or in conjunction with clinical presentation in PCP PCR-positive patients.

RESULTS

With PCP PCR alone as the reference method, BDG (≥80 pg/mL) had a sensitivity of 69.8%, specificity of 81.2%, PPV of 34.6%, and NPV of 95.2% for PCP. At ≥200 pg/mL in patients with a positive PCR and a compatible PCP clinical syndrome, BDG had a sensitivity of 70%, specificity of 100%, PPV of 100%, and NPV of 52.0% for PCP.

CONCLUSIONS

Patients negative by both BDG and PCR were unlikely to have PCP. In patients with a compatible clinical syndrome for PCP, higher BDG values (>200 pg/mL) were consistently associated with clinically-significant PCP infections among PCP PCR-positive oncology patients.

Exploring the roles of MACIT and multiplexin collagens in stem cells and cancer

The extracellular matrix (ECM) is ubiquitously involved in neoplastic transformation, tumour growth and metastatic dissemination, and the interplay between tumour and stromal cells and the ECM is now considered crucial for the formation of a tumour-supporting microenvironment. The 28 different collagens (Col) form a major ECM protein family and display extraordinary functional diversity in tissue homeostasis as well as in pathological conditions, with functions ranging from structural support for tissues to regulatory binding activities and storage of biologically active cryptic domains releasable through ECM proteolysis. Two subfamilies of collagens, namely the plasma membrane-associated collagens with interrupted triple-helices (MACITs, including ColXIII, ColXXIII and ColXXV) and the basement membrane-associated collagens with multiple triple-helix domains with interruptions (multiplexins, including ColXV and ColXVIII), have highly interesting regulatory functions in tissue and organ development, as well as in various diseases, including cancer. An increasing, albeit yet sparse, data suggest that these collagens play crucial roles in conveying regulatory signals from the extracellular space to cells. We summarize here the current knowledge about MACITs and multiplexins as regulators of stemness and oncogenic processes, as well as their roles in influencing cell fate decisions in healthy and cancerous tissues. In addition, we present a bioinformatic analysis of the impacts of MACITs and multiplexins transcript levels on the prognosis of patients representing a wide array of malignant diseases, to aid future diagnostic and therapeutic efforts.

Role of the tumor microenvironment in digestive neuroendocrine tumors

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) represent a group of heterogeneous tumors whose incidence increased over the past few years. Around half of patients already present with metastatic disease at the initial diagnosis. Despite extensive efforts, cytotoxic and targeted therapies have provided only limited efficacy for patients with metastatic GEP-NETs, mainly due to the development of a certain state of resistance. One factor contributing to both the failure of systemic therapies and the emergence of an aggressive tumor phenotype may be the tumor microenvironment (TME), comprising dynamic and adaptative assortment of extracellular matrix components and non-neoplastic cells, which surround the tumor niche. Accumulating evidence shows that the TME can simultaneously support both tumor growth and metastasis and contribute to a certain state of resistance to treatment. In this review, we summarize the current knowledge of the TME of GEP-NETs and discuss the current therapeutic agents that target GEP-NETs and those that could be of interest in the (near) future.

Recombined humanized endostatin (Endostar) combined with chemotherapy for advanced bone and soft tissue sarcomas in stage IV

PURPOSE

This retrospective case-series study evaluated efficacy and safety of Endostar combined with chemotherapy in the treatment of advanced bone and soft tissue sarcomas in stage IV.

MATERIALS AND METHODS

Forty-seven patients diagnosed with stage IV bone and soft tissue sarcomas and treated with chemotherapy in Tianjin Medical University Cancer Institute & Hospital were reviewed. Of these patients, 23 patients were treated with Endostar plus chemotherapy (designated as combined group), and 24 patients received only chemotherapy (designated as control group). Progression-free survival (PFS), overall survival (OS), objective response rate (ORR) and clinical benefit response (CBR) were analyzed to find the difference between these two groups with the purpose to investigate the role of Endostar in metastatic sarcomas.

RESULTS

Endostar combined with chemotherapy had significantly increased PFS. In the combined group and control groups, the median PFS (8.6 months versus 4.4 months) and the CBR (47.8% versus 16.7%) showed significant difference (P = 0.032), while the median overall survival (11.7 months versus 10.6 months, P = 0.658) and the ORR (17.4% versus 8.3%, P = 0.167) showed no significant difference. The common grade 3-4 side effects for both groups were myelosuppression and transient elevation of transaminases.

CONCLUSION

Endostar combined with chemotherapy had significant activity to increase the PFS and improve CBR in patients with advanced sarcomas, with tolerable side effects.

Endostar in combination with postoperative adjuvant chemotherapy prolongs the disease free survival of stage IIIA NSCLC patients with high VEGF expression

Purpose

The aim of this study is to compare the therapeutic effect between endostar plus adjuvant chemotherapy and adjuvant chemotherapy alone in the patients with completely resected non-small cell lung cancer (NSCLC) at stage IB to IIIA.

Experimental Design

This is an open, multicenter, randomized (1:1) study with 250 NSCLC patients. Completely resected NSCLC patients at stages IB to IIIA were randomized to receive adjuvant NP plus endostar (Vinorelbine 25 mg/m² on day 1 and day 8 plus Cisplatin 75 mg/m² on day 1, and plus endostar 7.5 mg/m² per day iv for consecutive 14 days) or NP regimen alone. Every 21 days were set as one cycle for 4 cycles. The primary endpoint was disease-free survival (DFS). Secondary endpoints included tumor response rate, overall survival and safety.

Results

The two groups had no significant difference in the incidence of toxicity reaction. Endostar plus NP prolonged the DFS of patients with completely resected NSCLC at stage IIIA (19.33±3.73 vs 17.10±9.68 months) but with no statistical difference compared to NP alone. In the endostar plus NP group, those cases with high expression of vascular endothelial growth factor (VEGF) showed a significantly better DFS than those with low VEGF expression (48.45±3.52 vs 40.18±4.54 months, P<0.05).

Conclusions

Vascular targeted therapy with endostar plus NP prolongs the DFS of patients with complete resectable NSCLC in stage IIIA and significantly extends the DFS of NSCLC patients with high VEGF expression, but does not show benefits in OS for stage IB-IIIA.

Extracellular Matrix, a Hard Player in Angiogenesis

The extracellular matrix (ECM) is a complex network of proteins, glycoproteins, proteoglycans, and polysaccharides. Through multiple interactions with each other and the cell surface receptors, not only the ECM determines the physical and mechanical properties of the tissues, but also profoundly influences cell behavior and many physiological and pathological processes. One of the functions that have been extensively explored is its impingement on angiogenesis. The strong impact of the ECM in this context is both direct and indirect by virtue of its ability to interact and/or store several growth factors and cytokines. The aim of this review is to provide some examples of the complex molecular mechanisms that are elicited by these molecules in promoting or weakening the angiogenic processes. The scenario is intricate, since matrix remodeling often generates fragments displaying opposite effects compared to those exerted by the whole molecules. Thus, the balance will tilt towards angiogenesis or angiostasis depending on the relative expression of pro- or anti-angiogenetic molecules/fragments composing the matrix of a given tissue. One of the vital aspects of this field of research is that, for its endogenous nature, the ECM can be viewed as a reservoir to draw from for the development of new more efficacious therapies to treat angiogenesis-dependent pathologies.

Antiangiogenesis and vascular disrupting agents in cancer: circumventing resistance and augmenting their therapeutic utility

Angiogenesis is a process essential for tumor growth and metastasis. Inhibition of angiogenesis as an anticancer strategy has shown only moderately improved results and is beset with practical limitations, despite theoretical therapeutic advantages. Inevitably resistance develops, through redundancy of signaling pathways and selection for subclonal populations adapted for hypoxic conditions, with more invasive phenotypes. Antiangiogenic-targeted therapies may find improved efficacy in combination therapies; with others in this class, that directly or indirectly target separate pathways or different components of the same pathway, or with a separate class of tumor vasculature-disrupting agents. This review discusses the challenges and strategies for optimization of combination therapies including metronomic administration of drugs and the need for suitable prognostic and surrogate response biomarkers.

Endostatin and endorepellin: A common route of action for similar angiostatic cancer avengers

Traditional cancer therapy typically targets the tumor proper. However, newly-formed vasculature exerts a major role in cancer development and progression. Autophagy, as a biological mechanism for clearing damaged proteins and oxidative stress products released in the tumor milieu, could help in tumor resolution by rescuing cells undergoing modifications or inducing autophagic-cell death of tumor blood vessels. Cleaved fragments of extracellular matrix proteoglycans are emerging as key players in the modulation of angiogenesis and endothelial cell autophagy. An essential characteristic of cancer progression is the remodeling of the basement membrane and the release of processed forms of its constituents. Endostatin, generated from collagen XVIII, and endorepellin, the C-terminal segment of the large proteoglycan perlecan, possess a dual activity as modifiers of both angiogenesis and endothelial cell autophagy. Manipulation of these endogenously-processed forms, located in the basement membrane within tumors, could represent new therapeutic approaches for cancer eradication.

Chemotherapy for advanced non-pancreatic well-differentiated neuroendocrine tumours of the gastrointestinal tract, a systematic review and meta-analysis: A lost cause?

BACKGROUND

Chemotherapy is well-established in the treatment of patients with well-differentiated neuroendocrine tumours (NETs) arising from the pancreas (pNETs); however, its role in patients with gastrointestinal non-pancreatic NETs (non-pNETs) is uncertain. This systematic review assesses the evidence for the role of chemotherapy in well-differentiated non-pNET patients.

METHODS

Eligible studies (identified using MEDLINE) were those reporting response and/or survival data for patients with well-differentiated non-pNETs receiving systemic chemotherapy. The primary end-point was overall-response (OR) rate; secondary end-points were progression-free survival (PFS), overall survival (OS), disease-stabilization (DS) and disease-control (DC) rates.

RESULTS

Of 6434 studies screened, 20 were eligible: one randomised phase III trial, 2 randomised phase II studies, 10 single-arm phase II trials and 7 retrospective analyses including a total of 264 patients (median of 11 patients per study, range 6-49); and employing multiple chemotherapy schedules. The mean "median PFS" and "median OS" were 16.9 months (95%-confidence interval (CI) 3.8-30.04) and 32.2 months (95%-CI 10.4-54.2), respectively. The non-weighted mean OR, DS and DC rates were 11.5% (95%-CI 5.8-17.2), 56.5% (95%-CI 38.1-74.9) and 70.7% (95%-CI 54.9-86.5), respectively. In studies including both pNETs and non-pNET patients, meta-analysis showed a lower OR-rate in the non-pNET patients when compared to pNETs [odds ratio (OR) 0.35 (95% CI 0.18-0.66)]; however significance was lost when high-risk bias studies were excluded in a sensitivity analysis [OR 0.45 (95% CI 0.19-1.07); p-value 0.07].

CONCLUSION

Studies were of evidence level-C with heterogeneous populations and treatments; and small patient numbers. Well-designed, prospective studies are needed to adequately evaluate the role of chemotherapy in this setting.

Extension of the in vivo half-life of endostatin and its improved anti-tumor activities upon fusion to a humanized antibody against tumor-associated glycoprotein 72 in a mouse model of human colorectal carcinoma

Endostatin is an endogenous angiogenesis inhibitor that exhibits potential anti-tumor efficacy in various preclinical animal models. However, its relatively short in vivo half-life and the long-term, frequent administration of high doses limit its widespread clinical use. In this study, we evaluated whether a fusion protein of murine endostatin (mEndo) to a humanized antibody against tumor-associated glycoprotein 72 (TAG-72), which is highly expressed in several human tumor tissues including colon cancer, can extend the serum half-life and improve the anti-tumor efficacy of endostatin by targeted delivery to the tumor mass. The fusion protein (3E8-mEndo) and mEndo showed improved anti-angiogenic activity in vitro and in vivo, predominantly by interfering with pro-angiogenic signaling triggered by vascular endothelial growth factor (VEGF). Moreover, in mice treated with 3E8-mEndo, we observed a markedly prolonged serum half-life and significantly inhibited tumor growth. The improved anti-tumor activity of 3E8-mEndo can be partially explained by increased local concentration in the tumor mass due to targeted delivery of 3E8-mEndo to implanted colon tumors. Collectively, our data clearly indicate that tumor-targeting antibody fusions to endostatin are a powerful strategy that improves the poor pharmacokinetic profile and anti-tumor efficacy of endostatin.

Deciphering the anti-angiogenic effect of endostatin/cyclophosphamide to normalize tumor micrangium through notch signaling pathway in colon cancer

Background

The invasion of colon cancer is associated with the tumor angiogenesis. Endostatin is an important anti-angiogenic agent, and the additive effect of endostatin with a chemotherapeutic agent, cyclophosphamide, on micrangium has not been established.

Methods

Male BALB/c strain nude mice were injected with human colorectal carcinoma cells (HCT-116). The mice were divided into four groups (n = 15, each group) and were treated with different concentrations of endostatin (15, 10, and 5 mg/kg/day), cyclophosphamide (20, 10, and 5 mg/kg/day), and combination of endostatin/cyclophosphamide (15 + 20, 15 + 10, and 15 + 5 mg/kg/day). The tumor inhibition rate was evaluated, followed by the quantification of messenger ribonucleic acid (mRNA) and protein expression of notch signaling components NOTCH-1, NOTCH-3, NOTCH-4, JAG-1, DLL-4, Hes-1, and Hey-1 using quantitative polymerase chain reaction (qPCR). The protein expression of NOTCH-3, JAG-1, and DLL-4 was confirmed using western blotting. Microvessel density (MVD) was evaluated to detect micrangium following the treatment.

Results

The endostatin/cyclophosphamide-treated samples exhibited an additive effect on the tumor inhibition rate and the microvessel count. NOTCH-1, NOTCH-3, NOTCH-4, JAG-1, Hes-1, and Hey-1 expression levels were highly correlated and downregulated in the treated samples, whereas DLL-4 expression was upregulated that accounted for its anti-angiogenic property.

Conclusions

The combination treatment of colon cancer with endostatin and a chemotherapeutic agent, cyclophosphamide proves to be an efficient therapeutic strategy to inhibit the rapid vasculature formation confirmed by the differential expression of notch signaling components.

Endostatin's emerging roles in angiogenesis, lymphangiogenesis, disease, and clinical applications

BACKGROUND

Angiogenesis is the process of neovascularization from pre-existing vasculature and is involved in various physiological and pathological processes. Inhibitors of angiogenesis, administered either as individual drugs or in combination with other chemotherapy, have been shown to benefit patients with various cancers. Endostatin, a 20-kDa C-terminal fragment of type XVIII collagen, is one of the most potent inhibitors of angiogenesis.

SCOPE OF REVIEW

We discuss the biology behind endostatin in the context of its endogenous production, the various receptors to which it binds, and the mechanisms by which it acts. We focus on its inhibitory role in angiogenesis, lymphangiogenesis, and cancer metastasis. We also present emerging clinical applications for endostatin and its potential as a therapeutic agent in the form a short peptide.

MAJOR CONCLUSIONS

The delicate balance between pro- and anti-angiogenic factors can be modulated to result in physiological wound healing or pathological tumor metastasis. Research in the last decade has emphasized an emerging clinical potential for endostatin as a biomarker and as a therapeutic short peptide. Moreover, elevated or depressed endostatin levels in diseased states may help explain the pathophysiological mechanisms of the particular disease.

GENERAL SIGNIFICANCE

Endostatin was once sought after as the 'be all and end all' for cancer treatment; however, research throughout the last decade has made it apparent that endostatin's effects are complex and involve multiple mechanisms. A better understanding of newly discovered mechanisms and clinical applications still has the potential to lead to future advances in the use of endostatin in the clinic.

Gene therapy in pancreatic cancer

Pancreatic cancer (PC) is a highly lethal disease and notoriously difficult to treat. Only a small proportion of PC patients are eligible for surgical resection, whilst conventional chemoradiotherapy only has a modest effect with substantial toxicity. Gene therapy has become a new widely investigated therapeutic approach for PC. This article reviews the basic rationale, gene delivery methods, therapeutic targets and developments of laboratory research and clinical trials in gene therapy of PC by searching the literature published in English using the PubMed database and analyzing clinical trials registered on the Gene Therapy Clinical Trials Worldwide website (http://www. wiley.co.uk/genmed/ clinical). Viral vectors are main gene delivery tools in gene therapy of cancer, and especially, oncolytic virus shows brighter prospect due to its tumor-targeting property. Efficient therapeutic targets for gene therapy include tumor suppressor gene p53, mutant oncogene K-ras, anti-angiogenesis gene VEGFR, suicide gene HSK-TK, cytosine deaminase and cytochrome p450, multiple cytokine genes and so on. Combining different targets or combination strategies with traditional chemoradiotherapy may be a more effective approach to improve the efficacy of cancer gene therapy. Cancer gene therapy is not yet applied in clinical practice, but basic and clinical studies have demonstrated its safety and clinical benefits. Gene therapy will be a new and promising field for the treatment of PC.

Anti-tumor effect of a novel soluble recombinant human endostatin: administered as a single agent or in combination with chemotherapy agents in mouse tumor models

Background

Angiogenesis has become an attractive target in cancer treatment. Endostatin is one of the potent anti-angiogenesis agents. Its recombinant form expressed in the yeast system is currently under clinical trials. Endostatin suppresses tumor formation through the inhibition of blood vessel growth. It is anticipated that combined therapy using endostatin and cytotoxic compounds may exert an additive effect. In the present study, we expressed and purified recombinant human endostatin (rhEndostatin) that contained 3 additional amino acid residues (arginine, glycine, and serine) at the amino-terminus and 6 histidine residues in its carboxyl terminus. The recombinant protein was expressed in E. Coli and refolded into a soluble form in a large scale purification process. The protein exhibited a potent anti-tumor activity in bioassays. Furthermore, rhEndostatin showed an additive effect with chemotherapy agents including cyclophosphamide (CTX) and cisplatin (DDP).

Methods

rhEndostatin cDNA was cloned into PQE vector and expressed in E. Coli. The protein was refolded through dialysis with an optimized protocol. To establish tumor models, nude mice were subcutaneously injected with human cancer cells (lung carcinoma A549, hepatocellular carcinoma QGY-7703, or breast cancer Bcap37). rhEndostatin and/or DDP was administered peritumorally to evaluate the rate of growth inhibition of A549 tumors. For the tumor metastasis model, mice were injected intravenously with mouse melanoma B16 cells. One day after tumor cell injection, a single dose of rhEndostatin, or in combination with CTX, was administered intravenously or at a site close to the tumor.

Results

rhEndostatin reduced the growth of A549, QGY-7703, and Bcap37 xenograft tumors in a dose dependent manner. When it was administered peritumorally, rhEndostatin exhibited a more potent inhibitory activity. Furthermore, rhEndostatin displayed an additive effect with CTX or DDP on the inhibition of metastasis of B16 tumors or growth of A549 tumors.

Conclusion

Soluble rhEndostatin exhibits a potent anti-tumor activity in mouse xenograft models and it also has an additive effect with CTX and DDP, implying possible applications in clinical settings.

Expression of liver-targeting peptide modified recombinant human endostatin and preliminary study of its biological activities

Recombinant human endostatin (rEndostatin or endostar) has been shown to inhibit endothelial cells proliferation, migration, and angiogenesis and exhibits a broad spectrum of activities against solid tumors. However, rEndostatin is easily degradable and evenly distributed to all tissues. Selectively delivering rEndostatin to the lesion site might be more potent. The circumsporozoite protein (CSP) coats the malarial sporozoite and targets the liver for infection; I-plus of N end of CSP could specifically bind to the liver. Based on this, we hypothesize the fusion protein with introducing the CSP I-plus sequence into rEndostatin (rES-CSP) of which not only targets the liver, but also inhibits endothelial cells proliferation, migration, and tube formation. Therefore, it selectively reduces angiogenesis of hepatocellular carcinoma (HCC) and improves the anti-HCC effect. In this study, we synthesized a novel rES-CSP fusion gene by SOE-PCR and expressed the fusion protein in Escherichia coli BL2l (DE3). The suitable conditions were optimized by an orthogonal test (L(25)(5)(4)). The yields were 12 mg/l culture medium following refolding and purification on nickel-nitrilotriacetic acid (Ni-NTA) metal affinity chromatography matrices. The purified rES-CSP is specifically targeted to the hepatocyte and inhibited the proliferation and migration of human umbilical vein endothelial cells (HUVECs) in a dose-dependent manner and showed potent antiangiogenic capability on HUVECs tube formation assay and chick embryo chorioallantoic membrane (CAM) assay. These results lay the foundation for the further study of its targeting and anti-HCC in vivo and provide a feasible and convenient approach to produce liver-targeting drugs for treatment of the liver diseases.

Interferon alpha and rapamycin inhibit the growth of carcinoid and medullary thyroid cancer in vitro

Neuroendocrine tumors (NETs) are highly vascularized neoplasms characterized by rising incidence. Moreover, the neuroendocrine cells were shown to express vascular endothelial growth factor (VEGF) and VEGF receptors. Therefore, angiomodulators could be potentially a new group of drugs enhancing still unsatisfactory effectiveness of NET therapy. The aim of this study was to assess the direct influence of angiomodulators: VEGF and five endogenous and exogenous antiangiogenic compounds (endostatin, interferon alpha [IFNα], rapamycin, JV1-36, semaxinib [SU5416]) on the growth of two NET cell lines: lung carcinoid H727 cell line and medullary thyroid cancer TT cell line in vitro. IFNα and rapamycin induced the inhibitory effect on H727 and TT cell viability and proliferation, increasing apoptosis and arresting the cell cycle. Also semaxinib (10(-5)M) inhibited proliferation of both cell lines. VEGF and endostatin did not influence the growth of H727 and TT cells. The inhibitory effect of IFNα, rapamycin and semaxinib on carcinoid and medullary thyroid cancer growth was revealed in our in vitro study, although some other antiangiogenic agents did not directly influence H727 and TT cell growth. Thus, IFNα and mTOR inhibitors as multidirectionally acting drugs with antiangiogenic effect could be potentially efficient in treatment of neuroendocrine tumors and are worth further studies.

Phase I trial of M2ES, a novel polyethylene glycosylated recombinant human endostatin, plus gemcitabine in advanced pancreatic cancer

Pancreatic cancer is one of the most lethal and resistant to treatment of solid tumors. Combination therapies with various types of drugs against pancreatic cancer have been extensively investigated. Endostatin is a potent endogenous inhibitor of angiogenesis, which may be administered in combination with various chemotherapeutic agents in the treatment of several types of cancer. To the best of our knowledge, this phase I trial was the first clinical study to determine the tolerance, safety and efficacy of M₂ES, a novel polyethylene glycosylated recombinant human endostatin, administered concurrently with full-dose gemcitabine in patients with inoperable, locally advanced or metastatic pancreatic adenocarcinoma. A total of 16 patients were treated with gemcitabine (1,000 mg/m² on days 1, 8 and 15) and M₂ES (5-45 mg/m² on days 1, 8, 15 and 21) of each 28-day cycle. In 15 evaluable patients, the stable disease rate (SDR) was 40% (95% CI: 11.9-68.1%). In particular, a 75% SDR was observed in 3 out of 4 patients with a M₂ES dose level of 7.5 mg/m². The most noticeable M₂ES-related adverse events observed during the trial were grade 2 liver function abnormalities (6.3%) and grade 1 skin rash (6.3%). No dose-limiting toxicity was observed in any patients from all the dose levels. Therefore, there was no increased toxicity associated with the addition of M₂ES to gemcitabine and this combination was well tolerated.

Multicenter randomized phase 2 clinical trial of a recombinant human endostatin adenovirus in patients with advanced head and neck carcinoma

A randomized, open-label, phase 2, multicenter clinical trial was conducted to evaluate the efficacy and safety of the addition of a recombinant human endostatin adenovirus (E10A) to cisplatin and paclitaxel in patients with advanced head and neck squamous cell carcinoma or nasopharyngeal carcinoma. Patients with locally advanced or metastatic head and neck squamous cell carcinoma or nasopharyngeal carcinoma not suitable for operation or radiotherapy were randomly assigned to receive E10A plus chemotherapy every 3 weeks for a maximum of six cycles or to receive chemotherapy only. One hundred and thirty-six eligible patients were randomly assigned. The addition of E10A did not significantly improve the objective response rate (29.9 versus 39.7%, P = 0.154). However, patients who received endostatin had longer progression-free survival (7.03 versus 3.60 months, P = 0.006; hazard ratio: 0.55). The combination of E10A with chemotherapy benefited prior chemotherapy-treated patients and those who received three to four treatment cycles (6.50 versus 3.43 months, P = 0.003; 8.27 versus 4.27 months, P = 0.018; respectively). The overall disease control rate significantly increased from 80.6% in the control group to 92.6% in the test group (P = 0.034). Except for fever, no adverse events were associated with the E10A treatment. In summary, E10A plus chemotherapy is a safe and effective therapeutic approach in patients with advanced head and neck squamous cell carcinoma or nasopharyngeal carcinoma.

Treatment of medulloblastoma with oncolytic measles viruses expressing the angiogenesis inhibitors endostatin and angiostatin

Background

Medulloblastoma is the most common type of pediatric brain tumor. Although numerous factors influence patient survival rates, more than 30% of all cases will ultimately be refractory to conventional therapies. Current standards of care are also associated with significant morbidities, giving impetus for the development of new treatments. We have previously shown that oncolytic measles virotherapy is effective against medulloblastoma, leading to significant prolongation of survival and even cures in mouse xenograft models of localized and metastatic disease. Because medulloblastomas are known to be highly vascularized tumors, we reasoned that the addition of angiogenesis inhibitors could further enhance the efficacy of oncolytic measles virotherapy. Toward this end, we have engineered an oncolytic measles virus that express a fusion protein of endostatin and angiostatin, two endogenous and potent inhibitors of angiogenesis.

Methods

Oncolytic measles viruses encoding human and mouse variants of a secretable endostatin/angiostatin fusion protein were designed and rescued according to established protocols. These viruses, known as MV-hE:A and MV-mE:A respectively, were then evaluated for their anti-angiogenic potential and efficacy against medulloblastoma cell lines and orthotopic mouse models of localized disease.

Results

Medulloblastoma cells infected by MV-E:A readily secrete endostatin and angiostatin prior to lysis. The inclusion of the endostatin/angiostatin gene did not negatively impact the measles virus’ cytotoxicity against medulloblastoma cells or alter its growth kinetics. Conditioned media obtained from these infected cells was capable of inhibiting multiple angiogenic factors in vitro, significantly reducing endothelial cell tube formation, viability and migration compared to conditioned media derived from cells infected by a control measles virus. Mice that were given a single intratumoral injection of MV-E:A likewise showed reduced numbers of tumor-associated blood vessels and a trend for increased survival compared to mice treated with the control virus.

Conclusions

These data suggest that oncolytic measles viruses encoding anti-angiogenic proteins may have therapeutic benefit against medulloblastoma and support ongoing efforts to target angiogenesis in medulloblastoma.

Hallmarks of gastrointestinal neuroendocrine tumours: implications for treatment

In the past few years, there have been advances in the treatment of neuroendocrine tumours (NETs) and improvements in our understanding of NET biology. However, the benefits to patients have been relatively modest and much remains yet to be done. The 'Hallmarks of Cancer', as defined by Hanahan and Weinberg, provide a conceptual framework for understanding the aberrations that underlie tumourigenesis and to help identify potential targets for therapy. In this study, our objective is to review the major molecular characteristics of NETs, based on the recently modified 'Hallmarks of Cancer', and highlight areas that require further research.

Antiangiogenesis beyond VEGF inhibition: a journey from antiangiogenic single-target to broad-spectrum agents

Although the inhibition of angiogenesis is an established modality of cancer treatment, concerns regarding toxicity and drug resistance still constitute barriers to be overcome. For almost a decade since the approval of bevacizumab in 2004, the efforts on antiangiogenic therapeutics have been mainly focused in inhibiting the VEGF pathway. The ongoing understanding of the complexity of the angiogenic process has broadened the spotlight to include concurrent and downstream players to the list of targeted inhibitors. In this review, we summarize the currently existing and the promising antiangiogenic treatments, envisioning an apparent evolutionary trend towards the development of angiogenesis inhibitors of three modalities: single-target, multi-target, and broad-spectrum agents. The clinical efficacy and some structural aspects of monoclonal antibodies, small molecules, endogenous and synthetic angiogenesis inhibitors and their molecular targets are discussed, and the targeting of endothelial cells with the use of cytotoxic drugs in a metronomic schedule is appraised. The reader is invited to revisit current expectations about antiangiogenic therapy in an attempt to set consistent clinical endpoints from which patients could gain real and lasting clinical benefits.

Effects of endostar combined multidrug chemotherapy in osteosarcoma

Angiogenesis is closely related to tumor development and metastasis. Osteosarcoma is an angiogenesis-dependent tumor, and studies have shown that chemotherapy often induces angiogenesis. Endostatin is a broad spectrum angiogenesis inhibitor and, while pre-clinical trials have shown that the combination of endostatin with chemotherapy can enhance anti-tumor effects, this effect has not yet been shown in clinical trials. Here, we aimed to evaluate the clinical efficacy of endostar (ES, human recombinant endostatin) combined with chemotherapy in the treatment of osteosarcoma patients. A total of 116 newly diagnosed patients with osteosarcoma were enrolled in this study. All patients received 4cycles of chemotherapy with (54 cases) or without (62 cases) ES. ES was administered intravenously at a dose of 15mg/day for 2weeks during each cycle of chemotherapy. The tumors were removed by surgery after 2cycles of chemotherapy treatment, and their histologic response to chemotherapy was evaluated. Immunohistochemistry was used to measure VEGF and CD 31 expression. Chemotherapy increased VEGF expression and the presence of microvessels in osteosarcoma tissues compared with pre-chemotherapy. No significant difference was observed in the histologic response between the ES treatment and non-treatment groups. However, ES treatment significantly inhibited the chemotherapy-induced VEGF expression and presence of microvessels. The ES treatment did not affect the overall survival rate but did increase the event-free survival rate and decreased the occurrence of metastases. In conclusion, our results indicate that antiangiogenic therapy using ES has the potential to prevent the progression of metastases.

Role of radiotherapy for pancreatobiliary neuroendocrine tumors

Purpose

We investigated the role of radiotherapy (RT) for pancreatobiliary neuroendocrine tumors (PB-NETs).

Materials and Methods

We identified 9 patients with PB-NETs who received RT between January 2005 and March 2012. Of these 9 patients, 4 were diagnosed with NETs in the pancreas and 5 were diagnosed with NETs in the gallbladder. All patients received RT to the primary tumor or resection bed with a median total irradiation dose of 50.4 Gy, with or without chemotherapy.

Results

The tumor response rate and tumor control rate in the RT field were 60% and 100 %, respectively. All 4 patients who underwent surgery had no evidence of disease in the RT field. Of the 5 patients who received RT to the primary gross tumor, 1 had complete response, 2 had partial response, and 2 had stable disease in the RT field. The median time to progression was 11 months. Of the 9 patients, four patients had no progression, and 5 patients had progression of disease (locoregional, 2; distant, 2; locoregional/distant, 1). Of the 4 patients without progression, 3 were treated with RT in adjuvant or neoadjuvant setting, and one received RT to primary tumor. One patient experienced radiation-induced duodenitis at 3 months after concurrent chemoradiation without treatment-related mortality.

Conclusion

RT can yield local control for advanced PB-NETs. RT should be considered an essential part of multimodality treatment in management of advanced PB-NETs.

Pancreatic neuroendocrine tumors: approach to treatment with focus on sunitinib

Pancreatic neuroendocrine tumors (pNETs) are relatively rare malignancies. With secretory tumors such as insulinomas, vasoactive intestinal peptideomas, and gastrinomas, the hormone produced causes the symptom complex (e.g. hypoglycemia, peptic ulcer disease). With nonsecretory NETs, the clinical condition is determined by tumoral growth and metastasis. The course of metastatic pNETs may be indolent for several years but progression is often more rapid at later stages, leading to significant disability and a markedly negative impact on quality of life. Until recently, there were few effective systemic treatments for pNETs. Standard chemotherapy produces limited responses and has considerable toxicity. Somatostatin analogues control symptoms in some types of pNETs, but have not yet demonstrated antitumor activity. The recent introduction of targeted therapies, including the tyrosine kinase inhibitor sunitinib and the mammalian target of rapamycin inhibitor everolimus, yielded new opportunities for patients with advanced/metastatic pNETs. These drugs, which target key pathways in tumor proliferation and angiogenesis, provided clear clinical benefits in phase III clinical trials, including delayed tumor progression. The pivotal sunitinib phase III trial was discontinued prematurely due to higher rates of death and serious adverse events with placebo and greater progression-free survival (PFS) with sunitinib. In this trial, sunitinib demonstrated encouraging long-term responses as well as PFS and overall survival benefits, and an acceptable safety profile that allowed patients to preserve their quality of life. In every patient subgroup, including secretory and nonsecretory tumors, the hazard ratio for progression or death favored sunitinib. Circulating biomarkers are being investigated for the prediction and monitoring of responses to sunitinib. Although not fully evaluated in pNETs, biomarkers associated with response to sunitinib in several tumor types include soluble vascular endothelial growth factor receptor 2 and 3, interleukin 8, and stromal cell-derived factor 1α. Based on recent data, treatment algorithms have been updated for advanced and metastatic pNETs.

Systemic therapeutic options for carcinoid

"Carcinoids" are mostly slow-growing neuroendocrine neoplasms (NENs) with low proliferative activity. A wide range of therapeutic options with variable efficacy exist, including locoregional ablative strategies. Thereafter, some patients may not require medical therapy for years depending on the rate of progression or recurrence. However, the majority of patients require systemic treatment and therein lies the dilemma, since no antiproliferative agent is currently approved for carcinoids. Somatostatin analogs (SSAs), and to a lesser extent interferon-alpha, are standard therapy for carcinoids associated with the carcinoid syndrome. These drugs have some antiproliferative efficacy. SSAs rarely lead to tumor remission but may modestly prolong time to tumor progression. Chemotherapy is of limited value in carcinoids with low proliferation indices but may be useful in higher grade tumors. Peptide receptor-targeted radionuclide therapy may be of benefit and is mostly used after medical therapies fail. However, it is considered an investigational modality. More recently, targeted drugs such as mammalian target of rapamycin (mTOR) inhibitors and anti-angiogenics have been investigated. Objective remissions are rare. Their value remains to be rigorously elucidated. Increased efficacy requires a better understanding of the underlying tumor biology and identification of molecular pathological criteria to allow appropriate preselection of candidates for targeted therapies.

Elevated serum endostatin levels are associated with poor survival in patients with advanced-stage nasopharyngeal carcinoma

AIMS

To evaluate the prognostic value of serum endostatin levels in patients with advanced-stage nasopharyngeal carcinoma (NPC).

MATERIALS AND METHODS

Between August 2003 and March 2005, 218 patients with advanced-stage NPC were enrolled in this study, including 70 patients in the training cohort and 148 in the validation cohort. The pre-treatment serum endostatin and vascular endothelial growth factor (VEGF) levels were measured using competitive enzyme immunoassays. For the normal control, serums samples from 20 healthy individuals were also collected.

RESULTS

Serum endostatin levels in the patients with advanced-stage NPC were significantly higher than those of controls, but VEGF levels were similar in the two groups. Univariate analysis revealed significant differences between the high and low endostatin level groups regarding 5 year overall survival (63.9% versus 90.5%; P = 0.003), progression-free survival (PFS) (50.2% versus 79.3%; P = 0.003) and distant metastasis-free survival (DMFS) (59.1% versus 85.3%; P = 0.01) in the training cohort. Using the same cut-off value generated from the training cohort, there were also significant unfavourable correlations between serum endostatin levels and overall survival (P = 0.001), PFS (P = 0.001) and DMFS (P = 0.002) in the second independent validation cohort. Multivariate analysis using the entire group (n = 218) revealed that the serum endostatin level was an independent unfavourable prognostic factor for overall survival (hazard ratio 4.8; 95% confidence interval 2.48-9.23; P < 0.0001), PFS (hazard ratio 3.44; 95% confidence interval 2.06-5.74; P < 0.0001) and DMFS (hazard ratio 3.65; 95% confidence interval 1.92-6.94; P < 0.0001) in patients with advanced-stage NPC. No associations were observed between the outcomes and the serum VEGF levels in patients with advanced-stage NPC.

CONCLUSIONS

High endostatin levels are associated with poor survival and this knowledge may improve the risk stratification of patients with advanced-stage NPC.

Translation of molecular pathways into clinical trials of neuroendocrine tumors

Current treatment options for neuroendocrine tumors (NET) include somatostatin analogs, interferon-α, peptide receptor-targeted therapy and cytotoxic chemotherapy. Most patients undergo sequential therapies since these drugs are active only in subpopulations of patients and for a limited period of time. There is a need for novel drugs that are capable of amelioration of symptomatology (syndromic control) and/or tumor growth control. A number of diverse signaling pathways are involved in the pathogenesis of NET and tumor growth, thus many potential targets are available for drug targeting. Targeted therapies therefore represent an appropriate developmental therapeutic strategy given the multiplicity of potential targets in NET. These include but are not limited to: inhibitory or activating G protein-coupled receptors, receptor tyrosine kinases, ligands, and intracellular targets such as the mammalian target of rapamycin (mTOR). Numerous drugs that utilize single or multiple targets are currently in clinical development. Recently, two target-directed agents, the multiple tyrosine kinase inhibitor sunitinib and the mTOR inhibitor everolimus, have been approved for the treatment of progressive pancreatic NET. This review provides a broad overview of established and potential molecular targets in NET, summarizes data from phase II and III clinical trials with targeted drugs and outlines future therapeutic directions.

A shining light in the darkness for the treatment of pancreatic neuroendocrine tumors

Gastroenteropancreatic neuroendocrine tumors are rare neoplasms; past decades have seen limited research channeled into this area. Recently, 2 placebo-controlled phase III trials using 2 drugs--everolimus and sunitinib--with distinct molecular rationales achieved their principal objective of increasing survival in patients with advanced pancreatic neuroendocrine tumors (PNET). Nonetheless, several questions remain unanswered, notably defining the optimal schedule for integrating these targeted agents with conventional cytotoxics and other treatment options, and identifying appropriate biomarkers for patients with the potential to derive greater benefit. In this article, we analyze the results of the 2 largest studies ever completed in patients with PNETs and discuss the challenges for future drug development in this setting.

SUMMARY

Sunitinib and everolimus will become new treatment options for patients with PNETs and will be integrated into the complex therapeutic management of this disease. In this review, we summarize the evidence-based data of these drugs as well as the molecular-based science in this setting that will lay the groundwork for future studies.

Synergistic antitumor effects of endostar in combination with oxaliplatin via inhibition of HIF and CXCR4 in the colorectal cell line SW1116

Combination treatment with endostar, a novel modified endostatin, and cytotoxic chemotherapies showed a survival benefit in Chinese clinical trials. However, the exact mechanism for this synergism remains unclear. In this study, we report for the first time that the chemokine receptor CXCR4 and the hypoxia-inducible transcription factors (HIF)-1α and HIF-2α are involved in these synergistic antitumor effects in human colorectal cancer SW1116 cells in vitro when endostar treatment is combined with the cytotoxic drug oxaliplatin. Under normoxia, we demonstrate that endostar and oxaliplatin treatments synergize to inhibit SW1116 cell proliferation, Matrigel adhesion and invasion by reduction of CXCR4 expression. Consistently, these antitumor abilities of endostar and oxaliplatin were markedly reduced by silencing of CXCR4 in SW1116 cells. Under low oxygen conditions (hypoxia, 1% oxygen), enhanced proliferation of SW1116 cells exposed to oxaliplatin was observed due to the emergence of drug resistance. Strikingly, endostar overcame oxaliplatin-resistance, most likely as a consequence of reduced HIF-2α and CXCR4 levels. CXCR4, is only dependent on HIF-2α, which promotes more aggressive phenotype and more significant for oxaliplatin resistance in SW1116 cells. Our data not only provide clues to aid understanding of the mechanism of the synergism of endostar and chemotherapy under either normoxia or hypoxia, but also suggests a new strategy of combination endostar and chemotherapy treatments which might potentiate therapeutic efficacies and/or counteract chemotherapy resistance.

Engineering endostatin-expressing cartilaginous constructs using injectable biopolymer hydrogels

The release of an anti-angiogenic agent, such as type XVIII/endostatin, from an implantable scaffold may be of benefit in the repair of articular cartilage. The objectives of this study are to develop an injectable mesenchymal stem cell (MSC)-incorporating collagen-based hydrogel capable of undergoing covalent cross-linking in vivo and overexpressing endostatin using nonviral transfection, and to investigate methods for the retention of the endostatin protein within the scaffolds. The effects of different cross-linking agents (genipin, transglutaminase-2, and microbial transglutaminase) and different binding molecules for endostatin retention (heparin, heparan sulfate, and chondroitin sulfate) are evaluated. Cartilaginous constructs that overexpress endostatin for 3 weeks are successfully engineered. Most of the endostatin is released into the surrounding media and is not retained within the constructs. The presence of two common basement membrane molecules, laminin and type IV collagen, which have been reported in developing and mature articular cartilage and are generally associated with type XVIII collagen in vivo, is also observed in the engineered cartilaginous constructs. Endostatin-producing cartilaginous constructs can be formulated by growing nonvirally transfected mesenchymal stem cells in collagen gels covalently cross-linked using genipin, transglutaminase-2, and microbial transglutaminase. These constructs warrant further investigation for cartilage repair procedures. The novel finding of laminin and type IV collagen in the engineered cartilage constructs may be of importance for future work toward understanding the role of basement membrane molecules in chondrogenesis and in the physiology and pathology of articular cartilage.

Endostatin lowers blood pressure via nitric oxide and prevents hypertension associated with VEGF inhibition

Antiangiogenesis therapy has become a vital part of the armamentarium against cancer. Hypertension is a dose-limiting toxicity for VEGF inhibitors. Thus, there is a pressing need to address the associated adverse events so these agents can be better used. The hypertension may be mediated by reduced NO bioavailability resulting from VEGF inhibition. We proposed that the hypertension may be prevented by coadministration with endostatin (ES), an endogenous angiogenesis inhibitor with antitumor effects shown to increase endothelial NO production in vitro. We determined that Fc-conjugated ES promoted NO production in endothelial and smooth muscle cells. ES also lowered blood pressure in normotensive mice and prevented hypertension induced by anti-VEGF antibodies. This effect was associated with higher circulating nitrate levels and was absent in eNOS-knockout mice, implicating a NO-mediated mechanism. Retrospective study of patients treated with ES in a clinical trial revealed a small but significant reduction in blood pressure, suggesting that the findings may translate to the clinic. Coadministration of ES with VEGF inhibitors may offer a unique strategy to prevent drug-related hypertension and enhance antiangiogenic tumor suppression.