The therapeutic efficacy of anti vascular endothelial growth factor antibody, bevacizumab, and pemetrexed against orthotopically implanted human pleural mesothelioma cells in severe combined immunodeficient mice

Understanding the health benefits and technological properties of β-glucan for the development of easy-to-swallow gels to guarantee food security among seniors

The world's population is growing rapidly and the number of elderly people with undernutrition and malnutrition is increasing. Common health problems among seniors are cardiovascular, inflammatory, gastrointestinal, and cognitive disorders, cancer, diabetes, psychological and dental problems. The food industry is trying to meet the demands of an aging society, but these efforts are not sufficient. New strategies are needed, and they demand foods development with modified textures that are easy to swallow, such as gels suitable for seniors. Depending on the specific needs of the elderly, bioactive compounds with health benefits should be included in food systems. Novel foods may play an important role in the prevention, maintenance, and treatment of age-related diseases. One of the most studied bioactive compound is β-glucan, a polysaccharide with approved health claims confirmed by clinical trials, such as "β-glucan contributes to the maintenance of normal blood cholesterol levels" and "the consumption of β-glucan from oats or barley contributes to the reduction of postprandial glucose spikes." In this review, the health benefits, and technological properties of β-glucan for the development of senior-friendly ready-to-swallow gels were described. In addition, some patents and studies conducted in connection with the development of the gel systems were collected.

Malignant pleural mesothelioma nodules remodel their surroundings to vascularize and grow

Background

The microanatomical steps of malignant pleural mesothelioma (MPM) vascularization and the resistance mechanisms to anti-angiogenic drugs in MPM are unclear.

Methods

We investigated the vascularization of intrapleurally implanted human P31 and SPC111 MPM cells. We also assessed MPM cell's motility, invasion and interaction with endothelial cells in vitro.

Results

P31 cells exhibited significantly higher two-dimensional (2D) motility and three-dimensional (3D) invasion than SPC111 cells in vitro. In co-cultures of MPM and endothelial cells, P31 spheroids permitted endothelial sprouting (ES) with minimal spatial distortion, whereas SPC111 spheroids repealed endothelial sprouts. Both MPM lines induced the early onset of submesothelial microvascular plexuses covering large pleural areas including regions distant from tumor colonies. The development of these microvascular networks occurred due to both intussusceptive angiogenesis (IA) and ES and was accelerated by vascular endothelial growth factor A (VEGF-A)-overexpression. Notably, SPC111 colonies showed different behavior to P31 cells. P31 nodules incorporated tumor-induced capillary plexuses from the earliest stages of tumor formation. P31 cells deposited a collagenous matrix of human origin which provided "space" for further intratumoral angiogenesis. In contrast, SPC111 colonies pushed the capillary plexuses away and thus remained avascular for weeks. The key event in SPC111 vascularization was the development of a desmoplastic matrix of mouse origin. Continuously invaded by SPC111 cells, this matrix transformed into intratumoral connective tissue trunks, providing a route for ES from the diaphragm.

Conclusions

Here, we report two distinct growth patterns of orthotopically implanted human MPM xenografts. In the invasive pattern, MPM cells invade and thus co-opt peritumoral capillary plexuses. In the pushing/desmoplastic pattern, MPM cells induce a desmoplastic response within the underlying tissue which allows the ingrowth of a nutritive vasculature from the pleura.

Advances in Drug Treatments for Mesothelioma

INTRODUCTION

The paucity of the therapeutic armamentarium currently available for patients with malignant mesothelioma clearly represents a huge unmet need. Over the last years, based on new advances in understanding the biology of mesothelioma, new therapeutic approaches have been investigated.

AREAS COVERED

In this manuscript, the literature data regarding the advances in drug treatment for patients with mesothelioma are critically reviewed, focusing particularly on immunotherapy and targeted therapy.

EXPERT OPINION

The latest findings on immunotherapy and targeted therapy are changing the therapeutic armamentarium for mesothelioma. However, mesothelioma comprises of genomically different subtypes and the phenotypic diversity combined with the rarity of this disease represents a major criticality in developing new effective therapies. Although the first clinical data are encouraging, the treatment's stratification by molecular characteristics for mesothelioma is only at the beginning. Luckily, the rapid improvement of understanding the biology of mesothelioma is producing new opportunities in discovering new therapeutic targets to test in pre-clinical settings and to transfer in the clinical setting. In this evolving scenario, the future perspectives for mesothelioma patients seem really promising.

Bevacizumab plus cisplatin/pemetrexed then bevacizumab alone for unresectable malignant pleural mesothelioma: A Japanese safety study

Aims

Malignant pleural mesothelioma (MPM) is an aggressive malignancy with poor prognosis and limited treatment options. Cisplatin plus pemetrexed is the only approved first‐line treatment for patients with unresectable MPM. Recently, promising outcomes were observed with first‐line bevacizumab combined with cisplatin/pemetrexed, leading to the recommendation of this regimen as a first‐line treatment option for patients with MPM. Bevacizumab plus cisplatin/pemetrexed has been shown to be safe and effective in non–small cell lung cancer, however, there are no efficacy or safety data in Japanese patients with MPM treated with this regimen. We conducted a multicenter study to evaluate tolerability and safety for Japanese patients with chemotherapy‐naïve, unresectable MPM.

Methods

Eligible patients (n = 7) received bevacizumab plus cisplatin/pemetrexed (up to six cycles), then single‐agent bevacizumab until disease progression or onset of unacceptable adverse events (AEs), according to the 3+3 design analogy.

Results

One patient (14.3%) reported an AE (gastric ulcer) meeting tolerability criteria. All patients experienced gastrointestinal disorders, including nausea (grade 1/2 only, n = 6, 85.7%) and constipation (grade 1/2 only, n = 5, 71.4%). Five patients (71.4%) had grade 3 hypertension. Two patients discontinued treatment due to gastric ulcer (n = 1) and proteinuria (n = 1). At data cut‐off, four patients had stable disease, two had partial response and one had non‐complete response/non‐progressive disease due to the absence of target lesions.

Conclusions

Bevacizumab plus cisplatin/pemetrexed then bevacizumab was well tolerated in Japanese patients with MPM.

A Phase II Study of Pazopanib in Patients with Malignant Pleural Mesothelioma: NCCTG N0623 (Alliance)

PURPOSE

Preclinical and clinical data have shown promise in using antiangiogenic agents to treat malignant pleural mesothelioma (MPM). We conducted this phase II study to evaluate the efficacy and toxicity of single-agent pazopanib in patients with MPM.

MATERIALS AND METHODS

Patients with MPM who had received 0-1 prior chemotherapy regimens were eligible to receive pazopanib at a dose of 800 mg daily. The primary endpoint was progression-free survival rate at 6 months (PFS6), with a preplanned interim analysis for futility. Secondary endpoints included overall survival (OS), PFS, adverse events assessment and clinical benefit (complete response, partial response [PR], and stable disease [SD]).

RESULTS

Thirty-four evaluable patients were enrolled, with a median age of 73 years (49-84). The trial was closed early because of lack of efficacy at the preplanned interim analysis. Only 8 patients (28.6%; 95% confidence interval [CI], 13.2-48.7%) in the first 28 evaluable were progression-free at 6 months. PFS6 was 32.4% (95% CI, 17.4-50.5). There were 2 PR (5.9%) and 16 SD (47.1%). The overall median PFS and OS were 4.2 months (95% CI, 2.0-6.0) and 11.5 months (95% CI: 5.3-18.2), respectively. The median PFS and OS for the previously untreated patients was 5.4 months (95% CI, 2.7-8.5) and 16.6 months (95% CI, 6.6-30.6), respectively; and 2.0 months (95% CI, 1.3-4.2) and 5.0 months (95% CI: 3.0-11.9), respectively, for the previously treated patients. Grade 3 or higher adverse events were observed in 23 patients (67.6%).

CONCLUSION

Single-agent pazopanib was poorly tolerated in patients with MPM. The primary endpoint of PFS6 was not achieved in the current study. ClinicalTrials.gov identification number. NCT00459862.

IMPLICATIONS FOR PRACTICE

Single-agent pazopanib did not meet its endpoint in this phase II trial in malignant mesothelioma. Pazopanib is well tolerated in mesothelioma patients with a manageable toxicity profile. There is a need to better identify signals of angiogenesis that can be targeted in mesothelioma. Encouraging findings in frontline treatment warrant further investigations in combination with chemotherapy or immunotherapy.

Antiangiogeneic Strategies in Mesothelioma

There is a strong rationale for inhibiting angiogenesis in mesothelioma. Vascular endothelial growth factor (VEGF) is an autocrine growth factor in mesothelioma and a potent mitogen for mesothelial cells. Further, the abnormal tumor vasculature promotes raised interstitial pressure and hypoxia, which may be detrimental to both penetration and efficacy of anticancer agents. Antiangiogenic agents have been trialed in mesothelioma for close to two decades, with early phase clinical trials testing vascular targeting agents, the VEGF-A targeting monoclonal antibody bevacizumab, and numerous tyrosine kinase inhibitors, many with multiple targets. None of these have shown efficacy which has warranted further development as single agents in any line of therapy. Whilst a randomized phase II trial combining the multitargeted tyrosine kinase inhibitor nintedanib with platinum/pemetrexed chemotherapy was positive, these results were not confirmed in a subsequent phase III study. The combination of cisplatin and pemetrexed with bevacizumab, in appropriately selected patients, remains the only anti-angiogenic combination showing efficacy in mesothelioma. Extensive efforts to identify biomarkers of response have not yet been successful.

Liquid crystalline assembly for potential combinatorial chemo-herbal drug delivery to lung cancer cells

Background

Lung cancer is the most common cancer and the leading cause of total deaths worldwide. Its classified into two major types including non-small cell lung carcinoma (NSCLC) and small cell lung carcinoma (SCLC) based on the origin of abnormal lung cells as well as the smoking status of the patient. NSCLC is the most common and aggressive type of lung cancer representing 80%–85% of all cases.

Purpose

The aim of the study was to present lyotropic liquid crystalline nanoparticles (LCNPs) as promising carriers for co-delivery of the chemotherapeutic agent, pemetrexed (PMX) and the herbal drug, resveratrol (RSV) for effective lung cancer management.

Methods

The proposed PMX-RSV-LCNPs were prepared by hydrotrope method. Hydrophobic ion pairing with cetyl trimethyl ammonium bromide (CTAB) was implemented to increase the encapsulation efficiency of the hydrophilic PMX up to 95%±3.01%.

Results

The tailored PMX-RSV-LCNPs exhibited a particle size of 173±0.26 nm and biphasic release pattern with a relatively initial burst release within first 3–4 hour followed by sustained release up to 24 hours. Moreover, PMX-RSV-LCNPs manifested superior concentration and time dependent cytotoxicity profile against A549 lung cancer cells with IC₅₀ 4.0628 µg/mL. Besides, the enhanced cellular uptake profile based on bioadhesive properties of glyceryl monoolein (GMO) as well as energy independent (cholesterol dependent) pattern. In-vivo evaluations against urethane induced lung cancer bearing mice demonstrated the potentiality of PMX-RSV-LCNPs in tumor growth inhibition via inhibition of angiogenesis and induction of apoptosis. The results were supported by histopathological analysis and immunohistochemical Ki67 staining. Moreover, PMX-RSV-LCNPs displayed a promising safety profile via attenuating nephro- and hepatotoxicity.

Conclusion

PMX-RSV-LCNPs elaborated in the current study hold a great promise for lung cancer treatment.

Nivolumab Immunotherapy in Malignant Mesothelioma: A Case Report Highlighting a New Opportunity for Exceptional Outcomes

BACKGROUND Malignant pleural mesothelioma (MPM) is a highly lethal cancer with a median survival of ~12 months even with aggressive intervention. Frontline therapy relies on systemic cisplatin and pemetrexed chemotherapy and has a response rate of ~35-41%; currently, there are no US Food and Drug Administration approved second-line therapies for MPM. Herein, we present a patient with MPM who experienced rapid disease progression after standard therapy but who had an exceptional and sustained response to immune checkpoint inhibition with single agent nivolumab. CASE REPORT A 68-year-old male with a history of work-related asbestos exposure was diagnosed with MPM. He was treated with primary resection followed by systemic chemotherapy with cisplatin and pemetrexed. When chemotherapy failed, he was switched to immunotherapy with nivolumab and achieved an exceptional response. CONCLUSIONS We report the first case of a patient with MPM who experienced rapid disease progression after standard therapy but had an exceptional and sustained response to immune checkpoint inhibition with single agent nivolumab. As outcomes with traditional chemotherapy regimens remain disappointing, there is a substantial need for new approaches to MPM; our case highlights a new therapeutic opportunity even in the face of aggressive disease. Indeed, a new era of investigation utilizing immunotherapy for mesothelioma is beginning, with much anticipation.

Nintedanib Is Active in Malignant Pleural Mesothelioma Cell Models and Inhibits Angiogenesis and Tumor Growth In Vivo

Purpose: Malignant pleural mesothelioma (MPM) is an aggressive thoracic tumor type with limited treatment options and poor prognosis. The angiokinase inhibitor nintedanib has shown promising activity in the LUME-Meso phase II MPM trial and thus is currently being evaluated in the confirmatory LUME-Meso phase III trial. However, the anti-MPM potential of nintedanib has not been studied in the preclinical setting.Experimental Design: We have examined the antineoplastic activity of nintedanib in various in vitro and in vivo models of human MPM.Results: Nintedanib's target receptors were (co)expressed in all the 20 investigated human MPM cell lines. Nintedanib inhibited MPM cell growth in both short- and long-term viability assays. Reduced MPM cell proliferation and migration and the inhibition of Erk1/2 phosphorylation were also observed upon nintedanib treatment in vitro Additive effects on cell viability were detected when nintedanib was combined with cisplatin, a drug routinely used for systemic MPM therapy. In an orthotopic mouse model of human MPM, survival of animals receiving nintedanib per os showed a favorable trend, but no significant benefit. Nintedanib significantly reduced tumor burden and vascularization and prolonged the survival of mice when it was administered intraperitoneally. Importantly, unlike bevacizumab, nintedanib demonstrated significant in vivo antivascular and antitumor potential independently of baseline VEGF-A levels.Conclusions: Nintedanib exerts significant antitumor activity in MPM both in vitro and in vivo These data provide preclinical support for the concept of LUME-Meso trials evaluating nintedanib in patients with unresectable MPM. Clin Cancer Res; 24(15); 3729-40. ©2018 AACR.

Target therapy: new drugs or new combinations of drugs in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a disease with a poor prognosis due to its aggressive nature. The management of patients with MPM is controversial. Considering that the contribution of surgery and radiation therapy in the management of this disease is not yet established, systemic treatments are predominantly considered during the course of MPM. Unfortunately, the currently therapeutic armamentarium is scarce and its outcomes still appear modest. New treatment strategies are needed. In preclinical setting, cell cycle regulation, apoptosis, growth factor pathways, and angiogenesis pathways involved in the development of MPM have been identified. However, in clinical setting, several drugs targeting these pathways resulted without a significant activity. A deeper knowledge of the biology and pathogenesis of this disease is required to develop more effective tools for diagnosis, therapy and prevention. This paper reviews therapeutic advances in MPM, with a particular focus on new drugs and new association of drugs of target therapy.

Fibrocytes: A Novel Stromal Cells to Regulate Resistance to Anti-Angiogenic Therapy and Cancer Progression

An adequate blood supply is essential for cancer cells to survive and grow; thus, the concept of inhibiting tumor angiogenesis has been applied to cancer therapy, and several drugs are already in clinical use. It has been shown that treatment with those anti-angiogenic drugs improved the response rate and prolonged the survival of patients with various types of cancer; however, it is also true that the effect was mostly limited. Currently, the disappointing clinical results are explained by the existence of intrinsic or acquired resistance to the therapy mediated by both tumor cells and stromal cells. This article reviews the mechanisms of resistance mediated by stromal cells such as endothelial cells, pericytes, fibroblasts and myeloid cells, with an emphasis on fibrocytes, which were recently identified as the cell type responsible for regulating acquired resistance to anti-angiogenic therapy. In addition, the other emerging role of fibrocytes as mediator-producing cells in tumor progression is discussed.

The Effect of Aquaporin 1-Inhibition on Vasculogenic Mimicry in Malignant Mesothelioma

Malignant mesothelioma (MM) is an aggressive malignancy of the serosal membranes, with poor overall survival and quality of life. Limited targeted treatment strategies exist due to restricted knowledge of pathogenic pathways. Vasculogenic mimicry (VM) is a newly described phenomenon associated with increased aggressiveness in other malignancies, and has been characterized in MM. Normal mesothelium expresses aquaporin 1 (AQP1) and retained expression has been associated with improved survival in MM. AQP1 is expressed by normal vascular endothelium and is involved in mediating MM cell motility and proliferation. We investigated the role of AQP1 in VM, and its interaction with the pro-angiogenic factor vascular endothelial growth factor A (VEGFA), which is variably expressed in MM. Matrigel VM assays were performed using NCI-H226 and NCI-H28 MM cell lines and primary cells in hypoxia and normoxia. The synthetic blocker AqB050 and siRNA were used to inhibit AQP1, and bevacizumab was used to inhibit VEGF. Inhibition of AQP1 resulted in increased VEGFA secretion by MM cells and reduced VM in MM cell lines in hypoxia but not normoxia. No change in VM was seen in MM primary cells. Combined inhibition of AQP1 and VEGF had no effect on VM in normoxia. In a heterotopic xenograft mouse model, AqB050 treatment did not alter vessel formation. AQP1 may interact with VEGFA and play a role in VM, especially under hypoxic conditions, but the heterogeneity of MM cells may result in different dominant pathways between patients.

A review of bevacizumab in the treatment of malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive cancer with poor prognosis. Systemic chemotherapy is the primary treatment modality for the majority of patients. VEGF plays a key mitogen for MPM cells physiopathology. Bevacizumab, a monoclonal anti-VEGF antibody, was a rational approach to be tested in MPM. Based on the results of the Phase III IFCT-0701 mesothelioma avastin cisplatin pemetrexed study, cisplatin-pemetrexed-bevacizumab is now the accepted standard in France. The National Comprehensive Cancer Network guidelines have also included this combination as an option for standard front-line therapy. This review summarized the efficacy and safety data of bevacizumab in the treatment of patients with MPM.

Vasculogenic mimicry in malignant mesothelioma: an experimental and immunohistochemical analysis

Vasculogenic mimicry, the process in which cancer cells form angiomatoid structures independent of or in addition to host angiogenesis has been recorded in several otherwise non-endothelial malignant neoplasms. This study describes evidence of routine vascular mimicry by human mesothelioma cell lines in vitro, when the cell lines are cultured alone or co-cultured with human umbilical vascular endothelial cells, with the formation of angiomatoid tubular networks. Vasculogenic mimicry is also supported by immunohistochemical demonstration of human-specific anti-mitochondria antibody labelling of tumour-associated vasculature of human mesothelioma cells xenotransplanted into nude mice, and by evidence of vascular mimicry in some biopsy samples of human malignant mesotheliomas. These studies show mosaic interlacing of cells that co-label or label individually for immunohistochemical markers of endothelial and mesothelial differentiation. If vascular mimicry in mesothelioma can be characterised more fully, this may facilitate identification of more specific and targeted therapeutic approaches such as anti-angiogenesis in combination with chemotherapy and immunotherapy or other therapeutic approaches.

Antitumor effect of novel anti-podoplanin antibody NZ-12 against malignant pleural mesothelioma in an orthotopic xenograft model

Podoplanin (aggrus) is highly expressed in several types of cancers, including malignant pleural mesothelioma (MPM). Previously, we developed a rat anti-human podoplanin mAb, NZ-1, and a rat-human chimeric anti-human podoplanin antibody, NZ-8, derived from NZ-1, which induced antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity against podoplanin-positive MPM cell lines. In this study, we showed the antitumor effect of NZ-1, NZ-8, and NZ-12, a novel rat-human chimeric anti-human podoplanin antibody derived from NZ-1, in an MPM orthotopic xenograft SCID mouse model. Treatment with NZ-1 and rat NK (CD161a(+) ) cells inhibited the growth of tumors and the production of pleural effusion in NCI-H290/PDPN or NCI-H226 orthotopic xenograft mouse models. NZ-8 and human natural killer (NK) (CD56(+) ) cells also inhibited tumor growth and pleural effusion in MPM orthotopic xenograft mice. Furthermore, NZ-12 induced potent ADCC mediated by human MNC, compared with either NZ-1 or NZ-8. Antitumor effects were observed following treatment with NZ-12 and human NK (CD56(+) ) cells in MPM orthotopic xenograft mice. In addition, combined immunotherapy using the ADCC activity of NZ-12 mediated by human NK (CD56(+) ) cells with pemetrexed, led to enhanced antitumor effects in MPM orthotopic xenograft mice. These results strongly suggest that combination therapy with podoplanin-targeting immunotherapy using both NZ-12 and pemetrexed might provide an efficacious therapeutic strategy for the treatment of MPM.

New therapeutic strategies for malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a rare and aggressive malignant disease affecting the mesothelium, commonly associated to asbestos exposure. Therapeutic actions are limited due to the late stage at which most patients are diagnosed and the intrinsic chemo-resistance of the tumor. The recommended systemic therapy for MPM is cisplatin/pemetrexed regimen with a mean overall survival of about 12months and a median progression free survival of less than 6months. Considering that the incidence of this tumor is expected to increase in the next decade and that its prognosis is poor, novel therapeutic approaches are urgently needed. For some tumors, such as lung cancer and breast cancer, druggable oncogenic alterations have been identified and targeted therapy is an important option for these patients. For MPM, clinical guidelines do not recommend biological targeted therapy, mainly because of poor target definition or inappropriate trial design. Further studies are required for a full comprehension of the molecular pathogenesis of MPM and for the development of new target agents. This review updates pre-clinical and clinical data on the efficacy of targeted therapy and immune checkpoint inhibition in the treatment of mesothelioma. Finally, future perspectives in this deadly disease are also discussed.

Antagonizing the Hedgehog Pathway with Vismodegib Impairs Malignant Pleural Mesothelioma Growth In Vivo by Affecting Stroma

An autocrine-driven upregulation of the Hedgehog (Hh) signaling pathway has been described in malignant pleural mesothelioma (MPM), in which the ligand, desert Hh (DHH), was produced from tumor cells. However, our investigation revealed that the Hh pathway is activated in both tumor and stroma of MPM tumor specimens and an orthotopic immunocompetent rat MPM model. This was demonstrated by positive immunohistochemical staining of Glioma-associated oncogene 1 (GLI1) and Patched1 (PTCH1) in both tumor and stromal fractions. DHH was predominantly expressed in the tumor fractions. To further investigate the role of the Hh pathway in MPM stroma, we antagonized Hh signaling in the rat model of MPM using a Hh antagonist, vismodegib, (100 mg/kg orally). Daily treatment with vismodegib efficiently downregulated Hh target genes Gli1, Hedgehog Interacting Protein (Hhip), and Ptch1, and caused a significant reduction of tumor volume and tumor growth delay. Immunohistochemical analyses revealed that vismodegib treatment primarily downregulated GLI1 and HHIP in the stromal compartment along with a reduced expression of previously described fibroblast Hh-responsive genes such as Fibronectin (Fn1) and Vegfa Primary cells isolated from the rat model cultured in 3% O2 continued to express Dhh but did not respond to vismodegib in vitro However, culture supernatant from these cells stimulated Gli1, Ptch1, and Fn1 expression in mouse embryonic fibroblasts, which was suppressed by vismodegib. Our study provides new evidence regarding the role of Hh signaling in MPM stroma in the maintenance of tumor growth, emphasizing Hh signaling as a treatment target for MPM. Mol Cancer Ther; 15(5); 1095-105. ©2016 AACR.

Closing faucets: the role of anti-angiogenic therapies in malignant pleural diseases

Malignant pleural effusion (MPE) represents 15-35 % of pleural effusions and markedly worsens the prognosis and quality of life of patients with cancer. Malignant mesothelioma (MM) and lung adenocarcinoma are the most frequent primary and secondary causes, respectively, of MPE. Effective treatments for cancer-related MPE are warranted in order to improve symptoms, reduce the number of invasive pleural procedures, and prolong patient life. Since angiogenesis plays a key role in MPE development, the potential role of bevacizumab and other anti-angiogenic therapies have been explored in this review. No relevant phase III trials have specifically analysed the benefit from adding bevacizumab to platinum-based chemotherapy in lung cancer-related MPE. However, small retrospective series reported 71.4-93.3 % MPE control rate, a reduction in invasive procedures, and a safe profile with this combination. Being approved for the first-line treatment of non-squamous advanced NSCLC, the addition of bevacizumab should be considered for patients presenting with MPE. In addition, further studies in this are recommended. In MM, the addition of bevacizumab to platinum-based chemotherapy did not meet primary endpoints in two phase II trials. However, the beneficial results on OS reported in comparison with historical cohorts and the statistically significant benefit on PFS and OS observed in the phase III MAPS trial foretell an eventual role for the combination of platinum/pemetrexed/bevacizumab as front-line systemic therapy for pleural MM. To date, no other anti-angiogenic drug has showed significant benefit in the treatment of patients with either MPE or MM. However, new promising drugs such as ramucirumab or recombinant human endostar warrant further investigation.

Fibrocyte-like cells mediate acquired resistance to anti-angiogenic therapy with bevacizumab

Bevacizumab exerts anti-angiogenic effects in cancer patients by inhibiting vascular endothelial growth factor (VEGF). However, its use is still limited due to the development of resistance to the treatment. Such resistance can be regulated by various factors, although the underlying mechanisms remain incompletely understood. Here we show that bone marrow-derived fibrocyte-like cells, defined as alpha-1 type I collagen-positive and CXCR4-positive cells, contribute to the acquired resistance to bevacizumab. In mouse models of malignant pleural mesothelioma and lung cancer, fibrocyte-like cells mediate the resistance to bevacizumab as the main producer of fibroblast growth factor 2. In clinical specimens of lung cancer, the number of fibrocyte-like cells is significantly increased in bevacizumab-treated tumours, and correlates with the number of treatment cycles, as well as CD31-positive vessels. Our results identify fibrocyte-like cells as a promising cell biomarker and a potential therapeutic target to overcome resistance to anti-VEGF therapy.

Prognostic value of several biomarkers for the patients with malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a highly aggressive tumor of the pleura closely related to asbestos exposure. Rare as it is, the incidence of MPM is predicted to increase mainly as a result of a lengthy latency period from the initial asbestos exposure, making it a public health concern for the next decades. Moreover, the patients with MPM have an extremely poor prognosis due to its high resistance to conventional oncologic treatments and delayed diagnosis. Although the result of current therapeutic modalities based on patient features and clinical stages is very frustrating, great advances have been shown in the knowledge of molecular biology of MPM in recent years. This is accompanied by dozens of putative prognostic biomarkers that are actively involved in tumor biological activities. These prognostic candidates can offer us a new insight into the biological characteristics of MPM, contributing to development of individualized therapeutic strategies directed against oncogenesis and tumor progression. Thus, personalized approaches based on the molecular biology of the patient's tissue or body fluid will potentially improve the present disappointing outcome, bringing new hope for patients with MPM. This article reviews the principal and several novel biomarkers that can have an influence on prognosis, in the hope that they can provide us with a more profound understanding of the biology of this lethal disease.

Combinatorial anti-angiogenic gene therapy in a human malignant mesothelioma model

Anti-angiogenic gene therapy represents a promising strategy for cancer; however, it has rarely been tested in malignant mesothelioma, a highly aggressive tumor associated with asbestos with poor prognosis. In the present study, we investigated whether anti-angiogenic factors such as angiostatin, endostatin and the soluble form of vascular endothelial growth factor receptor 2 (sFlk1) were able to inhibit endothelial cell proliferation via lentivirus-mediated gene transfer into malignant mesothelioma cells in culture. We also assessed whether a dual-agent strategy had greater therapeutic benefit. Human malignant pleural mesothelioma MSTO-211H cells were transduced using lentiviral vectors that individually expressed angiostatin, endostatin and sFlk1 and linked to enhanced green fluorescent protein (EGFP) marker gene expression via an internal ribosome entry site. The lentivirus expressing EGFP alone was used as a control. The resultant cells designated as MSTO-A, MSTO-E, MSTO-F and MSTO-C were confirmed by western blot analysis and fluorescence microscopy to stably express the corresponding proteins. No differences were observed in the in vitro growth rates between any of these cells. However, co-culture of MSTO-A, MSTO-E and MSTO-F showed significant suppression of human umbilical endothelial cell growth in vitro compared with that of MSTO-C. Furthermore, a combination of any two among MSTO-A, MSTO-E and MSTO-F significantly enhanced efficacy. These results suggest that combinatorial anti-angiogenic gene therapy targeting different pathways of endothelial growth factor signaling has the potential for greater therapeutic efficacy than that of a single-agent regimen.

Identification of pregnancy-associated plasma protein A as a migration-promoting gene in malignant pleural mesothelioma cells: a potential therapeutic target

Despite recent advances in treatment, malignant pleural mesothelioma (MPM) remains a deadly disease. Targeted therapy generated broad interests and is highly expected for the treatment of MPM, yet promising preclinical results have not been translated into substantial clinical benefits for the patients. In this study, we tried to identify the genes which play functional roles in cell migration as well as to test whether they can be used as novel targets for molecular targeted therapy for MPM in preclinical model. In our study, pregnancy-associated plasma protein A (PAPPA) was identified as a gene whose expression level is correlated with MPM cell migration by correlation analysis combining MPM cell migration ability and their gene expression profiles. Highly migratory cells were selected from MPM cell lines, MSTO-211H, NCI-H290 and EHMES-1 in vitro and up-regulation of PAPPA in these cells were confirmed. In vitro, PAPPA was demonstrated to stimulate the MPM cell migration via cleavage of insulin-like growth factor-binding protein-4 and subsequent release of IGF-1. Gene silencing of PAPPA in MPM cells led to reduced migration, invasion and proliferation. Furthermore, PAPPA shRNA transfected NCI-H290 when orthotopically inoculated into pleural cavity of severe combined immunodeficiency recipient mice, failed to develop tumors and produce bloody pleural effusion as control shRNA transfected cells did. Our study suggests that PAPPA plays a functional role in promoting MPM cell migration and it might serve as a potential therapeutic target for the treatment of MPM.

Antitumor effect and antiangiogenic potential of the mTOR inhibitor temsirolimus against malignant pleural mesothelioma

The mTOR inhibitor temsirolimus has antitumor and antiangiogenic activity against several carcinomas, yet few reports document the efficacy of temsirolimus against malignant pleural mesothelioma (MPM). Therefore, we evaluated the efficacy of temsirolimus and the antiangiogenic effect of temsirolimus in the treatment of MPM. We examined the efficacy of temsirolimus alone and the efficacy of the combination of temsirolimus and cisplatin or pemetrexed against four MPM cell lines using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. The effect of temsirolimus on the production of proangiogenic cytokines by MPM cell lines was examined by enzyme-linked immunosorbent assay (ELISA). Expression of mTOR and proangiogenic cytokines in clinical specimens from MPM patients was determined by immunohistochemistry. Temsirolimus inhibited cell viability and suppressed cell proliferation of all MPM cell lines. Combined treatment with temsirolimus and cisplatin inhibited the viability of all MPM cell lines more effectively than temsirolimus alone. Temsirolimus strongly inhibited the phosphorylation of p70s6k, a downstream molecule of mTOR, in all MPM cell lines and led to an increase in the levels of cleaved caspase-3 in the H226 and Y-meso14 cells. Temsirolimus also inhibited the production of vascular endothelial growth factor (VEGF) and platelet-derived growth factor-AA (PDGF-AA). Phosphorylated mTOR and high expression of VEGF and PDGF were detected in 2 and 3, respectively, out of the 5 MPM specimens. These results suggest that temsirolimus has activity against MPM cells by inhibition of cell proliferation and angiogenesis, and may be beneficial for a subset of MPM patients with high mTOR expression.

Phase II study of pemetrexed and carboplatin plus bevacizumab as first-line therapy in malignant pleural mesothelioma

Background:

The aim of this open label phase II study (NCT00407459) was to assess the activity of the vascular endothelial growth factor (VEGF) inhibitor bevacizumab combined with pemetrexed and carboplatin in patients with previously untreated, unresectable malignant pleural mesothelioma (MPM).

Methods:

Eligible patients received pemetrexed 500 mg m⁻², carboplatin area under the plasma concentration–time curve (AUC) 5 mg ml⁻¹ per minute and bevacizumab 15 mg kg⁻¹, administered intravenously every 21 days for six cycles, followed by maintenance bevacizumab. The primary end point of the study was progression-free survival (PFS). A 50% improvement in median PFS in comparison with standard pemetrexed/platinum combinations (from 6 to 9 months) was postulated.

Results:

Seventy-six patients were evaluable for analysis. A partial response was achieved in 26 cases (34.2%, 95% CI 23.7–46.0%). Forty-four (57.9%, 95% CI 46.0–69.1%) had stable disease. Median PFS and overall survival were 6.9 and 15.3 months, respectively. Haematological and non-haematological toxicities were generally mild; however, some severe adverse events were reported, including grade 3–4 fatigue in 8% and bowel perforation in 4% of patients. Three toxic deaths occurred.

Conclusion:

The primary end point of the trial was not reached. However, due to the limitation of a non-randomised phase II design, further data are needed before drawing any definite conclusion on the role of bevacizumab in MPM.

[Bevacizumab in thoracic oncology: results and practical aspects]

Bevacizumab (Avastin(®)) is the first antiangiogenic therapy approved in non-small cell lung cancer (NSCLC). It is also currently the only agent in this family approved in NSCLC. This review focuses on results of clinical trials assessing bevacizumab in thoracic oncology. It also provides to clinicians practical advices for its prescription.

Recombinant human endostatin (endostar) decreased recurrent ascites, pleural fluid and ascitic VEGF in a case of advanced mesothelioma

We report a case of 43-year-old male with advanced malignant mesothelioma (MM) with a large amount of fluid in the pleural and peritoneal cavity. The addition of endostar to the gemcitabine-cisplatin regimen gave a prompt and significant improvement of clinical symptoms and disappearance of ascites. The patient is still progression free after 27 months. Endostar, in combination with chemotherapy should be explored in the treatment of MM, especially its effect on pleural and ascitic fluid.

Establishment of a novel experimental model of human angiosarcoma and a VEGF-targeting therapeutic experiment

BACKGROUND

Angiosarcoma is one of the most life-threatening neoplasms with strong resistance to conventional chemotherapy/radiotherapy; consequently, alternative therapeutic agents are urgently required. One factor in delaying the therapy development is the limitation of experimental models.

OBJECTIVE

We established a novel experimental angiosarcoma model.

METHODS

From surgically resected tissue, human AS cell line was established. Using xenograft of AS cell line, we performed therapeutic experiments with the anti-human VEGF Ab or the receptor tyrosine kinase inhibitor.

RESULTS

First we generated an angiosarcoma cell line, HAMON (human angiosarcoma, monoclonal), which expresses CD31 and produces tumors in immunodeficient mice. HAMON expresses VEGFR2 and that exogenous VEGF leads to HAMON proliferation in vitro. Anti-human VEGF Ab bevacizumab treatment failed to suppress HAMON proliferation in vitro and in vivo. Furthermore, the receptor tyrosine kinase inhibitor sunitinib did not suppress HAMON proliferation in vitro. Similarly, in in vivo therapeutic experiments, even high doses of sunitinib failed to inhibit tumor growth. Finally, we checked whether compensatory activation of VEGF signaling occurred after sunitinib addition. VEGF protein secretion, VEGF mRNA synthesis and VEGFR2 phosphorylation all were unaffected in HAMON after sunitinib treatment.

CONCLUSION

A novel in vitro and in vivo experimental model of human angiosarcoma has been successfully established. With this model, we were able to perform therapeutic experiments. In addition, our angiosarcoma cell line, HAMON, is quite useful for identifying key molecules in angiosarcoma.

SU6668, a multiple tyrosine kinase inhibitor, inhibits progression of human malignant pleural mesothelioma in an orthotopic model

BACKGROUND AND OBJECTIVE

Malignant pleural mesothelioma (MPM) is an aggressive neoplasm of the mesothelium with high chemotherapeutic resistance. In this study, the preclinical therapeutic activity of the multiple tyrosine kinase inhibitor, SU6668, against MPM was examined.

METHODS

Two human MPM cell lines with different pro-angiogenic cytokine expression, Y-MESO-14 cells that express high levels of vascular endothelial growth factor (VEGF) and MSTO-211H cells that express high levels of basic fibroblast growth factor (bFGF), were orthotopically inoculated into the thoracic cavities of mice with severe combined immunodeficiency. The mice with MPM were treated or not treated with SU6668 (200 mg/kg/day).

RESULTS

SU6668 abrogated the proliferation of endothelial cells stimulated by VEGF or bFGF, but did not directly affect the growth of human MPM cells in vitro. In this orthotopic implantation model, treatment with SU6668 effectively reduced tumour weight and pleural effusion volumes, in association with inhibition of the growth of tumour vasculature. More importantly, treatment with SU6668 significantly prolonged survival time in mice with MPM.

CONCLUSIONS

These findings suggest that SU6668 has a promising therapeutic effect on the progression of MPM in vivo through its anti-angiogenic effects.

Antitumor activity of MEK and PI3K inhibitors against malignant pleural mesothelioma cells in vitro and in vivo

Malignant pleural mesothelioma (MPM) is an aggressive malignancy for which there is no approved targeted therapy. We examined the therapeutic efficacy of the mitogen-activated protein kinase kinase (MEK) and phosphatidylinositol 3-kinase (PI3K) inhibitors against human MPM cell lines both in vitro and orthotopically inoculated into severe combined immunodeficient (SCID) mice. In addition, the molecular mechanisms of these agents were confirmed in vitro and in vivo. The MEK or the PI3K inhibitor suppressed MPM cell growth in vitro in a dose-dependent manner via induction of G1 cell cycle arrest and apoptosis. In addition, combined use of the MEK and PI3K inhibitors showed an additive or synergistic inhibitory effect on MPM cell growth compared to treatment with either individual drug. Treatment with MEK or PI3K inhibitor suppressed the production of thoracic tumors and pleural effusion and prolonged the survival time of EHMES-10 cell-bearing SCID mice. The combination therapy more effectively prolonged the survival time compared to treatment with either individual drug. Immunohistochemical and western blot analysis of thoracic tumors suggested that these agents induced cell cycle arrest, apoptosis and inhibition of tumor angiogenesis. Our results suggest that a combination of MEK and PI3K inhibitors is a promising therapeutic strategy for MPM.

Preclinical studies identify novel targeted pharmacological strategies for treatment of human malignant pleural mesothelioma

The incidence of human malignant pleural mesothelioma (hMPM) is still increasing worldwide. hMPM prognosis is poor even if the median survival time has been slightly improved after the introduction of the up-to-date chemotherapy. Nevertheless, large phase II/III trials support the combination of platinum derivatives and pemetrexed or raltitrexed, as preferred first-line schedule. Better understanding of the molecular machinery of hMPM will lead to the design and synthesis of novel compounds targeted against pathways identified as crucial for hMPM cell proliferation and spreading. Among them, several receptors tyrosine kinase show altered activity in subsets of hMPM. This observation suggests that these kinases might represent novel therapeutic targets in this chemotherapy-resistant disease. Over these foundations, several promising studies are ongoing at preclinical level and novel molecules are currently under evaluation as well. Yet, established tumour cell lines, used for decades to investigate the efficacy of anticancer agents, although still the main source of drug efficacy studies, after long-term cultures tend to biologically diverge from the original tumour, limiting the predictive potential of in vivo efficacy. Cancer stem cells (CSCs), a subpopulation of malignant cells capable of self-renewal and multilineage differentiation, are believed to play an essential role in cancer initiation, growth, metastasization and relapse, being responsible of chemo- and radiotherapy refractoriness. According to the current carcinogenesis theory, CSCs represent the tumour-initiating cell (TIC) fraction, the only clonogenic subpopulation able to originate a tumour mass. Consequently, the recently described isolation of TICs from hMPM, the proposed main pharmacological target for novel antitumoural drugs, may contribute to better dissect the biology and multidrug resistance pathways controlling hMPM growth.

Circulating vascular endothelial growth factor receptor 2/pAkt-positive cells as a functional pharmacodynamic marker in metastatic colorectal cancers treated with antiangiogenic agent

OBJECTIVE

The anti-vascular endothelial growth factor (VEGF) antibody bevacizumab has received considerable attention as a first-line treatment of advanced colorectal cancers. Difficulties associated with effectively monitoring the activity of this drug have prompted us to seek a pharmacodynamic marker suitable for defining the optimum biological dose and schedule of bevacizumab administration against colon cancer in early clinical trials.

METHODS

We evaluated inhibitory effects of bevacizumab on VEGF signaling and tumor growth in vitro and in vivo, and assessed phosphorylation of VEGF receptor 2 (VEGFR2) and downstream signaling in endothelial cells as pharmacodynamic markers using phospho-flow cytometry. We also validated markers in patients with metastatic colorectal cancer (mCRC) treated with bevacizumab-based chemotherapy.

RESULTS

In in vitro studies, bevacizumab inhibited proliferation of human umbilical vein endothelial cells in association with reduced VEGF signaling. Notably, bevacizumab inhibited VEGF-induced phosphorylation of VEGFR-2, Akt, and extracellular signal-regulated kinase (ERK). In vivo, treatment with bevacizumab inhibited growth of xenografted tumors and attenuated VEGF-induced phosphorylation of Akt and ERK. The median percentages of VEGFR2 + pAkt + and VEGFR2 + pERK + cells, determined by phospho-flow cytometry, were approximately 3-fold higher in mCRC patients than in healthy controls. Bevacizumab treatment decreased VEGFR2 + pAkt + cells in 18 of 24 patients on day 3.

CONCLUSION

Bevacizumab combined with chemotherapy decreased the number of VEGFR2 + pAkt + cells, reflecting impaired VEGFR2 signaling. Together, these data suggest that changes in the proportion of circulating VEGFR2 + pAkt + cells may be a potential pharmacodynamic marker of the efficacy of antiangiogenic agents, and could prove valuable in determining drug dosage and administration schedule.

Vatalanib in malignant mesothelioma: a phase II trial by the Cancer and Leukemia Group B (CALGB 30107)

INTRODUCTION

The Cancer and Leukemia Group B (CALGB) conducted a multi-center phase II trial to evaluate the efficacy and safety of vatalanib in previously untreated patients with malignant mesothelioma and to evaluate potential biomarkers of disease response (CALGB 30107).

METHODS

Treatment consisted of vatalanib 1250 mg given orally once daily. CT scans were obtained at baseline and every 6 weeks thereafter. Baseline serum levels of vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), thrombospondin-1 (TSP-1), and mesothelin were obtained. The primary endpoint was 3-month progression-free survival (PFS).

RESULTS

Forty-seven patients enrolled at 19 centers. The median age was 75 years, and the majority of patients (79%) had an ECOG performance status of 1. Tumors were classified as epithelial (77%), sarcomatoid (10%), or mixed (9%) histology. Toxicity was mild; the most common grade 3/4 adverse events were neutropenia (2%), nausea (15%), elevated alanine aminotransferase (11%), hypertension (2%), and gastrointestinal bleeding (2%). Partial responses were observed in 6% of patients and stable disease in 72% of patients. The 3-month PFS rate was 55% (95% CI: 40%, 68%). The median PFS was 4.1 months. Median overall survival was 10.0 months. There was no correlation between serum levels of VEGF, PDGF, TSP-1, or mesothelin and treatment response, PFS, or survival.

CONCLUSIONS

Vatalanib as a single agent with this dose and schedule does not warrant further study in this disease.

SASP mediates chemoresistance and tumor-initiating-activity of mesothelioma cells

Here we show that pemetrexed-treated mesothelioma cells undergo accelerated senescence. This is characterized by the secretion of proinflammatory and mitogenic cytokines, reminiscent of an SASP (senescence-associated secretory phenotype). Conditioned media from senescent MPM (malignant pleural mesothelioma) cells trigger the emergence of EMT (epithelial-to-mesenchymal)-like, clonogenic and chemoresistant cell subpopulations, expressing high levels of ALDH (aldehyde dehydrogenase) activity (ALDH(bright) cells). We show by fluorescence-activated cell sorting of purified ALDH(bright) and ALDH(low) cells, that both cell-autonomous and cell-non-autonomous mechanisms converge to maintain the SASP-induced, EMT-like cell subpopulations. Chemoresistant ALDH(bright) cells exist within primary MPM specimens and enrichment for ALDH(bright) cells correlates with an earlier tumor onset into NOD/SCID mice. We show that RAS(v12) expression induces SASP-like changes in untransformed human mesothelial cells, and that p53 ablation increases the effect of RAS(v12) expression. We identify STAT3 activation as a crucial event downstream to SASP signaling. In fact, small hairpin RNA-mediated ablation of STAT3 deeply attenuates the induction of EMT genes and the increase of ALDH(bright) cells induced by SASP-cytokines. This strongly affects the chemoresistance of MPM cells in vitro and leads to anticancer effects in vivo.

Pleural mesothelioma instigates tumor-associated fibroblasts to promote progression via a malignant cytokine network

The tumor microenvironment is crucial to the progression of various malignancies. Malignant pleural mesothelioma (MPM), which originates from the pleura, grows aggressively in the thoracic cavity. Here we describe an orthotopic implantation SCID mouse model of MPM and demonstrate that α-SMA-positive fibroblast-like cells accumulate in the tumors produced by the human MPM cell lines MSTO-211H and Y-Meso-14. We assessed the interaction between MPM cells and their microenvironments, focusing on tumor-associated fibroblasts. MSTO-211H and Y-Meso-14 cells produced fibroblast growth factor-2 (FGF-2) and/or platelet-derived growth factor-AA (PDGF-AA); they also enhanced growth, migration, and production of hepatocyte growth factor (HGF) by human lung fibroblast MRC-5 cells. MRC-5 cells stimulated HGF-mediated growth and migration of MSTO-211H and Y-Meso-14 cells in an in vitro coculture system. In the orthotopic model, tumor formation by MSTO-211H and Y-Meso-14 cells was significantly inhibited by TSU-68, an inhibitor of FGF, VEGF, and PDGF receptors; imatinib, an inhibitor of PDGF receptors; and NK4, an antagonist of HGF. Histological analyses of clinical specimens from 51 MPM patients revealed considerable tumor-associated fibroblasts infiltration and expression of HGF, together with FGF-2 or PDGF-AA, in tumors. These findings indicate that MPM instigates tumor-associated fibroblasts, promoting tumor progression via a malignant cytokine network. Regulation of this cytokine network may be therapeutically useful for controlling MPM.

Combined chemotherapy with cytotoxic and targeted compounds for the management of human malignant pleural mesothelioma

Human malignant pleural mesothelioma (hMPM) is an aggressive asbestos-associated cancer, the incidence of which is increasing and which, despite progress in diagnosis and therapy, continues to have a poor prognosis. Asbestos fibers induce aberrant cell signaling, leading to proto-oncogene activation and chemoresistance. In this review, we discuss the evolution of pharmacological management of hMPM up to the most recent advances. Monotherapy with single cytotoxic drugs achieves modest objective response rates, seldom reaching 30%. However, combination regimens using novel drugs and standard molecules are showing gradually improving responses and clinical benefits. Phase II/III studies have identified pemetrexed, a multitarget folate pathway inhibitor in combination with platinum derivatives, and the cisplatin/gemcitabine association as front-line chemotherapy for hMPM. Detailed knowledge of molecular mechanisms of signal transduction and neoangiogenesis in hMPM should aid in the design and screening of other promising compounds such as more efficacious receptor tyrosine kinase inhibitors.

Synergistic effect of non-transmissible Sendai virus vector encoding the c-myc suppressor FUSE-binding protein-interacting repressor plus cisplatin in the treatment of malignant pleural mesothelioma

Human malignant pleural mesothelioma (HMPM) is highly resistant to conventional therapy, and therefore novel therapies are required. We previously reported that overexpression of the FUSE-binding protein-interacting repressor (FIR), a c-myc transcriptional repressor, induces apoptosis via c-Myc suppression, and is thus a suitable cancer therapy. In the current preclinical trial, a fusion gene deleted non-transmissible Sendai virus vector encoding FIR (SeV/ΔF/FIR) was prepared and its cytotoxic activity against an orthotopic xenograft model of HMPM, in combination with cisplatin, was assessed. SeV/ΔF/FIR and a fusion gene deleted non-transmissible Sendai virus vector encoding green fluorescent protein (SeV/ΔF/GFP) were prepared. The transduction efficiency of these agents in terms of dose-dependent cytotoxicity and/or apoptosis induction was then assessed in a few HMPM cells. Combination therapy with SeV/ΔF/FIR plus cisplatin was evaluated in vitro and in a mouse model. SeV/ΔF/FIR significantly reduced cell viability in three HMPM cell lines but was less effective in non-tumor immortalized mesothelial cells. SeV/ΔF/FIR cytotoxicity was partly due to apoptosis induction via c-Myc suppression. In addition, SeV/ΔF/FIR showed synergistic antitumor effects in combination with cisplatin, as was revealed by isobologram analysis in MSTO-211H. Moreover, combination therapy with SeV/ΔF/FIR plus cisplatin demonstrated significant tumor reduction and improvement in survival rate in an animal model. Combination therapy with SeV/ΔF/FIR plus cisplatin has therapeutic potential against HMPM. SeV/ΔF/FIR plus cisplatin will be an attractive modality against HMPM in the future.

PET imaging of tumor angiogenesis in mice with VEGF-A-targeted (86)Y-CHX-A″-DTPA-bevacizumab

Bevacizumab is a humanized monoclonal antibody that binds to tumor-secreted vascular endothelial growth factor (VEGF)-A and inhibits tumor angiogenesis. In 2004, the antibody was approved by the US Food and Drug Administration (FDA) for the treatment of metastatic colorectal carcinoma in combination with chemotherapy. This report describes the preclinical evaluation of a radioimmunoconjugate, (86)Y-CHX-A″-DTPA-bevacizumab, for potential use in Positron Emission Tomography (PET) imaging of VEGF-A tumor angiogenesis and as a surrogate marker for (90)Y-based radioimmunotherapy. Bevacizumab was conjugated to CHX-A″-DTPA and radiolabeled with (86)Y. In vivo biodistribution and PET imaging studies were performed on mice bearing VEGF-A-secreting human colorectal (LS-174T), human ovarian (SKOV-3) and VEGF-A-negative human mesothelioma (MSTO-211H) xenografts. Biodistribution and PET imaging studies demonstrated highly specific tumor uptake of the radioimmunoconjugate. In mice bearing VEGF-A-secreting LS-174T, SKOV-3 and VEGF-A-negative MSTO-211H tumors, the tumor uptake at 3 days postinjection was 13.6 ± 1.5, 17.4 ± 1.7 and 6.8 ± 0.7 % ID/g, respectively. The corresponding tumor uptake in mice coinjected with 0.05 mg cold bevacizumab were 5.8 ± 1.3, 8.9 ± 1.9 and 7.4 ± 1.0 % ID/g, respectively at the same time point, demonstrating specific blockage of the target in VEGF-A-secreting tumors. The LS-174T and SKOV3 tumors were clearly visualized by PET imaging after injecting 1.8-2.0 MBq (86)Y-CHX-A″-DTPA-bevacizumab. Organ uptake quantified by PET closely correlated (r(2) = 0.87, p = 0.64, n = 18) to values determined by biodistribution studies. This preclinical study demonstrates the potential of the radioimmunoconjugate, (86)Y-CHX-A″-DTPA-bevacizumab, for noninvasive assessment of the VEGF-A tumor angiogenesis status and as a surrogate marker for (90)Y-CHX-A″-DTPA-bevacizumab radioimmunotherapy.

Chemotherapy and radiotherapy for mesothelioma

Previously considered to be rare, malignant pleural mesothelioma (MPM) is a highly aggressive tumor with an increasing incidence linked to asbestos exposure, its main etiological factor. MPM is also a very important issue because patients have usually a short survival (median <12 months) despite current treatments. Moreover an optimal treatment for MPM is not defined yet, even if ERS/ESTS experts recently provided clear and up-to-date guidelines on MPM management. These guidelines on chemotherapy and radiotherapy for mesothelioma, as well as new therapeutic developments, are presented in this chapter.

The therapeutic efficacy of S-1 against orthotopically implanted human pleural mesothelioma cells in severe combined immunodeficient mice

Purpose

Malignant pleural mesothelioma (MPM) is a highly lethal neoplasm. S-1 has been developed as a novel oral antineoplastic agent based on the modulation of 5-fluorouracil (5-FU) bioactivity. This study was conducted to investigate the preclinical therapeutic effect of S-1 on MPM.

Methods

We used three human MPM cell lines, Y-MESO-14, NCI-H290 and MSTO-211H. In vitro proliferation of human MPM cells was determined by MTT assay. Human MPM cells were orthotopically implanted into thoracic cavity of SCID mice. Tumor-bearing mice were treated with S-1 or vehicle.

Results

The combination of 5-FU and 5-chloro-2,4-dihydroxypyridine (CDHP) was more effective than 5-FU alone in inhibiting MPM cell proliferation in vitro. This combination was most effective in Y-MESO-14 cells, which co-expressed high protein level of dihydropyrimidine dehydrogenase (DPD) and thymidine phosphorylase (TP). In vivo data showed that treatment with S-1 significantly reduced thoracic tumors and pleural effusion produced by Y-MESO-14 cells. Moreover, treatment with S-1 prolonged the survival of Y-MESO-14 cell-bearing SCID mice.

Conclusions

We demonstrated that S-1 was effective for inhibiting the proliferation of MPM cells, particularly with both DPD and TP expressions, suggesting that S-1 might be therapeutically effective for control of MPM.

Inhibition of Met/HGF receptor and angiogenesis by NK4 leads to suppression of tumor growth and migration in malignant pleural mesothelioma

NK4 exhibits two distinct biological actions: antagonistic inhibition of hepatocyte growth factor (HGF) through binding to the Met/HGF receptor, and antiangiogenic action through binding to perlecan. Here, the anti-tumor effect of NK4 on malignant pleural mesothelioma was investigated. Of the 7 human malignant mesothelioma cell lines (ACC-Meso-1, ACC-Meso-4, EHMES-1, EHMES-10, H28, H2052 and JMN-1B), only EHMES-10 cells formed subcutaneous tumors when implanted into mice. For EHMES-10 cells, HGF facilitated invasion of the cells in collagen gel, whereas NK4 and neutralizing anti-HGF antibody suppressed the HGF-induced invasion. In addition, NK4 but not anti-HGF antibody suppressed proliferation of EHMES-10 cells in collagen, suggesting that the suppression by NK4 was independent of the HGF-Met pathway. In the subcutaneous tumor model, recombinant adenovirus-mediated intratumoral expression of NK4 inhibited tumor growth, while the invasive characteristic of tumor cells was not observed. Analysis of Met receptor tyrosine phosphorylation, proliferation, apoptosis and blood vessels in the tumor tissues indicated that the inhibitory effect of NK4 expression might be primarily caused by the inhibition of tumor angiogenesis. In all the 7 mesothelioma lines, HGF stimulated Met tyrosine phosphorylation, and this was associated with enhanced cell migration. HGF-dependent Met activation and migration were inhibited by NK4. Since malignant pleural mesothelioma represents an aggressive neoplasm characterized by extensive invasive growth, suppression of invasive growth has therapeutic value. Thus, the simultaneous inhibition of the HGF-Met pathway and angiogenesis by NK4 for treatment of malignant pleural mesothelioma is significant, particularly to attenuate migration and invasive growth.

In vitro and in vivo therapeutic efficacy of the PPAR-γ agonist troglitazone in combination with cisplatin against malignant pleural mesothelioma cell growth

Malignant pleural mesothelioma (MPM), an aggressive and refractory tumor type, is increasing in frequency throughout the world. Peroxisome proliferator activated receptor-γ (PPAR-γ) agonists have anticancer activity against several cancer cell lines in vitro and in vivo. However, there have been no reports that PPAR-γ agonists induce growth inhibition of MPM cell lines. In this study, we investigated the inhibitory effect of a PPAR-γ agonist in combination with an anticancer agent on MPM cell growth in vitro and in vivo. We examined the therapeutic efficacy of the PPAR-γ agonist troglitazone (TGZ) in combination with cisplatin against a human MPM cell line, both in vitro and orthotopically inoculated into severe combined immunodeficient (SCID) mice. Troglitazone (TGZ) alone inhibited MPM cell growth in vitro in a dose-dependent manner via induction of G1 cell cycle arrest and apoptosis. The combination of TGZ and cisplatin showed an additive inhibitory effect on MPM cell growth compared to treatment with either individual drug. Treatment with 500 mg/kg or 1000 mg/kg TGZ effectively inhibited the production of thoracic tumors and pleural effusion in EHMES-10 cell-bearing SCID mice. Moreover, treatment with 500 mg/kg TGZ in combination with 3 mg/kg cisplatin more effectively prolonged survival compared to treatment with either individual drug. These results suggest that TGZ in combination with cisplatin may become a novel therapy for MPM.

Kinetics of host cell recruitment during dissemination of diffuse malignant peritoneal mesothelioma

Diffuse malignant mesothelioma is an aggressive tumor which displays a median survival of 11.2 months and a 5-year survival of less than 5% emphasizing the need for more effective treatments. This study uses an orthotopic model of malignant mesothelioma established in syngeneic, immunocompetent C57Bl/6 mice which produce malignant ascites and solid tumors that accurately replicate the histopathology of the human disease. Host stromal and immune cell accumulation within malignant ascites and solid tumors was determined using immunofluorescent labeling with confocal microscopy and fluorescence-activated cell sorting. An expression profile of cytokines and chemokines was produced using quantitative real-time PCR arrays. Tumor spheroids and solid tumors show progressive growth and infiltration with host stromal and immune cells including macrophages, endothelial cells, CD4(+) and CD8(+) lymphocytes, and a novel cell type, myeloid derived suppressor cells (MDSCs). The kinetics of host cell accumulation and inflammatory mediator expression within the tumor ascites divides tumor progression into two distinct phases. The first phase is characterized by progressive macrophage and T lymphocyte recruitment, with a cytokine profile consistent with regulatory T lymphocytes differentiation and suppression of T cell function. The second phase is characterized by decreased expression of macrophage chemotactic and T-cell regulating factors, an increase in MDSCs, and increased expression of several cytokines which stimulate differentiation of MDSCs. This cellular and expression profile suggests a mechanism by which host immune cells promote diffuse malignant mesothelioma progression.

ELECTRONIC SUPPLEMENTARY MATERIAL

The online version of this article (doi:10.1007/s12307-010-0048-1) contains supplementary material, which is available to authorized users.

Antiangiogenic cancer therapy combined with oncolytic virotherapy leads to regression of established tumors in mice

Clinical trials of oncolytic virotherapy have shown low toxicity and encouraging signs of efficacy. However, it remains critically important to develop methods for systemic viral delivery if such therapies are to be clinically implemented to treat established tumors. In this respect, much effort is being focused on combining oncolytic viruses with standard treatment modalities such as inhibitors of VEGF165 (an alternatively spliced isoform of VEGF-A) signaling, which are widely used to treat several different cancers. Here, we have demonstrated that combining VEGF165 inhibitors with systemic delivery of oncolytic viruses leads to substantial regression and cure of established tumors in immunocompetent mice. We have shown that manipulating VEGF165-mediated signaling by administering VEGF165 to mice harboring mouse melanoma cells that do not express VEGF165 and by administering a VEGF inhibitor and then withdrawing treatment to allow VEGF levels to rebound in mice harboring mouse melanoma cells expressing VEGF165 allows tumor-associated endothelial cells transiently to support viral replication. This approach led to direct tumor cell lysis and triggered innate immune-mediated attack on the tumor vasculature. It also resulted in long-term antitumor effects, even against tumors in which viral replication is poorly supported. Since this combinatorial approach targets the tumor endothelium, we believe these data have direct, wide-ranging, and immediate clinical applicability across a broad range of tumor types.

Expression of soluble vascular endothelial growth factor receptor-1 in human monocyte-derived mature dendritic cells contributes to their antiangiogenic property

The soluble form of vascular endothelial growth factor receptor-1 (sVEGFR-1) is produced from endothelial cells by alternative splicing of VEGFR-1 mRNA, and can inhibit angiogenesis by blocking the biological effects of VEGF. In this study, we show the expression of a large amount of sVEGFR-1 in human monocyte-derived mature dendritic cells (mDCs). As compared with monocytes and immature DCs, mDCs generated by TNF-alpha or soluble CD40L with IFN-gamma, but not LPS or other stimuli, preferentially produce sVEGFR-1. We also detected the mRNA of sVEGFR-1 generated by alternative splicing of VEGFR-1 mRNA in mDCs induced by TNF-alpha. The production of sVEGFR-1 showed a distinct contrast to those of VEGF in each DC matured with various stimuli. The supernatant of DCs matured with TNF-alpha or soluble CD40L with IFN-gamma showed inhibition of the tube formation of HUVECs, which was neutralized by anti-VEGFR-1 Ab, indicating that sVEGFR-1 secreted from mDCs was biologically active. Interestingly, the supernatant of mDCs generated with LPS increased HUVEC capillary-like formation in vitro. The ratio of sVEGFR-1 to VEGF clearly reflected the net angiogenic property of mDCs. Administration of mDCs induced by TNF-alpha into the s.c. tumor of PC-14 cells implanted in SCID mice demonstrated the inhibition of tumor growth via reduction of the number of CD31-positive vessels, indicating their in vivo antiangiogenic potential. These results suggest that sVEGFR-1 produced by mDCs contribute to their antiangiogenic property, and the ratio of sVEGFR-1 to VEGF might be a useful tool for evaluating their ability to regulate angiogenesis mediated by VEGF.