A function blocking anti-mouse integrin alpha5beta1 antibody inhibits angiogenesis and impedes tumor growth in vivo

Structural and functional characterization of integrin α5-targeting antibodies for anti-angiogenic therapy

Integrins are a large family of heterodimeric receptors important for cell adhesion and signaling. Integrin α5β1, also known as the fibronectin receptor, is a key mediator of angiogenesis and its dysregulation is associated with tumor proliferation, progression, and metastasis. Despite numerous efforts, α5β1-targeting therapeutics have been unsuccessful in large part due to efficacy and off-target effects. To mediate activation and signaling, integrins undergo drastic conformational changes. However, how therapeutics influence or are affected by integrin conformation remains incompletely characterized. Using cell biology, biophysics, and electron microscopy, we shed light on these relationships by characterizing two potentially therapeutic anti-α5β1 antibodies, BIIG2 and MINT1526A. We show that both antibodies bind α5β1 with nanomolar affinity and reduce angiogenesis in vitro. We demonstrate BIIG2 reduces tumor growth in two human xenograft mouse models and exhibits a strong specificity for connective tissue-resident fibroblasts and melanoma cells. Using electron microscopy, we map out the molecular interfaces mediating the integrin-antibody interactions and reveal that although both antibodies have overlapping epitopes and block fibronectin binding via steric hindrance, the effect on the conformational equilibrium is drastically different. While MINT1526A constricts α5β1's range of flexibility, BIIG2 binds without restricting the available conformational states. These mechanistic insights, coupled with the functional analysis, guide which aspects should be prioritized to avoid off-target effects or partial agonism in the design of future integrin-targeted therapeutics.

Exploring Integrin α5β1 as a Potential Therapeutic Target for Pulmonary Arterial Hypertension: Insights from Comprehensive Multicenter Preclinical Studies

Pulmonary arterial hypertension (PAH) is characterized by obliterative vascular remodeling of the small pulmonary arteries (PA) and progressive increase in pulmonary vascular resistance (PVR) leading to right ventricular (RV) failure. Although several drugs are approved for the treatment of PAH, mortality remains high. Accumulating evidence supports a pathological function of integrins in vessel remodeling, which are gaining renewed interest as drug targets. However, their role in PAH remains largely unexplored. We found that the arginine-glycine-aspartate (RGD)-binding integrin α5β1 is upregulated in PA endothelial cells (PAEC) and PA smooth muscle cells (PASMC) from PAH patients and remodeled PAs from animal models. Blockade of the integrin α5β1 or depletion of the α5 subunit resulted in mitotic defects and inhibition of the pro-proliferative and apoptosis-resistant phenotype of PAH cells. Using a novel small molecule integrin inhibitor and neutralizing antibodies, we demonstrated that α5β1 integrin blockade attenuates pulmonary vascular remodeling and improves hemodynamics and RV function in multiple preclinical models. Our results provide converging evidence to consider α5β1 integrin inhibition as a promising therapy for pulmonary hypertension.

One sentence summary

The α5β1 integrin plays a crucial role in pulmonary vascular remodeling.

Identification of a new bisindolinone arresting IGROV1 cells proliferation

In an initial screening, a series of novel Knoevenagel adducts were submitted to the National Cancer Institute for evaluation of antitumor activity in human cell lines. In particular, compound 5f showed remarkable selectivity against IGROV1, an ovarian cancer cell line, without affecting healthy human fibroblast cells. Analyses of cytotoxicity, cell proliferation, cell migration, epigenetic changes, gene expression, and DNA damage were performed to obtain detailed information about its antitumor properties. Our results show that 5f causes proliferation arrest, decrease in motility, histone hyperacetylation, downregulation of cyclin D1 and α5 subunit of integrin β1 gene transcription. In addition, 5f treatment reduces transcript and protein levels of cyclin D1, which increases sensitivity to ionizing radiation and results in DNA damage comparable to cyclin D1 gene silencing.

Integrinβ-1 in disorders and cancers: molecular mechanisms and therapeutic targets

Integrinβ-1 (ITGB1) is a crucial member of the transmembrane glycoprotein signaling receptor family and is also central to the integrin family. It forms heterodimers with other ligands, participates in intracellular signaling and controls a variety of cellular processes, such as angiogenesis and the growth of neurons; because of its role in bidirectional signaling regulation both inside and outside the membrane, ITGB1 must interact with a multitude of substances, so a variety of interfering factors can affect ITGB1 and lead to changes in its function. Over the past 20 years, many studies have confirmed a clear causal relationship between ITGB1 dysregulation and cancer development and progression in a wide range of benign diseases and solid tumor types, which may imply that ITGB1 is a prognostic biomarker and a therapeutic target for cancer treatment that warrants further investigation. This review summarizes the biological roles of ITGB1 in benign diseases and cancers, and compiles the current status of ITGB1 function and therapy in various aspects of tumorigenesis and progression. Finally, future research directions and application prospects of ITGB1 are suggested. Video Abstract.

EXOSC5 maintains cancer stem cell activity in endometrial cancer by regulating the NTN4/integrin β1 signalling axis

Endometrial carcinoma (EC) is a common type of uterine cancer in developed countries, originating from the uterine epithelium. The incidence rate of EC in Taiwan has doubled from 2005. Cancer stem cells (CSCs) are a subpopulation of cancer cells that have high tumorigenicity and play a crucial role in the malignant processes of cancer. Targeting molecules associated with CSCs is essential for effective cancer treatments. This study delves into the role of Exosome component 5 (EXOSC5) in EC. Data from The Cancer Genome Atlas suggests a correlation between high EXOSC5 mRNA expression and unfavorable EC prognosis. EXOSC5 knockdown diminished EC-CSC self-renewal and reduced expression of key cancer stemness proteins, including c-MYC and SOX2. Intriguingly, this knockdown significantly curtailed tumorigenicity and CSC frequency in EC tumor spheres. A mechanistic examination revealed a reduction in netrin4 (NTN4) levels in EXOSC5-depleted EC cells. Moreover, NTN4 treatment amplified EC cell CSC activity and, when secreted, NTN4 partnered with integrin β1, subsequently triggering the FAK/SRC axis to elevate c-MYC activity. A clear positive relation between EXOSC5 and NTN4 was evident in 93 EC tissues. In conclusion, EXOSC5 augments NTN4 expression, activating c-MYC via the integrin β1/FAK/SRC pathway, offering potential avenues for EC diagnosis and treatment.

Therapeutic targeting of anoikis resistance in cutaneous melanoma metastasis

The acquisition of resistance to anoikis, the cell death induced by loss of adhesion to the extracellular matrix, is an absolute requirement for the survival of disseminating and circulating tumour cells (CTCs), and for the seeding of metastatic lesions. In melanoma, a range of intracellular signalling cascades have been identified as potential drivers of anoikis resistance, however a full understanding of the process is yet to be attained. Mechanisms of anoikis resistance pose an attractive target for the therapeutic treatment of disseminating and circulating melanoma cells. This review explores the range of small molecule, peptide and antibody inhibitors targeting molecules involved in anoikis resistance in melanoma, and may be repurposed to prevent metastatic melanoma prior to its initiation, potentially improving the prognosis for patients.

Clinical Strategies Targeting the Tumor Microenvironment of Pancreatic Ductal Adenocarcinoma

Pancreatic cancer has a complex tumor microenvironment which engages in extensive crosstalk between cancer cells, cancer-associated fibroblasts, and immune cells. Many of these interactions contribute to tumor resistance to anti-cancer therapies. Here, new therapeutic strategies designed to modulate the cancer-associated fibroblast and immune compartments of pancreatic ductal adenocarcinomas are described and clinical trials of novel therapeutics are discussed. Continued advances in our understanding of the pancreatic cancer tumor microenvironment are generating stromal and immune-modulating therapeutics that may improve patient responses to anti-tumor treatment.

Matrix stiffening and acquired resistance to chemotherapy: concepts and clinical significance

Extracellular matrix (ECM) refers to the non-cellular components of the tumour microenvironment, fundamentally providing a supportive scaffold for cellular anchorage and transducing signaling cues that orchestrate cellular behaviour and function. The ECM integrity is abrogated in several cases of cancer, ending in aberrant activation of a number of mechanotransduction pathways and induction of multiple tumorigenic events such as extended proliferation, cell death resistance, epithelial-mesenchymal transition and most importantly the development of chemoresistance. In this regard, the present study mainly aims to elucidate how the ECM-stiffening process may contribute to the development of chemoresistance during cancer progression and what pharmacological approaches are required for tackling this issue. Hence, the first section of this review explains the process of ECM stiffening and the ways it may affect biochemical pathways to induce chemoresistance in a clinic. In addition, the second part focuses on describing some of the most important pharmacological agents capable of targeting ECM components and underlying pathways for overcoming ECM-induced chemoresistance. Finally, the third part discusses the obtained results from the application of these agents in the clinic for overcoming chemoresistance.

Integrin α5 mediates cancer cell-fibroblast adhesion and peritoneal dissemination of diffuse-type gastric carcinoma

Diffuse-type gastric carcinoma (DGC) has a poor prognosis due to its rapid diffusive infiltration and frequent peritoneal dissemination. DGC is associated with massive fibrosis caused by aberrant proliferation of cancer-associated fibroblasts (CAFs). Previously, we reported that direct heterocellular interaction between cancer cells and CAFs is important for the peritoneal dissemination of DGC. In this study, we aimed to identify and target the molecules that mediate such heterocellular interactions. Monoclonal antibodies (mAbs) against intact DGC cells were generated and subjected to high-throughput screening to obtain several mAbs that inhibit the adhesion of DGC cells to CAFs. Immunoprecipitation and mass spectrometry revealed that all mAbs recognized integrin α5 complexed with integrin β1. Blocking integrin α5 in DGC cells or fibronectin, a ligand of integrin α5β1, deposited on CAFs abrogated the heterocellular interaction. Administration of mAbs or knockout of integrin α5 in DGC cells suppressed their invasion led by CAFs in vitro and peritoneal dissemination in a mouse xenograft model. Altogether, these findings demonstrate that integrin α5 mediates the heterotypic cancer cell-fibroblast interaction during peritoneal dissemination of DGC and may thus be a therapeutic target.

The Role of the Innate Immune System in Cancer Dormancy and Relapse

Metastatic spread and recurrence are intimately linked to therapy failure, which remains an overarching clinical challenge for patients with cancer. Cancer cells often disseminate early in the disease process and can remain dormant for years or decades before re-emerging as metastatic disease, often after successful treatment. The interactions of dormant cancer cells and their metastatic niche, comprised of various stromal and immune cells, can determine the length of time that cancer cells remain dormant, as well as when they reactivate. New studies are defining how innate immune cells in the primary tumor may be corrupted to help facilitate many aspects of dissemination and re-emergence from a dormant state. Although the scientific literature has partially shed light on the drivers of immune escape in cancer, the specific mechanisms regulating metastasis and dormancy in the context of anti-tumor immunity are still mostly unknown. This review follows the journey of metastatic cells from dissemination to dormancy and the onset of metastatic outgrowth and recurrent tumor development, with emphasis on the role of the innate immune system. To this end, further research identifying how immune cells interact with cancer cells at each step of cancer progression will pave the way for new therapies that target the reactivation of dormant cancer cells into recurrent, metastatic cancers.

Integrins regulate stemness in solid tumor: an emerging therapeutic target

Integrins are the adhesion molecules and transmembrane receptors that consist of α and β subunits. After binding to extracellular matrix components, integrins trigger intracellular signaling and regulate a wide spectrum of cellular functions, including cell survival, proliferation, differentiation and migration. Since the pattern of integrins expression is a key determinant of cell behavior in response to microenvironmental cues, deregulation of integrins caused by various mechanisms has been causally linked to cancer development and progression in several solid tumor types. In this review, we discuss the integrin signalosome with a highlight of a few key pro-oncogenic pathways elicited by integrins, and uncover the mutational and transcriptomic landscape of integrin-encoding genes across human cancers. In addition, we focus on the integrin-mediated control of cancer stem cell and tumor stemness in general, such as tumor initiation, epithelial plasticity, organotropic metastasis and drug resistance. With insights into how integrins contribute to the stem-like functions, we now gain better understanding of the integrin signalosome, which will greatly assist novel therapeutic development and more precise clinical decisions.

Emerging antibody therapies for pancreatic adenocarcinoma: a review of recent phase 2 trials

Introduction: Pancreatic adenocarcinoma is now the third-leading cause of cancer-related deaths in the US which can be attributed to rising incidence, diagnosis at advanced stages and early development of metastasis. Systemic therapy remains palliative with early development of resistance possibly related to the constitutive activation of 'undruggable' KRAS, immunosuppressive microenvironment, and intense desmoplasia. The advancements in molecular biology has led to the development and investigation of targeted and immune therapeutics.Areas covered: This study provides a comprehensive review of the literature to further the understanding of molecular targets with their respective antibody-based therapies in clinical development in pancreatic cancer. PubMed was systematically searched for English-language articles discussing antibody-based therapies under phase 2 clinical trial investigation in pancreatic adenocarcinoma.Expert opinion: PDAC remains highly resistant to chemotherapy with no significant improvement in survival for patients with advanced or metastatic cancer. Unfortunately, the majority of the antibody-based targeted and immune therapeutics have failed to meet their primary efficacy endpoints in early phase trials. However, there are a few promising antibody-based drugs with intriguing preliminary data that merit further investigation, while many more continue to be developed and investigated preclinically, and in early phase trials.

RhoJ Regulates α5β1 Integrin Trafficking to Control Fibronectin Remodeling during Angiogenesis

Rho guanosine triphosphatases (GTPases) are master regulators of cell shape and cell movement [1]. The archetypal family members RhoA, Rac1, and Cdc42 arose early in eukaryotic evolution and coordinate a diverse range of cell morphologies and migrations. Evolution of the vertebrates was paralleled by expansion of this family through gene duplication. Emergence of an adaptive immune system and more complex neural systems presented new roles for Rho GTPases, filled by new family members. Cdc42 underwent gene duplication to produce two related proteins-RhoQ and RhoJ [2]. RhoQ is active in neural dynamics; however, RhoJ is highly expressed in endothelial cells under control of the endothelial-specific promoter ERG [3, 4]. RhoJ is required for angiogenesis [5, 6] and has multiple roles in this process [7, 8]. We recently demonstrated that RhoJ regulates the endosomal trafficking of podocalyxin during angiogenesis to control lumen formation [9]. Here, we use vesicle purification and proteomic analysis to identify the endothelial targets of RhoJ-mediated trafficking. We identify α5β1 integrin as a major RhoJ cargo and show that RhoJ regulates the intracellular trafficking of active α5β1 integrin in endothelial cells to repress fibronectin fibrillogenesis. Accordingly, mice lacking RhoJ show deregulated deposition of fibronectin around vessels during developmental angiogenesis. Intriguingly, we show that RhoJ acts in opposition to Cdc42 in this process through competition for a shared partner, PAK3. These studies identify a critical role for RhoJ in matrix remodeling during blood vessel formation and demonstrate a functional interrelationship between RhoJ and its evolutionary parent.

Cell Adhesion Molecules and Their Roles and Regulation in the Immune and Tumor Microenvironment

The immune system and cancer have a complex relationship with the immune system playing a dual role in tumor development. The effector cells of the immune system can recognize and kill malignant cells while immune system-mediated inflammation can also promote tumor growth and regulatory cells suppress the anti-tumor responses. In the center of all anti-tumor responses is the ability of the immune cells to migrate to the tumor site and to interact with each other and with the malignant cells. Cell adhesion molecules including receptors of the immunoglobulin superfamily and integrins are of crucial importance in mediating these processes. Particularly integrins play a vital role in regulating all aspects of immune cell function including immune cell trafficking into tissues, effector cell activation and proliferation and the formation of the immunological synapse between immune cells or between immune cell and the target cell both during homeostasis and during inflammation and cancer. In this review we discuss the molecular mechanisms regulating integrin function and the role of integrins and other cell adhesion molecules in immune responses and in the tumor microenvironment. We also describe how malignant cells can utilize cell adhesion molecules to promote tumor growth and metastases and how these molecules could be targeted in cancer immunotherapy.

Stromal fibronectin expression in patients with resected pancreatic ductal adenocarcinoma

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is characterized by an extremely dense stroma, which has a fundamental role in tumor progression. Fibronectin (FN1) is the main constituent of the tumor stroma in pancreatic cancer. This study aimed to explore the association between FN1 and clinicopathological characteristics and disease survival.

METHODS

Formalin-fixed paraffin-embedded tissue samples from 138 patients with PDAC were constructed into a tissue microarray, followed by immunohistochemical analysis with a recombinant monoclonal FN1 antibody. Chi-square test or Fisher's exact test were used for comparison of FN1 expression and relevant clinicopathological parameters. Kaplan-Meier survival curves and Cox regression analyses were used to assess the association between FN1 and survival.

RESULTS

FN1 was detected in the stromal compartment in most cases (117/138, 84.8%). Compared to the low FN1 expression group, the high FN1 expression group had significantly larger tumor size (P = 0.002), more advanced T stage (P = 0.039) and N stage (P = 0.009), and also worse AJCC stage (P = 0.003). However, stromal FN1 expression was not associated with disease-free survival or overall survival.

CONCLUSIONS

This study suggests that high stromal FN1 expression is associated with aggressive tumor characteristics in patients with resected PDAC. However, no association between FN1 expression and survival was found.

Nutrient scavenging in cancer

While cancer cell proliferation depends on access to extracellular nutrients, inadequate tumour perfusion means that glucose, amino acids and lipids are often in short supply. To overcome this obstacle to growth, cancer cells utilize multiple scavenging strategies, obtaining macromolecules from the microenvironment and breaking them down in the lysosome to produce substrates for ATP generation and anabolism. Recent studies have revealed four scavenging pathways that support cancer cell proliferation in low-nutrient environments: scavenging of extracellular matrix proteins via integrins, receptor-mediated albumin uptake and catabolism, macropinocytic consumption of multiple components of the tumour microenvironment and the engulfment and degradation of entire live cells via entosis. New evidence suggests that blocking these pathways alone or in combination could provide substantial benefits to patients with incurable solid tumours. Both US Food and Drug Administration (FDA)-approved drugs and several agents in preclinical or clinical development shut down individual or multiple scavenging pathways. These therapies may increase the extent and durability of tumour growth inhibition and/or prevent the development of resistance when used in combination with existing treatments. This Review summarizes the evidence suggesting that scavenging pathways drive tumour growth, highlights recent advances that define the oncogenic signal transduction pathways that regulate scavenging and considers the benefits and detriments of therapeutic strategies targeting scavenging that are currently under development.

Angiogenesis in pancreatic cancer: current research status and clinical implications

Pancreatic cancer is one of the most lethal malignancies worldwide. Although the standard of care in pancreatic cancer has improved, prognoses for patients remain poor with a 5-year survival rate of < 5%. Angiogenesis, namely, the formation of new blood vessels from pre-existing vessels, is an important event in tumor growth and hematogenous metastasis. It is a dynamic and complex process involving multiple mechanisms and is regulated by various molecules. Inhibition of angiogenesis has been an established therapeutic strategy for many solid tumors. However, clinical outcomes are far from satisfying for pancreatic cancer patients receiving anti-angiogenic therapies. In this review, we summarize the current status of angiogenesis in pancreatic cancer research and explore the reasons for the poor efficacy of anti-angiogenic therapies, aiming to identify some potential therapeutic targets that may enhance the effectiveness of anti-angiogenic treatments.

Role of glycosylation in hypoxia-driven cell migration and invasion

Hypoxia, a common condition of the tumor microenvironment, induces changes in the proteome of cancer cells, mainly via HIF-1, a transcription factor conformed by a constitutively expressed β-subunit and an oxygen-regulated α-subunit. In hypoxia, HIF-1α stabilizes, forms the heterodimeric complex with HIF-1β, and binds to Hypoxia Response Elements (HRE), activating gene expression to promote metabolic adaptation, cell invasion and metastasis. Furthermore, the focal adhesion kinase, FAK, is activated in hypoxia, promoting cell migration by mechanisms that remain unclear. In this context, integrins, which are glycoproteins required for cell migration, are possibly involved in hypoxia-induced FAK activation. Evidence suggests that cancer cells have an altered glycosylation metabolism, mostly by the expression of glycosyltransferases, however the relevance of glycosylation is poorly explored in the context of hypoxia. Here, we discuss the role of hypoxia in cancer, and its effects on protein glycosylation, with emphasis on integrins and cell migration.

CD93 promotes β1 integrin activation and fibronectin fibrillogenesis during tumor angiogenesis

Tumor angiogenesis occurs through regulation of genes that orchestrate endothelial sprouting and vessel maturation, including deposition of a vessel-associated extracellular matrix. CD93 is a transmembrane receptor that is upregulated in tumor vessels in many cancers, including high-grade glioma. Here, we demonstrate that CD93 regulates β1 integrin signaling and organization of fibronectin fibrillogenesis during tumor vascularization. In endothelial cells and mouse retina, CD93 was found to be expressed in endothelial filopodia and to promote filopodia formation. The CD93 localization to endothelial filopodia was stabilized by interaction with multimerin-2 (MMRN2), which inhibited its proteolytic cleavage. The CD93-MMRN2 complex was required for activation of β1 integrin, phosphorylation of focal adhesion kinase (FAK), and fibronectin fibrillogenesis in endothelial cells. Consequently, tumor vessels in gliomas implanted orthotopically in CD93-deficient mice showed diminished activation of β1 integrin and lacked organization of fibronectin into fibrillar structures. These findings demonstrate a key role of CD93 in vascular maturation and organization of the extracellular matrix in tumors, identifying it as a potential target for therapy.

Anti-Tumorigenic and Anti-Metastatic Activity of the Sponge-Derived Marine Drugs Aeroplysinin-1 and Isofistularin-3 against Pheochromocytoma In Vitro

Over 10% of pheochromocytoma and paraganglioma (PPGL) patients have malignant disease at their first presentation in the clinic. Development of malignancy and the underlying molecular pathways in PPGLs are poorly understood and efficient treatment strategies are missing. Marine sponges provide a natural source of promising anti-tumorigenic and anti-metastatic agents. We evaluate the anti-tumorigenic and anti-metastatic potential of Aeroplysinin-1 and Isofistularin-3, two secondary metabolites isolated from the marine sponge Aplysina aerophoba, on pheochromocytoma cells. Aeroplysinin-1 diminished the number of proliferating cells and reduced spheroid growth significantly. Beside these anti-tumorigenic activity, Aeroplysinin-1 decreased the migration ability of the cells significantly (p = 0.01), whereas, the invasion capacity was not affected. Aeroplysinin-1 diminished the high adhesion capacity of the MTT cells to collagen (p < 0.001) and, furthermore, reduced the ability to form spheroids significantly. Western Blot and qRT-PCR analysis showed a downregulation of integrin β1 that might explain the lower adhesion and migration capacity after Aeroplysinin-1 treatment. Isofistularin-3 showed only a negligible influence on proliferative and pro-metastatic cell properties. These in vitro investigations show promise for the application of the sponge-derived marine drug, Aeroplysinin-1 as anti-tumorigenic and anti-metastatic agent against PPGLs for the first time.

β1 and β3 integrins in breast, prostate and pancreatic cancer: A novel implication

Integrins are transmembrane glycoproteins that consist of an α and a β subunit. Specific integrin heterodimers preferentially bind to distinct extracellular matrix (ECM) proteins to affect the characteristics of cells or the components of the ECM. Among the different integrins, β1 and β3 integrins serve essential roles in the progression of different cancer-associated processes, including the initiation, proliferation, survival, migration and invasion. Furthermore, previous studies have revealed a ratio between these two integrins in cancer cells, which also demonstrated that the functions of these two integrins are paradoxical. This indicated that the proliferation and metastasis of cancer cells are not always parallel and may be considered independently maintained. Additionally, the present review may assist in understanding certain aspects of cancer, and in making clinical decisions in a novel and more comprehensive manner.

Integrin α5 triggers the metastatic potential in renal cell carcinoma

The therapy of advanced renal cell carcinoma (RCC) is still a major challenge. To intervene therapeutically a deeper comprehension of the particular steps of metastasis is necessary. In this context membrane bound receptors like integrins play a decisive role. We analyzed the integrin α5 expression in 141 clear cell RCC patients by Western blot. Patients with RCC expressed a significant higher level of integrin α5 in tumor than in normal tissue. The integrin α5 expression correlated with tumor grade, the development of distant metastases within five years after tumor nephrectomy and reduced survival. The RCC cell lines Caki-1 and CCF-RC1, which highly express integrin α5, were treated with fibronectin in combination with or without an inhibiting anti-integrin α5 antibody. Afterwards the migration, adhesion, viability and prominent signaling molecules were analyzed. Both cell lines showed a significant reduced migration potential as well as a decreased adhesion potential to fibronectin after treatment with an integrin α5 blocking antibody. A contribution of the AKT and ERK1/2 signaling pathways could be demonstrated. The results indicate integrin α5 as a potent marker to discriminate patients’ tumor prognosis. Consequently the integrin subunit α5 can be considered as a target for individual therapy of advanced RCC.

Nitric-oxide synthase trafficking inducer is a pleiotropic regulator of endothelial cell function and signaling

Endothelial nitric-oxide synthase (eNOS) and its bioactive product, nitric oxide (NO), mediate many endothelial cell functions, including angiogenesis and vascular permeability. For example, vascular endothelial growth factor (VEGF)-mediated angiogenesis is inhibited upon reduction of NO bioactivity both in vitro and in vivo Moreover, genetic disruption or pharmacological inhibition of eNOS attenuates angiogenesis during tissue repair, resulting in delayed wound closure. These observations emphasize that eNOS-derived NO can promote angiogenesis. Intriguingly, eNOS activity is regulated by nitric-oxide synthase trafficking inducer (NOSTRIN), which sequesters eNOS, thereby attenuating NO production. This has prompted significant interest in NOSTRIN's function in endothelial cells. We show here that NOSTRIN affects the functional transcriptome of endothelial cells by down-regulating several genes important for invasion and angiogenesis. Interestingly, the effects of NOSTRIN on endothelial gene expression were independent of eNOS activity. NOSTRIN also affected the expression of secreted cytokines involved in inflammatory responses, and ectopic NOSTRIN overexpression functionally restricted endothelial cell proliferation, invasion, adhesion, and VEGF-induced capillary tube formation. Furthermore, NOSTRIN interacted directly with TNF receptor-associated factor 6 (TRAF6), leading to the suppression of NFκB activity and inhibition of AKT activation via phosphorylation. Interestingly, TNF-α-induced NFκB pathway activation was reversed by NOSTRIN. We found that the SH3 domain of NOSTRIN is involved in the NOSTRIN-TRAF6 interaction and is required for NOSTRIN-induced down-regulation of endothelial cell proteins. These results have broad biological implications, as aberrant NOSTRIN expression leading to deactivation of the NFκB pathway, in turn triggering an anti-angiogenic cascade, might inhibit tumorigenesis and cancer progression.

The translational blocking of α5 and α6 integrin subunits affects migration and invasion, and increases sensitivity to carboplatin of SKOV-3 ovarian cancer cell line

Epithelial ovarian cancer is the most lethal gynecologic malignancy. Integrins, overexpressed in cancer, are involved in various processes that favor the development of the disease. This study focused on determining the degree of involvement of α5, α6 and β3 integrin subunits in the establishment/development of epithelial ovarian cancer (EOC), such as proliferation, migration, invasion, and response to carboplatin. The translation of the α5, α6 and β3 integrins was blocked using morpholines, generating morphant cells for these proteins, which were corroborated by immunofluorescence assays. WST-1 proliferation assay showed that silencing of α5, α6, and β3 integrins does not affect the survival of morphants. Wound healing and transwell chamber assays showed that blocking α5 and α6 integrins decrease, in lesser and greater level respectively, the migratory and the invasive capacity of SKOV-3 cells. Finally, blocking α5 and α6 integrins partially sensitized the cells response to carboplatin, while blocking integrin β3 generated resistance to this drug. Statistical analyses were performed with the GraphPad Prism 5.0 software employing one way and two-way ANOVA tests; data are shown as average±SD. Results suggest that α5 and α6 integrins could become good candidates for chemotherapy targets in EOC.

β1 Integrin as a Prognostic and Predictive Marker in Triple-Negative Breast Cancer

Triple negative breast cancer (TNBC) displays higher risk of recurrence and distant metastasis. Due to absence of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2), TNBC lacks clinically established targeted therapies. Therefore, understanding of the mechanism underlying the aggressive behaviors of TNBC is required for the design of individualized strategies and the elongation of overall survival duration. Here, we supported a positive correlation between β1 integrin and malignant behaviors such as cell migration, invasion, and drug resistance. We found that silencing of β1 integrin inhibited cell migration, invasion, and increased the sensitivity to anti-cancer drug. In contrast, activation of β1 integrin increased cell migration, invasion, and decreased the sensitivity to anti-cancer drug. Furthermore, we found that silencing of β1 integrin abolished Focal adhesion kinese (FAK) mediated cell survival. Overexpression of FAK could restore cisplatin-induced apoptosis in β1 integrin-depleted cells. Consistent to in vitro data, β1 integrin expression was also positively correlated with FAK (p = 0.031) in clinical tissue. More importantly, β1 integrin expression was significantly correlated with patient outcome. In summary, our study indicated that β1 integrin could regulate TNBC cells migration, invasion, drug sensitivity, and be a potential prognostic biomarker in TNBC patient survival.

Anti-vascular therapies in ovarian cancer: moving beyond anti-VEGF approaches

Resistance to chemotherapy is among the most important issues in the management of ovarian cancer. Unlike cancer cells, which are heterogeneous as a result of remarkable genetic instability, stromal cells are considered relatively homogeneous. Thus, targeting the tumor microenvironment is an attractive approach for cancer therapy. Arguably, anti-vascular endothelial growth factor (anti-VEGF) therapies hold great promise, but their efficacy has been modest, likely owing to redundant and complementary angiogenic pathways. Components of platelet-derived growth factor (PDGF), fibroblast growth factor (FGF), epidermal growth factor (EGF), and other pathways may compensate for VEGF blockade and allow angiogenesis to occur despite anti-VEGF treatment. In addition, hypoxia induced by anti-angiogenesis therapy modifies signaling pathways in tumor and stromal cells, which induces resistance to therapy. Because of tumor cell heterogeneity and angiogenic pathway redundancy, combining cytotoxic and targeted therapies or combining therapies targeting different pathways can potentially overcome resistance. Although targeted therapy is showing promise, much more work is needed to maximize its impact, including the discovery of new targets and identification of individuals most likely to benefit from such therapies.

Matrix control of pancreatic cancer: New insights into fibronectin signaling

Pancreatic ductal adenocarcinoma (PDA) is a highly metastatic disease that resists most current therapies. A defining characteristic of PDA is an intense fibrotic response that promotes tumor cell invasion and chemoresistance. Efforts to understand the complex relationship between the tumor and its extracellular network and to therapeutically perturb tumor-stroma interactions are ongoing. Fibronectin (FN), a provisional matrix protein abundant in PDA stroma but not normal tissues, supports metastatic spread and chemoresistance of this deadly disease. FN also supports angiogenesis, which is required for even hypovascular tumors such as PDA to develop and progress. Targeting components of the tumor stroma, such as FN, can effectively reduce tumor growth and spread while also enhancing delivery of chemotherapy. Here, we review the molecular mechanisms by which FN drives angiogenesis, metastasis and chemoresistance in PDA. In light of these new findings, we also discuss therapeutic strategies to inhibit FN signaling.

Anti-angiogenic alternatives to VEGF blockade

Angiogenesis is a major requirement for tumour formation and development. Anti-angiogenic treatments aim to starve the tumour of nutrients and oxygen and also guard against metastasis. The main anti-angiogenic agents to date have focused on blocking the pro-angiogenic vascular endothelial growth factors (VEGFs). While this approach has seen some success and has provided a proof of principle that such anti-angiogenic agents can be used as treatment, the overall outcome of VEGF blockade has been somewhat disappointing. There is a current need for new strategies in inhibiting tumour angiogenesis; this article will review current and historical examples in blocking various membrane receptors and components of the extracellular matrix important in angiogenesis. Targeting these newly discovered pro-angiogenic proteins could provide novel strategies for cancer therapy.

Membrane proteome analysis of glioblastoma cell invasion

Glioblastoma multiforme (GBM) tumor invasion is facilitated by cell migration and degradation of the extracellular matrix. Invadopodia are actin-rich structures that protrude from the plasma membrane in direct contact with the extracellular matrix and are proposed to participate in epithelial-mesenchymal transition. We characterized the invasiveness of 9 established GBM cell lines using an invadopodia assay and performed quantitative mass spectrometry-based proteomic analyses on enriched membrane fractions. All GBM cells produced invadopodia, with a 65% difference between the most invasive cell line (U87MG) and the least invasive cell line (LN229) (p = 0.0001). Overall, 1,141 proteins were identified in the GBM membrane proteome; the levels of 49 proteins correlated with cell invasiveness. Ingenuity Pathway Analysis predicted activation "cell movement" (z-score = 2.608, p = 3.94E(-04)) in more invasive cells and generated a network of invasion-associated proteins with direct links to key regulators of invadopodia formation. Gene expression data relating to the invasion-associated proteins ITGA5 (integrin α5), CD97, and ANXA1 (annexin A1) showed prognostic significance in independent GBM cohorts. Fluorescence microscopy demonstrated ITGA5, CD97, and ANXA1 localization in invadopodia assays, and small interfering RNA knockdown of ITGA5 reduced invadopodia formation in U87MG cells. Thus, invasion-associated proteins, including ITGA5, may prove to be useful anti-invasive targets; volociximab, a therapeutic antibody against integrin α5β1, may be useful for treatment of patients with GBM.

Tumor angiogenesis in the absence of fibronectin or its cognate integrin receptors

Binding of α5β1 and αvβ3/β5 integrin receptors on the endothelium to their fibronectin substrate in the extracellular matrix has been targeted as a possible means of blocking tumor angiogenesis and tumor growth. However, clinical trials of blocking antibodies and peptides have been disappointing despite promising preclinical results, leading to questions about the mechanism of the inhibitors and the reasons for their failure. Here, using tissue-specific and inducible genetics to delete the α5 and αv receptors in the endothelium or their fibronectin substrate, either in the endothelium or globally, we show that both are dispensable for tumor growth, in transplanted tumors as well as spontaneous and angiogenesis-dependent RIP-Tag-driven pancreatic adenocarcinomas. In the nearly complete absence of fibronectin, no differences in vascular density or the deposition of basement membrane laminins, ColIV, Nid1, Nid2, or the TGFβ binding matrix proteins, fibrillin-1 and -2, could be observed. Our results reveal that fibronectin and the endothelial fibronectin receptor subunits, α5 and αv, are dispensable for tumor angiogenesis, suggesting that the inhibition of angiogenesis induced by antibodies or small molecules may occur through a dominant negative effect, rather than a simple functional block.

Mesothelial cells promote early ovarian cancer metastasis through fibronectin secretion

Ovarian cancer (OvCa) metastasizes to organs in the abdominal cavity, such as the omentum, which are covered by a single layer of mesothelial cells. Mesothelial cells are generally thought to be "bystanders" to the metastatic process and simply displaced by OvCa cells to access the submesothelial extracellular matrix. Here, using organotypic 3D cultures, we found that primary human mesothelial cells secrete fibronectin in the presence of OvCa cells. Moreover, we evaluated the tumor stroma of 108 human omental metastases and determined that fibronectin was consistently overexpressed in these patients. Blocking fibronectin production in primary mesothelial cells in vitro or in murine models, either genetically (fibronectin 1 floxed mouse model) or via siRNA, decreased adhesion, invasion, proliferation, and metastasis of OvCa cells. Using a coculture model, we determined that OvCa cells secrete TGF-β1, which in turn activates a TGF-β receptor/RAC1/SMAD-dependent signaling pathway in the mesothelial cells that promotes a mesenchymal phenotype and transcriptional upregulation of fibronectin. Additionally, blocking α5 or β1 integrin function with antibodies reduced metastasis in an orthotopic preclinical model of OvCa metastasis. These findings indicate that cancer-associated mesothelial cells promote colonization during the initial steps of OvCa metastasis and suggest that mesothelial cells actively contribute to metastasis.

Focal adhesion signaling and therapy resistance in cancer

Interlocking gene mutations, epigenetic alterations and microenvironmental features perpetuate tumor development, growth, infiltration and spread. Consequently, intrinsic and acquired therapy resistance arises and presents one of the major goals to solve in oncologic research today. Among the myriad of microenvironmental factors impacting on cancer cell resistance, cell adhesion to the extracellular matrix (ECM) has recently been identified as key determinant. Despite the differentiation between cell adhesion-mediated drug resistance (CAMDR) and cell adhesion-mediated radioresistance (CAMRR), the underlying mechanisms share great overlap in integrin and focal adhesion hub signaling and differ further downstream in the complexity of signaling networks between tumor entities. Intriguingly, cell adhesion to ECM is per se also essential for cancer cells similar to their normal counterparts. However, based on the overexpression of focal adhesion hub signaling receptors and proteins and a distinct addiction to particular integrin receptors, targeting of focal adhesion proteins has been shown to potently sensitize cancer cells to different treatment regimes including radiotherapy, chemotherapy and novel molecular therapeutics. In this review, we will give insight into the role of integrins in carcinogenesis, tumor progression and metastasis. Additionally, literature and data about the function of focal adhesion molecules including integrins, integrin-associated proteins and growth factor receptors in tumor cell resistance to radio- and chemotherapy will be elucidated and discussed.

Integrin VLA-5 and FAK are Good Targets to Improve Treatment Response in the Philadelphia Chromosome Positive Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia bearing the Philadelphia chromosome is among the most difficult types of ALL to cure. However, the advent of targeted tyrosine kinase inhibitor (TKI) imatinib has ushered in a new era of treatments that have the potential to be less toxic to patients. Integrins and tyrosine kinases play important roles in mediating and transducing signals for cell survival and suppressing apoptosis. Focal adhesion kinase (FAK) is a non-receptor type tyrosine kinase that is constitutively activated in Ph+ ALL. We sought to investigate the specificity of integrin α5β1 (VLA-5) on Ph+ leukemia by its expression and function. We found VLA-5 expression increases after serum starvation. Integrin α5 inhibitory antibody inhibited adhesion of Ph+ leukemia to human fibronectin and acted synergistically with imatinib to induce Ph+ leukemia cell apoptosis. We used different strategies to block integrin signaling and knocked down the expression of integrin VLA-5 to observe the effect on proliferation and engraftment of Ph+ leukemia cells in immunodeficient mice. We found that blocking integrin activity by incubating Ph+ leukemia cells with disintegrin, a peptide inhibitor of integrins, or α5 inhibitory antibody, or knocking down the α5 integrin subunit impaired and delayed the engraftment of Ph+ leukemia in immunodeficient mice. We then treated mice xenografted with Ph+ leukemia cells with the FAK inhibitor TAE226 in combination with a BCR–ABL TKI nilotinib. While 2 weeks of treatment with TAE226 alone did not significantly inhibit leukemia growth in mice, TAE226 in combination with nilotinib provided the most optimum growth inhibition at 4–6 weeks. We conclude that blocking VLA-5 signaling or combining FAK inhibitors with TKI targeting BCL/ABL might be good strategies to improve treatments in patients with Ph+ ALL. By altering Ph+ leukemia cell interactions with the microenvironment, we may increase their susceptibility to therapy targeting BCR/ABL.

Integrin modulators: a patent review

INTRODUCTION

Integrins are heterodimeric cell surface receptors, which enable adhesion, proliferation, and migration of cells by recognizing binding motifs in extracellular matrix (ECM) proteins. As transmembrane linkers between the cytoskeleton and the ECM, they are able to recruit a huge variety of proteins and to influence signaling pathways bidirectionally, thereby regulating gene expression and cell survival. Hence, integrins play a key role in various physiological as well as pathological processes, which has turned them into an attractive target for pharmaceutical research.

AREAS COVERED

In this review, the latest therapeutic developments of drug candidates and recently patented integrin ligands are summarized.

EXPERT OPINION

Integrins have been proven to be valuable therapeutic targets in the treatment of several inflammatory and autoimmune diseases, where leukocyte adhesion processes are regulated by them. Furthermore, they play an important role in pathological angiogenesis and tumor metastasis, being a promising target for cancer therapy.

Novel strategies for the treatment of chondrosarcomas: targeting integrins

Chondrosarcomas are a heterogeneous group of malignant bone tumors that are characterized by the production of cartilaginous extracellular matrix. They are the second most frequently occurring type of bone malignancy. Surgical resection remains the primary mode of treatment for chondrosarcomas, since conventional chemotherapy and radiotherapy are largely ineffective. Treatment of patients with high-grade chondrosarcomas is particularly challenging, owing to the lack of effective adjuvant therapies. Integrins are cell surface adhesion molecules that regulate a variety of cellular functions. They have been implicated in the initiation, progression, and metastasis of solid tumors. Deregulation of integrin expression and/or signaling has been identified in many chondrosarcomas. Therefore, the development of new drugs that can selectively target regulators of integrin gene expression and ligand-integrin signaling might hold great promise for the treatment of these cancers. In this review, we provide an overview of the current understanding of how growth factors, chemokines/cytokines, and other inflammation-related molecules can control the expression of specific integrins to promote cell migration. We also review the roles of specific subtypes of integrins and their signaling mechanisms, and discuss how these might be involved in tumor growth and metastasis. Finally, novel therapeutic strategies for targeting these molecules will be discussed.

β1 integrins mediate resistance to ionizing radiation in vivo by inhibiting c-Jun amino terminal kinase 1

This study was carried out to dissect the mechanism by which β1 integrins promote resistance to radiation. For this purpose, we conditionally ablated β1 integrins in the prostatic epithelium of transgenic adenocarcinoma of mouse prostate (TRAMP) mice. The ability of β1 to promote resistance to radiation was also analyzed by using an inhibitory antibody to β1 , AIIB2, in a xenograft model. The role of β1 integrins and of a β1 downstream target, c-Jun amino-terminal kinase 1 (JNK1), in regulating radiation-induced apoptosis in vivo and in vitro was studied. We show that β1 integrins promote prostate cancer (PrCa) progression and resistance to radiation in vivo. Mechanistically, β1 integrins are shown here to suppress activation of JNK1 and, consequently apoptosis, in response to irradiation. Downregulation of JNK1 is necessary to preserve the effect of β1 on resistance to radiation in vitro and in vivo. Finally, given the established crosstalk between β1 integrins and type1 insulin-like growth factor receptor (IGF-IR), we analyzed the ability of IGF-IR to modulate β1 integrin levels. We report that IGF-IR regulates the expression of β1 integrins, which in turn confer resistance to radiation in PrCa cells. In conclusion, this study demonstrates that β1 integrins mediate resistance to ionizing radiation through inhibition of JNK1 activation.

Integrins and metastasis

Metastasis is a combination of biological events that makes the difference between cancer and other diseases. Metastasis requires flow of erroneous but precisely coordinated basic cellular activities like cell migration-invasion, cell survival-apoptosis, cell proliferation, etc. All of these processes require efficient regulation of cell attachment and detachment, which recruit integrin receptors in this flow of events. World literatures show several aspects of interrelation of integrins and metastasis. Integrin molecules are being used as prime target to battle metastasis. In this review we are collating the observations showing importance of integrin biology in regulation of metastasis and the strategies where integrin receptors are being used as targets to regulate metastasis.

Integrin α5β1, the Fibronectin Receptor, as a Pertinent Therapeutic Target in Solid Tumors

Integrins are transmembrane heterodimeric proteins sensing the cell microenvironment and modulating numerous signalling pathways. Changes in integrin expression between normal and tumoral cells support involvement of specific integrins in tumor progression and aggressiveness. This review highlights the current knowledge about α5β1 integrin, also called the fibronectin receptor, in solid tumors. We summarize data showing that α5β1 integrin is a pertinent therapeutic target expressed by tumoral neovessels and tumoral cells. Although mainly evaluated in preclinical models, α5β1 integrin merits interest in particular in colon, breast, ovarian, lung and brain tumors where its overexpression is associated with a poor prognosis for patients. Specific α5β1 integrin antagonists will be listed that may represent new potential therapeutic agents to fight defined subpopulations of particularly aggressive tumors.

Toward the goal of personalized therapy in pancreatic cancer by targeting the molecular phenotype

The purpose of this article is to provide a critical review of the molecular alterations in pancreatic cancer that are clinically investigated as therapeutic targets and their potential impact on clinical outcomes. Adenocarcinoma of exocrine pancreas is generally associated with poor prognosis and the conventional therapies are marginally effective. Advances in understanding the genetic regulation of normal and neoplastic development of pancreas have led to development and clinical evaluation of new therapeutic strategies that target the signaling pathways and molecular alterations in pancreatic cancer. Applications have begun to utilize the genetic targets as biomarkers for prediction of therapeutic responses and selection of treatment options. The goal of accomplishing personalized tumor-specific therapy with tolerable side effects for patients with pancreatic cancer is hopefully within reach in the foreseeable future.

Elevated expression of integrin αv and β5 subunit in laryngeal squamous-cell carcinoma associated with lymphatic metastasis and angiogenesis

In the past several years, the αv integrin subfamily has been repeatedly found to be involved in tumor progression and angiogenesis. The aim of this study was to investigate the expression of the integrin αv subfamily in laryngeal squamous cell carcinoma (LSCC), and to correlate the expression rate with tumor biological behavior and angiogenesis of the LSCC. The integrin αv subfamily, including αv, β1, β3, β5, β6 and β8 subunits, was immunohistochemically found to be expressed in 64 patients with LSCC, and we analyzed the relationship between the expression rate and the clinicopathological stage of this cancer. Immunohistochemical staining for CD105 was carried out in the same group of the patients. The intratumoral microvessel density (IMVD) of the LSCC was calculated by CD105 staining, and the correlation between the IMVD and αv subfamily expression was discussed. The results showed that all members of the integrin αv subfamily could be detected in the LSCC. The expression rate of integrin αv and β5 subunits in primary cancer was significantly higher than in normal tissue, and their expression rate in the group with lymphatic metastasis was significantly higher than in the group without metastasis. The IMVD of the group with positive expression of αv and β5 subunits was significantly higher than in the group with negative expression, but there were no significant effects on the β1, β3, β6 and β8 subunits in these biological processes. In conclusion, the expressions of integrin αv and β5 subunits were significantly associated with lymphatic metastasis and angiogenesis of the LSCC. Among the members of integrin αv subfamily, integrin αvβ5 might play an important role in invasion and metastases of the LSCC, and it may become a valuable marker for the evolution of the LSCC.

uPAR: a modulator of VEGF-induced angiogenesis

Vascular endothelial growth factor (VEGF)-initiated angiogenesis requires both coordinated proteolytic degradation of extracellular matrix provided by the urokinase plasminogen activator/urokinase receptor (uPA/uPAR) system and regulation of cell-migration provided by integrin-matrix interaction. Previously we have shown that stimulation of pericellular proteolysis induced by VEGF occurs via the VEGF receptor-2 leading to redistribution of uPAR to focal adhesions at the leading edge of endothelial cells. In our recent work published in Cardiovascular Research, we investigated the mechanisms underlying the uPAR-dependent modulation of VEGF-induced endothelial migration. By applying a micropatterning technique we described that VEGF stimulation results in complex formation between uPAR and α 5β 1-integrin on the cell surface. The subsequent internalization of this complex, important for receptor redistribution, was demonstrated by flow-cytometry and immunohistochemistry. Targeting of the interaction site between uPAR and α 5β 1 impairs receptor internalization and leads to the inhibition of endothelial cell migration in vitro and in an angiogenesis model in vivo. This proof-of-principle that the interface of uPAR and α 5β 1-integrin may represent a promising site to therapeutically target tumor angiogenesis raises hope for the development of an anti-angiogenic approach that is limited to only the mobilizing effect of VEGF to endothelial cells, and does not interfere with the inarguably positive effect of VEGF as survival factor.

Beta 1 integrin predicts survival in breast cancer: a clinicopathological and immunohistochemical study

Background

The main focus of several studies concerned with cancer progression and metastasis is to analyze the mechanisms that allow cancer cells to interact and quickly adapt with their environment. Integrins, a family of transmembrane glycoproteins, play a major role in invasive and metastatic processes. Integrins are involved in cell adhesion in both cell-extracellular matrix and cell-cell interactions, and particularly, β1 integrin is involved in proliferation and differentiation of cells in the development of epithelial tissues. This work aimed to investigate the putative role of β1 integrin expression on survival and metastasis in patients with breast invasive ductal carcinoma (IDC). In addition, we compared the expression of β1 integrin in patients with ductal carcinoma in situ (DCIS).

Methods

Through tissue microarray (TMA) slides containing 225 samples of IDC and 67 samples of DCIS, β1 integrin expression was related with several immunohistochemical markers and clinicopathologic features of prognostic significance.

Results

β1 integrin was overexpressed in 32.8% of IDC. In IDC, β1 integrin was related with HER-2 (p = 0.019) and VEGF (p = 0.011) expression and it had a significant relationship with metastasis and death (p = 0.001 and p = 0.05, respectively). Kaplan-Meier survival analysis showed that the overexpression of this protein is very significant (p = 0.002) in specific survival (number of months between diagnosis and death caused by the disease). There were no correlation between IDC and DCIS (p = 0.559) regarding β1 integrin expression.

Conclusions

Considering that the expression of β1 integrin in breast cancer remains controversial, specially its relation with survival of patients, our findings provide further evidence that β1 integrin can be a marker of poor prognosis in breast cancer.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/6652215267393871

Phase Ib safety and pharmacokinetic study of volociximab, an anti-α5β1 integrin antibody, in combination with carboplatin and paclitaxel in advanced non-small-cell lung cancer

BACKGROUND

This phase Ib study evaluated volociximab, an anti-α5β1 integrin antibody, in combination with carboplatin (Eli Lilly and Co., Indianapolis, IN) and paclitaxel (Taxol) in advanced, untreated non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Three cohorts were treated with volociximab (10, 20, or 30 mg/kg) for up to six 3-week cycles in combination with carboplatin-paclitaxel chemotherapy and continued as maintenance therapy for patients with stable disease (SD) or better. Dose-limiting toxic effects, adverse events (AEs), pharmacokinetics, and anti-volociximab antibodies were assessed.

RESULTS

A maximum tolerated dose was not reached up to the maximum planned dose of 30 mg/kg. In 29 patients who received volociximab, the most common grade≥3 AEs were neutropenia (24%), hyponatremia (17%), and fatigue (10%). Three patients experienced volociximab-related serious AEs. No hemorrhages were observed. Of 33 patients enrolled, 8 (24%) achieved a partial response and 17 (52%) had SD. The median progression-free survival was 6.3 months (95% confidence interval 5.5-8.1). Levels of potential biomarkers of angiogenesis or metastasis were reduced following six cycles of treatment.

CONCLUSIONS

Volociximab combined with carboplatin and paclitaxel was generally well-tolerated and showed preliminary evidence of efficacy in advanced NSCLC.