A phase 1, multicenter, open-label study of the safety of two dose levels of a human monoclonal antibody to human α(v) integrins, intetumumab, in combination with docetaxel and prednisone in patients with castrate-resistant metastatic prostate cancer

Targeting integrins in drug-resistant acute myeloid leukaemia

Acute myeloid leukaemia (AML) continues to have a poor prognosis, warranting new therapeutic strategies. The bone marrow (BM) microenvironment consists of niches that interact with not only normal haematopoietic stem cells (HSC) but also leukaemia cells like AML. There are many adhesion molecules in the BM microenvironment; therein, integrins have been of central interest. AML cells express integrins that bind to ligands in the microenvironment, enabling adhesion of leukaemia cells in the microenvironment, thereby initiating intracellular signalling pathways that are associated with cell migration, cell proliferation, survival, and drug resistance that has been described to mediate cell adhesion-mediated drug resistance (CAM-DR). Identifying and targeting integrins in AML to interrupt interactions with the microenvironment have been pursued as a strategy to overcome CAM-DR. Here, we focus on the BM microenvironment and review the role of integrins in CAM-DR of AML and discuss integrin-targeting strategies. LINKED ARTICLES: This article is part of a themed issue on Cancer Microenvironment and Pharmacological Interventions. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.2/issuetoc.

Integrin signaling in cancer: bidirectional mechanisms and therapeutic opportunities

Integrins are transmembrane receptors that possess distinct ligand-binding specificities in the extracellular domain and signaling properties in the cytoplasmic domain. While most integrins have a short cytoplasmic tail, integrin β4 has a long cytoplasmic tail that can indirectly interact with the actin cytoskeleton. Additionally, 'inside-out' signals can induce integrins to adopt a high-affinity extended conformation for their appropriate ligands. These properties enable integrins to transmit bidirectional cellular signals, making it a critical regulator of various biological processes.Integrin expression and function are tightly linked to various aspects of tumor progression, including initiation, angiogenesis, cell motility, invasion, and metastasis. Certain integrins have been shown to drive tumorigenesis or amplify oncogenic signals by interacting with corresponding receptors, while others have marginal or even suppressive effects. Additionally, different α/β subtypes of integrins can exhibit opposite effects. Integrin-mediated signaling pathways including Ras- and Rho-GTPase, TGFβ, Hippo, Wnt, Notch, and sonic hedgehog (Shh) are involved in various stages of tumorigenesis. Therefore, understanding the complex regulatory mechanisms and molecular specificities of integrins are crucial to delaying cancer progression and suppressing tumorigenesis. Furthermore, the development of integrin-based therapeutics for cancer are of great importance.This review provides an overview of integrin-dependent bidirectional signaling mechanisms in cancer that can either support or oppose tumorigenesis by interacting with various signaling pathways. Finally, we focus on the future opportunities for emergent therapeutics based on integrin agonists. Video Abstract.

Targeting the "sweet spot" in septic shock - A perspective on the endothelial glycocalyx regulating proteins Heparanase-1 and -2

Sepsis is a life-threatening syndrome caused by a pathological host response to an infection that eventually, if uncontrolled, leads to septic shock and ultimately, death. In sepsis, a massive aggregation of pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) cause a cytokine storm. The endothelial glycocalyx (eGC) is a gel like layer on the luminal side of the endothelium that consists of proteoglycans, glycosaminoglycans (GAG) and plasma proteins. It is synthesized by endothelial cells and plays an active role in the regulation of inflammation, permeability, and coagulation. In sepsis, early and profound injury of the eGC is observed and circulating eGC components correlate directly with clinical severity and outcome. The activity of the heparan sulfate (HS) specific glucuronidase Heparanase-1 (Hpa-1) is elevated in sepsis, resulting in shedding of heparan sulfate (HS), a main GAG of the eGC. HS induces endothelial barrier breakdown and accelerates systemic inflammation. Lipopolysaccharide (LPS), a PAMP mainly found on the surface of gram-negative bacteria, activates TLR-4, which results in cytokine production and further activation of Hpa-1. Hpa-1 shed HS fragments act as DAMPs themselves, leading to a vicious cycle of inflammation and end-organ dysfunction such as septic cardiomyopathy and encephalopathy. Recently, Hpa-1's natural antagonist, Heparanase-2 (Hpa-2) has been identified. It has no intrinsic enzymatic activity but instead acts by reducing inflammation. Hpa-2 levels are reduced in septic mice and patients, leading to an acquired imbalance of Hpa-1 and Hpa-2 paving the road towards a therapeutic intervention. Recently, the synthetic antimicrobial peptide 19-2.5 was described as a promising therapy protecting the eGC by inhibition of Hpa-1 activity and HS shed fragments in animal studies. However, a recombinant Hpa-2 therapy does not exist to the present time. Therapeutic plasma exchange (TPE), a modality already tested in clinical practice, effectively removes injurious mediators, e.g., Hpa-1, while replacing depleted protective molecules, e.g., Hpa-2. In critically ill patients with septic shock, TPE restores the physiological Hpa-1/Hpa-2 ratio and attenuates eGC breakdown. TPE results in a significant improvement in hemodynamic instability including reduced vasopressor requirement. Although promising, further studies are needed to determine the therapeutic impact of TPE in septic shock.

Emerging therapeutic opportunities for integrin inhibitors

Integrins are cell adhesion and signalling proteins crucial to a wide range of biological functions. Effective marketed treatments have successfully targeted integrins αIIbβ3, α4β7/α4β1 and αLβ2 for cardiovascular diseases, inflammatory bowel disease/multiple sclerosis and dry eye disease, respectively. Yet, clinical development of others, notably within the RGD-binding subfamily of αv integrins, including αvβ3, have faced significant challenges in the fields of cancer, ophthalmology and osteoporosis. New inhibitors of the related integrins αvβ6 and αvβ1 have recently come to the fore and are being investigated clinically for the treatment of fibrotic diseases, including idiopathic pulmonary fibrosis and nonalcoholic steatohepatitis. The design of integrin drugs may now be at a turning point, with opportunities to learn from previous clinical trials, to explore new modalities and to incorporate new findings in pharmacological and structural biology. This Review intertwines research from biological, clinical and medicinal chemistry disciplines to discuss historical and current RGD-binding integrin drug discovery, with an emphasis on small-molecule inhibitors of the αv integrins.

Integrins are key signalling molecules that are present on the surface of subsets of cells and are therefore good potential therapeutic targets. In this Review, Hatley and colleagues discuss the development of integrin inhibitors, particularly the challenges in developing inhibitors for integrins that contain an αv-subunit, and suggest how these challenges could be addressed.

Bone-targeted therapy in castration-resistant prostate cancer: where do we stand?

INTRODUCTION

In the last years, there have been significant developments in the therapeutic armamentarium of metastatic castration-resistant prostate cancer (mCRPC). New evidence shows that the addition of bone-targeted agents (BTA) to "life-prolonging agents" result in improved clinical benefit. This review aims to give an overview of data for the use of BTAs in a new era of mCRPC where new agents are used in daily practice.

EVIDENCE ACQUISITION

A non-systematic review of the literature was performed combining the keywords: "castration-resistant prostate cancer" and "bone-targeted therapy". The primary objective was to provide a critical assessment of data for the use of BTAs in mCRPC, and the secondary objective was to assess novel targeted therapy.

EVIDENCE SYNTHESIS

Zoledronic acid and denosumab have shown to be effective in reducing the risk of SREs in patients with mCRPC. The point at which treatment with bisphosphonates or denosumab should be initiated during PCa evolution has yet to be determined. The EMA has restricted the usage of Ra-223 to patients who have had two previous treatments for mCRPC to the bone or who cannot receive other treatments. Ra-223 should only be used as monotherapy or in combination with ADT for the treatment of mCRPC, symptomatic bone metastases and without visceral metastases. With recent developments in PSMA-targeted radiopharmaceuticals, PSMA RLT agents are now under investigation for the treatment of mCRPC.

CONCLUSIONS

Reducing skeletal-related morbidity remains a crucial goal of palliative life-extending therapy in mCRPC. New data about dosing schedules and combinations of different treatments will continue to refine the optimal strategy for incorporating BTAs into the new treatment paradigms for PCa. Novel molecules such as PSMA-targeted small molecules promise theranostic agents in the management of PCa patients.

Bone-targeted therapies to reduce skeletal morbidity in prostate cancer

Bone metastases are the main driver of morbidity and mortality in advanced prostate cancer. Targeting the bone microenvironment, a key player in the pathogenesis of bone metastasis, has become one of the mainstays of therapy in men with advanced prostate cancer. This review will evaluate the data supporting the use of bone-targeted therapy, including (1) bisphosphonates such as zoledronic acid, which directly target osteoclasts, (2) denosumab, a receptor activator of nuclear factor-kappa B (RANK) ligand inhibitor, which targets a key component of bone stromal interaction, and (3) radium-223, an alpha-emitting calcium mimetic, which hones to the metabolically active areas of osteoblastic metastasis and induces double-strand breaks in the DNA. Denosumab has shown enhanced delay in skeletal-related events compared to zoledronic acid in patients with metastatic castration-resistant prostate cancer (mCRPC). Data are mixed with regard to pain control as a primary measure of efficacy. New data call into question dosing frequency, with quarterly dosing strategy potentially achieving similar effect compared to monthly dosing for zoledronic acid. In the case of radium-223, there are data for both pain palliation and improved overall survival in mCRPC. Further studies are needed to optimize timing and combination strategies for bone-targeted therapies. Ongoing studies will explore the impact of combining bone-targeted therapy with investigational therapeutic agents such as immunotherapy, for advanced prostate cancer. Future studies should strive to develop biomarkers of response, in order to improve efficacy and cost-effectiveness of these agents.

New Strategies Using Antibody Combinations to Increase Cancer Treatment Effectiveness

Antibodies have proven their high value in antitumor therapy over the last two decades. They are currently being used as the first-choice to treat some of the most frequent metastatic cancers, like HER2⁺ breast cancers or colorectal cancers, currently treated with trastuzumab (Herceptin) and bevacizumab (Avastin), respectively. The impressive therapeutic success of antibodies inhibiting immune checkpoints has extended the use of therapeutic antibodies to previously unanticipated tumor types. These anti-immune checkpoint antibodies allowed the cure of patients devoid of other therapeutic options, through the recovery of the patient’s own immune response against the tumor. In this review, we describe how the antibody-based therapies will evolve, including the use of antibodies in combinations, their main characteristics, advantages, and how they could contribute to significantly increase the chances of success in cancer therapy. Indeed, novel combinations will consist of mixtures of antibodies against either different epitopes of the same molecule or different targets on the same tumor cell; bispecific or multispecific antibodies able of simultaneously binding tumor cells, immune cells or extracellular molecules; immunomodulatory antibodies; antibody-based molecules, including fusion proteins between a ligand or a receptor domain and the IgG Fab or Fc fragments; autologous or heterologous cells; and different formats of vaccines. Through complementary mechanisms of action, these combinations could contribute to elude the current limitations of a single antibody which recognizes only one particular epitope. These combinations may allow the simultaneous attack of the cancer cells by using the help of the own immune cells and exerting wider therapeutic effects, based on a more specific, fast, and robust response, trying to mimic the action of the immune system.

αvβ3 and α5β1 integrin-specific ligands: From tumor angiogenesis inhibitors to vascularization promoters in regenerative medicine?

Integrins are cell adhesion receptors predominantly important during normal and tumor angiogenesis. A sequence present on several extracellular matrix proteins composed of Arg-Gly-Asp (RGD) has attracted attention due to its role in cell adhesion mediated by integrins. The development of ligands that can bind to integrins involved in tumor angiogenesis and brake disease progression has resulted in new investigational drug entities reaching the clinical trial phase in humans. The use of integrin-specific ligands can be useful for the vascularization of regenerative medicine constructs, which remains a major limitation for translation into clinical practice. In order to enhance vascularization, immobilization of integrin-specific RGD peptidomimetics within constructs is a recommended approach, due to their high specificity and selectivity towards certain desired integrins. This review endeavours to address the potential of peptidomimetic-coated biomaterials as vascular network promoters for regenerative medicine purposes. Clinical studies involving molecules tracking active integrins in cancer angiogenesis and reasons for their failure are also addressed.

Differential Effect on Bone Lesions of Targeting Integrins: Randomized Phase II Trial of Abituzumab in Patients with Metastatic Castration-Resistant Prostate Cancer

PURPOSE

Integrins play a critical role in the progression of prostate cancer and its bone metastases. We investigated the use of the pan-αv integrin inhibitor abituzumab in chemotherapy-naïve patients with asymptomatic or mildly symptomatic metastatic castration-resistant prostate cancer.

EXPERIMENTAL DESIGN

PERSEUS (NCT01360840) was a randomized, double-blind phase II study. Men with pathologically confirmed prostate cancer and radiologic progression of bone lesions in the 28 days prior to randomization were assigned to receive abituzumab 750 mg or 1,500 mg or placebo (1:1:1) every 3 weeks in combination with luteinizing hormone-releasing hormone agonist/antagonist therapy. The primary endpoint was progression-free survival (PFS).

RESULTS

The intent-to-treat population comprised 180 patients, 60 in each arm. The primary endpoint of PFS was not significantly different with abituzumab-based therapy compared with placebo [abituzumab 750 mg, 3.4 months, HR = 0.89; 95% confidence interval (CI), 0.57-1.39; abituzumab 1,500 mg, 4.3 months, HR = 0.81; 95% CI, 0.52-1.26; placebo, 3.3 months], but the cumulative incidence of bone lesion progression was lower with abituzumab than with placebo for up to 24 months (cumulative incidence 23.6% vs. 41.1% at 6 months, 26.1% vs. 45.4% at 12 months). Two partial tumor responses were observed (1 abituzumab 1,500 mg and 1 placebo). Approximately 85% to 90% of patients experienced at least one treatment-emergent adverse event (TEAE) in the different arms, but the incidences of serious TEAEs and TEAEs with fatal outcome were similar in the three arms.

CONCLUSIONS

Although PFS was not significantly extended, abituzumab appears to have specific activity in prostate cancer-associated bone lesions that warrants further investigation. Clin Cancer Res; 22(13); 3192-200. ©2016 AACR.

Strategies to inhibit tumor associated integrin receptors: rationale for dual and multi-antagonists

The integrins are a family of 24 heterodimeric transmembrane cell surface receptors. Involvement in cell attachment to the extracellular matrix, motility, and proliferation identifies integrins as therapeutic targets in cancer and associated conditions: thrombosis, angiogenesis, and osteoporosis. The most reported strategy for drug development is synthesis of an agent that is highly selective for a single integrin receptor. However, the ability of cancer cells to change their integrin repertoire in response to drug treatment renders this approach vulnerable to the development of resistance and paradoxical promotion of tumor growth. Here, we review progress toward development of antagonists targeting two or more members of the Arg-Gly-Asp (RGD) binding integrins, notably αvβ3, αvβ5, αvβ6, αvβ8, α5β1, and αIIbβ3, as anticancer therapeutics.

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.

Dual inhibition of αV integrins and Src kinase activity as a combination therapy strategy for colorectal cancer

Both Src and αV integrins are important for tumor growth and angiogenesis. They are interconnected and responsible for important features of the tumor phenotype including invasiveness, metastasis, angiogenesis, and resistance to apoptosis. This study examines whether combinational inhibition of both integrin and Src pathways would exert greater antiangiogenesis and antitumor effects than either pathway alone. Using in-vitro cell culture systems, the activity of CNTO95 (Intetumumab), an αV integrin inhibitor, and dasatinib, an Src inhibitor, on proliferation, adhesion, and migration was evaluated in colon cancer cell lines, HCT-116 and RKO, as well as HUVEC cells. The antiangiogenic effect of this combinatory regimen was also tested using an in-vitro tubular network formation assay. The effects of CNTO95 and dasatinib on the activation of Src and integrin pathway signal transduction were also determined by western blotting. The combination of CNTO95 plus dasatinib inhibited adhesion, migration, and paxillin phosphorylation in both HCT-116 and RKO cells. CNTO95 and dasatinib also led to increased apoptosis of HCT-116 cells; however, similar effects were not observed in RKO cells. In addition, dual treatment of CNTO95 and dasatinib exerted enhanced effects on HUVEC cell proliferation, invasion, tubular network formation, and paxillin phosphorylation. In conclusion, our results suggest that concurrent inhibition of both the integrin and the Src pathways exert more pronounced antiangiogenic and antitumor effects than with either pathway being inhibited alone.

Pain questionnaire performance in advanced prostate cancer: comparative results from two international clinical trials

PURPOSE

To compare pain assessment questionnaires commonly used in advanced prostate cancer trials and to determine the psychometric characteristics and longitudinal relationships by contrasting questionnaire data from two international phase 2 trials.

METHODS

Scores from the Present Pain Intensity (PPI) question of the McGill Pain Questionnaire, the pain intensity scale of the Brief Pain Inventory (BPI), and the Functional Assessment of Cancer Therapy-Prostate (FACT-P) were analyzed using Pearson correlation, intraclass correlation coefficient, and Cronbach's α, respectively. Concordance was evaluated with Cohen's kappa coefficient and McNemar test at baseline (n = 224) and two subsequent observations.

RESULTS

PPI and FACT-P scores were associated with the BPI score at baseline for Trials 1 and 2: PPI r = 0.66 and 0.80, respectively (P < 0.001); FACT-P (pain scale) r = -0.76 and -0.82, respectively (P < 0.001). However, concordance analysis revealed that the BPI identified pain (score > 0) at higher rates than the PPI: at baseline, BPI: 89 % (64/72) and 77 % (95/124), PPI: 68 % (49/72) and 64 % (79/124) [Trials 1 and 2, respectively; McNemar test (P < 0.001) for both studies]. The FACT-P pain scale identified pain similarly to the BPI pain intensity scale; longitudinal analysis produced comparable findings. All pain scales met standard psychometric acceptability criteria, but the BPI and FACT-P performed better than the PPI.

CONCLUSIONS

Data suggest the BPI pain intensity and FACT-P pain scales are better than the PPI question at capturing the pain experience among patients with advanced prostate cancer. Additional comparative research is needed in larger population samples.

A randomized, double-blind, multicenter, phase 2 study of a human monoclonal antibody to human αν integrins (intetumumab) in combination with docetaxel and prednisone for the first-line treatment of patients with metastatic castration-resistant prostate cancer

BACKGROUND

Intetumumab is a fully human mAb with antiangiogenic, antitumor properties which has shown potential therapeutic effect in castration-resistant prostate cancer (CRPC) patients.

PATIENTS AND METHODS

In a phase 2, randomized, double-blind, multicenter study, men with metastatic CRPC without prior systemic nonhormonal therapy were randomly assigned to 75-mg/m(2) docetaxel (Taxotere) and 5-mg prednisone plus placebo (N = 65) or 10-mg/kg intetumumab (N = 66) q3w. Placebo patients with progressive disease (PD) could cross over to 10-mg/kg intetumumab alone or with docetaxel. The primary end-point was progression-free survival (PFS). The secondary end-points included tumor response (complete response + partial response, CR + PR), prostate-specific antigen (PSA) response, and overall survival (OS).

RESULTS

All efficacy end-points favored placebo over intetumumab, including PFS (median 11.0 versus 7.6 months, P = 0.014), tumor response (20% versus 16%, P = 0.795), PSA response (68% versus 47%, P = 0.018), OS (median 20.6 versus 17.2 months, P = 0.163). Common all-grade adverse events (AEs) with placebo and intetumumab were alopecia (43% versus 26%); diarrhea, leukopenia (both 34% versus 27%); neutropenia (35% versus 23%). Grade ≥ 3 leukopenia (28% versus 17%) and neutropenia (26% versus 18%) occurred more often with placebo than with intetumumab. Intetumumab serum concentrations increased with repeated dosing and did not reach steady-state. Greater decreases in N-telopeptide of type I collagen (NTx), C-telopeptide (CTx) and CTCs occurred with intetumumab than with placebo.

CONCLUSION

The addition of intetumumab to docetaxel resulted in shorter PFS without additional toxicity among CRPC patients.

The effect of alpha-v integrin inhibition on the malignant characteristics of medulloblastoma

OBJECT

Hypoxia induces an aggressive phenotype in some brain tumors in part due to hypoxia-inducible factor-1α (HIF-1α) and integrin expression. The importance of hypoxia in medulloblastoma is unclear and the interaction of HIF-1α and c-Myc in medulloblastoma has not been explored. The objective of this study was to determine if hypoxia induces an aggressive phenotype in human medulloblastoma cells that constitutively express high (D283 Med) or low (DAOY) levels of c-Myc and to determine if blocking α(v) integrins with the monoclonal antibody intetumumab inhibits hypoxia-induced cellular stress responses.

METHODS

Cells were grown at 21% and 1% O(2) and in the presence or absence of intetumumab. Measures of malignancy evaluated included cell proliferation, cell migration, and expression of vascular endothelial growth factor (VEGF), α(v) integrins, HIF-1α, and c-Myc.

RESULTS

Both cell lines robustly expressed α(v) integrins. Hypoxic DAOY cells showed significantly increased proliferation compared with normoxic controls (p < 0.05), whereas D283 Med cells did not. Both cell lines exhibited a dose-dependent decrease in proliferation when treated with intetumumab (p < 0.05). Hypoxia did not increase DAOY migration, but intetumumab significantly inhibited migration at both oxygen conditions (p < 0.05). Intetumumab significantly decreased VEGF levels in DAOY cells at both oxygen conditions (p < 0.05) and in normoxic D283 cells (p < 0.01). Neither cell line demonstrated increased HIF-1α expression in response to hypoxia. However, hypoxic D283 Med cells grown in the presence of intetumumab demonstrated significantly decreased c-Myc expression (p < 0.05).

CONCLUSIONS

Hypoxia did not clearly induce a more aggressive phenotype in medulloblastoma cells. Despite this result, intetumumab decreased medulloblastoma cell proliferation and migration and variably decreased VEGF and c-Myc expression in hypoxic conditions. Targeting α(v) integrins represents a promising potential adjuvant modality in the treatment of medulloblastoma, particularly subtypes that metastasize and overexpress VEGF and c-Myc.

RGD-Binding Integrins in Prostate Cancer: Expression Patterns and Therapeutic Prospects against Bone Metastasis

Prostate cancer is the third leading cause of male cancer deaths in the developed world. The current lack of highly specific detection methods and efficient therapeutic agents for advanced disease have been identified as problems requiring further research. The integrins play a vital role in the cross-talk between the cell and extracellular matrix, enhancing the growth, migration, invasion and metastasis of cancer cells. Progression and metastasis of prostate adenocarcinoma is strongly associated with changes in integrin expression, notably abnormal expression and activation of the β₃ integrins in tumour cells, which promotes haematogenous spread and tumour growth in bone. As such, influencing integrin cell expression and function using targeted therapeutics represents a potential treatment for bone metastasis, the most common and debilitating complication of advanced prostate cancer. In this review, we highlight the multiple ways in which RGD-binding integrins contribute to prostate cancer progression and metastasis, and identify the rationale for development of multi-integrin antagonists targeting the RGD-binding subfamily as molecularly targeted agents for its treatment.

Targeting αV-integrins decreased metastasis and increased survival in a nude rat breast cancer brain metastasis model

Brain metastases commonly occur in patients with breast, lung and melanoma systemic cancers. The anti-α(V) integrin monoclonal antibody intetumumab binds cell surface proteins important for adhesion, invasion and angiogenesis in the metastatic cascade. The objective of this study was to investigate the anti-metastatic effect of intetumumab in a hematogenous breast cancer brain metastasis model. Female nude rats received intra-carotid infusion of human brain-seeking metastatic breast cancer cells (231BR-HER2) and were randomly assigned into four groups: (1) control; (2) intetumumab mixed with cells in vitro 5 min before infusion without further treatment; (3) intetumumab intravenously 4 h before and weekly after cell infusion; (4) intetumumab intravenously weekly starting 7 days after cell infusion. Brain metastases were detected by magnetic resonance imaging (MRI) and immunohistochemistry. Comparisons were made using the Kruskal-Wallis test and Dunnett's test. Survival times were estimated using Kaplan-Meier analysis. All control rats with brain tissue available for histology (9 of 11 rats) developed multiple brain metastases (median = 14). Intetumumab treatment either in vitro prior to cell infusion or intravenous before or after cell infusion prevented metastasis formation on MRI and decreased the number of metastases on histology (median = 2, p = 0.0055), including 30 % of animals without detectable tumors at the end of the study. The overall survival was improved by intetumumab compared to controls (median 77+ vs. 52 days, p = 0.0277). Our results suggest that breast cancer patients at risk of metastases might benefit from early intetumumab treatment.

Expression of αV-integrins in uterine serous papillary carcinomas; implications for targeted therapy with intetumumab (CNTO 95), a fully human antagonist anti-αV-integrin antibody

OBJECTIVE

Uterine serous papillary carcinoma (USPC) is an aggressive variant of endometrial cancer characterized by an innate resistance to chemotherapy and poor prognosis. In this study, we evaluated the expression of αV-integrins in primary USPC cell lines and the in vitro ability of intetumumab (CNTO 95), a fully human monoclonal antibody against αV-integrins, to inhibit USPC cell adhesion and migration.

MATERIALS AND METHODS

The surface expression of integrins belonging to the αV-family, including αVβ3, αVβ5, and αVβ6, was evaluated in 6 primary USPC cell lines using flow cytometry analysis. To test the ability of intetumumab to inhibit USPC cell adhesion and migration, adhesion assays in the presence of vitronectin and migration assays through an 8.0-μm pore polycarbonate membrane also were performed.

RESULTS

We found high expression of the αV-subunit on the cell surface of all 6 primary USPC cell lines tested (100% positive cells; mean fluorescence intensity range, 13.1-39.5). When the expression of single heterodimeric integrins was evaluated, αVβ3, αVβ5, and αVβ6 were expressed on 37.5%, 32.0%, and 16.3% of cells (mean fluorescence intensity range, 6.5-16.2, 9.2-32.5, and 6.2-11.5, respectively). Importantly, in functional assays, low doses of intetumumab were effective in inhibiting adhesion (0.15 μg/mL, P = 0.003) and migration (1.25 μg/mL P = 0.02) of primary USPC cell lines.

CONCLUSIONS

The αV-integrins are overexpressed on the cell surface of primary USPC cell lines. Intetumumab may significantly inhibit USPC cell adhesion and migration pathways and may therefore represent a novel treatment option for patients harboring this rare but highly aggressive variant of endometrial cancer.

Critical analysis of simultaneous blockage of histone deacetylase and multiple receptor tyrosine kinase in the treatment of prostate cancer

BACKGROUND

The concept of molecular tumor targeting might be an innovative option to treat advanced prostate cancer. We analyzed the effect of combining the multiple receptor tyrosine kinase inhibitor AEE788 and the histone deacetylase (HDAC) inhibitor valproic acid (VPA) on adhesion and growth properties of prostate cancer cell lines.

METHODS

PC-3, DU-145, and LNCaP cells were treated with AEE788, VPA or with an AEE788-VPA combination, and cell cycle progression investigated. Furthermore, tumor cell adhesion to vascular endothelium or to immobilized extracellular matrix proteins was evaluated, and integrin α and β subtypes were analyzed. Finally, effects of drug treatment on cell signaling pathways were determined.

RESULTS

AEE788 moderately and VPA strongly reduced tumor cell adhesion and growth. VPA impaired cell cycle progression and altered the expression level of the cell cycle regulating proteins cdk1, cdk2, cdk4, cyclin B, D1, cyclin E, p21, and p27. VPA also acted on the membranous, cytoplasmic, and gene expression pattern of various integrin α and β subtypes. AEE788 acted likewise, but more moderately. Combining AEE788 and VPA did not result in an additive anti-tumor effect. Signaling analysis revealed that the EGFr downstream target Akt was similarly modified in the presence of VPA or the VPA-AEE788 combination, but not influenced by AEE788 alone.

CONCLUSIONS

The AEE788-VPA combination has no advantage over VPA monotreatment in vitro. The non-responsiveness of Akt