How not to discover a drug - integrins.

INTRODUCTION: Integrins are a family of 24 cell adhesion receptors that play a role in the biggest unmet needs in medicine - cardiovascular disease, immunology and cancer. Their discovery promised huge potential for the pharmaceutical industry. Areas covered. Over 35-years since their discovery, there is little to show for the hundreds of billions of dollars of investment in anti-integrin drug discovery programmes. In this review the author discusses the reasons for the failure of this promising class of drugs and the future for this class of drugs. Expert opinion. Within 10-years, there was a plethora of potent, specific anti-integrin molecules and since their discovery, many of these agents have entered clinical trials. The success in discovering these agents was due to recently discovered monoclonal antibody technology. The integrin-recognition domain Arg-Gly-Asp (RGD) provided the basis for discovering small molecule inhibitors to integrins - both cyclic peptides and peptidomimetics. Most agents failed in the Phase III clinical trials and those agents that did make it to the market were plagued with issues of toxicity and limited efficacy and were soon replaced with non-integrin targeting agents. Their failure was due to a combination of poor pharmacokinetics and pharmacodynamics, complicated by the complex pathophysiology of integrins.

Dose Escalation Assessment Among Targeted Immunomodulators in the Management of Inflammatory Bowel Disease.

BACKGROUND: The need for individualized treatment regimens is becoming more important in the management of patients with inflammatory bowel disease (IBD). Gastroenterologists may dose adjust either by increasing the dose or shortening the dosing interval from the initial recommended maintenance dose to achieve an appropriate clinical response. Understanding the role of dose escalation in the treatment of IBD in clinical practice provides payers in the United States insight into the real-world cost-effectiveness of targeted immunomodulators (TIMs) in the management of IBD. OBJECTIVE: To assess the prevalence and magnitude of dose escalation for approved IBD therapies. METHODS: Using the Source Healthcare Analytics database, patients with IBD who initiated treatment with a drug of interest from July 2015 to June 2017 were identified. Patient utilization of the TIMs was tracked for 12 months following initiation. All included patients had at least 2 diagnoses for ulcerative colitis or Crohn disease before TIM initiation and at least 5 claims for a drug of interest within the 12 months following initiation. Dose escalation was defined as an increase of at least 30% in the average daily dose (ADD) relative to the patient's expected maintenance dose on 2 consecutive prescriptions. The proportion of patients with dose escalation in the first 12 months after treatment initiation was determined. The magnitude of dose escalation was determined by calculating the patient's ADD across all noninduction dose claims and comparing it with the expected daily dose. Dose escalation prevalence and magnitude were used to quantify the equivalent patient treatment rate representing the number of patients per 100 that could have been treated with standard dosing, given the prevalence of dose escalation in the treated population. RESULTS: 7,028 patients (2,406 infliximab, 1,966 adalimumab, 1,745 vedolizumab, 472 ustekinumab, 285 certolizumab pegol, and 154 golimumab) met eligibility criteria and were included in the study. Among IBD therapies, dose escalation occurred most frequently with infliximab (39%), followed by adalimumab (28%), vedolizumab (23%), ustekinumab (22%), certolizumab pegol (20%), and golimumab (14%). The magnitude of dose escalation was greatest for ustekinumab (131%), followed by infliximab (70%), vedolizumab (62%), adalimumab (59%), certolizumab pegol (50%), and golimumab (45%). The calculated patient equivalence was highest for infliximab (128) and ustekinumab (128) compared with adalimumab (116), vedolizumab (114), certolizumab pegol (110), and golimumab (106). CONCLUSIONS: Among patients with IBD, dose escalation occurred with all TIMs examined with varying degrees of prevalence and magnitude. Real-world utilization patterns of TIMs indicate that dose escalation is an important part of the clinical management of IBD and needs to be considered when evaluating the cost-effectiveness of IBD treatments. DISCLOSURES: Financial support for this study was provided by AbbVie, which participated in study design, research, data collection, analysis and interpretation of data, writing, reviewing, and approving the publication. All authors contributed to the development of the publication and maintained control over the final content. Ehrenberg and McDonald are employees of IQVIA, which received funding from AbbVie to participate in this research. Griffith and Theigs are employed by AbbVie and may own stock or stock options in AbbVie.

Rate of Adverse Events and Associated Health Care Costs for the Management of Inflammatory Bowel Disease in Germany.

PURPOSE: Therapeutic management of inflammatory bowel disease (IBD) is challenging, and available therapies are associated with adverse events (AEs) that may lead to treatment discontinuation. This study evaluated the rate of drug-related AEs of special interest (AESIs) associated with IBD therapies and compare health care costs among patients with IBD who did and did not experience AESIs. METHODS: A retrospective cohort analysis was conducted using claims data from a German Sickness Fund (Allgemeine Ortskrankenkasse PLUS). Patients were diagnosed with ulcerative colitis (UC) or Crohn's disease (CD) and newly initiating treatment with immunosuppressant, anti-tumor necrosis factor α, or anti-integrin therapies from January 1, 2011, to December 31, 2015. Patients were required to have continuous insurance coverage and no evidence of use of these IBD therapies for 12 months before the date of newly initiating therapy (index date). Rates of AESIs were based on 28 different events or chronic conditions associated with IBD treatment. Direct health care costs were reported separately for patients who did or did not experience AESIs. Only treatment periods lasting ≥60 days were considered. AESI rates related to all possible treatment patterns were calculated and reported as the number of events per 10,000 patient-years. Health care costs were calculated based on IBD-related health care resource use. FINDINGS: A total of 1126 (CD, n = 676; UC, n = 450) patients met the inclusion criteria. Mean age was 36.5 years for patients with CD and 42.5 years for patients with UC; 60.5% and 47.6% were female, respectively. Median observed time since the index date was 1460 and 1552 days, for patients with CD and UC. The overall rate for any AESI was 1392.4 and 1917.9 events per 10,000 patient-years in patients with CD and those with UC. Severe infections and diabetes mellitus were the most common AESIs. Significant differences in mean total direct health care costs were found for CD patients with AESIs versus those without (€8920.08 and €6004.86; P < 0.001). A similar trend was observed with mean drug costs and mean medical costs. In UC, total direct health care costs, although generally higher in patients with AESIs, were not significantly different; however, medical costs were (€1946.93 vs €971.28; P < 0.001). IMPLICATIONS: AEs are common in patients with IBD treated with current therapies and associated with substantial health care costs. An urgent need exists for development of IBD treatments that are associated with lower rates of AEs.

Incidence, Prevention and Management of Anti-Drug Antibodies Against Therapeutic Antibodies in Inflammatory Bowel Disease: A Practical Overview.

The introduction of biologic therapy has revolutionized the treatment of inflammatory bowel disease (IBD). However, like all therapeutic proteins, monoclonal antibodies have immunogenic potential which is influenced by multiple drug- and patient-related factors. The reported incidence of anti-drug antibodies (ADAs) towards biologic drugs in IBD varies greatly in the literature and depends not only on differences in sensitization but also on the assay methodology and the timepoint of measurement. Sensitization with formation of ADAs is associated with an increased risk of infusion reactions, accelerated drug clearance, and a loss of response (LOR) to drug. Recently, a greater understanding of the pharmacokinetics of therapeutic antibodies has led to the development of new strategies to reduce immunogenicity and more efficient use of these drugs. These preventive strategies include regular scheduled dosing with maintenance of stable therapeutic trough drug concentrations, and co-administration of an immunosuppressive. Sub-therapeutic drug concentrations with low levels of ADAs can generally be overcome with dose escalation, whereas the presence of high concentrations of ADAs requires a switch to another therapeutic agent.

A review of the cost-effectiveness of vedolizumab for treating moderate- to severely active ulcerative colitis.

INTRODUCTION: Vedolizumab is a novel humanised monoclonal IgG1 antibody gut selective anti-integrin specifically targeting α4ß7 integrins in the gut and found to be efficacious in the treatment of ulcerative colitis. Areas covered: Research investigating the cost-effectiveness of vedolizumab is limited. This review considers data from the manufacturers, the evidence research group commissioned by NICE to conduct a single technology appraisal, and the decision of NICE itself to appraise what is currently known about the cost-effectiveness of vedolizumab for moderately to severely active ulcerative from a UK perspective. Expert commentary: Based on the very limited data currently available, it can be concluded that vedolizumab is a cost-effective option for those with moderately to severely active ulcerative colitis who are anti-TNFa naive; however, there is a need for further research comparing vedolizumab with other biologic therapies which may alter perceptions of cost-effectiveness.

Pharmacodynamic assessment of vedolizumab for the treatment of ulcerative colitis.

INTRODUCTION: Vedolizumab is an anti-integrin approved for the treatment of Crohn's disease and ulcerative colitis. By binding the α4ß7-integrin heterodimer, vedolizumab blocks leukocyte translocation into gastrointestinal tissue. AREAS COVERED: This review discusses the chemistry, pharmacologic properties, clinical efficacy, and safety of vedolizumab in ulcerative colitis. Other medications available for the treatment of ulcerative colitis are also discussed. EXPERT OPINION: Vedolizumab is a promising new agent for the treatment of ulcerative colitis. Its mechanism of action differs from TNF-α inhibitors and immune suppressants, allowing it to be used in cases of TNF-α inhibitor failure or non-response, or as a first-line biologic drug. Available safety data suggests that vedolizumab is not associated with an increased risk of infection or malignancy; however, additional post-marketing data are required to confirm these initial reports. Vedolizumab is likely to be used in growing numbers of patients over the coming years.

Thrombolytic effects of the snake venom disintegrin saxatilin determined by novel assessment methods: a FeCl3-induced thrombosis model in mice.

Saxatilin, a novel disintegrin purified and cloned from the venom of the Korean snake Gloydius saxatilis, strongly inhibits activation and aggregation of platelets. Glycoprotein (GP) IIb/IIIa receptor antagonists can resolve thrombus, so saxatilin might also have thrombolytic effects. We investigated the thrombolytic effects of saxatilin in mice using a ferric chloride-induced carotid arterial thrombosis model. Thrombotic occlusion and thrombus resolution were evaluated quantitatively by measuring blood flow in the carotid artery with an ultrasonic flow meter and calculating the degree of flow restoration on a minute-by-minute basis; results were confirmed by histological examination. Saxatilin dissolved thrombi in a dose-dependent manner. Saxatilin at 5 mg/kg restored blood flow to baseline levels. As saxatilin dose increased, time to recanalization decreased. A bolus injection of 10% of a complete dose with continuous infusion of the remaining dose for 60 minutes resulted in effective recanalization without reocclusion. The thrombolytic effect of saxatilin was also demonstrated in vitro using platelet aggregometry by administering saxatilin in preformed thrombi. Bleeding complications were observed in 2 of 71 mice that received saxatilin. Fibrin/fibrinogen zymography and platelet aggregometry studies indicated that saxatilin does not have fibrinolytic activity, but exerted its action on platelets. Integrin-binding assays showed that saxatilin inhibited multiple integrins, specifically α2bß3 (GP IIb/IIIa), α5ß1, αvß3, αvß1, and αvß5, which act on platelet adhesion/aggregation. Saxatilin inhibited multiple integrins by acting on platelets, and was safe and effective in resolving thrombi in mice.

Cilengitide: an RGD pentapeptide ανß3 and ανß5 integrin inhibitor in development for glioblastoma and other malignancies.

Cilengitide, a cyclicized arginine-glycine-aspartic acid-containing pentapeptide, potently blocks ανß3 and ανß5 integrin activation. Integrins are upregulated in many malignancies and mediate a wide variety of tumor-stroma interactions. Cilengitide and other integrin-targeting therapeutics have preclinical activity against many cancer subtypes including glioblastoma (GBM), the most common and deadliest CNS tumor. Cilengitide is active against orthotopic GBM xenografts and can augment radiotherapy and chemotherapy in these models. In Phase I and II GBM trials, cilengitide and the combination of cilengitide with standard temozolomide and radiation demonstrate consistent antitumor activity and a favorable safety profile. Cilengitide is currently under evaluation in a pivotal, randomized Phase III study (Cilengitide in Combination With Temozolomide and Radiotherapy in Newly Diagnosed Glioblastoma Phase III Randomized Clinical Trial [CENTRIC]) for newly diagnosed GBM. In addition, randomized controlled Phase II studies with cilengitide are ongoing for non-small-cell lung cancer and squamous cell carcinoma of the head and neck. Cilengitide is the first integrin inhibitor in clinical Phase III development for oncology.

Biological and molecular properties of a new alpha(v)beta3/alpha(v)beta5 integrin antagonist.

The aim of the present study was to identify specific alpha(v)beta3/alpha(v)beta5 integrin antagonists active on tumor-induced angiogenesis. To this purpose, in vitro integrin-binding assays were used to screen a library of conformationally constrained bicyclic lactam Arg-Gly-Asp-containing pseudopeptides. The results identified ST1646 as a high-affinity specific ligand for alpha(v)beta3 and alpha(v)beta5 integrins with negligible interacting with alpha5beta1 integrin. In all the assays, ST1646 was equipotent to or more potent than the well-characterized integrin antagonists c(RGDfV) and cyclo(Arg-Gly-Asp-d-Phe-[NMe]Val) (EMD121974). In the chorioallantoic membrane assay, topical administration of ST1646 was able to prevent the angiogenic responses elicited by recombinant fibroblast growth factor-2 or vascular endothelial growth factor. In addition, systemic administration of ST1646 in mice exerted a significant antiangiogenic activity on neovascularization triggered by mammary carcinoma MDA-MB435 cells implanted s.c. in a dorsal air sac via a (Millipore Filter Corporation, Bedford, MA) chamber. Moreover, ST1646 delivery via an osmotic pump inhibited the growth and vascularization of tumor xenografts originating from the injection of alpha(v)beta3/alpha(v)beta5-expressing human ovarian carcinoma cells in nude mice. In agreement with the biochemical and pharmacologic studies, Monte Carlo/Stochastic Dynamics simulation showed that the bicyclic scaffold in ST1646 forced the compound to assume a preferred conformation superimposable to the X-ray conformation of alpha(v)beta3-bound EMD121974. Accordingly, computer-docking studies indicated that the ST1646-alpha(v)beta3 integrin complex maintains the ligand-receptor distances and interactions observed in the crystalline EMD121974-alpha(v)beta3 integrin complex. Taken together, these observations indicate that ST1646 represents a dual alpha(v)beta3/alpha(v)beta5 integrin antagonist with interesting biochemical and biological features to be tested in cancer therapy.

Comparative assessment of the ligand and metal ion binding properties of integrins alpha9beta1 and alpha4beta1.

Integrins alpha9beta1 and alpha4beta1 form a distinct structural class, but while alpha4beta1 has been subjected to extensive study, alpha9beta1 remains poorly characterized. We have used the small molecule N-(benzenesulfonyl)-(L)-prolyl-(L)-O-(1-pyrrolidinylcarbonyl)tyrosine (3) to investigate the biochemical properties of alpha9beta1 and directly compare these properties with those of alpha4beta1. Compound 3 has a high affinity for both integrins with K(D) values of < or =3 and 180 pM for alpha9beta1 in 1 mM Mn2+ (activating) and 1 mM Ca2+ and 1 mM Mg2+ (nonactivating) conditions and < or =5 and 730 pM for alpha4beta1 under the corresponding conditions. Ca2+ treatment promoted the binding of 3 to both integrins (EC50 = 30 microM Ca2+ in both cases). Compound 3 binding to both integrins was also stimulated by the addition of the activating monoclonal antibody TS2/16. These findings indicate that the mechanisms by which metal ions and TS2/16 regulate ligand binding to alpha9beta1 and alpha4beta1 are similar. The binding of 3 to both integrins induced the mAb 9EG7 LIBS epitope, a property consistent with occupancy of the receptor's ligand binding site by 3. But whereas EGTA treatment inhibited the binding of 9EG7 to alpha4beta1, it stimulated the binding of 9EG7 to alpha9beta1. The 9EG7 and TS2/16 effects point to contributions of the beta1-chains on binding. Cross-linking data revealed that the integrin alpha-chains are also involved in binding the small molecule, as stable linkages were observed on both the alpha9 chain of alpha9beta1 and the alpha4 chain of alpha4beta1. Extensive structure-activity analyses with natural and synthetic ligands indicate distinct features of the ligand binding pockets. Most notable was the estimated >1000-fold difference in the affinity of the integrins for VCAM-1, which binds alpha4beta1with an apparent K(D) of 10 nM and alpha9beta1 with an apparent K(D) of >10 microM. Differences were also seen in the binding of alpha9beta1 and alpha4beta1 to osteopontin. Compound 3 competed effectively for the binding of VCAM-1 and osteopontin to both integrins. While these studies show many similarities in the biochemical properties of alpha9beta1 and alpha4beta1, they identify important differences in their structure and function that can be exploited in the design of selective alpha9beta1 and alpha4beta1 inhibitors.

A homogeneous fluorometric assay for measuring cell adhesion to immobilized ligand using V-well microtiter plates.

We have developed a homogeneous high-capacity assay format for measuring integrin- and selectin-dependent cell binding to immobilized ligand using V-well microtiter plates. 2',7'-Bis(2-carboxyethyl)-5-(and-6)-carboxylfluorescence, acetoxymethylester-labeled cells are added to ligand-coated V-shaped microtiter wells. Bound cells are separated from free cells using centrifugal force to produce shear stress. Nonadherent cells accumulate in the nadir of the well and are measured using a fluorescence plate reader. Antibody or low-molecular-weight inhibitors of either the ligand or the cell surface receptor result in less cell binding, more cells in the pellet, and increased signal. The optimization and validation of the very late antigen-4/vascular cell adhesion molecule-1 assay is described in detail. We demonstrate that this assay can be rapidly adapted to measure other integrin- and selectin-mediated interactions. This assay format has several advantages over conventional assays. The centrifugal process is biologically relevant and eliminates the washing steps to remove nonadherent cells that can cause well-to-well and plate-to-plate variation. Because the assay is robust with a high signal-to-noise ratio and low variability, it is ideally suited for studying multiple parameters of cell adhesion and for high capacity screening.

Endothelial response to cardiopulmonary bypass surgery.

BACKGROUND: The vascular endothelium has been shown to actively participate in maintaining normal cardiovascular homeostasis by influencing the regulation of membrane permeability, lipid transport, vasomotor tone, coagulation, fibrinolysis, and inflammation. Endothelial cells are very responsive to a wide range of local and systemic stimuli that occur during cardiopulmonary bypass (CPB) operation. Major pathologic conditions result from impaired vascular function secondary to CPB, including vasospasm, coagulopathy, and widespread neutrophil adhesion secondary to a systemic inflammatory response. Additionally, more chronic responses to endothelial cell injury include the development of intimal hyperplasia and arteriosclerosis, both of which limit the long-term success of coronary artery bypass grafting. METHODS: Because of the increasingly recognized role of the endothelium in the maintenance of normal cardiovascular function, this article will review the normal structure and function of the endothelium, as well as the major pathologic conditions that result in response to CPB. RESULTS: Potential treatments to counteract endothelial cell dysfunction secondary to CPB are under active investigation. Strategies may be directed toward blocking single cytokines, integrins, or adhesion molecules involved in endothelial dysfunction or, alternatively, toward targeting a molecular event that governs the expression of these proinflammatory, procoagulant, and vasoactive genes. In our laboratory, we have used both strategies to study the pathologic response to CPB. We blocked neutrophil adhesion in subhuman primates with a monoclonal antibody. Alternatively, we targeted the transcriptional activation of multiple genes involved in the endothelial cell's response to CPB. CONCLUSIONS: Although both therapies help elucidate the multiple, redundant pathways involved in the pathologic response to CPB, it is through molecular biology that we are beginning to understand the mechanics of transcriptional control and translational expression that occurs in the endothelial cell in response to CPB. This knowledge will allow the development of therapies that inhibit not a single cytokine or adhesion molecule, but rather an array of substances that result in the endothelial cell's pathologic response to CPB.