Jochen Knolle

Icatibant, a New Bradykinin-Receptor Antagonist, in Hereditary Angioedema

BACKGROUNDnHereditary angioedema is characterized by recurrent attacks of angioedema of the skin, larynx, and gastrointestinal tract. Bradykinin is the key mediator of symptoms. Icatibant is a selective bradykinin B2 receptor antagonist.nnnMETHODSnIn two double-blind, randomized, multicenter trials, we evaluated the effect of icatibant in patients with hereditary angioedema presenting with cutaneous or abdominal attacks. In the For Angioedema Subcutaneous Treatment (FAST) 1 trial, patients received either icatibant or placebo; in FAST-2, patients received either icatibant or oral tranexamic acid, at a dose of 3 g daily for 2 days. Icatibant was given once, subcutaneously, at a dose of 30 mg. The primary end point was the median time to clinically significant relief of symptoms.nnnRESULTSnA total of 56 and 74 patients underwent randomization in the FAST-1 and FAST-2 trials, respectively. The primary end point was reached in 2.5 hours with icatibant versus 4.6 hours with placebo in the FAST-1 trial (P=0.14) and in 2.0 hours with icatibant versus 12.0 hours with tranexamic acid in the FAST-2 trial (P<0.001). In the FAST-1 study, 3 recipients of icatibant and 13 recipients of placebo needed treatment with rescue medication. The median time to first improvement of symptoms, as assessed by patients and by investigators, was significantly shorter with icatibant in both trials. No icatibant-related serious adverse events were reported.nnnCONCLUSIONSnIn patients with hereditary angioedema having acute attacks, we found a significant benefit of icatibant as compared with tranexamic acid in one trial and a nonsignificant benefit of icatibant as compared with placebo in the other trial with regard to the primary end point. The early use of rescue medication may have obscured the benefit of icatibant in the placebo trial. (Funded by Jerini; ClinicalTrials.gov numbers, NCT00097695 and NCT00500656.)

Preclinical Evaluation of the Novel Small-Molecule Integrin α5β1 Inhibitor JSM6427 in Monkey and Rabbit Models of Choroidal Neovascularization

OBJECTIVEnTo evaluate the pharmacologic activity and tolerability of JSM6427, a potent and first selective small-molecule inhibitor of integrin alpha5beta1, in monkey and rabbit models of choroidal neovascularization (CNV).nnnMETHODSnJSM6427 selectivity for alpha5beta1 was evaluated by in vitro binding assays while the ability of JSM6427 to inhibit CNV was investigated in a laser-induced monkey model and a growth factor-induced rabbit model. Intravitreal injections of JSM6427 (100, 300, or 1000 microg) or vehicle were administered immediately after the CNV induction procedure and at weekly intervals for 4 weeks. Fluorescein angiography was performed weekly. Ocular tolerability was evaluated ophthalmoscopically and histologically in both models; additional assessments in monkeys included electroretinography, biomicroscopy, pathological examination, and analysis of JSM6427 pharmacokinetics.nnnRESULTSnJSM6427 was highly selective for the alpha5beta1-fibronectin interaction. Weekly intravitreal injections of JSM6427 resulted in a statistically significant dose-dependent inhibition of CNV in laser-induced and growth factor-induced models without any ocular JSM6427-related adverse effects. JSM6427 was cleared through the systemic circulation with no evidence of systemic accumulation.nnnCONCLUSIONSnIntravitreal JSM6427 provided dose-dependent inhibition of CNV in monkey and rabbit experimental models.nnnCLINICAL RELEVANCEnJSM6427 may provide a new approach for the treatment of ocular neovascular diseases such as age-related macular degeneration in humans.

α5β1 Integrin Blockade Inhibits Lymphangiogenesis in Airway Inflammation

The integrin alpha5beta1 has been previously implicated in tumor angiogenesis, but its role in the remodeling of both blood vessels and lymphatics during inflammation is at an early stage of understanding. We examined this issue using a selective, small-molecule inhibitor of alpha5beta1 integrin, 2-aroylamino-3-{4-[(pyridin-2-ylaminomethyl)heterocyclyl]phenyl}propionic acid (JSM8757), in a model of sustained airway inflammation in mice with Mycoplasma pulmonis infection, which is known to be accompanied by robust blood vessel remodeling and lymphangiogenesis. The inhibitor significantly decreased the proliferation of lymphatic endothelial cells in culture and the number of lymphatic sprouts and new lymphatics in airways of mice infected for 2 weeks but did not reduce remodeling of blood vessels in the same airways. In inflamed airways, alpha5 integrin immunoreactivity was present on lymphatic sprouts, but not on collecting lymphatics or blood vessels, and was not found on any lymphatics of normal airways. Macrophages, potential targets of the inhibitor, did not have alpha5 integrin immunoreactivity in inflamed airways. In addition, macrophage recruitment, assessed in infected airways by quantitative reverse transcription-polymerase chain reaction measurements of expression of the marker protein ionized calcium-binding adapter molecule 1 (Iba1), was not reduced by JSM8757. We conclude that inhibition of the alpha5beta1 integrin reduces lymphangiogenesis in inflamed airways after M. pulmonis infection because expression of the integrin is selectively increased on lymphatic sprouts and plays an essential role in lymphatic growth.

Assessment of the Integrin α5β1 Antagonist JSM6427 in Proliferative Vitreoretinopathy Using In Vitro Assays and a Rabbit Model of Retinal Detachment

PURPOSEnTo explore the role of integrin alpha5beta1 in proliferative vitreoretinopathy (PVR) pathogenesis by evaluating the expression alpha5beta1 on ARPE-19 cells and patient proliferative membranes, quantifying the inhibitory effects of JSM6427 (a small molecule alpha5beta1 inhibitor) on ARPE-19 cell adhesion and migration, and assessing the therapeutic potential of JSM6427 in a rabbit retinal detachment model.nnnMETHODSnExpression of alpha5beta1 was evaluated on activated ARPE-19 cells by flow cytometry and on PVR membranes by immunohistochemistry. ARPE-19 cells were used in fibronectin-dependent adhesion and migration assays with various concentrations of JSM6427; IC(50) was calculated. In the rabbit model, eyes were intravitreally injected with vehicle or JSM6427 on day 0 or 1 after retinal detachment; BrdU was administered intravitreally on day 3, and retinal tissues were harvested on day 3 (4 hours later) or 7. Retinal scarring, cellular proliferation, and inflammatory responses were quantified, and retinal morphology was analyzed in retinal sections.nnnRESULTSnActivated ARPE-19 cells and PVR membranes expressed high levels of alpha5beta1; expression was low in control eyes. JSM6427 provided a dose-dependent blockade of ARPE-19 cell adhesion to fibronectin (IC(50), 7.1 +/- 2.5 microM) and inhibition of migration (IC(50), 6.0 +/- 4.5 microM). In the rabbit model, intravitreal injection of JSM6427 provided significant inhibition of proliferation of retinal cells (Müller cells, microglia, and macrophages) on days 3 and 7 after detachment and inhibition of inflammatory response and retinal scarring on day 7 after detachment.nnnCONCLUSIONSnJSM6427 is a promising treatment for PVR, with data suggesting that inhibition of alpha5beta1-fibronectin interactions addresses multiple pathways involving retinal pigment epithelial, glial, and inflammatory cells.

RGD Mimetics containing a central hydantoin scaffold: αVβ3 vs αIIbβ3 selectivity requirements

Abstract The synthesis of a series of RGD mimetic α V β 3 antagonists containing a hydantoin scaffold is shown. The results demonstrate some of the structural requirements for the design of selective α V β 3 antagonists (vs α IIb β 3 ) in terms of the Arg-mimetic, the distance between N- and C-terminus and the lipophilic side chain.

Effect of Selective or Combined Inhibition of Integrins αIIbβ3 and αvβ3 on Thrombosis and Neointima After Oversized Porcine Coronary Angioplasty

Background—Thrombosis and neointima formation limit the efficacy of coronary angioplasty (PTCA). Clinical trials have implicated the adhesion molecules integrin αIIbβ3 and integrin αvβ3 in these processes. The roles of these molecules in vascular smooth muscle cell adhesion, platelet aggregation, and the thrombotic and neointimal response to oversize porcine PTCA was investigated by use of a selective αIIbβ3 antagonist (lamifiban), a selective αvβ3 antagonist (VO514), and a combined αIIbβ3/αvβ3 antagonist (G3580). Methods and Results—In vitro, both αvβ3 inhibitors caused dose-dependent inhibition of porcine vascular smooth muscle cell adhesion to vitronectin but not to collagen type IV, fibronectin, or laminin, whereas selective αIIbβ3 inhibition had no effect. Intravenous infusions of either αIIbβ3 inhibitor in swine profoundly inhibited ex vivo platelet aggregation to ADP, whereas selective αvβ3 inhibition had no effect. In a porcine PTCA model, intravenous infusions of the integrin antagonists were adm...