Nicole Eter

Intraocular Pharmacokinetics of Bevacizumab After a Single Intravitreal Injection in Humans

PURPOSE To investigate intraocular concentrations and pharmacokinetics of bevacizumab after a single intravitreal injection in humans. DESIGN Prospective, noncomparative, interventional case series. METHODS We included 30 nonvitrectomized eyes of 30 patients (age range, 43 to 93 years) diagnosed with clinically significant cataract and concurrent macular edema secondary to neovascular age-related macular degeneration, diabetic retinopathy, or retinal venous occlusion in the same eye. All patients received an intravitreal injection of 1.5 mg bevacizumab. Between one and 53 days after injection, an aqueous humor sample was obtained during elective cataract surgery. Concentrations of unbound bevacizumab in these samples were quantified by enzyme-linked immunosorbent assay. RESULTS Concentration of bevacizumab in aqueous humor peaked on the first day after injection with a mean concentration (c(max)) of 33.3 microg/ml (range, 16.6 to 42.5 microg/ml) and subsequently declined in a monoexponential fashion. Nonlinear regression analysis determined an elimination half-time (t(1/2)) of 9.82 days (R(2) = 0.81). No significant differences between diagnosis subgroups were noted. CONCLUSIONS In human nonvitrectomized eyes, the aqueous half-life of 1.5 mg intravitreally injected bevacizumab is 9.82 days.

Clinical evaluation of simultaneous confocal scanning laser ophthalmoscopy imaging combined with high‐resolution, spectral‐domain optical coherence tomography

Acta Ophthalmol. 2010: 88: 842–849

Combined treatment of acute subretinal haemorrhages with intravitreal recombined tissue plasminogen activator, expansile gas and bevacizumab: a retrospective pilot study

Purpose:  To assess the effectiveness of consecutive intravitreal injections of recombined tissue plasminogen activator (rtPA), expansile gas and bevacizumab in eyes with acute subretinal haemorrhage (SRH).

Tracking Progression with Spectral-Domain Optical Coherence Tomography in Geographic Atrophy Caused by Age-Related Macular Degeneration

PURPOSE To investigate, with the use of spectral-domain optical coherence tomography (SD-OCT), microstructural alterations over time in eyes with progressive geographic atrophy (GA) due to age-related macular degeneration. METHODS Forty-six eyes of 26 patients (median age, 77.9 years [interquartile range (IQR), 71.8-81.0]) with GA without evidence of active or previous neovascular disease at baseline were examined by simultaneous confocal scanning laser ophthalmoscopy (cSLO) and SD-OCT. Serial examinations with alignment of follow-up to baseline scans were performed over a median period of 12.2 months (IQR, 10.2-15.3). Longitudinal SD-OCT variations were evaluated, including quantification of retinal thickness (RT) change and lateral spread of GA (LSGA) at a temporal, nasal, inferior, and superior GA border-section in each eye. RESULTS GA-enlargement was characterized by progressive loss of the outer hyperreflective SD-OCT bands and by thinning of the outer nuclear layer with subsequent approach of the outer plexiform layer toward Bruchs membrane. In the perilesional zone, various dynamic changes were recorded, including migration of hyperreflective material and changes in drusen height. At the borders, there was a median RT change of -14.09 microm/y (IQR -26.21 to -7.48 microm/y). The median LSGA was 106.90 microm/y (IQR, 55.44-161.70 microm/y). Both parameters showed only moderate intraocular agreement (RT change: intraclass correlation coefficient [ICC], 0.54; 95% CI, 0.39-0.67; LSGA: ICC, 0.49; 95% CI, 0.34-0.64) and no statistical significant difference for one location (RT change, P = 0.125; LSGA, P = 0.516; likelihood ratio test). CONCLUSIONS Combined cSLO and SD-OCT imaging provides unprecedented insight into dynamic microstructural changes of GA enlargement that may help to better understand the pathogenesis of the disease. Quantitative progression data indicate local factors may exist that drive progression in junctional areas (ClinicalTrials.gov number, NCT00393692).

Human RPE stem cells grown into polarized RPE monolayers on a polyester matrix are maintained after grafting into rabbit subretinal space.

Summary Transplantation of the retinal pigment epithelium (RPE) is being developed as a cell-replacement therapy for age-related macular degeneration. Human embryonic stem cell (hESC) and induced pluripotent stem cell (iPSC)-derived RPE are currently translating toward clinic. We introduce the adult human RPE stem cell (hRPESC) as an alternative RPE source. Polarized monolayers of adult hRPESC-derived RPE grown on polyester (PET) membranes had near-native characteristics. Trephined pieces of RPE monolayers on PET were transplanted subretinally in the rabbit, a large-eyed animal model. After 4 days, retinal edema was observed above the implant, detected by spectral domain optical coherence tomography (SD-OCT) and fundoscopy. At 1 week, retinal atrophy overlying the fetal or adult transplant was observed, remaining stable thereafter. Histology obtained 4 weeks after implantation confirmed a continuous polarized human RPE monolayer on PET. Taken together, the xeno-RPE survived with retained characteristics in the subretinal space. These experiments support that adult hRPESC-derived RPE are a potential source for transplantation therapies.

In Vivo Visualization of Dendritic Cells, Macrophages, and Microglial Cells Responding to Laser-Induced Damage in the Fundus of the Eye

PURPOSE To study the in vivo response of mononuclear phagocytes (i.e., dendritic cells [DCs] and macrophages [MPhis]) in the posterior eye segment after laser-induced injury, and to gain a better understanding of the role of these cells in inflammatory eye disease. METHODS CX(3)CR1(GFP/+) knockin mice were used, in which DCs, MPhis, and microglia cells (microGCs) are constitutively fluorescent. These reporter mice were examined by a confocal scanning laser ophthalmoscope (cSLO) after argon laser coagulation. cSLO was complemented by fluorescence microscopy of retinal flatmounts and eye cryosections, to study cell morphology and location, and by multicolor flow cytometry, to determine the number and identity of the fluorescent cells. RESULTS The retina of healthy reporter mice featured abundant fluorescent microGCs. After laser injury to the fundus, these cells accumulated and migrated laterally toward injury after 60 minutes. Distinctly shaped fluorescent cells accumulated within laser spots and were identified by flow cytometry and immunofluorescence microscopy as DCs and MPhis in the retina and choroid. The DCs rapidly disappeared from the retina, whereas the MPhis stayed longer. Choroidal infiltrates were detectable even 35 days after laser injury, in particular in larger spots resulting from higher laser intensity. In addition, nonfluorescent granulocytes were detected in the choroid. CONCLUSIONS The synergistic use of ophthalmoscopy, flow cytometry, and immunofluorescence microscopy allows detailed dissection of the in vivo response of mononuclear phagocytes to laser injury of the fundus. The number of microGCs increased in the retina. DCs and MPhis were present in the retina and choroid infiltrate. MPhis and granulocytes persisted in the choroid infiltrate longer than previously thought.

INTRAVITREAL BEVACIZUMAB FOR NEOVASCULAR AGE-RELATED MACULAR DEGENERATION

ZusammenfassungDie Wirksamkeit des Anti-VEGF-Therapiekonzepts bei der neovaskulären altersabhängigen Makuladegeneration (AMD) konnte bereits für Pegaptanib und Ranibizumab gezeigt werden. Mit Bevacizumab steht ein Antikörper gegen den vaskulären endothelialen Wachstumsfaktor (VEGF) zur Verfügung, der ursprünglich für onkologische Anwendungsgebiete mit intravenöser Applikation entwickelt wurde. Im „Off-label use“ von Bevacizumab zeigte sich in ersten Fallberichten auch ein Therapieeffekt nach intravitrealer Applikation bei der neovaskulären AMD. Weltweit wurden mittlerweile auf diese Weise, auch aufgrund der mitunter erstaunlich positiven morphologischen und funktionellen Effekte, schon mehrere Tausend Patienten behandelt. Allerdings fehlen kontrollierte, prospektive Studien zur Sicherheit und Wirksamkeit von Bevacizumab bei der neovaskulären AMD. Hier sollen aktuelle Daten zusammengefasst und diskutiert werden. Mit dem Pooling von Daten und einer dafür eigens eingerichteten webbasierten Datenbank sollen bald aussagekräftigere Ergebnisse zur Verfügung stehen. Insbesondere gibt es noch offene Fragen hinsichtlich Dosierung, Applikationsintervall, Gesamtdauer der Applikation, biologischer Halbwertszeit und Langzeitsicherheit des Medikaments.AbstractThe efficacy and safety of the therapeutic anti-VEGF concept has already been demonstrated for pegaptanib and ranibizumab. Bevacizumab acts as an antibody against all VEGF-A isoforms and has been developed for oncological indications with intravenous application. Initial reports on intravitreal administration in patients with neovascular age-related macular disease (AMD) have shown beneficial morphological and functional effects. In the meantime, bevacizumab has been used off-label in thousands of patients with AMD. However, data from prospective, controlled, randomized trials on both safety and efficacy are lacking. Herein recent experiences with bevacizumab are summarized and discussed. Furthermore, a web-based platform for online data registration and pooled analyses is presented.

Comparison of fluorescein angiography and optical coherence tomography for patients with choroidal neovascularization after photodynamic therapy.

Purpose: To investigate retinal morphology by means of fluorescein angiography (FA) and optical coherence tomography (OCT) in patients who had undergone photodynamic therapy (PDT) with verteporfin at their 3-month-interval examination. Methods: Sixty patients with predominantly classic choroidal neovascularization (CNV) secondary to age-related macular degeneration were evaluated with FA and OCT 3 months after their last PDT. FA images were evaluated in a masked fashion for staining of and leakage from the lesion and also for cystoid loculation of fluorescein in the macula. OCT was used to evaluate foveal thickness and the presence of subretinal fluid or cystoid spaces within the retina, also in a masked fashion. Results: The median age of the 60 patients was 78 years, and the median visual acuity of the eyes examined was 20/100. The median number of previous PDT sessions was 2. Fluorescein staining was seen in 57 eyes (95%), and fluorescein leakage was seen in 50 eyes (83%). Cystoid loculation of fluorescein was seen in 21 eyes (35%). By OCT, cystoid spaces in the macula were seen in 42 patients (70%), and subretinal fluid was seen in 15 patients (25%). Leakage seen shown by FA was correlated with the OCT finding of cystoid spaces but not with the OCT finding of subretinal fluid. Some patients had leakage during FA that did not have any observable induced OCT abnormality attributable to fluid accumulation. Conclusions: After PDT leakage from CNV seen during FA is associated with intraretinal fluid, often seen in loculated cystoid spaces, but not with subretinal fluid.

New Pharmacologic Approaches to Therapy for Age-Related Macular Degeneration

As a result of a better understanding of molecular mechanisms, a variety of new Pharmacologic treatments have recently been developed for patients with age-related macular degeneration (AMD). Efficacy and tolerability have been demonstrated for drugs targeting vascular endothelial growth factor (VEGF), a key player in the pathogenesis of choroidal neovascularization. Both pegaptanib (anti-VEGF aptamer) and ranibizumab (anti-VEGF antibody fragment), applied at 4- to 6-week intervals into the vitreous, modified the natural course of the disease in phase III clinical studies. Corticosteroids with anti-angiogenic properties also represent a treatment option for wet AMD. Both intravitreal triamcinolone and anecortave acetate, administered juxtasclerally, are currently being pursued.The combination of different treatment strategies and potential synergistic effects offers new perspectives. While photodynamic therapy (PDT) combined with intravitreal triamcinolone is already frequently applied, other combinations (e.g. anti-VEGF drugs with PDT or antifibrotic agents) appear to be attractive alternatives. Pigment epithelium-derived factor represents another potential target, as well as inhibitors of matrix-metalloproteinases. With the advent of gene therapy, the use of small interfering RNA (siRNA) is also on the horizon.Prophylactic measures are still limited. The combination of vitamins C and E, β-carotene, and zinc as used in the AREDS (Age-Related Eye Disease Study) reduces risk for conversion from early- to late-stage disease in patients with high-risk features, at least to some extent. Lutein and zeaxanthin dietary supplements for improvement of macular pigment density need to be investigated in future longitudinal trials.

VEGF-Production by CCR2-Dependent Macrophages Contributes to Laser-Induced Choroidal Neovascularization

Age-related macular degeneration (AMD) is the most prevalent cause of blindness in the elderly, and its exsudative subtype critically depends on local production of vascular endothelial growth factor A (VEGF). Mononuclear phagocytes, such as macrophages and microglia cells, can produce VEGF. Their precursors, for example monocytes, can be recruited to sites of inflammation by the chemokine receptor CCR2, and this has been proposed to be important in AMD. To investigate the role of macrophages and CCR2 in AMD, we studied intracellular VEGF content in a laser-induced murine model of choroidal neovascularisation. To this end, we established a technique to quantify the VEGF content in cell subsets from the laser-treated retina and choroid separately. 3 days after laser, macrophage numbers and their VEGF content were substantially elevated in the choroid. Macrophage accumulation was CCR2-dependent, indicating recruitment from the circulation. In the retina, microglia cells were the main VEGF+ phagocyte type. A greater proportion of microglia cells contained VEGF after laser, and this was CCR2-independent. On day 6, VEGF-expressing macrophage numbers had already declined, whereas numbers of VEGF+ microglia cells remained increased. Other sources of VEGF detectable by flow cytometry included in dendritic cells and endothelial cells in both retina and choroid, and Müller cells/astrocytes in the retina. However, their VEGF content was not increased after laser. When we analyzed flatmounts of laser-treated eyes, CCR2-deficient mice showed reduced neovascular areas after 2 weeks, but this difference was not evident 3 weeks after laser. In summary, CCR2-dependent influx of macrophages causes a transient VEGF increase in the choroid. However, macrophages augmented choroidal neovascularization only initially, presumably because VEGF production by CCR2-independent eye cells prevailed at later time points. These findings identify macrophages as a relevant source of VEGF in laser-induced choroidal neovascularization but suggest that the therapeutic efficacy of CCR2-inhibition might be limited.