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      Effects of topical and subconjunctival use of bevacizumab on corneal neovascularization in rabbits' eyes Translated title: Efeitos do uso tópico e subconjuntival do bevacizumabe na neovascularização corneana de olhos de coelhos

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          ABSTRACT Purpose: To evaluate and compare the effects of topical application and subconjunctival injection of bevacizumab on corneal neovascularization (CNV) in rabbits' eyes after chemical burning of the cornea. Methods: The animals were randomly distributed into four groups of five animals. In one group, the drug was instilled, while in another, it was administered by subconjunctival injection. The two procedures using bevacizumab were compared with instillation and subconjunctival injection of saline solution (S). Neovascularization was evaluated according to the size of the invasion area of new blood vessels and through computerized analysis of this area. The data were analyzed using the Kruskal-Wallis test followed by Dunn's test for two-by-two comparison of the groups, to assess the external examination of CNV. Analysis of variance was used to assess the area of CNV. P<0.05 was considered statistically significant. Results: Assessing both the external examination and the invasion area of neovessels on the 5th and 10th days, there was a clear difference between the groups. The group to which saline solution had been applied showed higher scores for CNV, as well as increases in the invasion area of neovessels. Two-by-two comparison of groups revealed no significant differences. However, an analysis of the factors involved (injection vs. instillation and bevacizumab vs. saline solution) showed that injection did not differ from instillation, but that bevacizumab differed from saline solution. Conclusion: Bevacizumab showed an inhibitory effect on CNV in rabbits' eyes after chemical burning of the cornea. There was no difference between the topical or subconjunctival administration of bevacizumab in the inhibition of CNV.

          Translated abstract

          RESUMO Objetivos: Avaliar e comparar o efeito do uso tópico e da injeção subconjuntival do bevacizumabe na neovascularização corneana de olhos de coelhos após queimadura química. Métodos: Os animais foram distribuídos de forma aleatória em quatro grupos de cinco animais. Em um grupo de coelhos a droga foi instilada, enquanto em outro foi aplicada injeção subconjuntival, sendo os dois procedimentos comparados com a instilação e injeção subconjuntival de soro fisiológico 0,9% (SF) e entre si. A neovascularização foi avaliada conforme o tamanho da área de invasão dos neovasos e com análise computadorizada da mesma. Na análise de dados aplicou-se o teste de Kruskal-Wallis seguido do teste de Dunn com p<0,05 para comparação dos grupos dois a dois na análise do exame externo da neovascularização corneana. Na análise da área de neovascularização corneana, aplicou-se o teste F de análise de variância. A significância estatística foi definida como valor de p<0.05. Resultados: A avaliação do exame externo e da área de invasão de neovasos, no 5º e 10º dia, mostrou nítida diferença entre os grupos. Com o uso de soro fisiológico houve maior graduação na escala de neovascularização corneana e também na área de invasão dos nevasos, o que demonstrou o efeito inibitório do bevacizumabe. Nas comparações dos grupos dois a dois não foram detectadas diferenças significativas, porém, ao analisar os fatores envolvidos (procedimentos: injeção ou instilação, e as drogas: bevacizumabe ou soro fisiológico), verificou-se que a injeção não diferiu da instilação, mas o bevacizumabe diferiu do soro fisiológico. Conclusão: O bevacizumabe apresentou efeito inibitório na neovascularização corneana de olhos de coelhos após queimadura química, tanto por via tópica como por via subconjuntival e não houve diferença entre a via tópica e a via subconjuntival de administração do bevacizumabe na inibição da neovascularização corneana.

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          Most cited references 30

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          Systemic bevacizumab (Avastin) therapy for neovascular age-related macular degeneration twelve-week results of an uncontrolled open-label clinical study.

          To evaluate the short-term safety of systemic bevacizumab (Avastin, Genentech, Inc., South San Francisco, CA) and its effects on visual acuity (VA) and subfoveal choroidal neovascularization (CNV) in patients with neovascular age-related macular degeneration (AMD). Open-label, single-center, uncontrolled clinical study. Age-related macular degeneration patients with subfoveal CNV (N = 9) and best-corrected VA letter scores of 70 to 20 (approximate Snellen equivalent, 20/40-20/400). Patients were treated at baseline with an infusion of bevacizumab (5 mg/kg), followed by 1 or 2 additional doses given at 2-week intervals. Safety assessments were performed at all visits. Ophthalmologic evaluations included protocol VA measurements and ocular examinations, along with optical coherence tomography (OCT) imaging, fluorescein angiography, and indocyanine green angiography. Safety assessments were performed, along with assessments of changes from baseline in VA scores, OCT measurements, and angiographic lesion characteristics. There were no serious ocular or systemic adverse events identified. By 6 weeks, the only adverse event identified was a mild elevation of systolic blood pressure (BP) (+12 mmHg; P = 0.035), and this elevation was controlled by either changing or initiating antihypertensive medication. By 12 weeks, the elevation of systolic BP was no longer significant (P = 0.51). In the study eyes, significant increases in VA were evident within 1 week of treatment, and by 12 weeks, the median and mean VA letter scores increased by 8 letters (P = 0.011) and 12 letters (P = 0.008), respectively. The median and mean central retinal thickness measurements decreased by 157 microm (P = 0.008) and 177 microm (P = 0.001), respectively. In the fellow eyes at 12 weeks, the median and mean VA letter scores increased by 27 letters (P = 0.018) and 16 letters (P = 0.012), and the median and mean central retinal thickness measurements decreased by 59 mum (P = 0.028) and 92 microm (P = 0.06). In all study eyes, angiography revealed a marked reduction or an absence of leakage from CNV. Overall, bevacizumab therapy was well tolerated, with an improvement in VA, OCT, and angiographic outcomes. Although these preliminary results are promising, a randomized controlled clinical trial is necessary before concluding that systemic bevacizumab therapy is safe and effective for patients with neovascular AMD.
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            Role of vascular endothelial growth factor in physiologic and pathologic angiogenesis: therapeutic implications.

            Angiogenesis, or formation of new blood vessels from pre-existing ones, is essential for normal development and wound healing/reproductive functions in adults. Abnormal regulation of angiogenesis has been implicated in the pathogenesis of several disorders, including cancer. Vascular endothelial growth factor (VEGF)-A is a pivotal stimulator of angiogenesis because its binding to VEGF receptors has been shown to promote endothelial cell migration and proliferation, two key features required for the development of new blood vessels. In addition, VEGF-A increases vascular permeability, which may also contribute to angiogenesis and tumor growth. Recognition of the central role of VEGF-A in angiogenesis has led to the hypothesis that its inhibition may represent a novel and effective approach to the treatment of cancer and other conditions characterized by pathologic angiogenesis. Several lines of evidence support this idea, and early clinical experience with the humanized anti-VEGF-A monoclonal antibody bevacizumab (Avastin, rhuMAb-VEGF; Genentech, South San Francisco, CA) has been encouraging. Clinical efficacy of antiangiogenic therapy with bevacizumab is being evaluated in several phase 3 trials in various types of cancer, as well as in patients with age-related macular degeneration. Copyright 2002, Elsevier Science (USA). All rights reserved.
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              Inhibition of platelet-derived growth factor B signaling enhances the efficacy of anti-vascular endothelial growth factor therapy in multiple models of ocular neovascularization.

              'Vascular endothelial growth factor-A (VEGF-A) blockade has been recently validated as an effective strategy for the inhibition of new blood vessel growth in cancer and ocular pathologies. However, several studies have also shown that anti-VEGF therapy may not be as effective in the treatment of established unwanted blood vessels, suggesting they may become less dependent on VEGF-A for survival. The VEGF-A dependence of vessels may be related to the presence of vascular mural cells (pericytes or smooth muscle cells). Mural cell recruitment to the growing endothelial tube is regulated by platelet-derived growth factor-B (PDGF-B) signaling, and interference with this pathway causes disruption of endothelial cell-mural cell interactions and loss of mural cells. We have investigated the basis of blood vessel dependence on VEGF-A in models of corneal and choroidal neovascularization using a combination of reagents (an anti-VEGF aptamer and an anti-PDGFR-beta antibody) to inhibit both the VEGF-A and PDGF-B signaling pathways. We demonstrate that neovessels become refractory to VEGF-A deprivation over time. We also show that inhibition of both VEGF-A and PDGF-B signaling is more effective than blocking VEGF-A alone at causing vessel regression in multiple models of neovascular growth. These findings provide insight into blood vessel growth factor dependency and validate a combination therapy strategy for enhancing the current treatments for ocular angiogenic disease.

                Author and article information

                Role: ND
                Role: ND
                Role: ND
                Role: ND
                Arquivos Brasileiros de Oftalmologia
                Arq. Bras. Oftalmol.
                Conselho Brasileiro de Oftalmologia (São Paulo, SP, Brazil )
                August 2017
                : 80
                : 4
                : 252-256
                Londrina Paraná orgnameUniversidade Estadual de Londrina orgdiv1Department of Statistics Brazil
                Londrina Paraná orgnameUniversidade Estadual de Londrina orgdiv1Department of Clinical Surgery Brazil

                This work is licensed under a Creative Commons Attribution 4.0 International License.

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