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Posts Tagged ‘macular edema’


Treatments for macular degenaration

Larry H. Bernstein, MD, FCAP, Curator

LPBI

 

 

Eylea outperforms Avastin for diabetic macular edema with moderate or worse vision loss

NIH-funded clinical trial shows Eylea, Avastin, and Lucentis perform similarly when vision loss is mild.

http://www.nih.gov/news-events/news-releases/eylea-outperforms-avastin-diabetic-macular-edema-moderate-or-worse-vision-loss

image of a patient having an eye exam

A two-year clinical trial that compared three drugs for diabetic macular edema (DME) found that gains in vision were greater for participants receiving the drug Eylea (aflibercept) than for those receiving Avastin (bevacizumab), but only among participants starting treatment with 20/50 or worse vision.  Gains after two years were about the same for Eylea and Lucentis (ranibizumab), contrary to year-one results from the study, which showed Eylea with a clear advantage. The three drugs yielded similar gains in vision for patients with 20/32 or 20/40 vision at the start of treatment. The clinical trial was conducted by the Diabetic Retinopathy Clinical Research Network (DRCR.net), which is funded by the National Eye Institute, part of the National Institutes of Health.

“This rigorous trial confirms that Eylea, Avastin, and Lucentis are all effective treatments for diabetic macular edema,” said NEI Director Paul A. Sieving, M.D., Ph.D. “Eye care providers and patients can have confidence in all three drugs.”

Eylea, Avastin, and Lucentis are all widely used to treat DME, a consequence of diabetes that can cause blurring of central vision due to the leakage of fluid from abnormal blood vessels in the retina. The macula is the area of the retina used when looking straight ahead. The drugs are injected into the eye and work by inhibiting vascular endothelial growth factor (VEGF), a substance that can promote abnormal blood vessel growth and leakage. Although the drugs have a similar mode of action, they differ significantly in cost. Based on Medicare allowable charges, the per-injection costs of each drug at the doses used in this study were about $1850 for Eylea, about $60 for Avastin, and about $1200 for Lucentis.

DRCR.net investigators enrolled 660 people with DME at 89 clinical trial sites across the United States. When the study began, participants on average were 61 years old with 17 years of type 1 or type 2 diabetes. Only people with a visual acuity of 20/32 or worse were eligible to participate (to see clearly, a person with 20/32 vision would have to be 20 feet away from an object that a person with normal vision could see clearly at 32 feet). At enrollment, about half the participants had 20/32 to 20/40 vision. The other half had 20/50 or worse vision. In many states, a corrected visual acuity of 20/40 or better in at least one eye is required for a driver’s license that allows both day- and nighttime driving.

Each participant was assigned randomly to receive Eylea (2.0 milligrams/0.05 milliliter), Avastin (1.25 mg/0.05 mL), or Lucentis (0.3 mg/0.05 mL). Participants were evaluated monthly during the first year and every 4-16 weeks during the second year. Most participants received monthly injections during the first six months. Thereafter, participants received additional injections of assigned study drug until DME resolved or stabilized with no further vision improvement.  Subsequently, injections were resumed if DME worsened. Additionally, laser treatment was given if DME persisted without continual improvement after six months of injections. Laser treatment alone was the standard treatment for DME until widespread adoption of anti-VEGF drugs a few years ago.

Among participants with 20/40 or better vision at the trial’s start, all three drugs improved vision similarly on an eye chart. On average, participants’ vision improved from 20/40 vision to 20/25.

Among participants with 20/50 or worse vision at the trial’s start, visual acuity on average improved substantially in all three groups. At two years, Eylea participants were able to read about 3.5 additional lines on an eye chart; Lucentis participants were able to read about three additional lines, and Avastin participants improved about 2.5 lines, compared with visual acuity before treatment. Eylea outperformed Avastin at the one- and two-year time points. While Eylea outperformed Lucentis at the one-year time point, by the two-year time point gains in visual acuity were statistically no different. At the end of the trial, average visual acuity was 20/32 to 20/40 among participants in all three groups.

“The results of the DRCR Network’s comparison of Eylea, Avastin, and Lucentis will help doctors and their patients with diabetic macular edema choose the most appropriate therapy,” said John A. Wells, M.D., the lead author of the study and a retinal specialist at the Palmetto Retina Center, Columbia, South Carolina. “The study suggests there is little advantage of choosing Eylea or Lucentis over Avastin when a patient’s loss of visual acuity from macular edema is mild, meaning a visual acuity of 20/40 or better. However, patients with 20/50 or worse vision loss may benefit from Eylea, which over the course of the two-year study outperformed Lucentis and Avastin.”

The number of injections participants needed was about the same for all three treatment groups. Eylea, Avastin, and Lucentis participants on average required nine injections in the first year of the study and five in the second year.

The need for laser treatment varied among the three treatment groups. By two years, 41 percent of participants in the Eylea group received laser treatment to treat their macular edema, compared with 64 percent of participants in the Avastin group and 52 percent in the Lucentis group.

The risk of heart attack, stroke, or death from a cardiovascular condition or an unknown cause by end of the trial was higher among participants in the Lucentis group. Twelve percent of Lucentis participants had at least one event, compared with five percent of participants in the Eylea group and eight percent of participants in the Avastin group. This difference in cardiovascular rates has not been seen across all other studies, and therefore may be due to chance. Continued assessment of these serious cardiovascular events and their association with these drugs is important in future studies. Cardiovascular events such as heart attack and stroke are common complications of diabetes. The occurrence of eye complications, such as eye infections and inflammation, was similar for all three drugs.

Results of the study were published online today in Ophthalmology, the journal of the American Academy of Ophthalmology. Eylea and Lucentis were provided by drug manufacturers Regeneron and Genentech, respectively. Additional research funding for this study was provided by the National Institute of Diabetes and Digestive and Kidney Diseases, also a part of NIH.

“This important study would not have happened without funding from the National Institutes of Health and the cooperation of two competing companies,” said Adam R. Glassman, M.S., principal investigator of the DRCR.Net Coordinating Center at the Jaeb Center for Health Research.

The DRCR.net is dedicated to facilitating multicenter clinical research of diabetic eye disease. The Network formed in 2002 and comprises more than 350 physicians practicing at more than 140 clinical sites across the country. For more information, visit the DRCR.net website at http://drcrnet.jaeb.org/(link is external).

The study was funded by grants EY14231, EY14229, and EY18817.

The study is registered as NCT01627249 at ClinicalTrials.gov.

Macular edema can arise during any stage of diabetic retinopathy and is the most common cause of diabetes-related vision loss. About 7.7 million Americans have diabetic retinopathy. Of these, about 750,000 have DME. The NEI provides information about diabetic eye disease athttp://www.nei.nih.gov/health/diabetic. View an NEI video about how diabetic retinopathy can be detected through a comprehensive dilated eye exam at http://youtu.be/sQ-0RkPu35o(link is external).

NEI leads the federal government’s research on the visual system and eye diseases. NEI supports basic and clinical science programs that result in the development of sight-saving treatments. For more information, visit http://www.nei.nih.gov.

 

 

Vascular Endothelial Growth Factor (VEGF) and Its Role in Non-Endothelial Cells: Autocrine Signalling by VEGF

Angela M. Duffy, David J. Bouchier-Hayes, and Judith H. Harmey.     http://www.ncbi.nlm.nih.gov/books/NBK6482/

Vascular endothelial growth factor (VEGF) is a potent angiogenic factor and was first described as an essential growth factor for vascular endothelial cells. VEGF is up-regulated in many tumors and its contribution to tumor angiogenesis is well defined. In addition to endothelial cells, VEGF and VEGF receptors are expressed on numerous non-endothelial cells including tumor cells. This review examines the relevance of VEGF signalling in non-endothelial cells and explores the probable mechanisms involved.

Vascular endothelial growth factor (VEGF), also known as vascular permeability factor (VPF), was originally described as an endothelial cell-specific mitogen.1 VEGF is produced by many cell types including tumor cells,2,3 macrophages,4 platelets,5 keratinocytes,6 and renal mesangial cells.7 The activities of VEGF are not limited to the vascular system; VEGF plays a role in normal physiological functions such as bone formation,8 hematopoiesis,9wound healing,10 and development.11

Anti-VEGF strategies to treat cancers were designed to target the pro-angiogenic function of VEGF and thereby inhibit neovascularization. However, anti-VEGF therapies may have a dual effect since evidence is accumulating to support the existence of both paracrine and autocrine VEGF loops within tumors. It has been suggested that direct stimulation of tumor cells by VEGF may protect the cells from apoptosis and increase their resistance to conventional chemotherapy and radiotherapy.12 Chemotherapy and radiotherapy have been shown to increase VEGF within tumors,13 and this increased VEGF may in fact protect tumor cells from these interventions. Anti-VEGF therapies are therefore likely to target both the pro-angiogenic activity of VEGF and the anti-apoptotic/pro-survival functions of VEGF.

VEGF and the Central Nervous System (CNS)      

In the central nervous system (CNS) both positive (pro-migratory) and negative (anti-migratory) regulatory factors are essential for axonal guidance.17 Following prolonged exposure, Sema3A, a member of the semaphorin family, acts as an inhibitor of neuronal migration and induces neuronal cell death18 through the neuropilin-1 receptor (NP-1).19However, in addition to Sema3A binding, NP-1 also acts as an additional receptor for VEGF165 isoform.20 The relationship between Sema3A and VEGF was explored in Dev cells,21 undifferentiated cells derived from a cerebellar medullablastoma that behave as pluripotential neural progenitor cells.22 NP-1 mRNA expression was detected in Dev cells by RT-PCR and in situ hybridization. Western blotting and immunohistochemical analysis confirmed that NP-1 was expressed on the cell surface. VEGF165 or anti-NP-1 antibody blocked the effect of Sema3A on these cells, suggesting that VEGF165 binds competitively to NP-1 to block Sema3A signalling.

Dev cells also expressed VEGFR-1 and blockade of VEGFR-1 reduced the inhibition of neuronal cell migration by Sema3A.21 It appears that both NP-1 and VEGFR-1 are required for Sema3A activity in these neuronal cells. NP-1 binds with high affinity to VEGFR-1.24NP-1 has a very short intracellular domain and appears to require a coreceptor to transduce a signal20 thus, VEGFR-1 may serve as a coreceptor for NP-1 in the modulation of Sema3A signalling. Both VEGF121 and VEGF165 inhibited Sema3A-induced apoptosis, and at higher concentrations reduced apoptosis below basal levels indicating an additional neuroprotective effect.

VEGF is induced in many CNS pathologies where it may have a neuroprotective role. VEGF has a neurotrophic effect and enhances survival of Schwann cells,25 and protects hippocampal neurons from ischemic injury.26 Impaired VEGF induction in the spinal cord results in motor neuron degeneration.27 In addition, when cerebellar granule neurons (CGNs) were exposed to 5% hypoxia for 9 hours VEGF, VEGFR-1 and VEGFR-2 expression increased, and a neutralizing antibody to VEGF, DC 101, inhibited hypoxic preconditioning.28 Thus, VEGF autocrine or paracrine mechanisms appear to play a role in CGN cell survival following hypoxic preconditioning. In CGNs Akt (also known as Protein Kinase B/ PKB) was phosphorylated in response to VEGF and other studies have shown that VEGF stimulation in neurons is linked to PI3-K (Phosphatidylinositol 3′-kinase) and Akt activation and neuronal protection.29

VEGFA       http://www.uniprot.org/uniprot/P15692

Growth factor active in angiogenesis, vasculogenesis and endothelial cell growth. Induces endothelial cell proliferation, promotes cell migration, inhibits apoptosis and induces permeabilization of blood vessels. Binds to the FLT1/VEGFR1 and KDR/VEGFR2 receptors, heparan sulfate and heparin. NRP1/Neuropilin-1 binds isoforms VEGF-165 and VEGF-145. IsoformVEGF165B binds to KDR but does not activate downstream signaling pathways, does not activate angiogenesis and inhibits tumor growth.

GO:1902336 positive regulation of retinal ganglion cell axon guidance  

ID GO:1902336
Name positive regulation of retinal ganglion cell axon guidance
Ontology Biological Process
Definition Any process that activates or increases the frequency, rate or extent of retinal ganglion cell axon guidance.
PMID:21658587
GONUTS GO:1902336 Wiki Page
Acknowledgements This term was created by the GO Consortium

Synonym

up-regulation of retinal ganglion pathfinding

cell axon pathfinding

up regulation of retinal ganglion cell axon pathfinding

activation of retinal ganglion cell axon pathfinding

activation of retinal ganglion cell axon guidance

upregulation of retinal ganglion cell axon pathfinding

up regulation of retinal ganglion cell axon guidance

up-regulation of retinal ganglion cell axon guidance

upregulation of retinal ganglion cell axon guidance

positive regulation of retinal ganglion cell axon pathfinding

 

What Is Age-Related Macular Degeneration?       http://www.webmd.com/eye-health/macular-degeneration/age-related-macular-degeneration-overview
Macular degeneration is the leading cause of severe vision loss in people over age 60. It occurs when the small central portion of the retina, known as the macula, deteriorates. The retina is the light-sensing nerve tissue at the back of the eye. Because the disease develops as a person ages, it is often referred to as age-related macular degeneration (AMD). Although macular degeneration is almost never a totally blinding condition, it can be a source of significant visual disability.

There are two main types of age-related macular degeneration:

Dry form. The “dry” form of macular degeneration is characterized by the presence of yellow deposits, called drusen, in the macula. A few small drusen may not cause changes in vision; however, as they grow in size and increase in number, they may lead to a dimming or distortion of vision that people find most noticeable when they read. In more advanced stages of dry macular degeneration, there is also a thinning of the light-sensitive layer of cells in the macula leading to atrophy, or tissue death. In the atrophic form of dry macular degeneration, patients may have blind spots in the center of their vision. In the advanced stages, patients lose central vision.
Wet form. The “wet” form of macular degeneration is characterized by the growth of abnormal blood vessels from the choroid underneath the macula. This is called choroidal neovascularization. These blood vessels leak blood and fluid into the retina, causing distortion of vision that makes straight lines look wavy, as well as blind spots and loss of central vision. These abnormal blood vessels and their bleeding eventually form a scar, leading to permanent loss of central vision.
Most patients with macular degeneration have the dry form of the disease and can lose some form of central vision. However, the dry form of macular degeneration can lead to the wet form. Although only about 10% of people with macular degeneration develop the wet form, they make up the majority of those who experience serious vision loss from the disease.

 

 

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