CD11b + Monocytes and Anti-VEGF Injections in Wet AMD and PCV
Anti-vascular endothelial growth factor (Anti-VEGF) eye injection drugs are the most common and effective treatments for the wet form of age-related macular degeneration (AMD)1, as well as for polypoidal choroidal vasculopathy (PCV).2
What is macular degeneration?
Macular degeneration is the leading cause of vision loss in the U.S. It occurs when certain cells in the portion of the eye called the macula begin to deteriorate. The macula is the central portion of the retina, which is light-sensing tissue in the back of the eye. Because the macula is at the center of the retina, when it fails the result is a loss of sight in the center of the visual field, while the peripheral vision usually remains unaffected.
Types of macular degeneration
There are two types of age-related macular degeneration - dry and wet. Wet or neovascular AMD is less common (10-20% of cases), but is considered to be more advanced.5,6 Wet AMD occurs when abnormal blood vessels grow underneath the retina. These vessels tend to leak fluid or bleed, causing damage and distortion of the macula resulting in vision loss.7 The growth of these new blood vessels is known as Choroidal Neovascularization (CNV).
What is polypoidal choroidal vasculopathy?
Polypoidal Choroidal Vasculopathy (PCV) is form of macular degeneration with some controversy over whether it is a subtype of wet AMD or a separate clinical entity. Like wet AMD, genetic testing indicates that it is a type of choroidal neovascularization. Both have the telltale growth of abnormal new blood vessels and loss of vision from bleeding, leaking, and scar tissue accumulation. PCV is distinctive in that it can present unilaterally (in just one eye) and that it presents with what appears to be a different type of vascular network. PCV also tends to impact different populations to lesser and greater degrees.8
CD11b + monocytes and anti-VEGF injections
New research finds that the proportion of CD11b + monocytes present in the eyes of patients correlated with and predicted the number of anti-VEGF injections needed to treat these conditions. Not only does this research point to improved insight into long-term patient treatment needs, but also indicates that targeting these monocytes could potentially lead to new effective treatments.3,4
However, though there are distinct differences between wet AMD and PCV, the correlation between the CD11b + monocyte counts and the future number of necessary anti-VEGF injections was consistent across both conditions.
What are CD11b + monocytes?
The CD11b + monocyte is a type of white blood cell found to be increased in patients with wet AMD and PCV, and is implicated in the formation of the conditions. In this study, pre-treatment measurements of the number of cells positively estimated the number of injections that would be necessary for continued treatment based on patient symptoms at 12, 24, and 36 months.
Pretty amazingly, part of the analysis showed that at the far out 36 month point CD11b + levels could correctly classify the patients needing less than or more than 12 injections 100% of the time. In addition, the correlation held regardless of which anti-VEGF medication (ranibizumab or aflibercept) the patients took.3,4
The researchers conclude with proposing that CD11b + levels may help with disease prognosis and give patients a better idea of what the long-term treatment regimen might look like. In addition, they believe that the correlation found here indicates that focusing on CD11b + monocytes may lead to new therapies for CNV-dominated diseases. They acknowledge, however, that additional longitudinal studies are necessary to determine the clinical relevance of the findings.
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