All are Anti – VEGF EXCEPT:
**Question:** All are Anti - VEGF EXCEPT:
A. Bevacizumab (Avastin)
B. Ranibizumab (Lucentis)
C. Aflibercept (Eylea)
D. Pegaptanib (Macugen)
**Core Concept:**
Anti-VEGF agents are a class of medications that target vascular endothelial growth factor (VEGF), a protein involved in the process of angiogenesis and vascular permeability. Angiogenesis is the formation of new blood vessels, which can be beneficial in cases like stimulating tissue healing, but detrimental in conditions like wet age-related macular degeneration (AMD) and diabetic macular edema (DME) where uncontrolled angiogenesis leads to leakage and vision loss.
**Why the Correct Answer is Right:**
Option D, Pegaptanib, is NOT an anti-VEGF agent because it is a monoclonal antibody fragment targeting only VEGF-A, a specific isoform of VEGF, whereas the other options are full monoclonal antibodies targeting multiple VEGF isoforms. This difference in specificity results in different clinical applications.
**Why Each Wrong Option is Incorrect:**
A. Bevacizumab (Avastin) and B. Ranibizumab (Lucentis) are correct because they are full monoclonal antibodies targeting all VEGF isoforms. This broader spectrum of action makes them more effective for various retinal disorders like wet AMD and DME.
C. Aflibercept (Eylea) is correct because it is a full monoclonal antibody fusion protein that binds to and neutralizes all VEGF isoforms and placental growth factor (PlGF), which further enhances its efficacy in treating retinal disorders.
**Clinical Pearl:**
The key to understanding anti-VEGF agents lies in understanding the difference between monoclonal antibody fragments and fusion proteins when targeting multiple VEGF isoforms. Pegaptanib is a monoclonal antibody fragment targeting a specific isoform (VEGF-A), while bevacizumab and ranibizumab are full monoclonal antibodies targeting multiple VEGF isoforms, and aflibercept is a fusion protein combining VEGF-Trap and Fc region of human IgG1, which neutralizes all VEGF isoforms and PlGF, making it more effective in treating retinal disorders.