The CATT (Comparison of Age-Related Macular Degeneration Treatments Trials) established non-inferiority of bevacizumab compared to ranibizumab for neovascular AMD. The key molecular difference between these agents is:
- A Ranibizumab is a full-length IgG1 monoclonal antibody; bevacizumab is a Fab fragment
- B Both are identical Fab fragments differing only in glycosylation
- C Bevacizumab is a full-length IgG1 antibody; ranibizumab is a humanized Fab fragment without the Fc region ✓
- D Ranibizumab binds all VEGF isoforms; bevacizumab binds only VEGF-A165
Explanation
Bevacizumab (Avastin) is a full-length humanized IgG1 monoclonal antibody containing both Fab and Fc regions; it was originally developed for colorectal cancer. Ranibizumab (Lucentis) is a recombinant humanized Fab fragment derived from the same parent antibody — it lacks the Fc region, giving it a smaller molecular weight (~48 kDa vs. ~149 kDa), which theoretically enhances intraocular penetration and reduces systemic VEGF suppression. The CATT trial showed that 2-year visual outcomes were clinically equivalent between these agents, with bevacizumab being significantly less expensive, which has major pharmacoeconomic implications.
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.