Two drugs commonly used to treat age-related macular degeneration (AMD) yield similar improvements in vision for patients receiving treatments on a monthly or as-needed basis, according to a study from researchers at the Center for Preventive Ophthalmology and Biostatistics (CPOB) at the Perelman School of Medicine at the University of Pennsylvania. The year-two results of the Comparison of AMD Treatment Trials (CATT) support the findings from the first year of the study that evaluated the effects of Avastin ® (bevacizumab) — the off-label drug most frequently used to treat AMD — and Lucentis® (ranibizumab), a drug approved by the FDA in 2006 for the treatment of AMD. Full long-term results of the CATT, a two-year clinical trial, are published in the current issue of Ophthalmology.
"Regardless of which drug is used, treating AMD requires repeated treatment to prevent loss of vision. These year-two results show that long-term treatment with either Avastin or Lucentis results in similar levels of improvement for these patients suffering from AMD," said Maureen Maguire, PhD, corresponding author on the study and director, CPOB. "We knew these options were available and the drugs were effective in the short-term, but what's become more clear is that the differences between the two drugs over a longer period of time are still almost non-existent — the impact on vision is virtually the same, no matter which drug is used."
Improvement in visual clarity served as the primary outcome measure for the year-two results. AMD is the leading cause of vision loss and blindness in older Americans. In its advanced stages, the wet form of AMD spurs the growth of abnormal blood vessels, which leak fluid and blood into the macula — the central portion of the retina that allows us to look straight ahead and to perceive fine visual detail - and obscure vision. Accumulation of fluid and blood damages the macula causing loss of central vision. Without treatment, most patients with AMD are unable to drive, read, recognize faces or perform tasks that require hand-eye coordination.
Avastin — a drug approved for the treatment of some cancers but not AMD — and Lucentis block growth of abnormal blood vessels and leakage of fluid from the vessels. CATT was originally designed to compare the effectiveness of Avastin and Lucentis as a treatment for AMD. However, in the initial studies for AMD, Lucentis was administered monthly. For the year-two study, researchers focused on determining whether "as-needed" dosing would produce the same long-term visual improvements.
At enrollment, patients were assigned to one of four treatment groups defined by drug (Avastin or Lucentis) and dosing regimen (monthly or as-needed). Patients in the monthly dosing groups received a treatment injection every 28 days. Patients in the as-needed groups received a treatment at baseline and were then examined every 28 days to determine medical need for additional treatment. The original CATT study followed 1185 patients treated at 43 clinical centers in the United States. During year two, researchers examined the continued effects seen in 1107 patients.
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