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Monthly dosing slightly edges out as-needed protocol, 2-year CATT results find
FORT LAUDERDALE, Fla. — Monthly dosing with either bevacizumab or ranibizumab yielded slightly better visual acuity than as-needed dosing, with a 2.4 letter difference, a speaker said here regarding the 2-year results of the CATT.
The Comparison of Age-Related Macular Degeneration Treatment Trials (CATT) is no longer a non-inferiority trial, Daniel F. Martin, MD, said at the Association for Research in Vision and Ophthalmology meeting; rather, the 2-year results are intended to evaluate outcomes.
A total of 1,107 patients with neovascular age-related macular degeneration completed the second year of the trial. The patients who were initially given monthly treatment, with either Avastin (bevacizumab, Genentech) or Lucentis (ranibizumab, Genentech), were randomized to monthly treatment or as-needed treatment.
For the most part, at year 1, there was no statistically significant difference between bevacizumab and ranibizumab, with a point estimate of –1.4 letters, Dr. Martin said. However, at 2 years, comparing monthly and as-needed dosing, there was a 2.4 letter difference in favor of monthly dosing.
“For the first time, this is statistically significant,” Dr. Martin said, although he stressed that the magnitude of the difference is small.
“Previous conditioning with monthly treatments didn’t make a difference,” he said, later adding, “The take-home message is, if you’re going to treat with monthly treatment, for the small difference, the 2.4-letter difference, you can’t stop.”
In another finding at 2 years, the proportion of patients whose neovascular AMD was completely dry after monthly therapy with ranibizumab was greater than those on bevacizumab.
“A lot has been made out of this, and I want to emphasize that the differences we’re talking about are very small,” Dr. Martin said.
Furthermore, the proportion of patients with new geographic atrophy is greater in those on monthly doses of ranibizumab, he said. Again, the differences are slight, and their meaningfulness is still in question.
- Disclosure: Dr. Martin has no relevant financial disclosures.
Perspective
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The take-home messages of this study are that bevacizumab and ranibizumab are similar in improving visual acuity when given monthly. Monthly dosing with either medication resulted in slightly better vision than PRN dosing (2.2 to 3.9 letters), and this visual acuity benefit with monthly dosing is lost if the patient reverts back to PRN dosing. Ranibizumab seems more efficacious at resolving fluid on OCT. A greater number of patients receiving ranubizumab had geographic atrophy after 2 years of treatment, which may reflect an increased risk of outer retinal degeneration, or may be a secondary finding due to the greater amount of resolution of fluid and the “uncovering” of geographic atrophy in that group that may not be seen due to higher amounts of fluid in the bevacizumab group. It still is unclear why patients receiving bevacizumab had a higher rate of adverse events, as the discrepancy in adverse events were mostly in organ systems that are not thought to be affected by anti-VEGF medications (eg, the gastrointestinal system). This increased risk may be due to chance, an imbalance between enrolled groups, or may represent a true increased risk.
As a practitioner, it still remains unclear which medication and what regimen to choose for our patients. Ranibizumab is better at resolving fluid on OCT, and may result in slightly fewer adverse events in organ systems like the GI system. However, it is much more costly than bevacizumab, which results in similar visual acuity results when given monthly. PRN dosing with either medication resulted in slightly worse visual acuity than monthly dosing (two to four letters), and patients and practitioners should be aware that this type of regimen may not be quite as efficacious as monthly injections. At Wills Eye Institute and many other practices around the country, however, we use “treat-and-extend” as our primary treatment regimen, as we believe that this does not allow for the re-accumulation of fluid on OCT like the PRN regimen does, and may lead to better visual acuity results than the PRN regimen did in the CATT study. However, further study regarding alternative treatment regimens still is needed to elucidate whether these regimens can be as effective as monthly injections.