CATT at 2 Years: The Facts

Charles C. Wykoff, MD, PhD; David M. Brown, MD


August 13, 2012

In This Article

Bevacizumab vs Ranibizumab in CATT

At the CATT 2-year endpoint, differences in visual acuity outcomes between the 2 drugs when given monthly or as needed were not statistically significant. In comparison, many of the secondary anatomic outcomes suggested that bevacizumab is biologically inferior to ranibizumab. For example, the proportion of patients who were completely dry as measured by optical coherence tomography (OCT) was 13.9% with as-needed bevacizumab vs 30.2% with monthly bevacizumab, and 22.3% with as-needed ranibizumab vs 45.5% with monthly ranibizumab (P < .001). Similarly, inhibition of CNV lesion growth differed significantly between the 2 monthly treatment groups, with a mean change of -0.4 mm2 CNV in patients receiving ranibizumab and +1.6 mm2 CNV in patients receiving bevacizumab (P <.01).

Finally, when both drugs were used as-needed with the same retreatment criteria, bevacizumab increased the treatment burden. Patients receiving as-needed bevacizumab required a mean of 14.1 injections vs 12.6 with as-needed ranibizumab (P = .01).

Another interesting finding in the 2-year data involved the presence of geographic atrophy. Geographic atrophy was not mentioned in the primary endpoint analysis at 1 year, nor was assessment of geographic atrophy described in the methodology of the CATT study.[16] Nevertheless, geographic atrophy was found to be greater in the groups that received monthly treatment (19% with bevacizumab and 30% with ranibizumab) than in the as-needed treatment groups (14% with bevacizumab and 16% with ranibizumab; P = .007 for dosing regimen differences and P = .13 for drug differences). The significance of this imbalance is unknown. Because this finding represents the prevalence of geographic atrophy at 2 years and not necessarily a difference in progression of geographic atrophy, it may reflect a baseline imbalance. It is also difficult to accurately assess geographic atrophy on color photographs in the presence of retinal edema. Because the reported prevalence of geographic atrophy correlates inversely with the ability of the drug and dosing regimens to eliminate retinal fluid, the reported findings on geographic atrophy may be an artifact secondary to confounding retinal edema.

IVAN: 1-Year Interim Data

The IVAN trial is a United Kingdom-based study involving 610 patients comparing bevacizumab with ranibizumab, given either monthly or as needed.[17] All patients received 3 initial monthly treatments instead of the single initial treatment used in CATT, and the as-needed regimen required 3 treatments if active disease was detected.

The primary efficacy and safety endpoints are to be assessed at 2 years, but at the 1-year interim data analysis, the visual acuity efficacy endpoint was inconclusive because bevacizumab did not meet the prespecified noninferiority criterion of 3.5 letters, and the mean difference in visual acuity at 1 year was 2.9 letters better with ranibizumab than with bevacizumab (P = .056). In comparison, monthly treatment was equivalent to as-needed treatment.

Of 10 secondary outcomes reported in IVAN, 5 revealed statistically significant results in comparing drugs and regimens. Bevacizumab treatment led to lower serum VEGF concentrations (P = .0044) compared with ranibizumab treatment. Monthly treatment led to less fluorescein leakage (P = .0017), smaller lesion size (P = 0.014), less fluid on OCT (P < .001), and thinner foveal thickness on OCT (P = .0048). According to investigators, these statistically significant secondary outcome differences are "unlikely to be clinically meaningful."[17]


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