Tuesday, May 03, 2011

CATT Update 15: Preliminary Two-Year Safety Data Presented at ARVO

Two of the  authors of the CATT Study, that was published in the NEJM last Thursday (see CATT Update 14: One-Year Study Results Show Equivalency Between Avastin and Lucentis), Drs. Dan Martin and Maureen McGovern, presented additional information about the study at the opening day ARVO Meeting, to about 2000 eager attendees. As reported by MedPageToday, their presentation included preliminary two-year safety data from the landmark CATT trial.

Major adverse events during the trial's second year appeared to be about equal, in contrast with the one-year results which suggested that ranibizumab (Lucentis) might be somewhat safer than off-label bevacizumab (Avastin) for patients with wet age-related macular degeneration (AMD).

Nevertheless, when study co-leaders Daniel Martin, MD, of the Cleveland Clinic, and Maureen Maguire, PhD, of the University of Pennsylvania, took the podium at ARVO on Sunday afternoon, they surprised attendees with some data not included in the NEJM paper -- a glimpse of safety results in patients completing the study's second year of treatment.

They showed that rates of death, stroke, and all arteriothrombotic events were equal between the two drugs during the trial's second year:

    * All-cause mortality: ranibizumab 2.8%, bevacizumab 2.9% (P=1.00)
    * Arteriothrombotic events: ranibizumab 2.2%, bevacizumab 1.7% (P=0.68)
    * Stroke: ranibizumab 1.2%, bevacizumab 1.2% (P=1.00)

These data did not distinguish between the two treatment regimens that were tested in the four-arm trial, which was sponsored by the National Eye Institute. Patients received one of the two drugs by intravitreal injection either on a fixed monthly schedule or "as needed," based on whether fluid buildup was detected in retinal imaging conducted monthly.

According to the data reported in NEJM, serious systemic adverse events in aggregate during the first year were significantly more common with bevacizumab with a risk ratio of 1.29, at a 95% confidence interval, 1.01 to 1.66. (When the dosing regimen groups were combined, the proportions of patients with serious systemic adverse effects were 24.1% for bevacizumab and 19.0% for ranibizumab.)

Efficacy data from the second year of the CATT (Comparison of AMD Treatment Trials) study were not reported at the ARVO session. Those data are expected to be released at a later meeting.

Top-line efficacy results from the one-year data indicated that the two drugs were nearly equal to each other and that as-needed dosing was effective but slightly less so than the fixed monthly schedule.

During their presentation, Martin and Maguire highlighted five issues still to be answered in the full two-year data. Those include whether:

    * Visual acuity findings will change during the second year
    * Anatomical differences (favoring ranibizumab after one year) are related to long-term visual outcomes
    * As-needed dosing remains effective past the first year of treatment
    * Spectral-domain optical coherence tomography for retinal imaging increases fluid detection rates and therefore the number of injections under as-needed dosing
    * Patient genotype affects outcomes or dosing requirements


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