By Adrian Galbreth
After all the furore surrounding the use of two new eye drugs for the treatment of age-related macular degeneration (AMD), a new study has revealed that they are equally effective.
There has recently been much debate about the use of the drug Avastin by health experts in the NHS instead of Lucentis as, even though the latter drug is more costly, it was claimed to be more effective.
However, that theory has been disproved in a two-year study, the results of which have been published in the journal Ophthalmology after first being reported in the New England Journal of Medicine.
Of the two drugs, Avastin is currently most frequently used to treat AMD but, prior to the two-year Comparison of AMD Treatments Trials (CATT), the medications had never been compared head-to-head.
Lucentis was approved by the U.S. Food and Drug Administration (FDA) in 2006 for the treatment of AMD while Avastin, which is very similar to Lucentis, is not approved by the FDA for this purpose, although has clearance for other indications.
Avastin and Lucentis block growth of abnormal blood vessels and leakage of fluid from the vessels and most eye experts use them on an as-needed basis when there is evidence of active disease, such as fluid leakage.
CATT was designed to compare Avastin and Lucentis with monthly and as-needed treatment schedules, with the start of the study seeing that each patient were assigned to four treatment groups defined by drug (Avastin or Lucentis) and dosing regimen (monthly or as-needed).
After one year, patients initially assigned to monthly treatment were randomly reassigned to monthly or as-needed treatment without changing their drug assignment, while after two years visual acuity with monthly treatment was slightly better than with as-needed dosing, regardless of the drug.
When measured against an eye chart, monthly treatment resulted in a mean improvement of about half a line better than as-needed dosing, while switching to as-needed treatment after one year of monthly treatment yielded outcomes nearly equal to those obtained with as-needed treatment for the full two years.
Changes in retinal anatomy differed by drug and frequency of treatment, but did not have an impact on vision through two years, explained Dr Daniel Martin, study chair for CATT and chairman of the Cole Eye Institute at the Cleveland Clinic.
"Both drugs were highly effective regardless of the approach to dosing. There was slightly less vision gain with as-needed treatment. Patients seeking the small extra advantage of monthly treatment need to be mindful of the additional burden, risks, and costs of monthly injections," he explained.
"Since as-needed dosing required ten fewer eye injections over the course of two years and yielded similar visual results, many patients may choose this option."
Dr Maureen Maguire, principal investigator at the CATT Coordinating Center at the University of Pennsylvania, explained that the median age of patients in CATT was over 80 years, and a high rate of hospitalisations would be anticipated as a result of chronic or acute medical conditions more common to older populations.
She noted that serious adverse events occurred in 40 per cent of patients receiving Avastin and a 32 per cent rate for patients receiving Lucentis.
However, Avastin's adverse events were distributed across many different conditions, most of which were not associated with Avastin when evaluated in cancer clinical trials, in which the drug was administered at 500 times the dose used for AMD.
Dr Maguire said that fewer doses were associated with a higher rate of serious adverse events, which is not a typical dose-response relationship, while the number of deaths, heart attacks and strokes were low and similar for both drugs during the study.
"The dramatic and lasting improvement in vision with these two drugs is extraordinary. At two years, two-thirds of patients had driving vision (20/40 vision or better). With previous treatments, only 15 per cent of patients retained similar visual acuity," she concluded.
by Emily Tait