CATT STUDY IN PRACTICE

While the Comparison of AMD Treatment Trial (CATT Study) results reassured some clinicians of the non-inferiority of bevacizumab (Avastin) compared to ranibizumab (Lucentis) in the treatment of exudative age-related macular degeneration (AMD), the study also provided important insights into other aspects relating to the clinical management of the disease, according to a presentation here.

“Although the most important finding of the CATT study was proving that bevacizumab is as effective as ranibizumab in preserving and improving visual acuity in wet AMD, the study also gave important pointers for dosing schedule and follow-up,†Gabriel Goscas MD told delegates attending the World Ophthalmology Congress. “There is a consensus now for a monthly follow-up that looks at systemic as well as ophthalmic factors. Furthermore, each intravitreal treatment decision must be based on the performed examination and we also know now that an induction phase is not necessary,†he said. Dr Coscas, Emeritus Professor and chairman of ophthalmology at the University of Paris XII, France, said that the CATT study merited its designation as a landmark clinical trial. “It was presented at all the major meetings and the results were widely disseminated to all the media. The significance of the trial lies in the fact that this was the first study organised for the comparison of two major drugs and was sponsored by ophthalmologists and research institutes in the United States rather than the pharmaceutical industry,†he said.

Differences in cost

The cost implications of the CATT trial also loom large in any evaluation of the study’s impact, said Dr Coscas, bearing in mind that Lucentis is about 40 times more expensive than Avastin and reimbursement rules differ from country to country. “We are all aware of the differences in costs for the wider community between the two drugs,†he said. This is where randomised clinical trials such as the CATT study can really play an important role in influencing public health policy, said Dr Coscas. “We must make our opinions known to the health authorities and we must enable them to guide their decisions on a medical basis. As ophthalmologists, comparative studies of efficacy and safety are essential. With the growing body of data from all phase one, two and three clinical trials, the health authorities will be in a better position to make a decision based on the scientific evidence rather than just price and according to the rules of the different countries,†he said. Dr Coscas noted that ranibizumab has a robust safety and efficacy profile for ophthalmic use based on randomised clinical trials such as the MARINA and ANCHOR trials. Bevacizumab, by contrast, has been widely used off-label for ophthalmic use, but prior to CATT had no clinical trial data to support its use as a potential AMD treatment. In terms of optimal dosing strategies, Dr Coscas said that attempts to treat less than monthly have been shown to be inferior to monthly treatments in the PEER, EXCITE and SUSTAIN trials, but there remains a strong interest in reducing the frequency of injections and controls for follow-up.

Caution needed

Turning to the safety data, Dr Coscas said that no statistically significant differences in ocular and systemic safety were found between the two drugs in the CATT trial. Nevertheless, he said that longer follow-up was needed to know more about possible systemic side effects of Avastin, and he advised particular caution in treating patients with myocardial infarction, cardiovascular disease and gastrointestinal haemorrhages. Dr Coscas said that the CATT study also revealed some surprises. Firstly, the absence of an induction phase in the Avastin patients treated on an as-needed basis did not worsen the group results. Furthermore, ranibizumab seemed to be more efficient in drying and thinning retinas without impacting on the final visual acuity results. Summing up, Dr Coscas said that it will be interesting to see if the second-year data confirms the initial results of the CATT trial and perhaps answers some other key questions relating to anti-VEGF therapies.