Avastin versus Lucentis

A recent study from Bashshur and colleagues reported on 60 patients who were treated with Avastin® and then followed for one year. They gave their AMD patients one injection of Avastin 2.5 mg and then followed them monthly with OCTs. The injections were repeated every month until the macula was dry on OCT. If the OCT was dry, the authors didn’t give an injection but asked the patient to return in one month. The treatment paradigm was similar to the PrONTO study except in PrONTO, Lucentis® .5mg was used instead of Avastin and the patient first received three monthly injections followed by additional injections as needed. The other difference was that Bashshur and colleagues would not reinject if the eye showed persistent subretinal or intraretinal fluid after three injections. They believe that these eyes often remain stable. Therefore they would follow them and only reinject if they worsened. In the PrONTO study, any fluid on OCT was an indication for another injection.

I could criticize the paper because there were only 60 patients and nine of them were lost to follow-up. Still it struck me how similar these results were using Avastin to the results of the PrONTO study, (also a small study), which used Lucentis. The authors used 2.5mg of Avastin which is twice the 1.25mg dose usually used successfully in the US. The higher dose may be the reason however that most of their patients had a dry macula one month after the first injection. In my experience, 1.25mg of Avastin often doesn’t result in a dry macula at one month so maybe the higher dose is useful at least for the first dose.

The Comparison of AMD Treatment Trials (CATT) is starting and will be the definitive study comparing Avastin to Lucentis for the treatment of wet AMD. The results of Bashshur and colleagues however predict that at most, we’ll find only a modest difference between the two drugs.

References:

1. Bashshur, ZF AJO 2008;145:249-256.

2. Lalwani GA, Fung AE, Michels S, Dubovy SR, Feuer WJ Jr, Puliafito CA, Rosenfeld PJ. An OCT-Guided Variable-Dosing Regimen With Ranibizumab (Lucentis) in Neovascular AMD: Two Year Results of the PrONTO Study (Poster Session 247. 1834/B694) ARVO Annual Meeting: The Aging Eye. May 6-10 2007, Fort Lauderdale, FL. Available at http://tinyurl.com/yt5fwd. (you will need to enter "Pronto" in the search field and restrict it to "presentation title").

Cataract Surgery and AMD

In the Oct 31, 2005 blog, I stated that results from the Age-Related Eye Disease Study (AREDS) indicated that cataract surgery did not influence the course of AMD. Despite this report, there have been other smaller studies showing a possible link between cataract surgery and worsening of AMD. Specifically there was a concern that cataract surgery may hasten the onset of the wet form of AMD. The problem with all of the articles that showed a link is that the maculae of patients who had cataract surgery were not carefully examined prior to the surgery. Therefore these patients may already have had AMD, even subtle wet AMD, when they went to the doctor and complained about visual loss. The doctor thought the vision loss was due to the cataract and removed it only to find wet AMD that became obvious a few months later.

A recent article from Germany followed 696 patients who had early AMD for at least one year after cataract surgery. They compared that group to 202 patients with early AMD who didn’t have cataract surgery. After one year, wet AMD developed in 2.43% of the group who had cataract surgery and in 1.74% of the group who did not. There was no significant difference between the groups. There was a statistical difference in the visual acuity however. The group that had cataract surgery had better acuity on average than the group that did not, probably because there was no longer a cataract causing any vision loss.

This is a good article. When coupled with the AREDS results, I think it means that it’s safe for anyone with AMD to have cataract surgery when necessary. The surgery should not be delayed for fear of increasing the risk of wet AMD or vision loss.

Baatz H, Darawsha R, Ackermann H, Scharioth GB, de Ortueta D, Pavlidis M,
Hattenbach LO. Phacoemulsification does not induce neovascular age-related macular degeneration. Invest Ophthalmol Vis Sci. 2008 Mar;49(3):1079-83.

Intravitreal Injections at The University of Iowa

I thought it was time to update our “numbers” from the Department of Ophthalmology. The tables show the total number of injections performed at our main clinic. The decrease in numbers for November and December are mainly due to bad weather and some older patients going south for the winter. Our retinal doctors are using more Avastin® than Lucentis®. The main reason is that Avastin seems to last longer, six weeks or more, compared to four weeks for Lucentis. Therefore a person will need to come back less often for an injection. I believe however that Lucentis works a little faster. Most people who have had an injection of Lucentis have little or no remaining fluid beneath or within their retina at one month whereas it may take six or even eight weeks for those who have received Avastin to become “dry” on the OCT. The difference may be due to the greater VEGF binding affinity of Lucentis compared to Avastin. I could envision a scheme therefore of first giving Lucentis to dry out the retina quickly and then following this first dose with Avastin to reduce the number of total injections.

I don’t know this for sure however. We will know what to do once the Comparisons of AMD Treatment Trials, (CATT), is completed since it will compare Avastin and Lucentis head to head.