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Diabetic Macular Edema Improves with New Treatment

Posted: Sunday, May 09, 2010

Patients with diabetic macular edema saw more improvement when intravitreal ranibizumab (Lucentis) was added to photocoagulation laser treatment than with laser alone, according to results of a National Eye Institute-sponsored study.

The angiogenesis inhibitor restored at least 10 letters of visual acuity in 50% of patients when the drug was followed quickly by photocoagulation and in 47% when photocoagulation was delayed, compared with 28% of patients who had laser treatment alone (P<0.001 for both) in the Diabetic Retinopathy Clinical Research Network study.

Neil M. Bressler, MD, of Johns Hopkins reported at a press teleconference that, "No serious risks were associated with the intravitreal injections."

Frederick L. Ferris III, MD, clinical director of the National Eye Institute (NEI), called the results exciting.

"This is the first new treatment for diabetic macular edema in over a quarter of a century," he commented. Focal or grid photocoagulation became the standard of care for diabetic macular edema and has remained the mainstay of treatment since 1985.

Now with this "definitive" proof of superiority over laser alone, Bressler said, physicians should consider off-label use of ranibizumab, which is approved in age-related macular degeneration.

Whether other vascular endothelial growth factor (VEGF) inhibitors would be equally effective isn't clear yet, although there could be a class effect based on promising results in small, short-term studies, he noted.

That question is particularly relevant given that the VEGF inhibitor bevacizumab (Avastin) is a molecule closely related to ranibizumab but is available at a substantially lower price (roughly $50 compared with $2,000 per intravitreal injection).

Results from another NEI-sponsored study that compares bevacizumab and ranibizumab in age-related macular degeneration should answer whether the two drugs are interchangeable, as most clinicians suspect, Ferris said.

The American Academy of Ophthalmology released a statement saying it would review Bressler's results to determine whether ranibizumab plus laser treatment should be the new preferred therapy for most patients with diabetic macular edema.

Bressler's multicenter study randomized a total of 854 eyes in 691 diabetic patients with visual acuity of 20/32 to 20/320 and diabetic macular edema involving the fovea to receive double-blind treatment with one of several regimens:

    * Prompt laser with sham intravitreal injections as a control group
    * Intravitreal ranibizumab (0.5 mg) plus laser treatment within three to 10 days after injection
    * Ranibizumab injections (0.5 mg) plus laser treatment deferred by at least 24 weeks
    * Intravitreal injections with the corticosteroid triamcinolone (Triesence, Trivaris Intravitreal, 4 mg) plus prompt laser

Ranibizumab injections were scheduled to be monthly but were at investigator discretion if that month's visit showed "success" based on visual acuity and retinal thickness measurements. The median number of injections given was eight in the prompt laser group and nine in the delayed laser group out of a maximum 13 over one year.

Triamcinolone injections could be as often as every 16 weeks with sham injections as often as every four weeks in between. The median number given was three out of a possible four over the one year.

At the one-year primary outcome visit, "success" criteria with a visual acuity letter score of at least 84 (roughly 20/20 vision) or retinal thickness under 250 ¦Ìm on OCT central subfield was seen in:

    * 32% of eyes in the laser alone group
    * 64% in the ranibizumab and prompt laser group
    * 52% in the ranibizumab and deferred laser group
    * 56% in the triamcinolone group

For the primary outcome of best-corrected visual acuity at one year, the change from baseline was significantly greater in the ranibizumab groups compared with laser alone (+9 for both prompt and delayed laser versus +3, P<0.001).

The proportion of eyes with at least a 15 letter improvement in visual acuity was greater with ranibizumab (30% and 28% versus 15% laser alone, both P<0.001) while the proportion that lost at least 10 letters was lower (4% and 3% versus 13% laser alone, both P¡Ü0.001).

Triamcinolone improved the reduction in mean central subfield thickness significantly more than laser alone whereas ranibizumab did not, but the corticosteroid yielded no visual acuity benefit (+4 versus +3 laser alone, P=0.31).

In the second year of follow-up, the number of intravitreal ranibizumab injections dropped to four to five and yielded visual acuity outcomes similar to the one-year outcomes.

"No systemic events attributable to study treatment were apparent," the researchers said.

Practice Pearls:

* Caution interested patients that intravitreal use of ranibizumab and triamcinolone in diabetic macular edema is not approved by the FDA.
* Note that generalizability of the results to bevacizumab and other VEGF inhibitors is unclear.

Source: http://www.diabetesincontrol.com/index.php?option=com_content&view=article&id=9282&catid=53&Itemid=8, Elman MJ, et al "Randomized trial evaluating ranibizumab plus prompt or deferred laser or triamcinolone plus prompt laser for diabetic macular edema" Ophthalmology 2010; DOI: 10.1016/j.ophtha.2010.02.031.