Ranibizumab shows promise as DME treatment in pilot study

Ranibizumab injections reduced excess foveal thickness and improved visual acuity in patients with diabetic macular edema, a small nonrandomized study found. The study results "demonstrated that vascular endothelial growth factor is an important therapeutic target for diabetic macular edema," the study authors said.

Quan Dong Nguyen, MD, MSc, and colleagues at the Wilmer Eye Institute evaluated the effect of intraocular injections of 0.5 mg of ranibizumab in 10 patients with severe, chronic diabetic macular edema (DME) that had responded poorly to standard treatments. Eight patients had previously undergone at least two sessions of laser photocoagulation at least 5 months before study entry, and three patients had received intraocular corticosteroid injections at least 10 months before the study.

Investigators administered ranibizumab injections at baseline and at 1, 2, 4 and 6 months. At 7 months, mean foveal thickness had decreased significantly, from 503 µm at baseline to 257 µm (P = .005), a reduction of 85% of the excess foveal thickness that was present at baseline, according to the study authors.

Foveal thickness tended to increase gradually after each injection, but had not returned to baseline levels 3 months after the final injection, the authors noted.

"Regardless of the different patterns that were exhibited, all patients appeared to have a beneficial response to ranibizumab. The magnitude of the beneficial response is substantial," Dr. Nguyen and colleagues said.

Also at 7 months, mean macular volume had decreased significantly, from 9.22 mm³ at baseline to 7.47 mm³ (P = .009). This was a reduction of 77% of the excess volume at baseline. In addition, mean visual acuity improved significantly, by 12.3 letters, to 20/40 (P = .005). This increase correlated positively with the decrease in foveal thickness but occurred at a slower rate and did not fluctuate as foveal thickness increased.

"In view of this, it is not surprising that there was good maintenance of the improvement in visual acuity between 7 and 9 months, despite substantial worsening of foveal thickness, which indicates that return of thickening precedes loss of visual acuity," the authors said.

The study was initially sponsored by the Juvenile Diabetes Research Foundation and is being expanded to include another 10 patients through a grant from Genentech Inc. Peter A. Campochiaro, MD, one of the study's authors, recently presented results from the expanded study at the American Academy of Ophthalmology meeting in Las Vegas.

Dr. Nguyen and colleagues noted that a larger double-masked, randomized, controlled trial spanning several years is being planned to determine the value of ranibizumab as a long-term treatment for patients with DME.

The study is published in the December issue of the American Journal of Ophthalmology.