Dexamethasone: Data show implant improves vision in patients with RVO

New York-New data from phase III clinical trials of the dexamethasone 0.7 mg intravitreal implant (Ozurdex, Allergan) reaffirm that this novel pharmacotherapeutic intervention is well-tolerated and effectively improves vision in patients with macular edema secondary to a branch or central retinal vein occlusion, said Julia A. Haller, MD, at the 2009 Retina Congress. Dr. Haller is ophthalmologist-in-chief, Wills Eye Institute, and professor and chairwoman of ophthalmology, Jefferson Medical College, Thomas Jefferson University, Philadelphia.

Clinical trials, interim data

The primary outcome measure was time to achieve =15 letters (three-line) improvement in BCVA, and in each individual study as well as when the data were pooled, this endpoint was achieved significantly faster in the dexamethasone 0.7 mg group compared with the controls; within 1 to 2 months, 20% to 30% of patients who received the dexamethasone 0.7 mg implant gained at least three lines of BCVA versus only 7% to 12% of controls. The response to dexamethasone was similar among patients with branch RVO (BRVO) and central RVO (CRVO), and there also were statistically significant differences favoring the dexamethasone 0.7 mg group versus controls in mean change in BCVA at monthly follow-ups on days 30 to 180.

The implantation procedure was well-tolerated, and rates of anticipated corticosteroid-related ocular events, i.e., elevated IOP and cataract formation, were not different at 6 months when the active and control groups were compared.

One-year follow-up

In follow-up to 12 months among patients originally randomly assigned to receive dexamethasone 0.7 mg, 21% of patients with BRVO and 17% of patients with CRVO required no further treatment. Those who received a second implant had a good response and with no evidence of increased risk for adverse events relative to the first treatment, Dr. Haller explained.

Patients in the control group who received the dexamethasone implant also benefited with improvements in foveal thickness and vision that were similar to but not quite matching those observed in the original dexamethasone 0.7 mg cohort, she said.

Observing that it has been more than a decade since the last randomized controlled trial (RCT) of treatment for CRVO and 25 years since the last RCT for BRVO, these positive pivotal trial data for the dexamethasone implant are very exciting, as are the results reported at the Retina Congress for phase III studies of ranibizumab (Lucentis, Genentech), Dr. Haller said.

"When attempting to compare the data that are being reported for these different modalities, it will be important to consider that there are key differences in trial enrollment criteria and baseline characteristics of the patient populations that might influence the outcomes," she said. "However, one distinguishing feature to note in evaluating the role of different treatment options for RVO studies is the frequency of required intravitreal injections."