DEX implant improves visual acuity in patients with diabetic macular oedema

By Afsaneh Gray, medwireNews Reporter

Patients with diabetic macular oedema (DME) benefit from intravitreal dexamethasone (DEX) implants, a study shows, with the treatment improving best-corrected visual acuity (BCVA) with an acceptable safety profile.

The vascular endothelial growth factor (VEGF) inhibitor ranibizumab was the first treatment to be approved for DME, but the need for frequent injections is a burden for patients and some do not respond to the therapy, the study researchers explain.

Consequently, they conducted two large, multicenter clinical trials to evaluate the safety and efficacy of DEX implant 0.7 mg and 0.35 mg in patients with DME to support its regulatory approval as an alternative treatment.

The trials included a total of 1048 patients from 22 countries with DME, a BCVA of 20/50 to 20/200 Snellen equivalent and central retinal thickness (CRT) of at least 300 μm.

Patients were randomly assigned in a 1:1:1 ratio to the following groups: treatment with DEX implant 0.7 mg; treatment with DEX implant 0.35 mg; or sham procedure. They were seen every 1.5 months during year 1 and every 3 months during years 2 and 3 of follow-up.

The percentage of patients meeting the primary efficacy endpoint of at least a 15-letter improvement in BCVA from baseline was greater in both DEX implant groups (22.2% and 18.4% for 0.7 mg and 0.35 mg, respectively) than in the sham group (12.0%).

There was also a greater mean average reduction in CRT from baseline with DEX implant 0.7 mg (-111.6 μm) and 0.35 mg (-107.9 μm) than sham (-41.9 μm).

Rates of cataract-related adverse events in phakic eyes were raised in patients given the DEX implant 0.7 mg (67.9%) and 0.35 mg (64.1%) compared with sham (20.4%) groups.

However, “analysis of the proportion of patients gaining 3 lines in BCVA or achieving ≥20/40 vision showed separation of the DEX implant and sham curves in study year 3, when the influence of cataract was reduced because of cataract extractions,” lead author David Boyer (Retina-Vitreous Associates Medical Group, Los Angeles) and colleagues write.

Increases in intraocular pressure (IOP) were controlled with medication or no therapy in the vast majority of patients and there was no cumulative effect of DEX implant on IOP.

The researchers conclude that “with an average of only 4 to 5 injections over 3 years, patients treated with DEX implant achieved statistically significant and clinically meaningful visual improvements.”

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