Acucela’s oral DR drug shows potential for reducing retinal thickness

An experimental treatment for proliferative diabetic retinopathy (DR), emixustat hydrochloride, has shown promise in a phase 2 trial, according to a press release by Acucela.

Emixustat is an oral small molecule inhibitor of RPE65. Preclinical studies suggest emixustat reduces the retina’s metabolic burden and oxygen demand, possibly slowing the progression of DR.

“This proof of concept is exciting, as it not only addresses an important unmet need—but does so through oral administration, a first for the industry,” said Ryo Kubota, MD, PhD, Acucela’s chairman, president and CEO.

The trial’s 24 participants were randomly assigned to a 12-week regimen of emixustat or placebo. Emixustat doses were titrated to a maximum tolerated amount of 40 mg per day during the first 4 weeks, then held steady for the remainder of the treatment period. 

Investigators used spectral domain OCT to assess central subfield thickness at day 85, roughly 3 months after beginning treatment. Compared with controls, the emixustat group showed more reductions in central subfield thickness (48-micron difference over controls) and total macular volume (0.361 mm³ difference over controls).

According to Acucela, the findings hint at emixustat’s potential to decrease retinal thickness in patients with DR. The company is pursuing research partnerships and preparing to launch additional studies needed for regulatory approval.