Evaluation of Tonabersat for DME

Key Inclusion Criteria

1. Adults with type 1 or 2 diabetes mellitus

2. At least one eye with:

- Best corrected E-ETDRS visual acuity letter score ≥ 79 (i.e., 20/25 or better)

- Ophthalmoscopic evidence of center-involved DME in study eye confirmed by central
subfield thickness on spectral domain OCT

- Zeiss Cirrus: ≥ 290 µm in females, ≥ 305 µm in males

- Heidelberg Spectralis: ≥ 305 µm in females, ≥ 320 µm in males

- Recruitment will be monitored with a goal to have equal proportions in the
following categories above the CI-DME thresholds: <75 μm, 75 μm to <175 μm,
≥175 μm

3. Media clarity, pupillary dilation, and study participant cooperation sufficient for
adequate OCT

Key Exclusion Criteria

- Macular edema is considered to be due to a cause other than DME

- Major ocular surgery within prior 4 months, or anticipated after randomization

- History of focal/grid laser or other ocular surgical, intravitreal, or peribulbar
treatment for DR or DME within prior 1 year, and no more than 4 prior anti-VEGF
injections total

- Anticipated need to treat DME or DR during the first 6 months, or anticipated need for
cataract surgery during study period

- Any history of vitrectomy

- Systemic anti-VEGF or pro-VEGF treatment within 12 months prior to randomization

- History of chronic renal failure requiring dialysis or kidney transplant

- History of moderate to severe hepatic impairment, including known liver function test
(LFT) values > 3x's the upper limit of normal