A post hoc analysis of data from ZETA-1, a phase 2 clinical trial, has revealed promising results for APX3330, an oral Ref-1 inhibitor developed by Ocuphire Pharma, in slowing the progression of diabetic retinopathy (DR). The study, presented by Daniel Su and colleagues, evaluated the efficacy of APX3330 using a binocular 17-step Diabetic Retinopathy Severity Scale (DRSS) person-level scale, an FDA-agreed measure for assessing systemic agents in DR.

The multicenter, randomized, placebo-controlled trial involved 103 subjects with DRSS scores of 47, 53, or 61 without center-involved diabetic macular edema. A post hoc analysis focused on 68 subjects with two qualified eyes and DRSS scores of 43, 47, or 53 in both eyes. Results showed a numerical reduction in binocular ≥3-step worsening on the DRSS person-level scale at 24 weeks, with 5.7% of APX3330-treated subjects worsening compared to 15.2% of placebo subjects (P=0.26). Notably, there was a 100% reduction in binocular ≥4-step worsening in the APX3330 group (0%) compared to placebo (15.2%, P=0.07).

“APX3330 may represent a promising oral treatment option for delaying or preventing disease progression in NPDR patients who otherwise are monitored and untreated until they progress to sight-threatening disease,” the researchers concluded. These findings support further evaluation of APX3330 in phase 3 registration trials, potentially offering a non-invasive alternative to current treatments for non-proliferative diabetic retinopathy patients at risk of progressing to more severe stages of the disease.