Effect of the Orally-administered PKC ß Inhibitor, Ruboxistaurin, on Sustained Moderate Visual Loss in the PKC-DRS2 Study

Approximately 40% of patients with diabetes have some degree of retinopathy, placing them at risk for vision loss. The goal of this research was to evaluate the efficacy of the orally-administered PKC- ß inhibitor ruboxistaurin for the prevention of sustained moderate visual loss (SMVL) in patients with diabetes. Progression of diabetic retinopathy and diabetic macular edema (DME) were also assessed. All patients in the study had moderately severe or severe nonproliferative diabetic retinopathy (NPDR) with no history of panretinal photocoagulation. Patients with a history of focal laser photocoagulation were permitted to participate in the study. Participants in the study were randomly assigned to receive 32 mg ruboxistaurin per day or placebo.

The results of the study demonstrated that ruboxistaurin treatment was associated with a 40% reduction in the risk of SMVL (9.1% SMVL in the control group vs 5.5% in the ruboxistaurin group). When data from the original PKC-DRS study were reanalyzed, results were comparable, although they did not reach statistical significance due to sample size. In terms of visual acuity, patients treated with ruboxistaurin were twice as likely to gain letters and a third less likely to lose letters, both of which were statistically significant findings. Progression of DME was reduced in patients with clinically significant macular edema (CSME), but progression of retinopathy was not reduced. The results of this study demonstrated that ruboxistaurin can reduce the occurrence of SMVL in patients with moderately severe to severe NPDR and can reduce the progression of DME in patients with clinically significant macular edema.