Ranibizumab plus PRP better than PRP monotherapy for high-risk proliferative diabetic retinopathy
Panretinal photocoagulation (PRP) plus ranibizumab (RBZ) is more effective than PRP monotherapy for neovascularization (NV) regression in the eyes of patients with high-risk proliferative diabetic retinopathy (HR-PDR) over a 12-month period, according to a phase II/III study. Additionally, the combination therapy poses no safety concerns.
A total of 87 participants (aged ≥18 years) with type 1/2 diabetes and HR-PDR (mean age, 55.2 years; 37 percent female) were randomly assigned to receive RBZ+PRP (n=41) or PRP alone (n=46). The former received three monthly RBZ injections along with standard PRP, while the latter received standard PRP between day 1 and month 2.
Of the participants, 77 (88.5 percent) completed the study. Both groups had comparable overall baseline characteristics, except for age. [Ophthalmology 2018;125:691-700]
More patients in the RBZ+PRP group presented NV total reduction than in the PRP monotherapy group (92.7 percent vs 70.5 percent; p=0.009) at month 12. Reductions of NV on the disc (NVD) plus elsewhere (NVE) were also greater in the RBZ+PRP arm (93.3 percent and 91.4 percent, respectively) than in the PRP monotherapy arm (68.8 percent and 73.7 percent, respectively), significant only for NVE (p=0.048). The proportion of participants with complete NV total regression was higher in the RBZ+PRP vs PRP monotherapy group (43.9 percent vs 25.0 percent; p=0.066).
The mean best-corrected visual acuity at month 12 was 75.2 letters (20/32) vs 69.2 letters (20/40) in the RBZ+PRP and PRP monotherapy group, respectively (p=0.104). Over the follow-up period, the mean number of PRP treatment in the RBZ+PRP group was 3.5±1.3 vs 4.6±1.5 in the PRP monotherapy group (p=0.001). There were no reported deaths or unexpected adverse events.
“In this study, RBZ+PRP was more effective than PRP monotherapy in causing regression of NV area in HR-PDR eyes at 12 months follow-up, achieving our primary outcome,” the investigators said. “This conclusion reinforces the results obtained in previous studies, such as Protocol S and CLARITY study.” [Ophthalmologica 2015;235:34-41; Br J Ophthalmol 2009;93:1474-1478]
The Protocol S and the CLARITY study compared antivascular endothelial growth factor (anti-VEGF) therapy (RBZ and aflibercept, respectively) with PRP in PDR, but patients in the present study had more advanced disease. The investigators included only eyes with HR-PDR, while the Protocol S and CLARITY study included only 37 percent and 23 percent of eyes in this stage, respectively.
“Our therapeutic approach was also different because we used a combination of intravitreous injections of RBZ plus PRP in the study arm. We consider this combination to have a synergistic effect with an eventual reduction of NV compared with anti-VEGF monotherapy,” the investigators said.
The present study was limited by the fact that the investigators were aware of treatment assignment because only one group received intravitreal injection, and by the short follow-up period of 1 year. Therefore, studies with longer follow-up are warranted to establish the benefit of combined therapy (PRP + anti-VEGF injections) for PDR.