medwireNews: Results of the CLARITY trial suggest that aflibercept treatment may produce better visual outcomes than laser photocoagulation in patients with proliferative diabetic retinopathy.
The trial, which is published in The Lancet, shows that, among all randomized patients, the best corrected visual acuity in the 104 patients who underwent panretinal photocoagulation (PRP) fell by an average of 3.0 letters during the 52 weeks after treatment.
By contrast, the 105 patients who received intravitreal aflibercept achieved an average 1.1-letter improvement over the year, giving a significant adjusted difference of 3.9 letters between the groups. These patients received three injections of aflibercept 2 mg/0.05 mL at baseline and after 4 and 8 weeks. From week 12, they were reviewed every 4 weeks and given further injections as needed; they received an average of 1.4 additional injections.
The number of PRP sessions required during the first 12 weeks was between one and four for most eyes, but some required more, with one eye needing seven sessions. After this, 65% of patients needed supplemental sessions – an average of 1.17.
Sobha Sivaprasad (Moorfields Biomedical Research Centre, London, UK) and study co-authors highlight this point, saying that one reason for the current low acceptance of anti-vascular endothelial growth factor (VEGF) therapy in clinical practice is “because PRP is perceived to have a permanent effect and requires fewer follow-up visits.”
In a linked commentary, Daniel Shu Wei Ting and Tien Yin Wong, both from Singapore National Eye Centre, note that patients in the previous Diabetic Retinopathy Clinical Research Network did not achieve better visual outcomes with intravitreal ranibizumab than with PRP.
This could be because of differences between the anti-VEGF agents used, they suggest, with aflibercept having a higher binding affinity for its targets than does ranibizumab, meaning it might persist longer in the vitreous.
But they observe that it could also be due to differences in the trials’ patient populations; the ranibizumab trial recruited only untreated patients with high-risk proliferative diabetic retinopathy, and included those with macular edema, whereas only 23% of CLARITY participants were high risk, 47% had previously undergone PRP, and none had macular edema.
“Thus, inclusion of patients with less severe proliferative diabetic retinopathy in CLARITY might have led to greater visual gain and fewer injections,” write the commentators, although they stress that direct comparisons between studies should be done with caution.
“Clearly, a larger clinical trial with longer-term visual outcome, safety, and cost-effectiveness should be done to provide more evidence to inform clinical practice,” they say.
Aflibercept is already used to treat macular edema, and although no CLARITY patients had this at baseline, fewer in the aflibercept group developed it during follow-up, with 89% versus 71% of the PRP group remaining free of it by week 52. They also had a significantly lower incidence of new or increasing vitreous hemorrhage.
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