Real-world data has suggested that patients with diabetic macular edema (DME) receiving treatment with anti-vascular endothelial growth factors (anti-VEGFs) fare far worse than similar patients in clinical trials. Could this be because trials do not mimic real-world situations?

Analysis from nearly 6,000 patients in the US showed that patients received an average of eight injections in their first year of treatment, experiencing an improvement in vision by six letters. This is good news for patients burdened with the prospect of vision loss. However, when compared to those in clinical trials, the numbers don’t match up. For example, in a trial conducted by the Diabetic Retinopathy Clinical Research Network (DRCR), patients experienced an improvement of 13.3 letters. It is dangerous to compare results from trials with those in the real world; however, there is a clear discrepancy in the outcomes seen in trials and in reality.

Given the impressive results demonstrated in clinical trials, anti-VEGF therapies have become the gold standard of care for the treatment of DME. 97% of US physicians recently surveyed by GlobalData use an anti-VEGF therapy as a first-line therapy for DME. There are currently three anti-VEGFs used to treat DME: Regeneron’s Eylea (aflibercept) and Roche’s Lucentis (ranibizumab) and Avastin (bevacizumab). Despite its off-label use, Avastin currently holds approximately 60% of the patient share in the US.

"KOLs interviewed by GlobalData expressed the need for therapies that reduce the requirement for such frequent anti-VEGF injections."

Clinical trials are known to have a reputation for being designed to favour the most positive outcome and often fail to address the challenges faced in clinical practice. This is particularly true for DME, where the frequency and burden of anti-VEGF injections are a major challenge to patient care. Key opinion leaders (KOLs) interviewed by GlobalData expressed the need for therapies that reduce the requirement for such frequent anti-VEGF injections.

Frequent doctor visits are a common occurrence in a diabetic’s life; however studies have shown that the development of DME can result in an additional 12 visits a year for these already-burdened patients. This causes many missed visits and delayed treatments, which is one of the major reasons for the discrepancy between clinical and real-world outcomes – patients are getting fewer treatments. In the DRCR study patients received an average of 10 injections a year, compared to eight in the real world.

Another cause for inconsistency between outcomes is the diversity of patients in the clinical practice compared to the selectivity of clinical trials. DME patients may present with characteristics such as ischemia, extreme visual acuity, high HbA1C levels, or other comorbidities that would normally disqualifies them from clinical trials. Hence, the efficacy of anti-VEGF therapies in these patients is unclear, and may result in fluctuations in response. 

Despite the variation in response between real-world treatment and clinical trials, it cannot be denied that anti-VEGF therapies have revolutionized the treatment and life of patients with DME. However, the focus of development now turns towards reducing the burden felt by DME patients already weighed down by the burdens of diabetes.