Ranibizumab improves vision in patients with visual impairment due to DME: RESTORE study

Results from a new major diabetes eye health study may have the potential to change the way vision loss due to diabetic macular edema (DME), a serious and devastating complication of diabetes, is treated. One year results from the RESTORE study show that 37 per cent of patients treated with ranibizumab only and 43 per cent of those treated with ranibizumab plus laser therapy, had a significant improvement in visual acuity of 10 letters or more on an eye chart, compared to 16 per cent of patients treated with laser alone - the current standard treatment for visual impairment due to DME.

These findings represent an important advancement in ophthalmology and add to the evidence that supports ranibizumab as the first treatment in 25 years to demonstrate benefit over the current standard of care for visual impairment caused by DME.

"The RESTORE results confirm what we've already seen in previous studies - the effectiveness of ranibizumab to rapidly improve visual acuity in patients with DME," says Dr. Peter Kertes, Retina Specialist at Sunnybrook Health Sciences Centre, Associate Professor of Ophthalmology and Vision Sciences at the University of Toronto, and clinical investigator at one of the seven Canadian trial sites involved in the RESTORE study. "The incidence of diabetes is on the rise and so are the long-term complications such as diabetic macular edema. These data reinforce that ranibizumab not only halts the progression of DME, but it is the first treatment that has been shown to improve vision in a meaningful way for patients with vision loss from DME, a benefit that may change the way this condition is treated."

Ranibizumab is approved in more than 80 countries, including Canada, for the treatment of wet age-related macular degeneration (AMD). It is not currently approved in any market for the treatment of visual impairment due to DME.

The RESTORE study

The randomized, double-masked, multicenter RESTORE study involved 345 DME patients with an average age of 63 years randomized into three treatment arms: ranibizumab 0.5 mg plus sham laser treatment, ranibizumab plus active laser treatment, and sham injection plus active laser treatment. The primary endpoint was the mean change in best corrected visual acuity (BCVA) from baseline to the average level from months one to 12. Key secondary endpoints were the mean change in BCVA over time, and safety.

The RESTORE study showed that over one year, patients treated with ranibizumab plus laser were able to read an additional 5.9 letters on a standard eye chart, while those treated with ranibizumab alone could read 6.1 letters more than at the start of the study. This compared with patients receiving laser therapy alone who could read an additional 0.8 letters. All figures are mean averages for the year. The study met its primary endpoint (both ranibizumab arms p(less than)0.0001 vs. laser alone).

The safety profile of ranibizumab in RESTORE was consistent with that previously observed in large controlled clinical trials, with no new safety risks observed. No cases of endophthalmitis were reported. Ranibizumab showed a low incidence (less than one per cent) of increased intra-ocular pressure (IOP). In terms of systemic safety, there was a low incidence of hypertension (five to eight per cent) and arterial thromboembolic events (three to four per cent) in all treatment groups

The results from RESTORE mirror a recent study conducted by the Diabetic Retinopathy Clinical Research Network (DRCR.net) showing that after one year, nearly 50 per cent of eyes treated with ranibizumab and laser therapy demonstrated an improvement in vision of 10 letters or more on the eye chart, compared to 28 per cent with laser therapy alone.

Diabetes, diabetic retinopathy and diabetic macular edema (DME)

It is estimated that more than three million Canadians have diabetes, a disease associated with high levels of blood sugar which can damage many organs over time, including the eyes. Long-term diabetes can result in diabetic retinopathy, an eye disease characterized by changes in the blood vessels of the retina - the light-sensitive layer at the back of the eye.

Diabetic retinopathy is a leading cause of blindness in people under age 65, and almost all people with diabetes have some form of diabetic retinopathy.

While there are several forms of diabetic retinopathy, a number of people with the condition will develop DME, a serious eye condition which is caused by leakage of fluid in the central portion of the retina called the macula. The build-up of fluid causes swelling and thickening in the macula, distorting vision. Because this is the part of the eye responsible for sharp central vision, patients with visual impairment due to DME can find it hard to recognize faces and carry out everyday activities such as reading and driving. DME with visual impairment affects 1-3% of people with diabetes worldwide.