Eli Lilly yesterday said that it is planning to seek approval towards the end of the year for its new diabetic retinopathy therapy, Arxxant (roboxistaurin), but revealed that the compound also failed to demonstrate clinical benefit in another complication of diabetes known as peripheral neuropathy. Both diabetic retinopathy and diabetic neuropathy are caused by uncontrolled blood glucose, the former resulting in vision loss and blindness and the latter in deterioration of nerve function – they also represent a Holy Grail of drug development, with no therapies designed to target the underlying causes of the disease currently on the valuable US market.

In a late-stage study involving 685 patients with moderately severe to severe diabetic retinopathy, Arxxant (roboxistaurin) was shown to reduce the occurrence of vision loss, and Lilly is planning to follow up this success by investigating the compound’s use in another eye condition – diabetic macular oedema - expected to complete in 2010. Meanwhile, it was also studied in 500 patients to evaluate its benefit in treating the symptoms associated with diabetic peripheral neuropathy, but researchers found no difference between the placebo and Arxxant groups in terms of sensory symptom scores, including numbness, tingling and pain.

However, because there were no safety issues, Lilly says it will continue to study Arxxant in an ongoing, three-year trial in nerve dysfunction amongst DPN patients, which is scheduled to complete in 2007, and pointed out that, in contrast to the subjective nature of the first trial, the primary outcome will be an objective measure of nerve function. Said Executive Vice President, Science and Technology, Steven Paul: “While we are disappointed in the outcome of the trials for SDPN, we are extremely pleased to be one step closer to providing a possible solution for patients with diabetic retinopathy. If…approved by the FDA, it would be the first oral medication for the treatment of this serious complication of diabetes.”

Arxxant is a protein kinase C beta inhibitor, the first in a new class of compounds designed to block this enzyme, which has been implicated in the development of microvascular damage in diabetes. Nearly 75% of all people with diabetes have at least one diabetic microvascular complication, be it retinopathy, neuropathy or nephropathy (kidney).