Amarantus BioScience Holdings, Inc., a biotechnology company developing therapeutic and diagnostic product candidates in orphan indications and neurology, announced that the US Food and Drug Administration (FDA) has granted the company's investigational drug mesencephalic-astrocyte-derived neurotrophic factor (MANF) orphan drug designation for the treatment of retinal artery occlusion (RAO), a blockage of the blood supply to the retina which causes severe and sudden loss of vision.

MANF, a naturally-occurring protein that reduces and prevents apoptosis (programmed cell death) in response to injury or disease, was discovered utilizing Amarantus' proprietary PhenoGuard Protein Discovery Engine. Pre-clinical data demonstrated that MANF provided protective functional effects in an animal model of RAO. Moreover, toxicology studies have demonstrated that MANF was well-tolerated following a single intravitreal administration of a therapeutically relevant dose.

"We are extremely pleased to have received the second orphan drug designation for MANF for use in ophthalmologic disorders. At the end of 2014 we received orphan drug designation for MANF to treat retinitis pigmentosa (RP), and this additional designation for treatment of RAO is an important step in our regulatory strategy for what we believe has the potential to become a broad ophthalmic therapeutic franchise," said Gerald E. Commissiong, president & CEO of Amarantus BioSciences Holdings, Inc.

"RAO is an acute condition that can potentially lead to blindness and the toxicology data generated thus far directly supports the translational potential for MANF in this indication. We believe MANF has promise as a safe and effective therapeutic option to treat RAO and RP."

The FDA Orphan Drug designation programme provides a special status to drugs and biologics intended to treat, diagnose or prevent so-called orphan diseases and disorders that affect fewer than 200,000 people in the US. This designation provides for a seven-year marketing exclusivity period against competition, as well as certain incentives, including federal grants, tax credits and a waiver of PDUFA filing fees.

RAO is a rare eye condition caused by a loss of blood supply to the inner layer of the retina resulting in acute and often severe vision loss. The currently-available treatments are aimed at opening the occluded artery before irreversible damage occurs and most often do not improve visual acuity above natural history. There are no effective neuroprotective agents for the treatment of acute retinal ischemia available. The prevalence for RAO is approximately 10,450 patients in the United States.

MANF is believed to have broad potential because it is a naturally-occurring protein produced by the body for the purpose of reducing and preventing apoptosis (cell death) in response to injury or disease, via the unfolded protein response. By manufacturing MANF and administering it to the body, Amarantus is seeking to use a regenerative medicine approach to assist the body with higher quantities of MANF when needed. Amarantus is the front-runner and primary holder of intellectual property (IP) around MANF, and is initially focusing on the development of MANF-based protein therapeutics.

MANF's lead indication is retinitis pigmentosa, and additional indications including Parkinson's disease, diabetes and Wolfram's syndrome are currently pursued. Further applications for MANF may include Alzheimer's disease, traumatic brain injury (TBI), myocardial infarction, antibiotic-induced ototoxicity and certain other rare orphan diseases currently under evaluation.