MacuSight Announces Positive Initial Results From Phase 1 Study ofSirolimus in Diabetic Macular EdemaSirolimus Demonstrates Favorable Safety Profile and Improvements in Visual Acuity
UNION CITY, Calif., October 01, 2007 /PRNewswire/ -- MacuSight(TM), Inc., a developer of innovative therapeutics for the treatment of severe ocular diseases and conditions, today announced positive interim data from a Phase 1 study of its lead product candidate in patients with chronic, clinically significant diabetic macular edema (DME). Results from this prospective study of 50 patients demonstrated that MacuSight's proprietary formulation of sirolimus (rapamycin) was safe and well-tolerated in all doses tested with two different routes of administration. Additionally investigators noted improvements in visual acuity and foveal thickness reductions for up to 180 days following a single administration of sirolimus. These findings were presented at the 40th Annual Meeting of The Retina Society by Mark Blumenkranz, M.D., chairman of MacuSight's scientific advisory board and professor and chairman of the department of ophthalmology, Stanford University School of Medicine.
As part of the design of this randomized, open-label study, investigators evaluated the safety, tolerability and biological activity of sirolimus when delivered by either subconjunctival or intravitreal injection. Intravitreal injections (into the central cavity of the eye), while the standard route of administration for current therapies, are uncomfortable for many patients and are accompanied by the risk of serious infection in a small percentage of patients. In contrast, subconjunctival injections (just under the outer layer over the white of the eye) are designed to offer physicians and patients a less invasive and more convenient procedure. MacuSight's DME trial included ten treatment arms with patients receiving one of five doses of sirolimus via either a single subconjunctival injection or a single intravitreal injection. Preclinical studies suggested that a single administration may provide the patient with exposure to sirolimus for up to approximately three months.
In addition to safety and tolerability data, the study provided an initial assessment of sirolimus' biological activity in DME. At 45 and 90 days following treatment, patients receiving the two lowest doses of sirolimus by subconjunctival injection demonstrated mean improvements in visual acuity of 8.5 and 7.4 letters over baseline, respectively, using a standard (ETDRS) eye chart. Additionally, this group of patients also experienced anatomical improvements, with a mean decrease in foveal thickness that was consistent with the observed functional improvements in visual acuity. Preliminary data for these patients at 180 days following treatment suggest that these initial improvements in visual acuity and foveal thickness reductions were maintained, or even enhanced, over time in many patients.
"The fact that we are seeing measures of biological activity maintained, and, in some cases improving, through 180 days following a single subconjunctival injection, is somewhat surprising. This finding raises the possibility that sirolimus may be fundamentally changing the course of diabetic retinopathy through its impact on the mTOR (mammalian target of rapamycin) pathway rather than simply reversing macular edema in a more non-specific way," said Dr. Blumenkranz. "Further studies to support or refute this hypothesis will be necessary. However, if so, then the potential clinical utilization of the drug may eventually extend beyond those patients with clinically significant diabetic macular edema."
"The study's findings are intriguing, particularly in light of the fact that a majority of the participants had been previously treated for DME. As such, these results provide great excitement for researchers as we prepare to advance this product into Phase 2 clinical studies," stated David A. Weber, Ph.D., president and chief executive officer of MacuSight. "We are also delighted the drug appeared so effective by a simple subconjunctival injection, a route of administration that is able to decrease the risk and treatment burden to patients and physicians alike. As a result, we can confidently proceed with our clinical development of sirolimus as a product delivered via subconjunctival injection."
With regard to safety and tolerability, the study showed no evidence of increased intraocular pressure or inflammatory response to treatment. MacuSight intends to complete its collection and analysis of all data from this trial and present final findings later this year.
"From a patient treatment standpoint, the study findings related to the safety and biological activity of sirolimus administered through subconjunctival injection are very exciting," stated Pravin U. Dugel, M.D., clinical instructor, vitreoretinal diseases and surgery, department of ophthalmology, University of Arizona, partner at Retinal Consultants of Arizona in Phoenix, Arizona, and the study's lead investigator. "By offering both physicians and patients significant benefits in the way of reduced invasiveness, safety and ease of administration, the subconjunctival injection has the potential to dramatically improve the current DME treatment paradigm."
Additionally, MacuSight has completed enrollment of its second Phase 1 trial which is examining its same proprietary sirolimus formulation in patients with exudative age-related macular degeneration. Results from this second trial are expected to be presented during the first half of 2008.
Sirolimus, originally known as rapamycin, is a highly-potent, broad-acting compound that has demonstrated the ability to combat disease through multiple mechanisms of action including immunosuppressive, anti-angiogenic, anti-migratory, anti-proliferative, anti-fibrotic and anti-permeability activity. Based on the versatility associated with these multiple mechanisms of action, MacuSight believes that its sirolimus product may serve as a potentially highly-efficacious therapeutic for a wide range of ocular diseases and conditions, including the treatment and prevention of wet AMD.
As the active pharmaceutical ingredient in the FDA-approved products Rapamune(R) and CYPHER(R) Sirolimus-eluting Coronary Stent, sirolimus has been safely administered to humans for more than six years. MacuSight has developed a proprietary minimally-invasive, sustained administration approach for its novel liquid sirolimus formulation which it believes will provide the product with significant competitive advantages related to convenience, ease-of-use, compliance and safety.
About Diabetic Macular Edema
Diabetic macular edema (DME) is a serious manifestation of diabetic retinopathy that involves retinal swelling brought on by the leaking of fluid from small blood vessels within the macula. As the condition develops, central vision becomes blurred. DME can progress fairly rapidly and over just a few years can lead to permanent visual loss. There is a significant unmet need to both reverse the visual loss associated with DME and to help delay the progression of this condition.
MacuSight is a privately-held pharmaceutical company focused on developing innovative therapeutics for the treatment of severe ocular diseases and conditions. The company is dedicated to preserving patients' vision by identifying known, highly-potent and broad-acting small molecule drug compounds that may possess efficacy in treating and/or preventing diseases or conditions of the eye. As part of its unique product development philosophy, MacuSight also concentrates on the optimal delivery of these compounds into the eye. By combining its compounds with innovative delivery approaches, the company strives to optimize the efficacy, safety, convenience and cost- effectiveness of its product candidates.
The company's lead development program is centered on advancing sirolimus (rapamycin) as a potential next-generation therapeutic for the treatment and prevention of wet age-related macular degeneration (wet AMD) and the treatment of diabetic macular edema (DME), a manifestation of diabetic retinopathy.
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Posted: October 2007