Localized Delivery of Sirolimus to Vascular Grafts

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DESCRIPTION (provided by applicant): The Company's business and research efforts are focused on developing and commercializing a novel drug delivery approach to prevent the abnormal ingrowth of tissue (intimal hyperplasia) that can block the flow of blood through artificial blood vessels (vascular grafts) that are widely used in hemodialysis patients, and to restore blood flow through diseased arteries in the lower limbs. Although synthetic grafts in larger arteries perform well, there remains a compelling need to improve the performance of smaller diameter grafts that fail primarily as a result of obstructive tissue ingrowth. These grafts typically fail within a few months-to-years after surgical placement. Approximately $3B annually is spent on graft maintenance. The Company has developed a method for infusing drugs directly through the porous wall of clinical vascular grafts, such as expanded polytetrafluoroethylene (ePTFE), so that drug is infused only into the slowest moving blood layers along the graft wall. Consequently, drug is transported distally, localizing at troublesome venous anastomotic sites where abnormal tissue proliferation occurs. This method - based on well-known engineering principles - turns out to be extremely efficient for localizing drug delivery. Proof-of- concept with this approach has recently been confirmed in non-human primate studies, completed at the Oregon National Primate Research Center, showing that very low doses of sirolimus, locally infused through ePTFE grafts, can effectively and safely abolish the tissue ingrowth that would otherwise lead to graft obstruction. The goals of this Phase I SBIR application are to develop a FDA acceptable injectable sirolimus formulation that is: 1) soluble and stable for at least 30 days at body temperature 2) biocompatible with a commercially available low flow, refillable internal pump, tubing and graft cuff, and 3) that demonstrates the appropriate pharmacokinetic profile to provide sirolimus at effective local drug concentrations to suppress ePTFE graft failure without eliciting systemic immunosuppression. PUBLIC HEALTH RELEVANCE: The goals of this grant application are to develop a FDA acceptable injectable sirolimus formulation that is: 1) soluble and stable for at least 30 days at body temperature 2) biocompatible with a commercially available low flow, refillable internal pump, tubing and graft cuff, and 3) that demonstrates the appropriate pharmacokinetic profile to provide sirolimus at effective local drug concentrations to suppress ePTFE graft failure without eliciting systemic immunosuppression.