The process of restenosis following a revascularization procedure, begins at the time of percutaneous coronary intervention (PCI). Restenosis has long been seen a major impediment of effective long-term interventional cardiology, necessitating repeated procedures to deal with in situ recurrent stenosis of the original targeted vessel. The restenosis rates are between 30 to 50% of patients treated with balloon angioplasty and between 15 to 30% of patients treated with bare metal stents. There is currently high enthusiasm for drug-eluting stents already approved for the market and which have an overall restenosis rate of \<3% as reported in published reports for most clinical trial patient populations. However, there are subsets of patients (e.g., diabetic patients and patients with diffuse small vessel disease) that have restenosis rates around 10% despite the use of drug-eluting stents. It is probably too early to conclude that the currently approved drug-eluting stents are a panacea to relieve coronary arterial obstruction due to atherosclerotic heart disease. In fact, with the increased usage of the current drug-eluting stents on the market, there are reports of problems such as late stent malposition, subacute and late thromboses, and aneurysm formations due to the vessel toxicity associated with this method of treatment. There remains a definite need for a simple, safe and durable solution to restenosis.
The development of devices such as intravascular ultrasound has led to a greater understanding of restenosis mechanisms, especially after coronary artery stenting. It is presumed that the pathogenesis of coronary artery restenosis after a revascularization procedure entails two major processes. The first component (viz., recoil and remodeling) involves the mechanical collapse and constriction of the treated vessel; however, coronary stents provide luminal scaffolding that eliminates recoil and remodeling. The second component of coronary artery restenosis after a revascularization procedure is the endothelial response to injury. Whereas, the former focus in modulating the pathophysiological mechanisms involved in restenosis centered mainly on inhibition of platelet aggregation and function, current targets of pharmaceutical agents for this condition have shifted to inhibitors of the cell cycle, smooth muscle cell proliferation and migration, synthesis of extra-cellular matrix, and inflammatory mediators. Many different agents are currently being evaluated in pre-clinical and clinical studies.
AVI-4126, the active ingredient of RESTEN-MP, is a proprietary antisense drug designed to interfere with the ability of human \<c-myc\> gene to translate mRNA into MYC protein. Slow-push intravenous administration of RESTEN-MP in pharmacological doses in the restenosis porcine model prevented subsequent in-stent stenosis.
In addition to the standard safety assessments, assessments of the potential therapeutic value of RESTEN-MP as a neointimal hyperplasia inhibitor include late loss between the time of stent placement and 6 months thereafter.
