Peripheral arterial disease (PAD) is characterized by a reduction in blood flow to tissues outside of the heart, most commonly the lower leg, and usually is the result of atherosclerosis (the buildup of fatty deposits in arteries). Reduced blood flow leads to a decline in the health and functioning of the affected tissues. In the more severe form of critical limb ischemia (CLI), reduced transport of oxygen to tissues results in limb necrosis (ulcers and gangrene) and pain at rest.
PAD affects an estimated 8 million Americans (up to 20% of Americans aged 65 or older), and 35% of PAD patients experience hospitalization within 9 months of diagnosis. The yearly incidence of CLI is estimated at 125,000 to 250,000 US patients per year; 1-year mortality is 25%, but rises to 45% in the 40% of CLI patients whose only treatment option is major limb amputation.
Reduced blood flow to heart muscle is termed ischemic heart disease (IHD) and, like PAD, is usually the consequence of atherosclerosis. Current treatment regimens include drugs to maximize blood flow as well as interventions to restore the blood supply (angioplasty and bypass surgery).
Vical believes that its pDNA delivery technology represents the promise for new therapies for PAD and IHD. Delivering plasmids which encode growth factor proteins has been well documented to induce the growth and development of new blood vessels, a process known as angiogenesis. As a result, blood flow can be restored, rescuing tissues from the risk of ischemic damage and death.