Dr. Rajagopalan opened by noting that the level of disability associated with severe intermittent claudication is comparable with that of Class III congestive heart failure. About two thirds of patients have difficulty walking the equivalent of half a city block.

The goal of the Regional Angiogenesis with Vascular Endothelial Growth Factor in Peripheral Arterial Disease (RAVE) trial was to evaluate whether intramuscular delivery of endothelial growth factor would trigger angiogenesis in the affected limb and improve peak walking time, Gardner protocol exercise treadmill testing, or both in patients with severe disease.

Vascular Endothelial Growth Factor 121 was delivered intramuscularly as a transgene on a replication-deficient adenovirus, a technique that had achieved angiogenesis in animal models of coronary and peripheral ischemia.

Inclusion criteria were designed to identify people with severe, primarily unilateral disease with preserved inflow into the affected leg. Eligible patients had two baseline exercise treadmill tests with a peak walking time of 1 to 10 minutes and with the two results within 20% of each other. Potential subjects were also required to have adenoviral titers (Immunoglobulin M) of less than 1:50.

Exclusion criteria included general contraindications to growth factor treatment such as history of cancer or diabetic retinopathy; patients who were using either cilostazol or pentoxyfylline were only eligible if they discontinued the medication 1 or more weeks prior to baseline screening.

As shown in the flowchart, 229 people were recruited for the study, and 105 were randomized to placebo, low-dose gene therapy, or high-dose gene therapy based on diabetic status. Enrollment demographics showed that most patients had multiple risk factors for vascular disease, including diabetes (27%, 25%, and 30% for the 3 arms, respectively), active smoking, hypertension, and hypercholesterolemia.

Baseline circulation testing with use of an ankle brachial index showed that all three groups did, in fact, have primarily unilateral disease. Average index values for the affected leg were roughly 0.60, whereas values for the other leg were significantly higher (0.80 for placebo group and 0.90 for low-dose and high-dose gene therapy groups).

Safety data at 30 days after treatment were excellent, with no cases of cellulitis in the injected leg or increased liver function tests or increased skeletal muscle enzymes on blood testing. A dose-dependent edema in the affected leg was noted. Both placebo and low-dose groups had only mild edema, whereas there were some cases of moderate or severe edema in the high-dose group. There were no cases of bilateral edema.

Assessment of clinical endpoints at 12 weeks produced disappointing results: All three groups showed comparable increases in peak walking time and claudication onset time. Ankle brachial index values at rest and after exercise showed no change over time for any of the 3 treatment arms. A clinical measure of level of function showed that all 3 groups improved substantially from baseline. The same patterns were observed at 26 weeks.

The RAVE trial is the largest placebo-controlled adenoviral gene therapy trial to date for patients with cardiovascular disease. Gene therapy was shown to be safe through 52 weeks of follow-up, with the notation that edema was more common and somewhat more severe in the high-dose group. Perhaps most unexpected was the finding of a large, positive placebo response. There were no indications of treatment efficacy over placebo in any of the primary or secondary endpoints from baseline through 26 weeks.