ActivBiotics Inc., of Lexington, Mass., reported disappointing data from its Phase III study of rifalazil, an antibiotic aimed at treating intermittent claudication associated with peripheral arterial disease, showing that the drug failed statistically any clinically-relevant PAD parameters.

Results from the PROVIDENCE-1 (Prospective Evaluation of Rifalazil Effect on Vascular Symptoms of Intermittent Claudication and Other Endpoints in Chlamydia Seropositive Patients) study, reported in a late-breaking session at the American Heart Association's annual meeting in Orlando, Fla., showed that treatment with rifalazil did not yield any improvements in walking distance, which was the primary endpoint, or in claudication onset times. The company reported that the efficacy signal in the rifalazil-treated group was only 4 percent greater than the placebo group.

The study enrolled 297 patients with intermittent claudication due to PAD, and who also had high levels of antibodies to C. pneumoniae, an infections believed to play a role in accelerating the course of vascular diseases, such as PAD, by increasing inflammation in the arterial wall.

Rifalazil is designed to eradicate the C. pneumoniae bacteria. The trial's primary endpoint, a change in baseline peak walking time, was determined using treadmills. Patients also filled out quality-of-life questionnaires to chart progress at times throughout the one-year study.

Based on results, ActivBiotics concluded that C. pneumoniae likely does affect PAD in a way that can be treated with antibacterial therapy.

"Walking impairment in PAD patients remains a significant unmet medical need, but antichlamydial therapy does not appear to be the solution," Michael Jaff said in the company's press release. Jaff, an assistant professor at Harvard Medical School and medical director of the Vascular Center at Massachusetts General Hospital, chaired the trial's steering committee.

Rifalazil also is being tested in a 72-patient Phase II trial to examine the antibiotic's effect on atherosclerotic changes in the carotid artery.

Beyond that product, privately held ActivBiotics has in its pipeline M40403, a small molecule for inflammatory conditions, and compounds aimed at complicated skin and skin structure infections caused by Staphylococcus aureus, including methicillin-resistant S. aureus.

In other AHA news:

• Advanced Cell Technology Inc., of Los Angeles, said a clinical study of its myoblast therapy demonstrated marked improvement in heart failure symptoms after 12 months, indicating that the hearts of patients receiving ACT's therapy showed less cardiac remodeling (an increase in the size of the heart that signifies worsening of function) than control patients. A total of 23 patients with poor cardiac output and congestive heart failure enrolled in the study, with 11 in the control group getting standard therapy and the rest randomized to doses of 30, 100, 300 or 600 million autologous skeletal myoblasts (ASMs) via intracardiac injection. The company plans a Phase II trial, expected to start enrollment in the next few months, to use 3-dimensional guided catheter-based delivery for ASMs in ischemic cardiomyopathy.

• Nabi Biopharmaceuticals, of Boca Raton, Fla., successfully completed a Phase IIb trial of NicVAX (nicotine conjugate vaccine), its product for treating nicotine addiction and preventing smoking relapse, with final 12-month data confirming the significant trends seen in the six- and nine-month data for both smoking cessation and long-term smoking abstinence. A statistically significant number of patients were able to quit and remain abstinent over the 12-month period. Sixteen percent (eight of 51 patients) of those treated with the NicVAX optimal schedule and dose of 400 mcg showed continuous 12-month abstinence compared to 6 percent (six of 100 patients) on placebo. Data also showed that the high antibody responder group (top 30 percent of antibody responders) showed continuous abstinence rates almost three times those of the placebo group.