AHA: Early Results Promising for Antihypertensive Vaccine


ORLANDO, Nov. 7 -- An experimental vaccine may control morning blood pressure better than the daily medications it aims to replace, researchers said here.
Action Points
Explain to interested patients that the vaccine will require further study before it can become available clinically.
This study was published as an abstract and presented orally at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed publication.
The vaccine, which spurs immune response by binding angiotensin II to a virus-like particle, improved daytime systolic blood pressure better than placebo (P=0.0498), according to the results of an early-phase trial presented at the American Heart Association meeting.
The vaccine delivered its greatest benefit in the early morning hours between 5 a.m. and 8 a.m., when systolic pressure was 25 mm Hg lower than in the placebo group, and diastolic pressure was 13 mm Hg lower, reported Juerg Nussberger, M.D., of the University Hospital of the Canton of Vaud in Lausanne, Switzerland, and colleagues.
The majority of strokes and myocardial infarcts occur in the morning when blood pressure rises naturally with arousal from sleep but medications are at their lowest concentrations before patients take their morning pills, Dr. Nussberger said.
His group studied the vaccine CYT006-AngQb in 72 patients with mild to moderate hypertension in a double-blind phase IIa trial. Participants were randomized sequentially to receive injections of placebo, 100 µg vaccine, or 300 µg vaccine at baseline and at months one and three.
All patients in the vaccine groups had antibody responses, with higher concentrations in the higher dose group (P0.01). The half-life was 123 days, suggesting that the agent could be given three times a year, Dr. Nussberger said.
The larger vaccine dose reduced daytime ambulatory blood pressure, measured two weeks after the final dose, by 5.6 mm Hg for systolic pressure (P=0.007) and 2.8 mm Hg for diastolic pressure (P=0.034).
This improvement compared with baseline was significant versus placebo for systolic blood pressure (P=0.0498), although the comparisons between the lower vaccine dose and placebo were not.
The larger dose controlled systolic and diastolic pressure to the greatest degree compared with baseline in the early morning hours, (P0.0001 and P=0.0035, respectively).
"I have never seen such a thing with a drug," Dr. Nussberger said. "We didn't expect that, but it's crisp and clear."
Patients were followed for 12 months for safety outcomes without any treatment-related adverse events. Nearly all patients had a mild adverse event, typically at the injection site.
Headaches were also more common with the vaccine over the first couple of days after injection. These affected one-third of patients in the placebo and low-dose groups and two-thirds in the high-dose group, but none were severe.
A vaccine-based strategy for controlling hypertension is clearly not ready for clinical use, commented Daniel W. Jones, M.D., of the University of Mississippi Medical Center in Jackson, Miss., and president of the AHA. Further study will be needed, he said, particularly to determine if it is effective in older patients who typically have a blunted response to vaccines.
Nevertheless, it offers a "more permanent approach to blood pressure" that could provide an answer to medication noncompliance, he said.
The study was funded by Cytos, which is developing the vaccine.
Dr. Nussberger reported being a consultant for Cytos. Dr. Jones reported no conflicts of interest. Several of the co-authors of the study are employees of Cytos.Primary source: American Heart Association meetingSource reference: Nussberger J, et al "CYT006-AngQb, a Vaccine Against Hypertension Targeting Angiotensin II, Reduces Early-Morning and Day-Time Blood Pressure" AHA Meeting 2007; Abstract 2519.