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Vaccine could replace pills for hypertensive patients
7 November 2007
MedWire News: A novel vaccine that acts on angiotensin II appears to be well tolerated and effective at lowering daytime ambulatory blood pressure (BP) levels, reveal phase IIa clinical trial findings reported at the American Heart Association Annual Scientific Sessions in Orlando, Florida.
If the findings are borne out in further research, the vaccine could help hypertensive patients control their blood pressure by obviating the need to take medication - often a combination of different tablets - on a daily basis.
Lead investigator Juerg Nussberger (Centre Hospitalier Université Vaudois, Lausanne, Switzerland) explained: \"Despite the fact that effective drugs are available, only about one out of four people has their blood pressure successfully controlled. Many patients are unable or unwilling to take pills every day for the rest of their lives. If we could add or substitute a vaccine that would need to be given just every few months, I think we could achieve better control of high blood pressure.\"
The study showed that the vaccine blunted the early morning surge in BP. Early morning surges are associated with a very high risk for cardiovascular events - and current pharmacologic interventions are often at their least effective during this time.
The vaccine - CYT006-AngQb - is a virus-like particle, coupled with an angiotensin II peptide to provoke an immune response against angiotensin II.
Nussberger and team studied the tolerability and exploratory efficacy of CYT006-AngQb in 72 patients with mild-to-moderate hypertension, defined as 140-179/90-109 mmHg.
Patients were assigned to receive three injections of 100 ?g or 300 ?g of the vaccine or placebo at 0, 1, and 3 months and then followed-up for 8 months.
Results at 12 months showed that the vaccine was well tolerated. Most adverse events were mild and were related to local injection site reactions, and there were no serious treatment-related adverse events.
Antibody responses to angiotensin II were strong after vaccination and greater at the higher dose (p<0.01), Nussberger reported.
Furthermore, daytime ambulatory BP levels were reduced by the vaccine at both doses, significantly so at the higher dose. At 14 weeks, daytime systolic BP and diastolic BP were reduced from baseline levels by 5.6 mmHg (p=0.007) and 2.8 mmHg (p=0.034), respectively, in the 300 礸 group. This decrease in systolic BP was also significant compared with the placebo group.
The vaccine had a pronounced BP-lowering effect in the early morning, between the hours of 05.00 am and 08.00 am. After correcting for placebo changes, the average systolic and diastolic BP levels at 08.00 am were 25 and 13 mmHg lower, respectively, than baseline levels.
Commenting on how the vaccine could be so potent early in the morning, co-author Martin Bachman (Cytos Biotechnology AG, Zurich, Switzerland) likened its action to that of a sponge. \"The sponge empties out during the night when little angiotensin II is produced, so it is able to take up all the angiotensin II produced early in the morning,\" he said.
Nussberger said the next step in developing the vaccine will be to determine the optimal dose and injection regimen.
American Heart Association Annual Scientific Sessions; Orlando, Florida: 4-7 September
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发表于 2007-11-14 07:57:13