Tests of blood pressure vaccine promising: report

A vaccine appears to be safe and effective in lowering blood pressure in people with mild-to-moderate hypertension (high blood pressure), according to results of a study reported in The Lancet medical journal this week.

Lifestyle interventions and drug therapy are the mainstays of treatment for hypertension, but both require patient compliance to be effective, Dr. Ola Samuelsson and Dr. Hans Herlitz, from the Sahlgrenska University Hospital in Goteborg, Sweden, write in a related commentary. "If vaccination against high blood pressure were safe and effective in the long run, it might solve many problems of non-compliance."

Samuelsson and Herlitz say the results of the current study "are intriguing and promising, and vaccination for hypertension may turn out to be very useful in many patients."

The study involved 72 adults with mild-to-moderate high blood pressure who were randomly assigned to receive shots of the experimental vaccine called AngQb or inactive placebo at the start of the study and 4 and 12 weeks later.

The main focus of this study was on safety and tolerability, but 24-hour blood pressure was assessed prior to treatment and at week 14, Dr. Martin F. Bachmann, from Cytos Biotechnology AG in Zurich-Schlieren, Switzerland, and colleagues explain in their report.

Five patients dropped out of the study and were excluded from the efficacy analysis. All of them were in the AngQb group. Two of these patients were given AngQb 100 micrograms and three given AngQb 300 micrograms.

Two serious adverse events occurred in each of the vaccine groups and one occurred in the placebo group; none were thought to be treatment related.

Most adverse effects were mild, transient reactions at the site of injection. However, three patients in the low-dose AngQb group and four in the high-dose group experienced mild flu-like symptoms.

Vaccination with high-dose, but not low-dose, AngQb led to significant reductions in the average daytime blood pressure at week 14, relative to placebo, the team reports. "The drop in blood pressure was especially pronounced in the early morning," note the investigators, "when most cardiovascular events occur."

While the results are encouraging, the researchers point out that "this exploratory study still had a limited sample size, and the efficacy of AngQb was shown in an otherwise healthy hypertensive population. Later stage clinical trials will be needed to show efficacy and safety in a broader hypertensive population."

SOURCE: Lancet March 8, 2008.