Government shuts down HIV/AIDS vaccine trial

A key clinical trial that was working towards developing a vaccine to boost immunity to human immunodeficiency virus, also known as HIV, was ordered shut down this week. Apparently an independent panel of safety experts found that participants getting the vaccine appeared to be slightly more likely to contract the virus and no better at suppressing its replication than those who got a placebo.

The genetically engineered HVTN 505 vaccine, which was being used by the investigators involved in recruiting volunteers and running the trial at 21 sites across the country, including the AIDS research Alliance of America in Los Angeles, were ordered to stop immunizing volunteers and to inform the subjects enrolled in the study whether they got the experimental vaccine or the placebo. Nearly 2,500 subjects participated -- 1,250 men or transgender people who have sex with men got the investigational vaccine, while 1,244 received the placebo vaccine.

In a statement released Thursday afternoon, NIAID said there was a “non-statistically significant increase in HIV acquisition among volunteers in the investigational vaccine group compared to those in the placebo group.” The announcement came Thursday from the National Institutes of Health‘s National Institute of Allergy and Infectious Diseases, or NIAID, which developed the HVTN 505 vaccine and launched the advanced clinical trial in 2009.
Among volunteers who had been in the study a minimum of 28 weeks--enough time for the vaccine to have prompted the expected immune response--27 HIV infections occurred among the vaccine group and 21 among those who got the placebo. Of 23 volunteers who became infected with HIV in the first 28 weeks of the study, 14 had received the three-shot investigational vaccine regimen and nine had received the placebo.

The experimental vaccine, failed to reduce the viral load of pre-infected volunteers, which was designed to prime the immune system to mount a robust defense against all three subtypes of HIV virus. It was also a disappointment in its primary aim -- as a treatment for those who were already infected with HIV. Among those who had been in the study at least 28 weeks and followed for at least 20 weeks after diagnosis, 30 participants--half from the placebo group and half from the study’s active arm--were found to have a measurable viral load.

Earlier clinical trials had suggested the HVTN 505 vaccine had a good record of safety in those who got it. Uncircumcised enrollees, however, were required to be circumcised as a condition of participation.

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Park Sae-jin swatchsjp@ajunews.com