Washington Blade - October 25, 2007
Dyana Bagby

The STEP trial in the U.S. and other countries was halted Sept. 21 after three years of research when it was determined by an independent Data & Safety Monitoring Board that the vaccine did not stave off HIV infection nor reduce the virus in those who became infected.

In an Oct. 23 press release, the National Institute of Allergy & Infectious Diseases, part of the NIH, stated a similar trial in South Africa, known as the Phambili study and using the same HIV vaccine, also halted enrollment and immunizations. The South African trial was stopped because an independent DSMB there also determined the vaccine was not working.

The DSMB in South Africa also recommended volunteers be told whether they received the vaccine or placebo, be strongly encouraged to return to their study sites for protocol-related tests, and be counseled about the possibility "that those who received the vaccine may have an increased susceptibility to acquiring HIV infections," according to an NIH press release.

In the U.S., STEP study volunteers are also being contacted and told about the Phambili study, said Sarah Alexander of the HIV Vaccine Trials Network.

"We are talking to each and every participant and asking them to assume the worst and act as if they've been put at greater risk and to be extra vigilant in being safe," she said.

'A trend we are not comfortable with'

In the Phambili trial, 19 people who received the vaccine became infected with HIV, compared to 11 in the placebo group, Alexander said. The Phambili trial had approximately 800 volunteers. Globally, some 3,000 volunteers participated in the HIV vaccine trial. All volunteers were HIV negative when they began participation.

While the Phambili numbers are not statistically significant, "this is a trend we are not comfortable with," Alexander added.

And if the volunteers in South Africa are being "unblinded" and told if they received the vaccine or the placebo as well as being counseled, then the same has to be done in the U.S., Alexander said.

"Anyone who comes and asks to be unblinded can be unblinded," she added.

"Our No. 1 objective is safety," she said. "Volunteers are the most altruistic people."

She added that for vaccine participants, this is an "unnerving" development and investigators are working around the clock to figure out what the data means.

"We're as confused as you are - we don't know if this is related to the vaccine or behavior or by chance," she said. "And the truth is we may not be able to know."

Approximately 130 people at Emory University's Hope Clinic participated in the STEP study and are being contacted now about the results of the Phambili trial, said Dr. Mark Mulligan, executive director of the Hope Clinic, located in Atlanta.

A major difference for those participating in the Hope Clinic trial is that all participants received the necessary three injections while many in the South African trial only received two, he said.

"The vaccine itself cannot cause HIV - we must stress that," he added.

"We want our volunteers to know questions have come up," Mulligan added, "and are informing them in a letter that more infections turned up in the vaccine group and not the placebo group."

When "unblinding" of U.S. participants will occur is yet to be determined, Mulligan said, as study sites follow protocol.

"Detailed analyses of the available data are being conducted, including analyses to better understand if there may be an increased susceptibility to HIV infection among those volunteers who received the vaccine. The vaccine itself does not cause HIV infection," a Merck press release states.

The first detailed review of the STEP data will occur on Nov. 7 at a special open scientific session of the HIV Vaccine Trial Network in Seattle, according to Merck.

An e-mail obtained by Southern Voice, sent from the NYU School of Medicine to an HIV vaccine volunteer participant, stated that "there is a possibility that the vaccine may have made it easier for people [who received at least two of the three injections] to get infected with HIV.

"Because the number of people in the study who were infected with HIV is relatively small, it is hard for statisticians (people who analyze the data) to definitively link the vaccine to increased possibility of HIV infection," states the e-mail from the NYU School of Medicine.

"This means that factors other than the vaccine may explain the difference. It could mean that the apparent increased number of HIV infections in the vaccine arm may be due to differences among study volunteers that have nothing to do with the vaccine, such as sexual practices, recreational drug and alcohol use, health differences, or chance alone," the e-mail added.

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