POZLife: Life from the Infected and Effected point of veiw.

Failed HIV vaccine study disappoints local participants

Posted by pozlife on September 28, 2007


When news came last week that the HIV vaccine trial by Merck & Co. was discontinued because studies showed the vaccine was ineffective, volunteer participant Scott Smith of southwest Atlanta acknowledged disappointment.

“I was bummed. But I knew what the chances were,” he said.

Smith, 39, a volunteer for the vaccine research for just over two years at the Hope Clinic, a subsidiary of Emory University, also said he knew there was a chance the vaccine would fail.

“I wasn’t hysterical because I know there are other vaccines being tested.”

Smith will continue going to his scheduled appointments for however long researchers want to follow participants to find other useful information in the failed trial.

“Every test helps us get closer to a vaccine,” he said.

Smith was one of approximately 130 people taking part in the high-profile HIV vaccine research study at the Hope Clinic.

Globally, some 3,000 volunteers participated in the vaccine research, all of whom were HIV negative when the Phase II clinical trial began. Most volunteers, including those at the Hope Clinic, were gay men because they are at a higher risk of contracting HIV, said Dr. Mark Mulligan, executive director of the Hope Clinic.

The vaccine trial, called STEP and funded by the National Institute of Allergy & Infectious Diseases, part of the U.S. National Institutes of Health, was stopped Sept. 21 after the independent Data Safety Monitoring Board reviewed safety data and and determined the vaccine “did not prevent infection.”

Merck’s was the first major test of a new strategy in HIV vaccine research. The first wave of attempts to develop a vaccine tried to stimulate antibodies against the virus, but that hasn’t worked so far.

The new effort — an approach that is being tried in most other current research — is aimed at making the body produce more of a crucial immune cell called killer T cells. The goal is to simultaneously “train” those cells, like an army, to quickly recognize and destroy the AIDS virus when it enters cells in the bloodstream.

In volunteers who received at least one dose of the three-dose Merck vaccine series, 24 cases of HIV infection were observed in the 741 volunteers who received the vaccine and 21 cases of HIV infection were observed in the 762 participants in the placebo group.

The vaccine also did not reduce the amount of virus in the bloodstream of those who became infected, Merck officials stated.

While not giving an exact number, Dr. Carlos del Rio, who is in charge of the STEP study at the Hope Clinic, said some local volunteers became infected with HIV.

All volunteers were repeatedly counseled about how to reduce their risk of HIV infections, including use of condoms, according to Merck.

Mulligan of the Hope Clinic said he was deeply disappointed in the news but added that vaccine research takes many, many years.

“While disappointment was my main reaction, the next step is, OK, this is science and we’ve gotten a clear and strong answer what direction not to take,” Mulligan added. “We knew it might work, that it might not work. And we learn from that experience, so in that sense, it has been successful. Now we can throw our energy and efforts into other candidate vaccines.”

The STEP study, considered “the lead horse” of HIV vaccine research, “has dropped out of the race,” Mulligan said. “And now the others become more important. The importance of these additional candidates are amplified by this result.”

Del Rio remains optimistic and said the Hope Clinic will participate in future HIV vaccine studies, one set to begin this fall.

Named PAVE 100, this HIV vaccine study will also draw on ways to make “killer T cells,” but will utilize DNA.

“This is not the end,” del Rio said.


One Response to “Failed HIV vaccine study disappoints local participants”

  1. Source: http://www.sciencedaily.com/releases/2007/10/071012080135.htm

    Science Daily — The search for a vaccination against HIV has been in progress since 1984, with very little success. Traditional methods used for identifying potential cellular targets can be very costly and time-consuming.
    The key to creating a vaccination lies in knowing which parts of the pathogen to target with which antibodies. A new study by David Heckerman and colleagues from Massachusetts General Hospital, publishing in PLoS Computational Biology, has come up with a way to match pathogens to their antibodies.
    At the core of the human immune response is the train-to-kill mechanism in which specialized immune cells are sensitized to recognize small peptides from foreign pathogens (e.g., HIV). Following this sensitization, these cells are then activated to kill cells that display this same peptide. However, for sensitization and killing to occur, the pathogen peptide must be “paired up” with one of the infected person’s other specialized immune molecules–an HLA (human leukocyte antigen) molecule. The way in which pathogen peptides interact with these HLA molecules defines if and how an immune response will be generated.
    Heckerman’s model uses ELISpot assays to identify HLA-restricted epitopes, and which HLA alleles are responsible for which reactions towards which pathogens. The data generated about the immune response to pathogens fills in missing information from previous studies, and can be used to solve a variety of similar problems.
    The model was applied to data from donors with HIV, and made 12 correct predictions out of 16. This study, says David Heckerman, has “significant implications for the understanding of…vaccine development.” The statistical approach is unusual in the study of HLA molecules, and could lead the way to developing an HIV vaccine.
    Citation: Listgarten J, Frahm N, Kadie C, Brander C, Heckerman D (2007) A statistical framework for modeling HLA-dependent T cell response data. PLoS Comput Biol 3(10): e188. doi:10.1371/journal.pcbi.0030188
    Note: This story has been adapted from material provided by Public Library of Science.

    Fausto Intilla

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: