Thai AIDS vaccine — Too good to be true?

Scientists from around the globe announced limited success of a vaccine to protect people in Thailand from getting HIV, the virus that causes AIDS, two weeks ago. Since then, some scientists have raised questions about the study’s claims and how they were announced. Dr. Michael Lederman, a Case Western Reserve University School of Medicine professor and co-director of the Center for AIDS Research in Cleveland explains why the claims surprised him.

CLEVELAND, Ohio — Scientists from around the globe announced limited success of a vaccine to protect people in Thailand from getting HIV, the virus that causes AIDS, two weeks ago.

It was the first time a vaccine had shown any success at protecting people from the deadly virus. Many hailed the results, though limited, as important. But even then, the scientific community seemed skeptical about the vaccine study.

That’s partly because scientists from the U.S. Army, the National Institutes of Health (NIH), the Thai Ministry of Public Health and two companies that tested the vaccine last year could not explain why it appeared to protect a small percentage — about one in three people — from AIDS, while offering no protection to others, according to the New York Times.

On Monday, Jon Cohen, a longtime blogger on AIDS research, wrote in ScienceInsider that some researchers who received confidential briefings are complaining that a fuller analysis of the data “undermines even cautious claims of success, and they are raising questions about the way the results were announced.

In the Jan. 16 issue of Science magazine, AIDS researcher Dr. Michael Lederman and 21 other researchers said there is no “persuasive data” that the experimental vaccine would help protect against HIV infection.

Lederman, the Scott R. Inkley Professor of Medicine at Case Western Reserve University School of Medicine, and co-director of the Center for AIDS Research at Case and University Hospitals Case Medical Center, sat down with MedCity News this week to explain his reaction to the study of the vaccine. Lederman also is principle investigator of the AIDS Clinical Trials Unit at Case and UH, which belongs to a national clinical trials group that’s part of the NIH.

Q. How significant is the preliminary reporting on the Thai vaccine study?
A. I don’t know yet whether it’s going to be important. But the outcome was surprising.

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Q. Surprising? In what way?
A. Because the two vaccine candidates that are part of the study were not especially immunogenic in earlier studies. And we propose in current dogma to anticipate certain kinds of immune responses from vaccines that may be protective. The two vaccines in the Thai study didn’t generate these kinds of responses in the earlier studies. So there was a lot of controversy about the launch of this study.

Q. Could the dogma be wrong?
A. Dogma isn’t always right. Surprising results could actually be very interesting. But I think at this point, it’s too early to know whether this is confounded by other aspects of the cohort in the study. We really need to see more. And in fact, more will be available in mid-October at the Paris vaccine meeting.

Q. Are you going to the meeting?
A. Sadly, I won’t be there. I have an earlier commitment. If it turns out that this 31 percent or so protection is a plausible readout of the events as they happened, then it could be very interesting to try to decipher what about the vaccine provided protection. But I surely didn’t predict that this would be protective. I think we have to wait and see what the further analysis will show.

Q. In  your AIDS research, do you work with vaccines?
A. Just a little bit.

Q. Is that work a secret?
A. It’s not a secret. It’s just that we’ve been working on this project for five years, and we haven’t had a hit yet. It’s one of these things that is high risk/high yield. I love the project, but we’ve not found anything yet that’s been really helpful. I do other work on vaccines.

Q. Are you doing other vaccine work?
A. I’m interested in the determinants and predictors of vaccine responsiveness in humans. So we’ve done a lot of studies like that in HIV infection. We look at how people with HIV infection and HIV-related immune-deficiency respond or fail to respond to routine immunizations that are part of routine medical care. We use that as a probe to evaluate the mechanisms of immune-deficiency in HIV infection, which is the focus of my work. It’s largely pathogenesis.

Q. Pathogenesis?
A. How does HIV make you sick? What’s driving immune-deficiency. And if you learn more about that, then perhaps you can figure out how to reverse it.