Data Safety Monitoring Board Closes HIV Vaccine Study -- the End of Adenovirus as a Vaccine Vector?

April 29th, 2013

Data Safety Monitoring Board Closes HIV Vaccine Study — the End of Adenovirus as a Vaccine Vector?

On Friday, the NIH announced that HVTN 505, a clinical trial of an HIV vaccine using an adenovirus vector, would be stopped based on a finding of futility by an independent DSMB.

The study had enrolled some 2500 high-risk gay men in the United States. Here are the three key findings leading to this action:

New infections in placebo arm: 30
New infections in active vaccine arm: 41
Among those who got infected, no effect of the vaccine in lowering HIV viral load compared with placebo

While the difference between the two is numerically but not statistically different, it’s clearly in the wrong direction.

Furthermore, it hearkens back to the results of the STEP study — another HIV vaccine trial using an adenovirus vector, Ad5 — that demonstrated an increased susceptibility to HIV infection among participants with pre-study immunity to adenovirus. Though HVTN 505 excluded those who had antibodies to Ad5, the results from HVTN 505 suggest that something else might be going on, something related to Ad5 and protective HIV immunity.

(Confession: I have no idea what that might be.)

As with all studies closed by DSMBs, the detailed data analysis starts in earnest now. And though this outcome is clearly disappointing, it will be fascinating to see what the full results show, and most importantly whether we can learn anything about a way forward in this challenging research area.

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April 29th, 2013