A microbicidal gel containing the antiviral drug tenofovir, that had shown lots of promise in stopping AIDS transmission in earlier trials, was cancelled on Friday because it wasn't working. The other parts of the trial, which were testing tenofovir in pill form, have also been cancelled due to lack of results.
This is a big disappointment in the fight against AIDS, because many researchers had such high hopes for this drug. Over 5,000 women were enrolled in the trial, which started in 2009, and since some data is still being collected, researchers aren't yet able to examine the data for answers as to why the gel failed to be effective in preventing the HIV transmission. Data will continue to be collected until 2012, so no definitive answers can be found until then, but researchers think the failure to be effective might lie in that too few women used the gel on a regular basis, it caused inflammation that allowed the virus to enter the body more easily, or that the dosing schedule was incorrect.