In 2009, the results of an anti-HIV microbicide containing the drug PRO 2000 were released.

It did jack shit.

Rather than dumping a product that worked in the lab and in non-human primates, but not in humans, they tried again. At a higher dose– Study 1 had the drug at 0.5%. So this study had a no-drug control, the 0.5% ‘treatment’ group (which they knew was not therapeutic), and a 2.0% treatment group.

It didnt work at 2.0% either.


I hope they do another trial next year at 8.0%. Surely that will work.

[/bad mood ERV]

(Anti-HIV microbicide that actually kinda works)


  1. #1 daedalus2u
    September 20, 2010

    I was at a microbicide conference a year ago and microbicides were being pushed with an unrealistic optimism.

    I made a comment that because microbicides would never be as effective as a properly used male condom, there would never be a developed world market for them because of liability concerns. The hyper-optimistic dude disputed that. He said he thought they could be made as effective as the male condom and that there could be developed world markets for such things.

    I don’t think there will be another trial. There is no developed world market for such things and the microbicide effort is being badly run (in my opinion). They rushed relatively ineffective things into massively large and expensive clinical trials that have now failed.

    You did get the thing I sent you on my microbicide? That is something that might work, and it could be used in conjunction with just about anything.

  2. #2 Paul Browne
    September 21, 2010

    daedalus2u, while I was pleased when I read the results of the trial using the Tenofovir containing gel I tend to agree. Even if these gels can be made several times more effective than they currently are they will still come a relatively poor 2nd to correct condom use. Useful in limited circumstances perhaps, but something of an admission of failure.

    I suspect the reason why PRO 2000 worked in preclinical tests in macaques (and in vitro etc.) but not in women in the field was that the way the virus is administered intra-vaginally in these studies does not accurately represent actual sexual activity, which presumably adversly affects the protective gel layer. The failure of the gel as a barrier would also explain why a gel containing a powerful anti-viral (tenofovir) has been the most successful so far, it’s basically working as an intra-vaginal antiviral than as a barrier.

  3. #3 che
    September 21, 2010

    In all these trials counselling and condom use is heavily promoted to all participants and they all recieve STD treatment. Yet women in these trials are still being infected because they cannot negotiate condom use with their partners. Thats the heart of the problem.

    I think that the most effective intervention for preventing HIV infections is probably going to be a social, rather than medical intervention.

  4. #4 Vicki
    September 21, 2010

    Yes, in a sense that gel is an admission of failure. Or an admission of not even trying: how many groups (whether they’re focused on AIDS or not) are trying to change society enough that all, or even most, women can negotiate condom use every time? Or that women can negotiate for a closed relationship and count on that meaning actual exclusivity rather than one or both people involved having sex with other people but trying to hide it?

    Consider the number of people in nominally-monogamous heterosexual marriages in the U.S. who admit to affairs. I gather that in many such relationships, asking one’s partner to use a condom instead of or in addition to other contraception may be interpreted as either an accusation of, or admission to, an affair. It shouldn’t be, but such things are often irrational.

  5. #5 Richard Jefferys
    September 22, 2010

    You have things a bit mixed up here, the two articles are about the same trial MDP 301, the 2% arm was stopped early for lack of efficacy by the DSMB (in Feb 2008) but the 0.5% arm continued – the 0.5% results were announced last December but only published this week. Nobody would get away with starting a trial with an arm using an approach already shown to be ineffective. There was a smaller phase IIb trial of the same product at 0.5% that reported a trend toward efficacy (result was announced at CROI in 2009) but the larger MDP 301 result showed that was spurious

  6. #6 Rorschach
    September 22, 2010

    Aussie, Aussie, Aussie !!!

    Scientists reveal HIV cell mystery

  7. #7 ERV
    September 22, 2010

    omg, thank you, Richard– Theyre both MDP 301. Oh my god I totally raged out thinking these were different (HUGE) trials.


  8. #8 kmn
    September 24, 2010

    Not to mention, MDP is an older study. Visit for more up to date info on microbicide research.

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