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Author Topic: Celsentri CCR5-tropic HIV. tropism assay when does hiv make the switch  (Read 2287 times)

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Offline bimazek

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  • Posts: 781

Celsentri will only be effective against CCR5-tropic HIV

Because "CXCR4-tropic" and "dual-tropic" HIV is more common in people who have been infected with HIV for several years


How many years on average?????

Is this new med for people newly infected???

basically after say 15* years the virus changes to "CXCR4-tropic" and "dual-tropic" HIV so a CCR5 inhibitor will not work       (15* years--- i exagerate the number to make the point, i heard it is another number but not sure)

but a Dr. told me it was like 5 years or something???  so has anyone heard

obviously a test a new test called tropism assay    tropism test tells for sure

but what is the short answer

80/20 rule

80% of people who have the virus less than 7 years have CCR5 so this drug will work?????

anyone know the answer??????

is this drug for newbies for medium bees (3-9 years) or what exactly
from this site....

Celsentri will only be effective against CCR5-tropic HIV. It will not be effective against virus targeting CXCR4 (and will have a limited effect against HIV with the ability to target both receptors). Because "CXCR4-tropic" and "dual-tropic" HIV is more common in people who have been infected with HIV for several years – the people who are most likely going to be using Celsentri – a new laboratory test, Monogram Bioscience's Trofile® tropism assay, will be necessary before Celsentri is used, to determine if treatment with the drug will be useful.

Even among patients who begin Celsentri treatment with CCR5-tropic HIV, there is the possibility that their virus will switch to the CXCR4 receptor during therapy, meaning that the addition of Celsentri will no longer have any significant benefit. Much like drug-resistance testing, tropism testing can be ordered by a healthcare provider if Celsentri treatment failure is suspected.

What's more, because CXCR4-tropic HIV is usually seen in people who have advanced infection, experts have speculated that the emergence of CXCR4-tropic virus during entry inhibitor therapy would result in more rapid disease progression. In another Phase III study, however, patients who experienced a "switch" to CXCR4-tropic virus while taking Celsentri actually ended up with significantly greater CD4 cell counts. In other words, while therapy with a CCR5 inhibitor may not be virologically effective in patients who experience a switch to CXCR4-tropic HIV, it does not appear to be harmful.

Pfizer is committed to providing the FDA with long-term follow-up data from its ongoing clinical trials, as well as pediatric research and a patient registry, to help settle lingering questions and concerns. For its part, the FDA did not specify when it would issue an agency decision regarding the approval of Celsentri, but official word is expected in the coming weeks.

Offline Central79

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  • Posts: 527
Well, I think that in the majority of patients, HIV continues to use the CCR5 co-receptor permanently if it can.

After all, the MOTIVATE 1 and 2 studies that prove maraviroc/celsentri's efficacy were all done in highly treatment experienced patients - implying that they've had HIV for some time. I mean, I understand all of the patients were tested to make sure that their virus used CCR5, but if the switch to CXCR4 was really common, then it would have been hard to do the trials. And not much point in developing the drug from Pfizer's PoV.

So I'm not sure it's something that we really need to worry about - by the time most of the newer members here have to worry about their virus changing tropism, we will have something new. And the already treatment experienced people here will likely have a shot at maraviroc, and if that doesn't work there's plenty in the pipeline - darunavir and that new NNRTI by Tibotec and a lot more coming through.

I'm not going to worry about my virus changing tropism just yet.

« Last Edit: April 25, 2007, 03:53:21 PM by Matt Mee »
Diagnosed January 2006
26/1/06 - 860 (22%), VL > 500,000
24/4/06 - 820 (24.6%), VL 158,000
13/7/06 - 840 (22%), VL 268,000
1/11/06 - 680 (21%), VL 93,100
29/1/07 - 1,020 (27.5%), VL 46,500
15/5/07 - 1,140 (22.8%), VL not done.
13/10/07 - 759 (23.2%), VL 170,000
6/11/07 - 630 (25%), VL 19,324
14/1/08 - 650 (21%), VL 16,192
15/4/08 - 590 (21%), VL 40, 832

Offline HIVworker

  • Member
  • Posts: 918
  • HIV researcher
It is a how long is a piece of string question.
NB. Any advice about HIV is given in addition to your own medical advice and not intended to replace it. You should never make clinical decisions based on what anyone says on the internet but rather check with your ID doctor first. Discussions from the internet are just that - Discussions. They may give you food for thought, but they should not direct you to do anything but fuel discussion.


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