HIV is a wily foe. It seems that no matter what we throw at it, the virus changes and gets around it. We truly are dealing with a shape shifter.
And now as we’re learning more about the new class of co-receptor inhibitors, it seems that resistance will take a whole new turn. Instead of drugs binding to an enzyme and blocking HIV that way, it may be the case that the co-receptor blockers make the receptor change shape. Shape shifter indeed!
I’d like to thank Positively Aware for giving me the opportunity to edit this special issue on resistance. I learn a lot when I write, and this case is no exception. Each time I checked, articles kept popping up with a focus on some new wrinkle in resistance testing or its interpretation. For example, a study presented at a conference last fall reported on the successful use of artificial intelligence (computer analysis) to develop treatment recommendations based on genotypic resistance test results.
There’s no question that resistance testing is a significant advance in HIV care and has made a very positive difference in treatment. At the same time, as you’ll see in the articles in this issue, it’s continuing the push towards specialization. Doctors who aren’t HIV specialists may still deliver good care, but I honestly don’t know how they can keep up with all of the various considerations on resistance testing and how to use it in their practice—along with all the other important developments in HIV treatments and their side effects! As we learn more about resistance, and as the tests become more sophisticated, it becomes more and more difficult to read and interpret them.
The first article in this issue is kind of a “nuts and bolts” introduction to resistance testing. It defines many of the terms that are used in the later articles, including wild type, mutation, genotypic and phenotypic testing, and cross-resistance. Hopefully it will equip you to better understand resistance and the articles that follow.
The second article, by Dr. Chad Zawitz, describes how resistance testing is used in regular clinical practice. It discusses treatment guidelines on the use of resistance testing (which change every few months), some considerations on payment for genotypic and phenotypic resistance testing, and special concerns for incarcerated populations.
The third article, by Dr. Trevor Hawkins, goes into more detail on the limitations and challenges in using resistance testing. What do clinicians need to keep in mind when looking at resistance test results? What about new mutations that can reduce or reverse the effect of existing mutations? Are the interpretations that come with resistance test results reliable? What aspects of patient behavior can overwhelm the impact of viral mutations? Can drug level boosting make a difference?
The final article, by Dr. Andrew Zolopa, discusses making treatment decisions for patients with virus that is already resistant to medication. This is unfortunately becoming more and more common. A recent analysis showed that 13% of patients had virus that already had resistance mutations affecting nukes, NNRTIs, and protease inhibitors. This obviously complicates the selection of the next treatment regimen and highlights the need for resistance testing.
Viral resistance is truly a case for me, as the song says, that “the more I learn, the less I know.”
I hope you find this issue informative and helpful.
Sincerely,
Bob MunkCoordinator,
AIDS Info Net
http://www.aidsinfonet.org
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