Progressive multifocal
leukoencephalopathy (PML)

June 2007     View PDF     En español

Potent anti-HIV therapy

Several groups have reported symptom-free survival after a PML diagnosis of over ten years and counting for some people using potent anti-HIV therapy. Factors associated with improved survival include using an anti-HIV regimen with a protease inhibitor and changing to a new regimen after a PML diagnosis.

A more recent study shows extremely encouraging results, perhaps the best to date, with “enhanced” anti-HIV therapy. This is when Fuzeon (enfuvirtide, T-20) is added to a traditional regimen with protease inhibitors. At six months, the survival rate was 3 out of 4 people and the trend suggested this survival rate may hold to one year and beyond.

While there are no guidelines for anti-HIV therapy and PML, it would be fair to make a few assumptions based on gathered information. After a presumptive diagnosis of PML is made and whether or not a person elects to have a brain biopsy, it seems advisable to start or change to a new potent anti-HIV regimen including a protease inhibitor. Experienced neurologists who choose to treat PML with anti-HIV drugs once recommended using anti-HIV drugs that penetrate the blood-brain barrier. This included using high doses of AZT daily (1,000–1,200mg) because lower doses are not as effective at crossing this barrier. More recently, however, experts have changed their thinking about the importance of using drugs that cross the blood-brain barrier in a potent anti-HIV regimen when treating PML.

Increasingly they believe that the benefits of anti-HIV therapy are due to better immune responses throughout the body. This supports the notion of creating the most potent possible regimen based on resistance testing, history of anti-HIV drug use, and cross resistance issues. This is supported by the very encouraging results of the “enhanced” therapy study—where adding Fuzeon appears to have a profoundly beneficial effect, but is not believed to cross the blood-brain barrier whatsoever.
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