<http://www.montereyherald.com/health/ci_5720666>:

"Health officials repeated safety concerns about an experimental group
of HIV drugs Friday, days before government advisers will recommend
whether the first drug from the class merits approval.

[...]

Pfizer believes there is a clear unmet need for new drugs to fight HIV
in patients for whom other, older drugs no longer work. Celsentri is
unlike any other HIV medicines now on the market in that it targets
the cells of patients and not the virus itself.

[...]

The FDA and Pfizer both said that studies showed adding Celsentri to a
traditional HIV treatment regimen was more effective in dropping the
virus below detectable levels in patients.

But the FDA continues to be concerned about potential safety issues
with the entire class of drugs, called CCR5 receptor antagonists.
Those issues include the possibility the drugs could increase the
likelihood of infection, lymphoma or liver damage in HIV patients.

They've also been linked to heart rhythm changes in laboratory
animals.

Most worrisome is that the drugs could accelerate a shift from one
variant of HIV to a second, which is most often seen in the sickest
AIDS patients. Patients on Celsentri likely would have to be tested
regularly to monitor whether the drug is driving such a shift.

[...]

Since 1987, the FDA has approved 29 drugs, including combination
medicines, in four different classes to fight HIV. CCR5 receptor
antagonists would represent a new, fifth class."