Just a few days before an FDA advisory panel meets next Tuesday to review an experimental AIDS drug from Pfizer, agency reviewers reveal ongoing safety concerns about this entire new class of meds, called CCR5 receptor antagonists.

Both the FDA and Pfizer say studies showed that adding Celsentri to a traditional HIV regimen was more effective in dropping the virus below detectable levels in patients. But the agency worries about the possibility the drugs can increase the likelihood of infection, lymphoma or liver damage in HIV patients. They’ve also been linked to heart rhythm changes in lab animals.

Of particular concern is the possibility the drugs could accelerate a shift from one HIV strain to anotherr, which is often seen in the sickest AIDS patients. Celestri patients may have to be tested regularly to monitor whether the drug is driving such a shift. Still, FDA reviewers note no increase in lymphomas or infectionsi, but did notice a modest increase in liver problems.

Pfizer believes there is an unmet need for new HIV drugs for patients for whom older drugs no longer work. Celsentri is unlike any other HIV med - it targets the cells of patients and not the virus itself. FDA reviewers note there was a modest increase in liver problems. Pfizer, in its own analysis, argues the studies showed no significant effect on the heart or increased incidence of liver problems, cancer or infection compared with treatment with other HIV drugs.

The FDA has asked the experts whether Celsentri, if approved, would require special labeling or if further study of the drug’s safety is needed before it can be sold. FDA also asked whether the drug should be studied further in women and blacks.

Source: The Associated Press.
Further reading…
Bloomberg News;
Pfizer briefing document;
FDA cover memorandum;
FDA waiver.[tags]AIDS, Celsentri, Pfizer[/tags]