WASHINGTON -- Azithromycin (Zithromax, Zmax), an antibiotic generally used to treat infections of the lung, sinuses, and skin, should not be given long term to patients with cancers of the blood or lymph nodes who receive a stem cell transplant, the FDA said on Friday.
In a , the agency cited the results of a French clinical trial that found an increased risk of cancer relapse and even death with long-term use of azithromycin in this population, and added that the FDA is "reviewing additional data and will communicate our conclusions and recommendations when the review is complete."
The announcement noted that the drug should not be given to patients to prevent the inflammatory lung condition bronchiolitis obliterans syndrome, because azithromycin is "not approved" for this type of use, and "there are no known effective antibiotic treatments for prophylaxis of bronchiolitis obliterans syndrome."
In the meantime, the manufacturer of azithromycin said the company is supplying a who are caring for patients with donor stem cell transplants.
French researchers discovered this risk during a trial examining long-term effectiveness of azithromycin to prevent bronchiolitis obliterans syndrome in patients who underwent stem cell transplants to treat cancer of the blood or lymph nodes (e.g., leukemia, lymphomas). The FDA wrote that the researchers were forced to "stop the trial approximately 13 months after the study completed enrollment of 480 patients," due to unexpected increases in cancer relapses and deaths. About a third of patients on azithromycin treatment experienced a relapse and 95 patients died (compared with a 20.8% relapse rate with 66 patients dying in the placebo group), which led to a 2-year survival rate of 56.6% in the azithromycin group and 70.1% in the placebo group, the agency said.
The researchers concluded that "the risks of long-term azithromycin exposure after donor stem cell transplantation may exceed the benefits," although they said they could not determine why the rates of relapse and death were higher in the azithromycin group.