TUESDAY, Aug. 8, 2017 (HealthDay News) -- An antibiotic treatment intended to lower stem cell transplant patients' risk of developing a respiratory complication appears to have backfired.
French researchers explored the potential of administering the antibiotic azithromycin before and after stem cell transplantation to limit the risk for a condition known as bronchiolitis obliterans syndrome (BOS).
A significant number of blood cancer patients who undergo allogeneic stem cell transplant are at risk for developing BOS. It's a potentially deadly complication in which airflow to the lungs becomes progressively obstructed, turning routine breathing into an ordeal. Allogeneic transplants are ones where genetically similar, but not identically matched, material is transplanted.
The new investigation had to be stopped prematurely -- after just over a year. Preliminary indications suggested that the random pool of allogeneic stem cell transplant patients treated with antibiotics were actually more likely to develop BOS than those who were not getting azithromycin.
Dr. Henry Fung serves as vice chair of hematology and oncology at the Fox Chase Cancer Center in Philadelphia.
Although he was not a part of the current investigation, Fung was familiar with the results of the study and said, "in the absence of new scientific rationale on using azithromycin, a similar study should not be repeated."
Azithromycin "will not benefit patients undergoing an allogeneic stem cell transplant," Fung concluded.
Initially, the French investigation planned to include nearly 500 French blood cancer patients, average age 52. The patients began the allogeneic transplant process at one of 19 French bone marrow transplant facilities at some point between 2014 and 2015.
Fung, who's also director of the Fox Chase Cancer Center-Temple University Hospital Bone Marrow Transplant Program, noted that "allogeneic stem cell transplant is a life-saving procedure for many patients with blood cancers."
However, "the success ... [is] limited by long-term complications," he explained.
One complication is a condition known as graft-versus-host disease. This occurs when newly transplanted bone marrow and/or stem cells are seen by the patient's body as foreign material. The immune system then starts attacking the transplant.
The other is BOS.
And, BOS, "once diagnosed, is usually irreversible with no effective treatment available," Fung said.
Following allogeneic stem cell transplantation, roughly 4 percent to 6 percent of patients will develop BOS, the study authors said. That figure rises as high as 14 percent among those patients who also develop graft-versus-host disease.
The French researchers were led by Dr. Anne Bergeron from the Saint-Louis Hospital in Paris. The team noted that prior research had indicated that using the antibiotic azithromycin as a preventive therapy effectively reduced BOS risk among patients undergoing a lung transplant, during which BOS risk typically goes up.
To see whether the same would be true among stem cell transplant patients, the French study participants were randomly assigned to be treated with either azithromycin (250 milligrams three times a week for two years) or a placebo (dummy pill).
However, by December 2016 the investigation was halted, even before all the participants had completed their two-year antibiotic or placebo regimen.
The cited reason was an "unanticipated imbalance" in the incoming results. More people than anticipated in the group that had been getting the antibiotic were developing BOS.
The study findings were published in the Aug. 8 issue of the Journal of the American Medical Association.
There's more about BOS at the Rare Clinical Diseases Research Network.