Azithromycin Increases Mortality After Hematopoietic Stem Cell Transplantation

Bronchiolitis obliterans syndrome (BOS) may complicate both lung transplantation and allogeneic stem cell transplantation, and no reliably effective treatment exists. Azithromycin has been shown to reduce the incidence of BOS in lung transplant recipients (Eur Respir J 2011; 37:164).

To determine if azithromycin would provide a similar benefit for hematopoietic stem cell transplant (HSCT) recipients, investigators conducted a multicenter, randomized study (ALLOZITHRO) of 480 patients who underwent allogeneic HSCT for a hematologic malignancy. Patients received 2 years of azithromycin (250 mg three times weekly) or placebo.

The study was terminated after 13 months when it was determined that the risk for hematologic malignancy relapse was increased with azithromycin versus placebo (33.5% vs. 22.3%; hazard ratio, 1.7; P=0.002). Azithromycin recipients also had reduced airflow decline–free survival (the primary outcome; 32.8% vs. 41.3%; P=0.03), more cases of BOS (6% vs. 3%), and reduced 2-year survival (56.6% vs. 70.1%; P=0.02). Discontinuation rates were similarly high (>50%) in both treatment groups.