Relapse Rates in Patients Receiving Azithromycin for the Treatment of Bronchiolitis Obliterans after Allogeneic Hematopoietic Stem Cell Transplant

Introduction The FDA issued a warning on the increased risk of hematologic relapse based on the ALLOZITHRO trial, recommending azithromycin not be used long-term in patients that have undergone allogenic hematopoietic stem cell transplant (HSCT). In the ALLOZITHRO trial, azithromycin was started at the time of the conditioning regimen for prophylaxis of bronchiolitis obliterans (BO); however, at our site and many others across the country, azithromycin is initiated after BO. Objective The goal of this study was to evaluate if azithromycin used in treatment of BO is associated with an increase in the rate of relapse. Methods IRB approval was obtained prior to review of the electronic medical record and the Mayo Clinic HSCT database. Adult patients who received an allogeneic HSCT from January 2008 – August 2018 for a malignant disease and received ≥ 2 weeks of azithromycin were included in this study. Patients were excluded if they received Results Of 466 adult patients who received an allogenic HSCT at Mayo Clinic Hospital-Rochester for malignant disease, 185 patients received azithromycin. Of 185 patients who received azithromycin, 87 were excluded: declined research participation (n = 7), received Conclusion The use of azithromycin as treatment for BO was not associated with a high incidence of disease relapse in this study. Further research is needed to confirm our findings.