HOUSTON — When given after transplant, azithromycin does not increase the risk of relapse in patients with moderate to severe chronic graft-versus-host disease (cGVHD) and bronchiolitis obliterans syndrome (BOS), according to a retrospective study.
A prior study, ALLOZITHRO (JAMA. 2017 Aug 8;318[6]:557-66), showed an increased risk of relapse and death in patients who received azithromycin as BOS prophylaxis prior to hematopoietic cell transplant (HCT).
That discovery prompted the Food and Drug Administration to release a safety communication warning prescribers about the risks associated with azithromycin as BOS prophylaxis. However, it wasn’t clear if the same risks exist when azithromycin is given for cGVHD management after HCT.
To gain some insight, Mark Shamoun, MD, of the University of Michigan, Ann Arbor, and his colleagues examined data on patients with moderate to severe cGVHD and BOS who received azithromycin after undergoing HCT to treat a hematologic malignancy.
Dr. Shamoun presented the group’s findings at the Transplantation & Cellular Therapy Meetings.
The researchers reviewed data on 239 patients enrolled in the University of Michigan’s HCT database from 2010 to 2017. The median age at baseline was 55 years (range, 4-72 years).
The patients received transplants to treat acute myeloid leukemia or myelodysplastic syndromes (n = 141), acute lymphoblastic leukemia (n = 40), lymphoma (n = 26), chronic leukemia (n = 24), multiple myeloma (n = 6), and myeloproliferative neoplasms (n = 2).
The patients had matched related donors (43%) or matched unrelated donors (57%). Most patients received peripheral blood transplants (84%), though some received bone marrow (14%) or cord blood (2%). All patients had moderate (38%) or severe (62%) cGVHD.
Patients were split into two cohorts. Patients in cohort A (n = 86) had BOS and received azithromycin for more than 14 days.
Patients in cohort B (n = 153) either did not receive azithromycin or received it for 14 days or less. Fewer than 5% of patients in cohort B had BOS.
Most other baseline characteristics were similar between the cohorts. However, severe cGVHD was more prevalent in cohort A than B — 78% and 51%, respectively.
In cohort A, the median time to the start of azithromycin was 15 months after HCT (range, 3-68 months). The median duration of azithromycin treatment was 26 months (range, 1-77 months).
Results
The 2-year relapse rate was significantly lower in patients who received azithromycin than in those who did not — 4% and 17%, respectively (P = .001).
There was a significant difference in relapse rate both from the time of HCT (P = .001) and from the start of azithromycin or cGVHD (P = .011).
There was no significant difference in overall survival between the cohorts, either from the time of HCT (P = .294) or from the start of azithromycin or cGVHD (P = .428).
Dr. Shamoun said these results suggest azithromycin does not increase the risk of relapse when it is used to manage cGVHD. However, this study is limited by its retrospective nature. In addition, most patients in cohort B did not have BOS, severe cGVHD was more common in cohort A, and the incidence of relapse was not calculated from the time of azithromycin initiation in both cohorts. Therefore, additional investigation is needed.
Dr. Shamoun presented these results at Transplantation & Cellular Therapy Meetings, which is held by the American Society for Blood and Marrow Transplantation and the Center for International Blood and Marrow Transplant Research. At the meeting, the American Society for Blood and Marrow Transplantation announced a new name for the society, the American Society for Transplantation and Cellular Therapy (ASTCT).
Dr. Shamoun reported no conflicts of interest.
SOURCE: Shamoun M et al. TCT 2019, Abstract 33.