Azacitidine salvage therapy for relapse of myeloid malignancies following allogeneic hematopoietic SCT

Patients with hematopoietic malignancies relapsing after allogeneic hematopoietic SCT (allo-HSCT) have a poor prognosis. We retrospectively analyzed the patients who received azacitidine in our center in the course of treatment of their post-transplant relapse. We identified 31 patients. Relapse occurred at a median of 3.7 (1.7–37.6) months following allo-HSCT. Patients received a median number of three cycles (1–12) of azacitidine (7 days, 75 mg/m2 daily). Thirty-nine percent of patients had either a monosomal karyotype or a complex karyotype. Eleven patients (35%) received at least one DLI. Eleven patients responded to azacitidine, with four patients achieving a CR (13%). Median time to best response was 92 (35–247) days, with a median duration of 209 (64–751) days. One-year estimated survival rate was 14%. In conclusion, azacitidine may reinduce durable remissions in very few patients with AML or myelodysplastic syndrome. The toxicity related to azacitidine was high, although it may be difficult to distinguish between treatment-related side effects, namely due to cytopenia and toxicity due to the relapse or disease progression itself. Early administration of azacitidine after transplant followed by DLI should be considered as a pre-emptive therapy for potential relapse in patients with minimal residual disease or high-risk myeloid malignancies.