Relapse of AML after allogeneic hematopoietic stem cell transplantation (HSCT) has a poor prognosis, and standard of care therapy is lacking. Early (<6 months) relapse is associated with dismal outcome, while the majority of relapses occur early after transplantation. A more precise indication which patients could benefit from reinduction therapy is warranted.

We retrospectively analyzed outcomes of 83 patients with postallogeneic HSCT relapse. Patients were divided based on intention to treat (curative vs supportive care).

Of the 50 patients treated with curative intent, 44% reached complete remission (CR) upon reinduction chemotherapy, and of these patients, 50% survived. Two survivors reached CR after immunotherapy (donor lymphocyte infusion (DLI), without reinduction chemotherapy). Sixty‐nine percent of the survivors had received high‐intensity cytarabine treatment, followed by immunologic consolidation. Relapse <3 months after transplantation was predictive for adverse survival (P = .004), but relapse <6 months was not. In fact, >50% of the survivors had a relapse <6 months.

We confirmed the dismal prognosis of postallogeneic HSCT relapse. Importantly, our data demonstrate that patients fit enough to receive high‐dose chemotherapy, even when relapse occurred <6 months, had the best chance to obtain durable remissions, in particular when immunologic consolidation was performed after reaching CR.