Treatment of relapsed acute myeloid leukemia after allogeneic bone marrow transplantation with chemotherapy followed by G-CSF-primed donor leukocyte infusion: a high incidence of isolated extramedullary relapse.

For patients with acute myeloid leukemia (AML) relapsed after allogeneic bone marrow transplantation (BMT), donor leukocyte infusion (DLI) as sole therapy has very limited efficacy. We tested the effects of cytoreductive chemotherapy, followed immediately by G-CSF-primed DLI (chemotherapy followed by DLI, Chemo-DLI), in 16 AML patients who relapsed after allogeneic BMT. In all, 10 of these patients achieved complete remission (CR), four of whom remain alive in CR at a median follow-up of 1488 days after DLI. The 2-year overall survival (OS) for the entire cohort was 31%. The 1-year OS for patients with post-BMT remission of 6 months or longer was 55%, compared with 0% for patients with post-BMT remission of less than 6 months, making post-BMT remission duration the only significant prognostic factor for OS (P=0.015). These findings suggest that Chemo-DLI could induce durable remissions in a proportion of relapsed AML patients with relatively long post-BMT remission duration. All five patients who relapsed after achieving CR with Chemo-DLI relapsed at extramedullary sites in the presence of continuous bone marrow remission, suggesting uneven graft-versus-leukemia effects in different parts of the body. Although our data should be interpreted cautiously considering the limited number of patients, isolated extramedullary relapse seems to be common after Chemo-DLI.