Successful Treatment with Donor Leukocyte Transfusion Followed by Interferon-α in a Patient with Relapsed Chronic Myelogenous Leukemia after Allogeneic Bone Marrow Transplantation

Abstract

A 44-year-old man with CML in chronic phase was admitted for BMT from an HLA-identical sibling. Ph¹ positive cells were undetectable at 3 and 7 months after BMT but became detectable by cytogenetic analysis of bone marrow aspirates at 12 months after BMT. He was treated with IFN-α (6 million units/day, 3 times a week) without apparent effect. Donor leukocyte transfusion (DLT) was performed four times between 20 months and 23 months after BMT, transfusing 3.4×10⁸ mononuclear cells/kg. However, leukocytosis appeared and the NAP score declined at 25 months after BMT. FISH analysis revealed an increase in bcr-abl positive cells. IFN-α was restarted using the same schedule at 26 months after BMT. Three months after restarting IFN-α, the leukocyte count fell to the normal range, NAP score increased to a normal level, and bcr-abl positive cells decreased markedly. He has remained in hematological and cytogenetic remission for 20 months, and bcr-abl chimeric mRNA remained undetectable by PCR. These results suggest that CML which does not respond to DLT may be cured by subsequent IFN-α therapy, possibly by inducing anti-leukemia immune responses.