Sustained complete molecular remission after cessation of imatinib mesylate treatment in a patient with relapsed chronic myelogenous leukemia after allogeneic stem cell transplantation

: We present a case with sustained complete molecular response (CMR) after cessation of two months of imatinib mesylate (IM) treatment for chronic myelogenous leukemia (CML) relapsed after allogeneic stem cell transplantation (Allo-SCT). A 30-year-old previously healthy woman was seen in a clinic because of left abdominal discomfort. Splenomegaly and increased leukocytes with Philadelphia chromosome led to the diagnosis of CML in the accelerated phase. She received four months of IM treatment followed by allo-SCT from her HLA-matched sibling. She achieved and maintained CMR without developing acute GVHD for six months, when hematologic relapse occurred. While reducing the immunosuppressant, she received IM; however, it was discontinued two months later due to myelosuppression. Even after the termination of IM, the positivity of chimeric BCR-ABL gene detected by FISH analysis in peripheral blood continued to decrease. The molecular analysis of bone marrow one year after allo-PBSCT revealed CMR lasting for more than two years after cessation of IM. IM may possibly enhance the graft-versus-leukemia effects by reducing tumor burden in cases relapsed after allo-SCT.