Gemtuzumab ozogamicin-induced long-term remission in a woman with acute myelomonocytic leukemia and bone marrow relapse following allogeneic transplantation

A 56-year-old woman with acute myelomonocytic leukemia underwent myeloablative allogeneic hematopoietic stem cell transplantation (allo-SCT) from a matched unrelated donor in her first complete remission (CR). Veno-occlusive disease (VOD) prophylaxis consisted of low-dose heparin and ursodeoxycholic acid. Graft-versus-host disease (GVHD) prophylaxis comprised tacrolimus and short-term methotrexate. On day 14, VOD developed, but gradually resolved with supportive therapy. On day 58, she showed grade II acute GVHD, but this resolved spontaneously. On day 140, she developed hematological relapse with 40.2% marrow infiltration of CD33-positive blasts. Following the discontinuation of tacrolimus, gemtuzumab ozogamicin (GO) was administered. After GO administration, the patient exhibited mild VOD and severe pancytopenia with a sustained high fever for 6 weeks without evident infection. Bone marrow examination revealed severe hypoplastic marrow with 1.3% blasts 4 weeks after GO administration. Although transfusion-dependent pancytopenia persisted for 8 months after GO administration, bone marrow examination revealed the recovery of normal hematopoietic cells with 0.8% blasts. The patient has remained in CR with incomplete blood count recovery for 7 years following GO administration. Although the standard treatment for acute myeloid leukemia relapse after allo-SCT still remains to be established, GO may be a promising option.