Low-dose total body irradiation and G-CSF without hematopoietic stem cell support in the treatment of relapsed or refractory acute myelogenous leukemia (AML), or AML in second or subsequent remission

Purpose: Patients with relapsed acute myelogenous leukemia (AML), who are n ot eligible for bone marrow transplantation, have a poor prognosis when tre ated with chemotherapy alone. Total body irradiation (TBI) is an effective modality against AML when used in doses of 1000-1400 cGy with hematopoietic stem cell support. We undertook a phase I study of TBI with granulocyte-co lony-stimulating factor (G-CSF) support, without stem cell support in patie nts with AML either in relapse or second or subsequent remission. Methods and Materials: Patients with relapsed AML, or AML in second or subs equent remission were treated in a phase I study of TBI followed by G-CSF, The first dose level was 200 cGy, After the initial cohort of patients it w as clear that patients with overt leukemia did not benefit from this treatm ent, and subsequent patients were required to be in remission at the time o f TBI. Results: Eleven patients were treated, 4 in overt relapse, and 7 in remissi on. 200 cGy was used in all, and dose escalation was not possible due to pr olonged thrombocytopenia in all patients but one. Neutrophil recovery was a dequate in those patients who remained in remission after TBI. Patients wit h overt leukemia had transient reduction in blast counts, but rapid recurre nce of their leukemia. Patients treated in remission had short remissions, with the exception of one patient who is in remission 32 months after treat ment, Conclusion: There is some antileukemic effect of TBT even at 200 cGy, thoug h this dose appears to be too low to help a significant number of patients. If TBI is to be escalated without stem cell support, then a thrombopoietic agent will need to be used. (C) 1998 Elsevier Science Inc.