Cord blood transplantation using minimum conditioning regimens for patients with hematologic malignancies complicated by severe infections.

Patients with severe infections are thought to be ineligible for cord blood stem cell transplantation (CBT) because the conventional 5-6 day-conditioning regimens potentially makes them susceptible to fatal infections by the time neutrophil engraftment occurs. Two patients were treated with minimum conditioning regimens consisting of 30 mg/m(2) fludarabin (Flu) and 2 g/m(2) cyclophosphamide (CY) on day-1 and total body irradiation (TBI) of 2 or 4 Gy on day -1 or 0 followed by single unit CBT. The reasons for adopting such weak regimen were febrile neutropenia due to the rejection of the first cord blood (CB) graft given to a patient with follicular lymphoma resistant to chemotherapy and pulmonary aspergillosis in another patient with AML who relapsed after CBT. The AML patient received 40 mg/m(2) of melphalan on day-2 to reduce the leukemia burden. Both patients achieved 100% donor chimerism by day 19 and day 20 after CBT without an apparent exacerbation of the infections and remained in remission at 23 and 18 months after the CBT. These findings suggest that the 1-2 day regimens excluding antihuman thymocyte globulin may be sufficiently potent to ensure engraftment of CB in immunocompromised patients and safely administered even when patients are complicated by active infections.