Treosulfan-containing regimens achieve high rates of engraftment associated with low transplant morbidity and mortality in children with non-malignant disease and significant co-morbidities

SummaryTreosulfan is an immuno-suppressive and myeloablative alkylating agent thathas been introduced as a conditioning agent in stem cell transplantation(SCT). Most studies have been performed in adult patients with malignancywhere a low incidence of regimen-related toxicity has been reported. Wereport the use of treosulfan in 32 consecutive children undergoing SCT fornon-malignant disease. Patients received a total treosulfan dose of 36 or42 g/m 2 /patient given in three daily, divided doses. A range of otherconditioning agents and serotherapy was administered to patients whounderwent family donor SCT (n = 11), or unrelated donor SCT (n = 21).One patient (3%) died early. Transplant morbidity was limited and mucositiswas only mild. Dermatological toxicity was frequent but mild. Twenty-eightpatients (87AE5%) established donor cell engraftment. In 25 patients (78%)there was adequate, stable donor engraftment. Four patients have requiredadditional transplant procedures to maintain adequate donor-derivedhaemopoiesis. Twenty-seven patients (84%) survive with a median followup of 417 d. There were four late deaths due to progression of the underlyingdisease, graft-versus-host disease or infection. Treosulfan-based conditioningregimens achieve excellent engraftment with reduced regimen-related toxicityin children with non-malignant disease at high risk for both regimen-relatedtoxicity and graft failure.Keywords: conditioning, bone marrow transplantation, paediatrics, engraft-ment, treosulfan.