Improved Outcomes of Hematopoietic Stem Cell Transplantation in Patients With Infantile Malignant Osteopetrosis Using Fludarabine-Based Conditioning.

BACKGROUND: Hematopoietic stem cell transplantation (HSCT) is the only curative treatment for infantile malignant osteopetrosis (IMO), but is associated with a high incidence of adverse outcomes. In this study, we present our experience with HSCT for IMO patients comparing different types of conditioning regimens. METHODS: Thirty-eight patients with IMO (aged from 1 month to 6 years, median 0.66 years) who underwent allogeneic HSCT from 1983 in our hospital were included in this retrospective study. Fludarabine-based conditioning regimens were used in 26 patients and 12 patients were transplanted using other conditioning regimens. RESULTS: The overall survival after conditioning with fludarabine was 96% (25/26) versus 58% (7/12) for the alternative regimens (P = 0.004), with significantly fewer adverse effects including hypercalcemia and veno-occlusive disease of liver. All patients who survive are clinically well. CONCLUSIONS: We conclude that fludarabine-based conditioning regimens are safe and effective in patients with IMO, improving morbidity and mortality related to HSCT.

Bone marrow transplantation for non-malignant diseases using treosulfan-based conditioning.

BACKGROUND: Treosulfan (treo) is an alkylating agent with a low acute toxicity profile that is increasingly used in hematopoietic stem cell transplantation, predominantly in non-malignant diseases. Treosulfan is usually combined with additional agents, but there is scant evidence to allow comparison between different conditioning protocols using treosulfan. We present the experience of three pediatric transplantation centers in Israel using different treosulfan-based conditioning regimens. PROCEDURE: Data were collected retrospectively on 44 children who underwent 45 hematopoietic stem cell transplantations using treosulfan in combination with either fludarabine (flu) and thiotepa (tt) (n = 20), cyclophosphamide (cy) (n = 6) or fludarabine alone (n = 19). RESULTS: Overall survival (OS) was 70.5%. Disease free survival (DFS) was 54.6%. There was no statistically significant difference between treatment groups in either OS or DFS. Overall survival in patients younger than one year was higher (88.2%). There were significantly more patients with 100% donor chimerism transplanted with flu/treo/tt compared with flu/treo or treo/cy (94.7% compared to 66.7% and 16.7%, respectively). Further prospective studies are required to determine the optimal treosulfan-based preparative regimen for children with non-malignant diseases. Pediatr Blood Cancer 2015;62:299-304. © 2014 Wiley Periodicals, Inc.