Serious Late Complications After Hematopoietic Stem Cell Transplantation (HSCT) Following Myeloablative Conditioining (MAC) In Infants.

Recently, HSCT has been widely used as a curative therapy for refractory hematological/malignant diseases. However, late complications after HSCT such as endocrine disorders, infertility, short stature and secondary cancers have been recognized as serious problems in children. Late complications are assumed to be much more serious in younger children, especially in infants. Therefore, we retrospectively evaluated late complications among patients who underwent HSCT before one-year-old age in our institute to clarify this big issue.

We performed HSCT in 530 children from 1993 to 2009. Among these 530 patients, 33 were infants (younger than 1- year - old) at HSCT. 23 infants with malignant disorders consisted of neuroblastoma 10, hepatoblastoma 2, rhabdomyosarcoma 1, retinoblastoma 1, acute lymphoblastic leukemia 5, myelodysplastic syndrome 2, acute myelogenous leukemia 2, and 10 infants with non-malignant disorders consisted of immunodeficiency 5, familial hemophagocytic lymphohistiocytosis/hemophagocytic syndrome 2, congenital metabolic disorder 1, severe aplastic anemia 1, pure red cell aplasia 1 were included. 9 infants underwent autologous HSCT and 24 underwent allogeneic HSCT. 22 infants received MAC and 11 received reduced-intensity conditioning (RIC). 26 out of 33 patients have been alive (MAC, 18/22 = 81.8 %; RIC, 8/11 = 72.7 %). Body height (BH) of 5 patients in RIC group who have been surviving longer than 5 years after HSCT is equal or taller than -2 standard deviation (SD) of BH. However, BH of 6 out of 13 evaluable patients in MAC group remains shorter than -2 SD (the shortest, -5.3 SD) of BH. All survivors in MAC group are suffering from one or more late complications such as growth hormone secretion insufficiency, premature puberty, hypothyroidism, gonadal failure and secondary cancers, therefore, they needs treatment and support for these late complications.

The survival rate is similar (81.8 % versus 72.7 %) between MAC and RIC in infants, however, infants who underwent MAC-HSCT are suffering from late complications much more frequently and need treatment and support. These results suggest that less toxic conditioning should be adopted for infants who undergo HSCT to avoid serious late complications.

No relevant conflicts of interest to declare.