Allogeneic hematopoietic stem cell transplantation from unrelated donors is associated with higher infection rates in children with acute lymphoblastic leukemia-A prospective international multicenter trial on behalf of the BFM-SG and the EBMT-PDWP.

Severe infections (SI) significantly impact on non-relapse mortality after hematopoietic stem cell transplantation (HSCT). We assessed 432 children and adolescents with acute lymphoblastic leukemia (ALL) after total body irradiation based myeloablative HSCT within the multicenter ALL-BFM-SCT 2003 trial for SI grade 3 or higher according to common terminology criteria for adverse events. A total 172 patients experienced at least one SI. Transplantation from matched unrelated donors (MUD) was associated with any type of SI in the pre-engraftment period (hazard ratio [HR]: 2.57; P < .001), and with any SI between day +30 and + 100 (HR: 2.91; P = .011). Bacterial (HR: 2.24; P = .041) and fungal infections (HR: 4.06; P = .057) occurred more often in the pre-engraftment phase and viral infections more often before day +30 (HR: 2.66; P = .007) or between day +30 and + 100 (HR: 3.89; P = .002) after HSCT from MUD as compared to matched sibling donors. Chronic GvHD was an independent risk factor for any type of SI after day +100 (HR: 2.57; P < .002). We conclude that allogeneic HSCT from MUD in children and adolescents with pediatric ALL is associated with higher infection rates, which seems attributable to an intensified GvHD prophylaxis including serotherapy and methotrexate.

Constitutional mismatch repair deficiency and childhood leukemia/lymphoma--report on a novel biallelic MSH6 mutation.

Biallelic mutations of mismatch repair genes cause constitutional mismatch repair deficiency associated with an increased risk for childhood leukemia/lymphoma. We report on a case with constitutional mismatch repair deficiency caused by a novel MSH6 mutation leading to a T-cell lymphoma and colonic adenocarcinoma at six and 13 years of age, respectively. A review of the literature on hematologic malignancies in constitutional mismatch repair deficiency showed that in almost half of the 47 known constitutional mismatch repair deficiency families, at least one individual is affected by a hematologic malignancy, predominantly T-cell lymphomas. However, diagnosing constitutional mismatch repair deficiency may be difficult when the first child is affected by leukemia/lymphoma, but identification of the causative germline mutation is of vital importance: (i) to identify relatives at risk and exclude an increased risk in non-mutation carriers; (ii) to prevent hematopoietic stem cell transplantation from sibling donors also carrying a biallelic germline mutation; and (iii) to implement effective surveillance programs for mutation carriers, that may reduce constitutional mismatch repair deficiency-associated mortality.

Transplantation of highly purified CD34+ progenitor cells from alternative donors in children with refractory severe aplastic anaemia.

Without transplantation from a human leucocyte antigen-identical family donor, refractory severe aplastic anaemia (SAA) has an unfavourable prognosis. Conventional transplantation from a matched unrelated donor carries a high rate of mortality. We transplanted large numbers of highly purified CD34+ cells from matched unrelated (n = 4), mismatched unrelated (n = 4) and mismatched related (n = 1) donors into nine children with refractory SAA. The grafts consisted of granulocyte colony-stimulating factor-mobilized peripheral positively selected CD34+ cells. A median of 15.1 x 106/kg CD34+ stem cells and 11 x 103/kg CD3+ T-lymphocytes were infused. No additional pharmacological graft versus host disease (GVHD) prophylaxis was given. At a median follow-up of 47 (range 37-72) months, eight patients (89%) were in complete remission with >90% donor chimaerism and no evidence of GVHD. One patient died on day +238 as a consequence of GVHD. The use of highly purified mobilized CD34+ stem cells warrants further clinical exploration in children with refractory SAA.