Ruxolitinib for steroid-refractory graft versus host disease in pediatric HSCT: high response rate and manageable toxicity.

Ruxolitinib, a selective Janus Kinase (JAK) 1/2 inhibitor, is a promising treatment for the steroid-refractory graft-vs-host disease (GvHD) after hematopoietic stem cell transplantation (HSCT). Most studies have been performed in the adult population showing efficacy against GvHD. In this retrospective study, we evaluated the outcomes of 19 children who received ruxolitinib for refractory acute or chronic GvHD (cGvHD) after HSCT from two Pediatric Hemato-Oncology Departments in Spain between March 2017 and December 2018. Patients received a median number of 4 (IQR 2) previous lines of treatment before starting ruxolitinib. The overall response rate in acute GvHD (aGvHD) and cGvHD was 87% and 91%, respectively. Complete response (CR) was observed in 37% of aGvHD and 8.3% of cGvHD. Remarkably, 43% and 40% of patients with steroid-refractory gastrointestinal aGvHD and lung cGvHD achieved CR. During ruxolitinib treatment, there were 36%, 31%, and 10% infections caused by viruses, bacteria, and fungi, respectively. Overall, four patients interrupted ruxolitinib due to infectious complications, hematological, and liver toxicity. The 2-year overall survival was 71.9% (CI 95% 58.6-85.2). Our experience supports the use of ruxolitinib as an effective treatment for steroid-refractory acute and cGvHD in children with a moderate toxicity profile.

Selective T-cell depletion targeting CD45RA as a novel approach for HLA-mismatched hematopoietic stem cell transplantation in pediatric nonmalignant hematological diseases.

Severe aplastic anemia and congenital amegakaryocytic thrombocytopenia are rare bone marrow failure syndromes. Treatment for aplastic anemia consists of hematopoietic stem cell transplantation (HSCT) from a matched sibling donor or immunosuppressant drugs if there is no donor available. Congenital amegakaryocytic thrombocytopenia is a rare autosomal recessive disease that causes bone marrow failure and has limited treatment options, except for transfusion support and HSCT. In the absence of a suitable matched sibling donor, matched-unrelated, haploidentical, or mismatched donors may be considered. A 2-step partial T-cell-depletion strategy can remove CD45RA+ naïve T cells responsible for graft-versus-host disease (GvHD) while preserving memory T cells. Five patients underwent transplantation using this strategy with rapid neutrophil and platelet recovery. Acute and chronic GvHD ≥ grade 2 appeared in two and one patient, respectively. No severe infections were observed before day + 100. A high (60%) incidence of transplant-associated microangiopathy was observed. Three patients (60%) remain alive, with a median follow-up of 881 (range 323-1248) days. CD45RA-depleted HSCT is a novel approach for patients lacking a suitable matched donor; however, further improvements are needed.