Background: Allogeneic hematopoietic stem cell transplantation(allo-HSCT) is currently the only curative treatment for thalassemia major (TM). Cord blood (CB) from a sibling has different characteristics from marrow and has potential advantages and disadvantages as a stem cell source. Methods: We retrospectively analysed 68 children with β-TM who underwent fresh cord blood transplantation (F-CBT) from an human leukocyte antigen (HLA)-matched sibling donor (MSD) between June 2010 and July 2018 in the Department of Pediatrics, Nanfang Hospital and Haematology-Oncology, Shenzhen Children’s Hospital. Results: The median infused doses of total nucleated cells (TNCs) and CD34+ cells were 8.51×107/kg and 3.16×105/kg,respectively. The median time to neutrophil and platelet engraftment were respectively 27 days and 31 days. The cumulative probability of acute and chronic graft- versus-host disease (GVHD) were very low after F-CBT (7.8% and 0.0%, respectively). Of the 68 paediatric patients, 67 patients survived during a median follow-up period of 61 months.The estimated 5-year probability of overall survival (OS) and disease-free survival (DFS) were 98.5% and 92.4%, respectively. Three patients experienced graft rejection (GR) (4.5%) , and this study found that GR was higher in the thiotepa (TT)-free regimen group than that in the TT-based regimen group (0% vs.10.7%,P=0.038). Multivariable prognostic analysis, a conditioning regimen including TT, improved the DFS of patients with β-TM receiving F-CBT (P=0.032). Conclusions: The above results indicate that patients with β-TM have excellent outcomes after F-CBT from an HLA-MSD.

A 4-year-old child with β-thalassemia major underwent allogeneic hematopoietic stem cell transplantation (HSCT) on August 30, 2022 from a male haploidentical donor. He developed massive pericardial effusion (PE) secondary to a pulmonary infection. Methylprednisolone, tacrolimus discontinued, and pericardiocentesis were all ineffective. Since the interleukin-6 (IL-6) level in the PE was markedly increased (1868.58pg/ml), a total of two doses of tocilizumab was administered intravenously at a dosage of 5mg/kg every 2 weeks. PE remarkably reduced and completely resolved within 8 days. No recurrence of PE was observed in the follow up visits. Our results suggest that tocilizumab can be considered as a treatment of choice in massive PE after HSCT.

Background: Next-generation sequencing (NGS) is an emerging technology that can comprehensively assess the diversity of the immune system. We explored the feasibility of NGS in detecting minimal residual disease (MRD) in childhood acute lymphoblastic leukemia (ALL) based on immunoglobulin and T cell receptor. Methods: Bone marrow samples were collected pre- and post-treatment with pediatric ALL admitted to Shenzhen Children’s Hospital from February 1st, 2020 to January 31st, 2021. We analyzed the MRD detected by NGS, multiparametric flow cytometry (MFC) and real-time quantitative PCR (RQ-PCR), and analyzed risk factors of positive NGS-MRD at the end of B-ALL induction chemotherapy. Results: A total of paired 236 bone marrow samples were collected from 64 children with ALL (58 B-ALL and 6 T-ALL). The decrease in the clonal rearrangement frequency of IGH, IGK, and IGL was generally consistent after treatment. Positive MRD was detected in 57.5% (77/134) of B-ALL and 80% (12/15) of T-ALL by NGS after chemotherapy, which was higher than those detected by MFC and RQ-PCR. In B-ALL patients, MRD results detected by NGS were consistent with MFC（r = 0.708, p < 0.001）and RQ-PCR（r = 0.618, p < 0.001）. At the end of induction, NGS-MRD of 40.4% B-ALL was >0.01% and multivariate analysis indicated that ≧2 clonal rearrangement sequences before treatment were an independent factor of negative NGS-MRD. Conclusions: NGS is more sensitive than MFC and RQ-PCR for MRD measurement. B-ALL children with ≧2 clonal rearrangements detected by NGS before treatment are difficult to switch to negative MRD after chemotherapy.