Hemophagocytic lymphohistiocytosis-like toxicity following chimeric antigen receptor (CAR)-T cell therapy (carHLH) is a rare and fulminant complication. Currently, there are neither well-established diagnostic criteria nor optimal treatment option for carHLH. Given the similarities of hyperinflammatory process and cytokine profiles between cytokine release syndrome (CRS) and carHLH, tocilizumab and corticosteroids are the suggested front-line treatment options for both conditions. However, when carHLH is refractory to front-line treatment, alternative or adjunctive agents should be introduced to ameliorate ongoing hyperinflammation. Anakinra, a recombinant interleukin (IL)-1 receptor antagonist, has shown promising results in the management of carHLH. Although prospective trials are limited, the use of anakinra for severe CRS and carHLH has been increasing. In this case report, we present two cases of carHLH to discuss its characteristic clinical features, diagnostic criteria, and treatment option. In addition, we also highlight the clinical efficacy of anakinra for managing carHLH which was refractory to tocilizumab and dexamethasone.

Background: Allogeneic HSCT may improve survival in pediatric ALL patients who relapse. In this study, we analyzed the outcome and prognostic factors of 62 ALL patients (35 male, 56.5%) who received allogeneic HSCT in second complete remission (CR) at our institution between April 1st 2009 and December 31st 2019. Methods: The median time from diagnosis to relapse was 35.1 months (range, 6.0‒113.6 mo).Fifty-three patients (85.5%) experienced bone marrow relapse only. The number of patients who received transplant according to each donor type was as follows: HLA matched family donor 17 (27.4%), matched unrelated donor (UD) 22 (35.5%), mismatched donor 23 (37.1%). All patients received HSCT with a myeloablative conditioning, 58 patients (93.5%) with the incorporation of TBI [31 patients 12 Gray (Gy), 24 patients 13.2 Gy, 3 patients 8 Gy]. Results: The 5-year event-free survival (EFS), and overall survival of the study group was 41.3±6.3% (26/62), and 42.3±6.6% (27/62), respectively. The cumulative incidence of relapse and transplant-related mortality was 57.1±6.4% and 1.6±1.6%, respectively.Infant ALL, shorter time from diagnosis to relapse, and TBI dose of 12 Gy, rather than 13.2 Gy, resulted in significantly worse EFS. In multivariate analysis, infant ALL and TBI dose of 12 Gy during conditioning predicted significantly lower EFS. Conclusion In our study group, treatment with a higher dose of TBI during conditioning resulted in better EFS for ALL patients who underwent HSCT in second CR. Further study is needed to determine potential long-term complications associated with a higher TBI dose.