CAR-T Therapy Followed By Unrelated Cord Blood Transplantation for the Treatment of Children and Young Adults Relapsed/Refractory B-Cell ALL: Superior Survival but Relatively High Post-Transplant Relapse

Relapsed/refractory (R/R) acute lymphoblastic leukemia (ALL) has poor long-term survival even after chimeric antigen receptor (CAR)-T cell therapy or allogeneic hematopoietic stem cell transplantation (allo-HSCT). Several studies supported that CAR-T therapy followed by allo-HSCT is benefit for improving long-term leukemia free survival (LFS). Since probably a stronger graft versus leukemia (GVL) effect of unrelated cord blood transplantation (UCBT), it is uncertain whether consolidative UCBT is suitable for R/R B-ALL after CAR-T therapy. Here, we conducted a retrospective comparative study for R/R B-ALL patients receiving UCBT in our transplantation center. Totally 43 cases with R/R B-ALL who underwent UCBT were assigned to CAR-T group (patients achieved CR or CRi by CAR-T cell therapy before bridging to UCBT, n = 21) or non-remission (NR) group (n = 22). The median time from CAR-T infusion to UCBT was 62 (range, 42-185) days. All patients achieved neutrophil engraftment by day 42 in CAR-T group. The 180-day cumulative incidence of platelet engraftment was higher in CAR-T group than in NR group (90.5% vs 65.7%, P = 0.16). Incidence of grade II-IV and III-IV acute graft-versus-host disease (GVHD) were 28.6% and 23.8% in CAR-T group, which were both tendency lower than in NR group (45.5% and 31.8%, P = 0.32 and P = 0.63, respectively). No patient suffered from extensive chronic GVHD in CAR-T group, which was lower than in NR group (9.1%, P = 0.23). Lower 2-year cumulative incidence of transplant-related mortality (TRM), and higher probabilities of 2-year overall survival, leukemia free survival (LFS), graft-versus-host disease (GVHD)-free relapse-free survival (GRFS) were found in CAR-T group (4.8% vs 28.2%; 75.0% vs 37.7%; 49.8% vs 23.0%; 42.4% vs 14.8%; P = 0.037, 0.005, 0.028 and 0.017; respectively). However, 2-year cumulative incidence of relapse was comparably high between CAR-T and NR group (26.7% vs 38.3%; P = 0.41). CAR-T therapy followed by UCBT has a superior survival for R/R B-ALL, but remains relatively high post-transplant relapse rate. Prevention of relapse after UCBT is warranted in this patient cohort. Disclosures No relevant conflicts of interest to declare.

Sequential Transplantation of Haploidentical Stem Cell and Unrelated Cord Blood With Using ATG/PTCY Increases Survival of Relapsed/Refractory Hematologic Malignancies

Allogeneic haploidentical HSCT (haplo-HSCT) and unrelated umbilical cord blood transplantation(UCBT)are used in patients lacking HLA-identical sibling or unrelated donors. With myeloablative condition and GVHD prophylaxis of using low-dose ATG and post-transplantation cyclophosphamide (PTCY), we conducted a prospective clinical trial. Of eligible 122 patients from February 2015 to December 2019 in the study, 113 patients were involved. Forty-eight patients were in the group of sequential haplo-cord transplantation (haplo-cord HSCT), and 65 patients were in the group of single UCBT. The primary endpoint of 2-year disease-free survival (DFS) was no statistical difference between groups (64.1 vs. 56.5%), p>0.05. The analysis of subgroup patients with relapsed/refractory showed haplo-cord HSCT was associated with better OS (HR 0.348, 95% CI, 0.175–0.691; p=0.0025), DFS (HR 0.402, 95% CI, 0.208–0.779; p=0.0069), and GRFS (HR 0.235, 95% CI, 0.120–0.457, p<0.0001) compared to the single cord group. The 2-year’s probability in OS, DFS, and GRFS was 64.9 vs. 31.6%, 64.5 vs. 31.6%, and 60.8 vs. 15.0% in the haplo-cord group and single cord group, respectively. III-IV acute GVHD 8.3 vs. 6.2%, chronic GVHD 25.8 vs. 13.7%, and extensive chronic GVHD 5.3 vs. 1.8% were shown in corresponding group, p>0.05. The patients engrafted persistently with UCB showed better survival outcomes. Our sequential Haplo-cord HSCT with ATG/PTCY improved the survival of patients and might be an alternative transplantation approach for patients with relapsed/refractory hematologic malignancies.

Rothia mucilaginosa Meningitis in a Child with Myelodysplastic Syndromes

Rothia mucilaginosa is a Gram-positive coccus and an opportunistic pathogen in immunocompromised hosts. The microorganism has been implicated in serious infections, including bacteremia meningitis or endocarditis. However, there is a dearth of investigations on meningitis, especially in children. As this infection is rare and only a few cases have been recorded, evidence-based guidelines for adequate infection treatment are lacking. We herein report the case of a 12-year-old boy with myelodysplastic syndromes (MDS) presenting with a change in mental status who was diagnosed as having febrile neutropenia and bacterial meningitis caused by R. mucilaginosa at 23 days after unrelated cord blood transplant. In our case, the minimum inhibitory concentrations (MICs) of meropenem and vancomycin (VCM) were both ≤1 μg/mL, whereas the MIC of daptomycin (DAP) was 4 μg/mL. The patient was treated with intravenous antimicrobial therapy due to meropenem for 43 days because he had febrile neutropenia. During follow-up, the patient had no neurological complications. We retrospectively reviewed the antimicrobial susceptibility of all R. mucilaginosa isolates (n = 5) from blood or cerebrospinal fluid cultures at our hospital. The MIC of VCM was <0.5 μg/mL for all strains, whereas the MIC of DAP was ≥2 μg/mL for all strains. The MIC of MEPM was >1 μg/mL for one strain. We recommend choosing VCM as the primary treatment for invasive R. mucilaginosa infections until antimicrobial susceptibility results are known, especially in immunocompromised children.

Inflammatory monocytes promote pre-engraftment syndrome and tocilizumab can therapeutically limit pathology in patients

Unrelated cord blood transplantation (UCBT) is an effective treatment for hematopoietic disorders. However, this attractive approach is frequently accompanied by pre-engraftment syndrome (PES), severe cases of PES are associated with enhanced mortality and morbidity, but the pathogenesis of PES remains unclear. Here we show that GM-CSF produced by cord blood-derived inflammatory monocytes drives PES pathology, and that monocytes are the main source of IL-6 during PES. Further, we report the outcome of a single arm, single-center clinical study of tocilizumab in the treatment of steroid-refractory severe PES patients (www.chictr.org.cn ChiCTR1800015472). The study met the primary outcome measure since none of the patients was nonrelapse death during the 100 days follow-up. The study also met key secondary outcomes measures of neutrophil engraftment and hematopoiesis. These findings offer a therapeutic strategy with which to tackle PES and improve nonrelapse mortality.

Feasibility and Outcome of Haploidentical Hematopoietic Stem Cell Transplant with Post-Transplantation Cyclophosphamide in High-Risk Malignancies in Children

The use of haploidentical hematopoietic stem cell transplantation with post-transplant cyclophosphamide (Haplo-PTCy) is increasing in adults, but also in children; this procedure is a good alternative for transplanting pediatric patients lacking a matched family donor; indeed, this is very relevant in regions with economic constraints or with a population which is not well represented in the international donor registries which make access to unrelated cord blood units or bone marrow donors difficult.