The Choice of Either Conventional Chemotherapy or Inotuzumab Ozogamicin as Bridging Regimen Does Not Appear To Impact Clinical Response to CD19-Directed CAR-T Therapy in Pediatric B-ALL.

Bridging therapy (BT) given during the period between T-cell collection and initiation of lymphodepleting chemotherapy is indicated for most children with B-cell acute lymphoblastic leukemia (B-ALL) undergoing treatment with tisagenlecleucel (tisa-cel), a CD19-directed chimeric antigen receptor T-cell (CAR-T) therapy. Both conventional chemotherapy agents and B-cell directed antibody-based therapies such as antibody-drug conjugates and bispecific T-cell engagers have been used as systemic forms of BT. The purpose of this retrospective study was to evaluate if there are detectable differences in clinical outcomes based on the type of BT given (conventional chemotherapy or inotuzumab). A retrospective analysis was performed on all patients treated with tisa-cel at Cincinnati Children's Hospital Medical Center for B-ALL with bone marrow disease (with or without extramedullary disease). Patients who did not receive systemic BT were excluded. Only 1 patient received blinatumomab as BT and was therefore not included in this analysis to focus the analysis on the use of inotuzumab. Pre-infusion characteristics and post-infusion outcomes were collected. Fisher's exact test was used for categorical variables, and t-test or Mann-Whitney test was used for continuous parametric and non-parametric variables respectively. Mantel-Cox was used for survival analyses. Thirty-two patients received BT before CD19 CAR-T for medullary leukemia; 24 received conventional chemotherapy, and 8 received inotuzumab ozogamicin (InO). Cohorts were evenly matched regarding CAR-T indication, recipient age, and median CAR-T cell dose. There were no significant differences between the groups for attaining a minimal residual disease (MRD)-negative complete response after CAR-T, the percentage of patients who maintained prolonged B-cell aplasia, or the median duration of B-cell aplasia. Thirty-seven percent of patients in the conventional chemotherapy group and 43% in the antibody-based therapy group relapsed, with a median time to relapse in both groups of 5 months. No differences in event-free survival, the cumulative incidence of relapse, or overall survival were seen between the two groups. Initial response to tisa-cel, relapse rate, and survival were similar between patients who received BT with conventional chemotherapy or InO therapy. Because low disease burden at the time of infusion is a positive prognostic factor, choice of bridging regimen should focus on therapy that is anticipated to effectively lower disease burden and minimize treatment-related toxicity. Given the limitations associated with the single center retrospective analysis, a larger, multicenter study is needed to further explore these findings.

Higher doses of tisagenlecleucel are associated with improved outcomes: a report from the pediatric real-world CAR consortium.

Remarkable complete response rates have been shown with tisagenlecleucel, a chimeric antigen receptor (CAR) T-cell therapy targeting CD19, in patients up to age 26 years with refractory/relapsed B-cell acute lymphoblastic leukemia; it is US Food and Drug Administration approved for this indication. Currently, patients receive a single dose of tisagenlecleucel across a wide dose range of 0.2 to 5.0 × 106 and 0.1 to 2.5 × 108 CAR T cells per kg for patients ≤50 and >50 kg, respectively. The effect of cell dose on survival and remission is not yet well established. Our primary goal was to determine if CAR T-cell dose affects overall survival (OS), event-free survival (EFS), or relapse-free-survival (RFS) in tisagenlecleucel recipients. Retrospective data were collected from Pediatric Real World CAR Consortium member institutions and included 185 patients infused with commercial tisagenlecleucel. The median dose of viable transduced CAR T cells was 1.7 × 106 CAR T cells per kg. To assess the impact of cell dose, we divided responders into dose quartiles: 0.134 to 1.300 × 106 (n = 48 [27%]), 1.301 to 1.700 × 106 (n = 46 [26%]), 1.701 to 2.400 × 106 (n = 43 [24%]), and 2.401 to 5.100 × 106 (n = 43 [24%]). OS, EFS, and RFS were improved in patients who received higher doses of tisagenlecleucel (P = .031, .0079, and .0045, respectively). Higher doses of tisagenlecleucel were not associated with increased toxicity. Because the current tisagenlecleucel package insert dose range remains broad, this work has implications in regard to targeting higher cell doses, within the approved dose range, to optimize patients' potential for long-standing remission.

Ruxolitinib for the Treatment of Chronic GVHD and Overlap Syndrome in Children and Young Adults.

BACKGROUND: Ruxolitinib, a JAK1/2 inhibitor, is used to treat chronic graft versus host disease (cGVHD) in adult allogeneic hematopoietic stem cell transplant patients, but experience in children is limited, perhaps because of lack of pediatric dosing information. In this report, we describe our pediatric and young adult dosing strategy experience in cGVHD. METHODS: Ruxolitinib was administered orally at 5 mg twice daily for children ≥25 kg or 2.5 mg twice daily if <25 kg. The dose was halved with concurrent azole administration and increased to a maximum of 10 mg twice daily if tolerated. Responses were evaluated using the 2014 NIH consensus criteria. Phosphorylation of lymphocyte STAT5 following dosing, a surrogate of JAK inhibition, was evaluated by flow cytometry. RESULTS: Twenty patients with a median age 14.6 y (range 5-26 y) received ruxolitinib for severe (n = 9) and moderate (n = 11) cGVHD. Median steroid dose was 0.5 mg/kg/d (range 0.08-1.5 mg/kg/d) at ruxolitinib initiation. Two patients with moderate cGVHD achieved a complete response (CR), while 12 patients achieved a partial response (PR) at a median of 48 d (range 17-98 d) from the first ruxolitinib dose, for an overall response rate of 70%. Eleven patients are maintaining their PRs. pSTAT5 on lymphocytes was absent or decreased (0%-6% events) in 5 evaluated patients, suggesting adequate inhibition. Three patients discontinued ruxolitinib because of neutropenia, thrombocytopenia, or elevated alanine aminotransferase. Four patients developed bacterial infections, and 3 experienced symptomatic viral infections. Two patients died from complications related to progressive severe cGVHD. CONCLUSIONS: Ruxolitinib using our dosing strategy demonstrates promise for treating cGVHD in children.