Tabelecleucel for EBV+ PTLD after allogeneic HCT or SOT in a multicenter expanded access protocol.

ABSTRACT: Patients with Epstein-Barr virus (EBV)-positive posttransplant lymphoproliferative disease (EBV+ PTLD) in whom initial treatment fails have few options and historically low median overall survival (OS) of 0.7 months after allogeneic hematopoietic cell transplant (HCT) and 4.1 months after solid organ transplant (SOT). Tabelecleucel is an off-the-shelf, allogeneic EBV-specific cytotoxic T-lymphocyte immunotherapy for EBV+ PTLD. Previous single-center experience showed responses in patients with EBV+ PTLD after HCT or SOT. We now report outcomes from a multicenter expanded access protocol in HCT (n = 14) and SOT (n = 12) recipients treated with tabelecleucel for EBV+ PTLD that was relapsed/refractory (R/R) to rituximab with/without chemotherapy. The investigator-assessed objective response rate was 65.4% overall (including 38.5% with a complete and 26.9% with a partial response), 50.0% in HCT, and 83.3% in SOT. The estimated 1- and 2-year OS rates were both 70.0% (95% confidence interval [CI], 46.5-84.7) overall, both 61.5% (95% CI, 30.8-81.8) in HCT, and both 81.5% (95% CI, 43.5-95.1) in SOT (median follow-up: 8.2, 2.8, and 22.5 months, respectively). Patients responding to tabelecleucel had higher 1- and 2-year OS rates (94.1%) than nonresponders (0%). Treatment was well tolerated, with no reports of tumor flare, cytokine release syndrome, or rejection of marrow and SOT. Results demonstrate clinically meaningful outcomes across a broad population treated with tabelecleucel, indicating a potentially transformative and accessible treatment advance for R/R EBV+ PTLD after HCT or SOT. This trial was registered at www.ClinicalTrials.gov as #NCT02822495.

Anakinra for Refractory Cytokine Release Syndrome or Immune Effector Cell-Associated Neurotoxicity Syndrome after Chimeric Antigen Receptor T Cell Therapy.

Chimeric antigen receptor-engineered (CAR)-T cell therapy remains limited by significant toxicities, including cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS). The optimal management of severe and/or refractory CRS/ICANS remains ill-defined. Anakinra has emerged as a promising agent based on preclinical data, but its safety and efficacy in CAR-T therapy recipients are unknown. The primary objective of this study was to evaluate the safety of anakinra to treat refractory CRS and ICANS after CAR-T therapy. The secondary objective was to evaluate the impact of key treatment-, patient-, and disease-related variables on the time to CRS/ICANS resolution and treatment-related mortality (TRM). We retrospectively analyzed the outcomes of 43 patients with B cell or plasma cell malignancies treated with anakinra for refractory CRS or ICANS at 9 institutions in the United States and Spain between 2019 and 2022. Cause-specific Cox regression was used to account for competing risks. Multivariable cause-specific Cox regression was used to estimate the effect of anakinra dose on outcomes while minimizing treatment allocation bias by including age, CAR-T product, prelymphodepletion (pre-LD) ferritin, and performance status. Indications for anakinra treatment were grade ≥2 ICANS with worsening or lack of symptom improvement despite treatment with high-dose corticosteroids (n = 40) and grade ≥2 CRS with worsening symptoms despite treatment with tocilizumab (n = 3). Anakinra treatment was feasible and safe; discontinuation of therapy because of anakinra-related side effects was reported in only 3 patients (7%). The overall response rate (ORR) to CAR-T therapy was 77%. The cumulative incidence of TRM in the whole cohort was 7% (95% confidence interval [CI], 2% to 17%) at 28 days and 23% (95% CI, 11% to 38%) at 60 days after CAR-T infusion. The cumulative incidence of TRM at day 28 after initiation of anakinra therapy was 0% in the high-dose (>200 mg/day i.v.) recipient group and 47% (95% CI, 20% to 70%) in the low-dose (100 to 200 mg/day s.c. or i.v.) recipient group. The median cumulative incidence of CRS/ICANS resolution from the time of anakinra initiation was 7 days in the high-dose group and was not reached in the low-dose group, owing to the high TRM in this group. Univariate Cox modeling suggested a shorter time to CRS/ICANS resolution in the high-dose recipients (hazard ratio [HR], 2.19; 95% CI, .94 to 5.12; P = .069). In a multivariable Cox model for TRM including age, CAR-T product, pre-LD ferritin level, and pre-LD Karnofsky Performance Status (KPS), higher anakinra dose remained associated with lower TRM (HR, .41 per 1 mg/kg/day increase; 95% CI, .17 to .96; P = .039. The sole factor independently associated with time to CRS/ICANS resolution in a multivariable Cox model including age, CAR-T product, pre-LD ferritin and anakinra dose was higher pre-LD KPS (HR, 1.05 per 10% increase; 95% CI, 1.01 to 1.09; P = .02). Anakinra treatment for refractory CRS or ICANS was safe at doses up to 12 mg/kg/day i.v. We observed an ORR of 77% after CAR-T therapy despite anakinra treatment, suggesting a limited impact of anakinra on CAR-T efficacy. Higher anakinra dose may be associated with faster CRS/ICANS resolution and was independently associated with lower TRM. Prospective comparative studies are needed to confirm our findings.

A diagnostic classifier for pediatric chronic graft-versus-host disease: results of the ABLE/PBMTC 1202 study.

The National Institutes of Health Consensus criteria for chronic graft-versus-host disease (cGVHD) diagnosis can be challenging to apply in children, making pediatric cGVHD diagnosis difficult. We aimed to identify diagnostic pediatric cGVHD biomarkers that would complement the current clinical criteria and help differentiate cGVHD from non-cGVHD. The Applied Biomarkers of Late Effects of Childhood Cancer (ABLE) study, open at 27 transplant centers, prospectively evaluated 302 pediatric patients after hematopoietic cell transplant (234 evaluable). Forty-four patients developed cGVHD. Mixed and fixed effect regression analyses were performed on diagnostic cGVHD onset blood samples for cellular and plasma biomarkers, with individual markers declared relevant if they met 3 criteria: an effect ratio ≥1.3 or ≤0.75; an area under the curve (AUC) of ≥0.60; and a P value <5.814 × 10-4 (Bonferroni correction) (mixed effect) or <.05 (fixed effect). To address the complexity of cGVHD diagnosis in children, we built a machine learning-based classifier that combined multiple cellular and plasma biomarkers with clinical factors. Decreases in regulatory natural killer cells, naïve CD4 T helper cells, and naïve regulatory T cells, and elevated levels of CXCL9, CXCL10, CXCL11, ST2, ICAM-1, and soluble CD13 (sCD13) characterize the onset of cGVHD. Evaluation of the time dependence revealed that sCD13, ST2, and ICAM-1 levels varied with the timing of cGVHD onset. The cGVHD diagnostic classifier achieved an AUC of 0.89, with a positive predictive value of 82% and a negative predictive value of 80% for diagnosing cGVHD. Our polyomic approach to building a diagnostic classifier could help improve the diagnosis of cGVHD in children but requires validation in future prospective studies. This trial was registered at www.clinicaltrials.gov as #NCT02067832.

Ibrutinib Treatment of Pediatric Chronic Graft-versus-Host Disease: Primary Results from the Phase 1/2 iMAGINE Study.

Chronic graft-versus-host disease (cGVHD) is a potentially life-threatening complication of allogeneic hematopoietic stem cell transplantation. Clinical data surrounding cGVHD therapies in younger children are limited and critically needed. Primary endpoints were to determine the recommended pediatric equivalent dose (RPED) and assess pharmacokinetics (PK) and safety. Secondary endpoints included overall response rate (ORR; comprising complete response and partial response) according to the 2014 National Institutes of Health criteria at 24 weeks, overall survival, and duration of response (DOR). Here we present the primary results from the open-label, multicenter, international phase 1/2 iMAGINE study (PCYC-1146-IM), which evaluated the PK, safety, and efficacy of ibrutinib in patients age ≥1 to <22 years with treatment-naive (TN) or relapsed/refractory (R/R) moderate/severe cGVHD. Patients age <12 years received once-daily ibrutinib starting at 120 mg/m2 and escalating to 240 mg/m2 (full adult dose equivalent) after 14 days if free from ibrutinib-related grade ≥3 toxicity; patients age ≥12 years received once-daily ibrutinib 420 mg. Fifty-nine patients (12 TN and 47 with R/R cGVHD; median age, 13 years; range, 1 to 19 years) were enrolled. Plasma concentration-time profiles for ibrutinib 240 mg/m2 (the RPED) were comparable to those observed in adults with cGVHD at a dose of 420 mg/day. Safety was consistent with the known profile of ibrutinib in cGVHD. ORR by 24 weeks was 64% (38 of 59), including 83% (10 of 12) for the TN subgroup and 60% (28 of 47) for R/R. Among 46 responders (median follow-up, 20 months; range, 2 to 32 months), 12-month DOR for each subgroup was 60% (95% confidence interval [CI], 25% to 83%) in TN patients and 58% (95% CI, 35% to 75%) in R/R patients. Responses were durable, with numerically higher rates than those previously observed with ibrutinib in adults, demonstrating that ibrutinib provides clinically meaningful activity with acceptable safety in children with moderate/severe cGVHD.

Randomized Phase III BMT CTN Trial of Calcineurin Inhibitor-Free Chronic Graft-Versus-Host Disease Interventions in Myeloablative Hematopoietic Cell Transplantation for Hematologic Malignancies.

PURPOSE: Calcineurin inhibitors (CNI) are standard components of graft-versus-host disease (GVHD) prophylaxis after hematopoietic cell transplantation (HCT). Prior data suggested that CNI-free approaches using donor T-cell depletion, either by ex vivo CD34 selection or in vivo post-transplant cyclophosphamide (PTCy) as a single agent, are associated with lower rates of chronic GVHD (cGVHD). METHODS: This multicenter phase III trial randomly assigned patients with acute leukemia or myelodysplasia and an HLA-matched donor to receive CD34-selected peripheral blood stem cell, PTCy after a bone marrow (BM) graft, or tacrolimus and methotrexate after BM graft (control). The primary end point was cGVHD (moderate or severe) or relapse-free survival (CRFS). RESULTS: Among 346 patients enrolled, 327 received HCT, 300 per protocol. Intent-to-treat rates of 2-year CRFS were 50.6% for CD34 selection (hazard ratio [HR] compared with control, 0.80; 95% CI, 0.56 to 1.15; P = .24), 48.1% for PTCy (HR, 0.86; 0.61 to 1.23; P = .41), and 41.0% for control. Corresponding rates of overall survival were 60.1% (HR, 1.74; 1.09 to 2.80; P = .02), 76.2% (HR, 1.02; 0.60 to 1.72; P = .95), and 76.1%. CD34 selection was associated with lower moderate to severe cGVHD (HR, 0.25; 0.12 to 0.52; P = .02) but higher transplant-related mortality (HR, 2.76; 1.26 to 6.06; P = .01). PTCy was associated with comparable cGVHD and survival outcomes to control, and a trend toward lower disease relapse (HR, 0.52; 0.28 to 0.96; P = .037). CONCLUSION: CNI-free interventions as performed herein did not result in superior CRFS compared with tacrolimus and methotrexate with BM. Lower rates of moderate and severe cGVHD did not translate into improved survival.

Metabolomic identification of α-ketoglutaric acid elevation in pediatric chronic graft-versus-host disease.

Chronic graft-versus-host disease (cGVHD) is the most common cause for non-relapse mortality postallogeneic hematopoietic stem cell transplant (HSCT). However, there are no well-defined biomarkers for cGVHD or late acute GVHD (aGVHD). This study is a longitudinal evaluation of metabolomic patterns of cGVHD and late aGVHD in pediatric HSCT recipients. A quantitative analysis of plasma metabolites was performed on 222 evaluable pediatric subjects from the ABLE/PBMTC1202 study. We performed a risk-assignment analysis at day + 100 (D100) on subjects who later developed either cGVHD or late aGVHD after day 114 to non-cGVHD controls. A second analysis at diagnosis used fixed and mixed multiple regression to compare cGVHD at onset to time-matched non-cGVHD controls. A metabolomic biomarker was considered biologically relevant only if it met all 3 selection criteria: (1) P ≤ .05; (2) effect ratio of ≥1.3 or ≤0.75; and (3) receiver operator characteristic AUC ≥0.60. We found a consistent elevation in plasma α-ketoglutaric acid before (D100) and at the onset of cGVHD, not impacted by cGVHD severity, pubertal status, or previous aGVHD. In addition, late aGVHD had a unique metabolomic pattern at D100 compared with cGVHD. Additional metabolomic correlation patterns were seen with the clinical presentation of pulmonary, de novo, and progressive cGVHD. α-ketoglutaric acid emerged as the single most significant metabolite associated with cGVHD, both in the D100 risk-assignment and later diagnostic onset analysis. These distinctive metabolic patterns may lead to improved subclassification of cGVHD. Future validation of these exploratory results is needed. This trial was registered at www.clinicaltrials.gov as #NCT02067832.

Blood and Marrow Transplant Clinical Trials Network State of the Science Symposium 2021: Looking Forward as the Network Celebrates its 20th Year.

In 2021 the BMT CTN held the 4th State of the Science Symposium where the deliberations of 11 committees concerning major topics pertinent to a particular disease, modality, or complication of transplant, as well as two committees to consider clinical trial design and inclusion, diversity, and access as cross-cutting themes were reviewed. This article summarizes the individual committee reports and their recommendations on the highest priority questions in hematopoietic stem cell transplant and cell therapy to address in multicenter trials.

Treosulfan-based conditioning is feasible and effective for cord blood recipients: a phase 2 multicenter study.

Although the use of treosulfan (TREO) in conventional donor hematopoietic cell transplantation (HCT) has been extensively evaluated, its use in cord blood transplantation (CBT) for hematologic malignancies has not been reported. Between March 2009 and October 2019, 130 CBT recipients were enrolled in this prospective multicenter phase 2 study. The conditioning regimen consisted of TREO, fludarabine, and a single fraction of 2 Gy total-body irradiation. Cyclosporine and mycophenolate mofetil were used for graft-versus-host disease prophylaxis. The primary end point was incidence of graft failure (GF), and based on risk of GF, patients were classified as low risk (arm 1, n = 66) and high risk (arm 2, n = 64). The median age was 45 years (range, 0.6-65 years). Disease status included acute leukemias in first complete remission (CR; n = 56), in ≥2 CRs (n = 46), and myelodysplastic (n = 25) and myeloproliferative syndromes (n = 3). Thirty-five patients (27%) had received a prior HCT. One hundred twenty-three patients (95%) engrafted, with neutrophil recovery occurring at a median of 19 days for patients on arm 1 and 20 days for patients on arm 2. The 3-year overall survival, relapse-free survival (RFS), transplant-related mortality, and relapse for the combined groups were 66%, 57%, 18%, and 24%, respectively. Among patients who had a prior HCT, RFS at 3 years was 48%. No significant differences in clinical outcomes were seen between the 2 arms. Our results demonstrate that TREO-based conditioning for CBT recipients is safe and effective in promoting CB engraftment with favorable clinical outcomes. This trial was registered at www.clinicaltrials.gov as #NCT00796068.

Immune profile differences between chronic GVHD and late acute GVHD: results of the ABLE/PBMTC 1202 studies.

Human graft-versus-host disease (GVHD) biology beyond 3 months after hematopoietic stem cell transplantation (HSCT) is complex. The Applied Biomarker in Late Effects of Childhood Cancer study (ABLE/PBMTC1202, NCT02067832) evaluated the immune profiles in chronic GVHD (cGVHD) and late acute GVHD (L-aGVHD). Peripheral blood immune cell and plasma markers were analyzed at day 100 post-HSCT and correlated with GVHD diagnosed according to the National Institutes of Health consensus criteria (NIH-CC) for cGVHD. Of 302 children enrolled, 241 were evaluable as L-aGVHD, cGVHD, active L-aGVHD or cGVHD, and no cGVHD/L-aGVHD. Significant marker differences, adjusted for major clinical factors, were defined as meeting all 3 criteria: receiver-operating characteristic area under the curve ≥0.60, P ≤ .05, and effect ratio ≥1.3 or ≤0.75. Patients with only distinctive features but determined as cGVHD by the adjudication committee (non-NIH-CC) had immune profiles similar to NIH-CC. Both cGVHD and L-aGVHD had decreased transitional B cells and increased cytolytic natural killer (NK) cells. cGVHD had additional abnormalities, with increased activated T cells, naive helper T (Th) and cytotoxic T cells, loss of CD56bright regulatory NK cells, and increased ST2 and soluble CD13. Active L-aGVHD before day 114 had additional abnormalities in naive Th, naive regulatory T (Treg) cell populations, and cytokines, and active cGVHD had an increase in PD-1- and a decrease in PD-1+ memory Treg cells. Unsupervised analysis appeared to show a progression of immune abnormalities from no cGVHD/L-aGVHD to L-aGVHD, with the most complex pattern in cGVHD. Comprehensive immune profiling will allow us to better understand how to minimize L-aGVHD and cGVHD. Further confirmation in adult and pediatric cohorts is needed.

Benefits and challenges with diagnosing chronic and late acute GVHD in children using the NIH consensus criteria.

Chronic graft-versus-host disease (cGVHD) and late acute graft-versus-host disease (L-aGVHD) are understudied complications of allogeneic hematopoietic stem cell transplantation in children. The National Institutes of Health Consensus Criteria (NIH-CC) were designed to improve the diagnostic accuracy of cGVHD and to better classify graft-versus-host disease (GVHD) syndromes but have not been validated in patients <18 years of age. The objectives of this prospective multi-institution study were to determine: (1) whether the NIH-CC could be used to diagnose pediatric cGVHD and whether the criteria operationalize well in a multi-institution study; (2) the frequency of cGVHD and L-aGVHD in children using the NIH-CC; and (3) the clinical features and risk factors for cGVHD and L-aGVHD using the NIH-CC. Twenty-seven transplant centers enrolled 302 patients <18 years of age before conditioning and prospectively followed them for 1 year posttransplant for development of cGVHD. Centers justified their cGVHD diagnosis according to the NIH-CC using central review and a study adjudication committee. A total of 28.2% of reported cGVHD cases was reclassified, usually as L-aGVHD, following study committee review. Similar incidence of cGVHD and L-aGVHD was found (21% and 24.7%, respectively). The most common organs involved with diagnostic or distinctive manifestations of cGVHD in children include the mouth, skin, eyes, and lungs. Importantly, the 2014 NIH-CC for bronchiolitis obliterans syndrome perform poorly in children. Past acute GVHD and peripheral blood grafts are major risk factors for cGVHD and L-aGVHD, with recipients ≥12 years of age being at risk for cGVHD. Applying the NIH-CC in pediatrics is feasible and reliable; however, further refinement of the criteria specifically for children is needed.

Genetic mechanisms of target antigen loss in CAR19 therapy of acute lymphoblastic leukemia.

We identified genetic mutations in CD19 and loss of heterozygosity at the time of CD19- relapse to chimeric antigen receptor (CAR) therapy. The mutations are present in the vast majority of resistant tumor cells and are predicted to lead to a truncated protein with a nonfunctional or absent transmembrane domain and consequently to a loss of surface antigen. This irreversible loss of CD19 advocates for an alternative targeting or combination CAR approach.

Synthetic lethality of TNK2 inhibition in PTPN11-mutant leukemia.

The protein tyrosine phosphatase PTPN11 is implicated in the pathogenesis of juvenile myelomonocytic leukemia (JMML), acute myeloid leukemia (AML), and other malignancies. Activating mutations in PTPN11 increase downstream proliferative signaling and cell survival. We investigated the signaling upstream of PTPN11 in JMML and AML cells and found that PTPN11 was activated by the nonreceptor tyrosine/serine/threonine kinase TNK2 and that PTPN11-mutant JMML and AML cells were sensitive to TNK2 inhibition. In cultured human cell-based assays, PTPN11 and TNK2 interacted directly, enabling TNK2 to phosphorylate PTPN11, which subsequently dephosphorylated TNK2 in a negative feedback loop. Mutations in PTPN11 did not affect this physical interaction but increased the basal activity of PTPN11 such that TNK2-mediated activation was additive. Consequently, coexpression of TNK2 and mutant PTPN11 synergistically increased mitogen-activated protein kinase (MAPK) signaling and enhanced colony formation in bone marrow cells from mice. Chemical inhibition of TNK2 blocked MAPK signaling and colony formation in vitro and decreased disease burden in a patient with PTPN11-mutant JMML who was treated with the multikinase (including TNK2) inhibitor dasatinib. Together, these data suggest that TNK2 is a promising therapeutic target for PTPN11-mutant leukemias.

Outcomes of Measurable Residual Disease in Pediatric Acute Myeloid Leukemia before and after Hematopoietic Stem Cell Transplant: Validation of Difference from Normal Flow Cytometry with Chimerism Studies and Wilms Tumor 1 Gene Expression.

We enrolled 150 patients in a prospective multicenter study of children with acute myeloid leukemia undergoing hematopoietic stem cell transplantation (HSCT) to compare the detection of measurable residual disease (MRD) by a "difference from normal" flow cytometry (ΔN) approach with assessment of Wilms tumor 1 (WT1) gene expression without access to the diagnostic specimen. Prospective analysis of the specimens using this approach showed that 23% of patients screened for HSCT had detectable residual disease by ΔN (.04% to 53%). Of those patients who proceeded to transplant as being in morphologic remission, 10 had detectable disease (.04% to 14%) by ΔN. The disease-free survival of this group was 10% (0 to 35%) compared with 55% (46% to 64%, P < .001) for those without disease. The ΔN assay was validated using the post-HSCT specimen by sorting abnormal or suspicious cells to confirm recipient or donor origin by chimerism studies. All 15 patients who had confirmation of tumor detection relapsed, whereas the 2 patients with suspicious phenotype cells lacking this confirmation did not. The phenotype of the relapse specimen was then used retrospectively to assess the pre-HSCT specimen, allowing identification of additional samples with low levels of MRD involvement that were previously undetected. Quantitative assessment of WT1 gene expression was not predictive of relapse or other outcomes in either pre- or post-transplant specimens. MRD detected by ΔN was highly specific, but did not identify most relapsing patients. The application of the assay was limited by poor quality among one-third of the specimens and lack of a diagnostic phenotype for comparison.

A phase II/III randomized, multicenter trial of prednisone/sirolimus versus prednisone/ sirolimus/calcineurin inhibitor for the treatment of chronic graft-versus-host disease: BMT CTN 0801.

Initial therapy of chronic graft-versus-host disease is prednisone ± a calcineurin-inhibitor, but most patients respond inadequately. In a randomized, adaptive, phase II/III, multicenter trial we studied whether prednisone/sirolimus or prednisone/sirolimus/photopheresis was more effective than prednisone/sirolimus/calcineurin-inhibitor for treating chronic graft-versus-host disease in treatment-naïve or early inadequate responders. Primary endpoints of this study were proportions of subjects alive without relapse or secondary therapy with 6-month complete or partial response in phase II, or with 2-year complete response in phase III. The prednisone/sirolimus/photopheresis arm closed prematurely because of slow accrual and the remaining two-drug versus three-drug study ended in phase II due to statistical futility with 138 evaluable subjects. The two-drug and three-drug arms did not differ in rates of 6-month complete or partial response (48.6% versus 50.0%, P=0.87), or 2-year complete response (14.7% versus 15.5%, P=0.90). Serum creatinine values >1.5 times baseline were less frequent in the calcineurin-inhibitor-free arm at 2 months (1.5% versus 11.7%, P=0.025) and 6 months (7.8% versus 24.0%, P=0.016). Higher adjusted Short Form-36 Physical Component Summary and Physical Functioning scores were seen in the two-drug arm at both 2 months (P=0.02 and P=0.04, respectively) and 6 months (P=0.007 and P=0.001, respectively). Failure-free survival and overall survival rates at 2 years were similar for patients in the the two-drug and three-drug arms (48.6% versus 46.2%, P=0.78; 81.5% versus 74%, P=0.28). Based on similar long-term outcomes, prednisone/sirolimus is a therapeutic alternative to prednisone/sirolimus/calcineurin-inhibitor for chronic graft-versus-host disease, being easier to administer and better tolerated. Clinicaltrials.gov identifier: NCT01106833.

Treosulfan, Fludarabine, and Low-Dose Total Body Irradiation for Children and Young Adults with Acute Myeloid Leukemia or Myelodysplastic Syndrome Undergoing Allogeneic Hematopoietic Cell Transplantation: Prospective Phase II Trial of the Pediatric Blood and Marrow Transplant Consortium.

This multicenter study evaluated a treosulfan-based regimen in children and young adults with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) undergoing allogeneic hematopoietic cell transplant (HCT). Forty patients with median age 11 years (range, 1 to 19) underwent allogeneic HCT for AML in first (n = 18), second (n = 11), and third or greater remission (n = 3) or MDS (n = 8) using bone marrow (n = 25), peripheral blood stem cells (n = 5), or cord blood (n = 9). The regimen consisted of body surface area (BSA)-based treosulfan 10 g/m2/day (BSA ≤ .5 m2), 12 g/m2/day (BSA > .5 to 1.0 m2), or 14 g/m2/day (BSA > 1.0 m2) on days -6 to -4; fludarabine 30 mg/m2/day on days -6 to -2; and a single fraction of 200 cGy total body irradiation on day -1. Graft-versus-host disease (GVHD) prophylaxis included tacrolimus and methotrexate for marrow and peripheral blood stem cell and cyclosporine/mycophenolate mofetil for cord blood. One-year overall survival, disease-free survival, and nonrelapse mortality were 80%, 73%, and 3%, respectively. One-year relapse was 38% for AML and 13% for MDS. No serious organ toxicities were observed. All 37 assessable patients engrafted. Cumulative incidences of grades II to IV acute GVHD and chronic GVHD were 22% and 40%, respectively. BSA-based treosulfan dosing resulted in predictable area under the curve and maximum concentration, which is required for dosing without measuring individual pharmacokinetic parameters. Observed differences in pharmacokinetics did not impact disease control or regimen toxicity. This BSA-based treosulfan regimen resulted in excellent engraftment and disease-free survival and minimal toxicity and transplant-related mortality (3%) in children and young adults with AML and MDS.

Late cardiovascular morbidity and mortality following pediatric allogeneic hematopoietic cell transplantation.

We analyzed late cardiovascular outcomes of 661 patients who survived at least 2 years from hematopoietic cell transplantation for childhood hematologic malignancy between 1995 and 2008. Center for International Blood and Marrow Transplant Research data was supplemented with surveys focused on cardiotoxicity and potential risk factors. The median duration of follow-up was 97 months (range 24-230). 4.2% of survivors experienced at least one of the primary outcomes including coronary artery disease (0.2%), cerebrovascular accident (0.6%), cardiomyopathy (3%), and cardiac-related death (0.5%). Patients who received anthracycline chemotherapy (HR 4.67, p = 0.036) or cranial or chest radiation (HR 5.58, p < 0.0001; HR 2.18, p = 0.0087) were at increased risk for developing one of the primary outcomes. Dyslipidemia was diagnosed in 18% of survivors. Pre-transplant anthracycline (HR 1.74, p < 0.0001) and chest radiation (HR 1.34, p = 0.0371) were risk factors for dyslipidemia. Overweight/obese body mass status was present in 63% of patients at baseline, 65% at 2 years, and 52% at most recent evaluation. Diabetes was diagnosed in 7% of subjects. In conclusion, severe cardiovascular complications were infrequently reported. The incidence of risk factors including obesity and dyslipidemia were significant and will likely increase the risk of cardiovascular disease over time in transplant survivors.

Tisagenlecleucel in Children and Young Adults with B-Cell Lymphoblastic Leukemia.

BACKGROUND: In a single-center phase 1-2a study, the anti-CD19 chimeric antigen receptor (CAR) T-cell therapy tisagenlecleucel produced high rates of complete remission and was associated with serious but mainly reversible toxic effects in children and young adults with relapsed or refractory B-cell acute lymphoblastic leukemia (ALL). METHODS: We conducted a phase 2, single-cohort, 25-center, global study of tisagenlecleucel in pediatric and young adult patients with CD19+ relapsed or refractory B-cell ALL. The primary end point was the overall remission rate (the rate of complete remission or complete remission with incomplete hematologic recovery) within 3 months. RESULTS: For this planned analysis, 75 patients received an infusion of tisagenlecleucel and could be evaluated for efficacy. The overall remission rate within 3 months was 81%, with all patients who had a response to treatment found to be negative for minimal residual disease, as assessed by means of flow cytometry. The rates of event-free survival and overall survival were 73% (95% confidence interval [CI], 60 to 82) and 90% (95% CI, 81 to 95), respectively, at 6 months and 50% (95% CI, 35 to 64) and 76% (95% CI, 63 to 86) at 12 months. The median duration of remission was not reached. Persistence of tisagenlecleucel in the blood was observed for as long as 20 months. Grade 3 or 4 adverse events that were suspected to be related to tisagenlecleucel occurred in 73% of patients. The cytokine release syndrome occurred in 77% of patients, 48% of whom received tocilizumab. Neurologic events occurred in 40% of patients and were managed with supportive care, and no cerebral edema was reported. CONCLUSIONS: In this global study of CAR T-cell therapy, a single infusion of tisagenlecleucel provided durable remission with long-term persistence in pediatric and young adult patients with relapsed or refractory B-cell ALL, with transient high-grade toxic effects. (Funded by Novartis Pharmaceuticals; ClinicalTrials.gov number, NCT02435849 .).

Allogeneic Hematopoietic Cell Transplantation Using Treosulfan-Based Conditioning for Treatment of Marrow Failure Disorders.

Hematopoietic cell transplantation (HCT) is effective in the treatment of inherited marrow failure disorders and other nonmalignant diseases. Conventional myeloablative conditioning regimens have been associated with high transplant-related mortality, particularly in patients with comorbid conditions. Here we report on 14 patients with marrow failure disorders (Shwachman-Diamond syndrome, n = 3; Diamond Blackfan anemia, n = 4; GATA2 deficiency, n = 2; paroxysmal nocturnal hemoglobinuria, n = 4; and an undefined marrow failure disorder, n = 1) who underwent HCT on a prospective, phase II, multicenter clinical trial. Patients were given HLA-matched related (n = 2) or unrelated (n = 12) grafts after conditioning with treosulfan (42 g/m2), fludarabine (150 mg/m2), ± thymoglobulin (n = 11; 6 mg/kg). All patients engrafted. At a median follow-up of 3 years, 13 patients are alive with complete correction of their underlying disease. These results indicate that the combination of treosulfan, fludarabine, and thymoglobulin is effective at establishing donor engraftment with a low toxicity profile and excellent disease-free survival in patients with marrow failure disorders.

Phase 3 trial of defibrotide for the treatment of severe veno-occlusive disease and multi-organ failure.

Hepatic veno-occlusive disease (VOD), also called sinusoidal obstruction syndrome (SOS), is a potentially life-threatening complication of hematopoietic stem cell transplantation (HSCT). Untreated hepatic VOD/SOS with multi-organ failure (MOF) is associated with >80% mortality. Defibrotide has shown promising efficacy treating hepatic VOD/SOS with MOF in phase 2 studies. This phase 3 study investigated safety and efficacy of defibrotide in patients with established hepatic VOD/SOS and advanced MOF. Patients (n = 102) given defibrotide 25 mg/kg per day were compared with 32 historical controls identified out of 6867 medical charts of HSCT patients by blinded independent reviewers. Baseline characteristics between groups were well balanced. The primary endpoint was survival at day +100 post-HSCT; observed rates equaled 38.2% in the defibrotide group and 25% in the controls (23% estimated difference; 95.1% confidence interval [CI], 5.2-40.8;P= .0109, using a propensity-adjusted analysis). Observed day +100 complete response (CR) rates equaled 25.5% for defibrotide and 12.5% for controls (19% difference using similar methodology; 95.1% CI, 3.5-34.6;P= .0160). Defibrotide was generally well tolerated with manageable toxicity. Related adverse events (AEs) included hemorrhage or hypotension; incidence of common hemorrhagic AEs (including pulmonary alveolar [11.8% and 15.6%] and gastrointestinal bleeding [7.8% and 9.4%]) was similar between the defibrotide and control groups, respectively. Defibrotide was associated with significant improvement in day +100 survival and CR rate. The historical-control methodology offers a novel, meaningful approach for phase 3 evaluation of orphan diseases associated with high mortality. This trial was registered at www.clinicaltrials.gov as #.