Memory T-cell enriched haploidentical transplantation with NK cell addback results in promising long-term outcomes: a phase II trial.

BACKGROUND: Relapse remains a challenge after transplantation in pediatric patients with hematological malignancies. Myeloablative regimens used for disease control are associated with acute and long-term adverse effects. We used a CD45RA-depleted haploidentical graft for adoptive transfer of memory T cells combined with NK-cell addback and hypothesized that maximizing the graft-versus-leukemia (GVL) effect might allow for reduction in intensity of conditioning regimen. METHODS: In this phase II clinical trial (NCT01807611), 72 patients with hematological malignancies (complete remission (CR)1: 25, ≥ CR2: 28, refractory disease: 19) received haploidentical CD34 + enriched and CD45RA-depleted hematopoietic progenitor cell grafts followed by NK-cell infusion. Conditioning included fludarabine, thiotepa, melphalan, cyclophosphamide, total lymphoid irradiation, and graft-versus-host disease (GVHD) prophylaxis consisted of a short-course sirolimus or mycophenolate mofetil without serotherapy. RESULTS: The 3-year overall survival (OS) and event-free-survival (EFS) for patients in CR1 were 92% (95% CI:72-98) and 88% (95% CI: 67-96); ≥ CR2 were 81% (95% CI: 61-92) and 68% (95% CI: 47-82) and refractory disease were 32% (95% CI: 11-54) and 20% (95% CI: 6-40). The 3-year EFS for all patients in morphological CR was 77% (95% CI: 64-87) with no difference amongst recipients with or without minimal residual disease (P = 0.2992). Immune reconstitution was rapid, with mean CD3 and CD4 T-cell counts of 410/µL and 140/µL at day + 30. Cumulative incidence of acute GVHD and chronic GVHD was 36% and 26% but most patients with acute GVHD recovered rapidly with therapy. Lower rates of grade III-IV acute GVHD were observed with NK-cell alloreactive donors (P = 0.004), and higher rates of moderate/severe chronic GVHD occurred with maternal donors (P = 0.035). CONCLUSION: The combination of a CD45RA-depleted graft and NK-cell addback led to robust immune reconstitution maximizing the GVL effect and allowed for use of a submyeloablative, TBI-free conditioning regimen that was associated with excellent EFS resulting in promising long-term outcomes in this high-risk population. The trial is registered at ClinicalTrials.gov (NCT01807611).

Reduced toxicity conditioning for hematopoietic stem cell transplantation in children with Diamond-Blackfan anemia.

Not available.

Retrospective analysis of veno-occlusive disease/sinusoidal obstruction syndrome in paediatric patients undergoing hematopoietic cell transplantation -a multicentre study.

Background: Sinusoidal obstruction syndrome is a potentially fatal complication following hematopoietic cell transplantation, high-intensity chemotherapies and increasingly seen with calicheamicin based leukemia therapies. Paediatric specific European Society for Blood and Marrow Transplantation (pEBMT) diagnostic criteria have demonstrated benefit in single center studies compared to historic criteria. Yet, the extent to which they have been universally implemented remains unclear. Methods: We conducted a retrospective multi-centre study to examine the potential impact of the Baltimore, modified Seattle and pEBMT criteria on the incidence, severity, and outcomes of sinusoidal obstruction syndrome among paediatric hematopoietic cell transplantation patients. Findings: The incidence of sinusoidal obstruction syndrome in this cohort (n = 488) was higher by pEBMT (21.5%) vs historic modified Seattle (15.6%) and Baltimore (7.0%) criteria (p < 0.001). Application of pEBMT criteria identified 44 patients who were not previously diagnosed with sinusoidal obstruction syndrome. Overall, 70.5% of all patients diagnosed with sinusoidal obstruction syndrome ultimately developed very severe disease and almost half of diagnosed patients required critical care support. Overall survival was significantly lower in patients who were diagnosed with sinusoidal obstruction syndrome vs those who were not. Interpretation: Taken together, pEBMT criteria may be a sensitive method for prompter diagnosis of patients who subsequently develop severe/very severe sinusoidal obstruction syndrome. To our knowledge, this is the first multi-centre study in the United States (US) to demonstrate that pEBMT guidelines are associated with earlier detection of sinusoidal obstruction syndrome. Since early initiation of definitive treatment for sinusoidal obstruction syndrome has been associated with improved survival in paediatric patients and implementation of pEBMT criteria appears feasible in the US, universal adoption should facilitate prompter diagnosis and lead to improved outcomes of children with sinusoidal obstruction syndrome. Funding: None.

Disease Status and Interval between Hematopoietic Cell Transplantations Predict Outcome of Pediatric Patients Who Undergo Subsequent Transplantation for Relapsed Hematologic Malignancy.

Patients with hematologic malignancies who relapse after allogeneic hematopoietic cell transplantation (HCT) have a poor prognosis. Although proceeding to subsequent HCT can provide potential for long-term survival, there are limited data to guide which patients are most likely to benefit and which HCT strategies are best in this heavily pretreated population. The goals of this study were to describe the clinical outcomes of subsequent HCT in pediatric patients with relapsed hematologic malignancies in a cohort enriched for haploidentical donors, and to evaluate the associations of patient-, disease-, and treatment-related factors with survival. We retrospectively evaluated patients who underwent a subsequent HCT for management of post-HCT relapse at a single institution between 2000 and 2021. Among 106 patients who underwent a second allogeneic HCT, the 1-year event-free survival (EFS) was 34% and 1-year overall survival (OS) was 46%, with a 5-year EFS of 26% and 5-year OS of 31%. Only disease-related factors were associated with outcome after second HCT-specifically, the interval between HCTs and the presence or absence of active disease at the time of HCT. In this cohort, patient- and treatment-related factors were not associated with differences in EFS or OS. Patients undergoing a third or fourth HCT (n = 13) had comparable survival outcomes to those undergoing a second HCT. Our experience highlights that a subsequent HCT has curative potential for a subset of patients who relapse after HCT, including those who undergo a subsequent HCT from a haploidentical donor. Although relapse and treatment-related toxicities remain major challenges, our study indicates that achieving complete remission prior to subsequent HCTs has the potential to further improve outcomes.

Outcomes following intolerance to calcineurin inhibitor-based graft-versus-host disease prophylaxis in children after allogeneic hematopoietic cell transplantation.

Calcineurin inhibitors (CNI), cyclosporine and tacrolimus, are commonly used for pharmacologic prophylaxis of graft-versus-host disease after allogeneic hematopoietic cell transplantation (HCT). Unfortunately, their use is associated with significant toxicities. While intolerance to CNI is well defined, there is very little information on how they impact outcomes after HCT in children. Our retrospective study in a cohort of 82 children shows a high intolerance rate of 39% in this population associated with lower event-free survival and a higher transplant-related mortality.

Preferential expansion of CD8+ CD19-CAR T cells postinfusion and the role of disease burden on outcome in pediatric B-ALL.

T cells expressing CD19-specific chimeric antigen receptors (CD19-CARs) have potent antileukemia activity in pediatric and adult patients with relapsed and/or refractory B-cell acute lymphoblastic leukemia (B-ALL). However, not all patients achieve a complete response (CR), and a significant percentage relapse after CD19-CAR T-cell therapy due to T-cell intrinsic and/or extrinsic mechanisms. Thus, there is a need to evaluate new CD19-CAR T-cell products in patients to improve efficacy. We developed a phase 1/2 clinical study to evaluate an institutional autologous CD19-CAR T-cell product in pediatric patients with relapsed/refractory B-ALL. Here we report the outcome of the phase 1 study participants (n = 12). Treatment was well tolerated, with a low incidence of both cytokine release syndrome (any grade, n = 6) and neurotoxicity (any grade, n = 3). Nine out of 12 patients (75%) achieved a minimal residual disease-negative CR in the bone marrow (BM). High disease burden (≥40% morphologic blasts) before CAR T-cell infusion correlated with increased side effects and lower response rate, but not with CD19-CAR T-cell expansion. After infusion, CD8+ CAR T cells had a proliferative advantage over CD4+ CAR T cells and at peak expansion, had an effector memory phenotype with evidence of antigen-driven differentiation. Patients that proceeded to allogeneic hematopoietic cell transplantation (AlloHCT) had sustained, durable responses. In summary, the initial evaluation of our institutional CD19-CAR T-cell product demonstrates safety and efficacy while highlighting the impact of pre-infusion disease burden on outcomes. This trial was registered at www.clinicaltrials.gov as #NCT03573700.

Sub-myeloablative Second Transplantations with Haploidentical Donors and Post-Transplant Cyclophosphamide have limited Anti-Leukemic Effects in Pediatric Patients.

Pediatric patients with high-risk hematologic malignancies who experience relapse after a prior allogeneic hematopoietic cell transplant (HCT) have an exceedingly poor prognosis. A second allogeneic HCT offers the potential for long-term cure but carries high risks of both subsequent relapse and HCT-related morbidity and mortality. Using haploidentical donors for HCT (haploHCT) can expand the donor pool and potentially enhance the graft-versus-leukemia effect but is accompanied by a risk of graft-versus-host disease (GVHD). The goal of this protocol was to intensify the antileukemia effect of haploHCT for pediatric patients with hematologic malignancies that relapsed after prior allogeneic HCT, while limiting regimen-associated toxicities. This phase II clinical trial evaluated a sub-myeloablative preparative regimen consisting of anti-thymocyte globulin, clofarabine, cytarabine, busulfan, and cyclophosphamide, in combination with plerixafor to sensitize leukemic blasts. Participants received a mobilized peripheral blood unmanipulated haploidentical donor graft with one dose of post-transplant cyclophosphamide as GVHD prophylaxis, followed by natural killer (NK) cell addback. Here we report the clinical outcomes and immune reconstitution of 17 participants treated on the study and 5 additional patients treated on similar single-patient treatment plans. Of the 22 participants analyzed, 12 (55%) had active disease at the time of HCT. The regimen provided robust immune reconstitution, with 21 participants (95%) experiencing neutrophil engraftment at a median of 14 days after HCT. In this high-risk population, the overall survival was 45% (95% confidence interval [CI], 24%-64%), with a 12-month event-free survival of 31% (95% CI, 14%-51%) and cumulative incidence of relapse at 12 months of 50% (95% CI, 27%-69%). Four participants (18%) remain in remission at >5 years follow-up. Expected HCT-related organ-specific toxicities were observed, and 13 participants (59%) experienced acute or chronic GVHD. This intensified but sub-myeloablative regimen, followed by a high-dose unmanipulated haploidentical graft, post-transplantation cyclophosphamide, and NK cell infusion, resulted in adequate immune reconstitution but failed to overcome the elevated risks of relapse and treatment-related morbidity in this high-risk population.

Outcomes of pediatric patients who relapse after first HCT for acute leukemia or MDS.

Disease relapse remains a major cause of treatment failure in patients receiving allogeneic hematopoietic cell transplantation (alloHCT) for high-risk acute leukemias or myelodysplastic syndromes (MDS). Comprehensive data on outcomes after post-transplant relapse are lacking, especially in pediatric patients. Our objective was to assess the impact of various transplant-, patient-, and disease-related variables on survival and outcomes in patients who relapse after alloHCT. We describe our institutional experience with 221 pediatric patients who experienced disease relapse after their first alloHCT for acute leukemias or MDS between 1990 and 2018. In a multivariable model, being in first complete remission at first alloHCT, longer duration of remission after alloHCT, experiencing GVHD and receiving a transplant in a more recent time period were significantly associated with a higher likelihood of receiving a second alloHCT after post-transplant relapse. Of these variables, only longer interval from alloHCT to relapse, receiving a second alloHCT or DLI, and receiving a transplant in a more recent time period were associated with improved overall survival. Our data support pursuing second alloHCT for patients who have experienced relapse after their first transplant, as that remains the only salvage modality with a reasonable chance of inducing long-term remission.

Outcome of Acute Respiratory Failure Secondary to Engraftment in Children After Hematopoietic Stem Cell Transplant.

Introduction: Respiratory complications due to engraftment syndrome (ES) in the post-hematopoietic stem cell transplant (HSCT) setting can lead to acute respiratory failure (ARF). Outcomes of children developing ARF due to engraftment are unknown. Methods: We conducted a retrospective analysis of 1,527 pediatric HSCT recipients and identified children who developed ARF due to ES over a 17-year period. Thirty patients that developed ARF and required invasive mechanical ventilation (IMV) due to ES were included in this study. Results: The survival rate for our cohort was 80% [alive at intensive care unit (ICU) discharge]. The most common underlying primary disease was hematologic malignancy, and 67% of children underwent allogeneic HSCT. Further, 73% required vasopressor drips and 23% underwent dialysis. Survivors had a shorter median ICU length of stay than did non-survivors (15 vs. 40 days, respectively, p = 0.01). Survivors had a significantly lower median cumulative fluid overload % on days 4 and 5 after initiation of IMV than did non-survivors (2.8 vs. 14.0 ml/kg, p = 0.038 on day 4, and 1.8 vs. 14.9 ml/kg, p = 0.044 on day 5, respectively). Conclusion: Our results suggest that children who develop ARF during engraftment have better ICU survival rates than do those with other etiologies of ARF post-HSCT. Furthermore, fluid overload contributes to mortality in these children; therefore, strategies to prevent and address fluid overload should be considered.

Improved survival rate in T-cell depleted haploidentical hematopoietic cell transplantation over the last 15 years at a single institution.

T-cell depletion of an HLA-haploidentical (haplo) graft is often used to reduce the risk of graft-versus-host disease (GVHD), but the lack of donor T cells in the infused product may lead to graft failure, slow T-cell reconstitution, infections, and relapse. More selective T-cell depletion targeting CD45RA can effectively deplete naive T cells but preserve large numbers of memory T cells leading to robust engraftment of diverse T-cell populations and reduction of viremia in the early posttransplant period. Herein, we report the outcome of 143 pediatric and young adult hematologic malignancy patients receiving a first allogeneic hematopoietic cell transplantation (HCT) on six consecutive ex vivo T-cell depleted haploHCT protocols over the past 15 years at a single institution-including the first 50 patients on an active CD45RA-depleted haploHCT study in which patients also received NK-cells and pharmacological GvHD prophylaxis post transplant. Our data demonstrated an increase in the 3-year overall survival and event-free survival in nonchemorefractory recipients receiving CD45RA-depleted grafts (78.9% and 77.7%, respectively) compared with historic T-cell depleted haploHCT cohorts (46.7% and 42.7%, respectively, p = 0.004, and 0.003). This improvement was primarily due to a reduction in transplant related mortality without significant increase in the rates of GVHD.

Secondary hemophagocytic syndrome after autologous hematopoietic cell transplant and immune therapy for neuroblastoma.

Secondary hemophagocytic syndrome (HPS) has been described after autologous hematopoietic cell transplant (AutoHCT). We report two cases of secondary HPS after novel consolidation therapy for high-risk neuroblastoma as part of an institutional phase 2 trial incorporating immunotherapy into a "standard" AutoHCT regimen. Both patients developed liver dysfunction beyond expected course of hepatic veno-occlusive disease, coagulopathy, hyperferritinemia, and when evaluated, elevated soluble interleukin-2 receptor and hemophagocytosis. These cases highlight the need for clinicians to have a high index of suspicion for immune-related complications in patients receiving immune therapies.

High white blood cell concentration in the peripheral blood stem cell product can induce seizures during infusion of autologous peripheral blood stem cells.

Seizures as a complication of the infusion of autologous peripheral blood stem cells (PBSC) are rare. Seizures during infusion of autologous PBSC in 3 of our patients prompted us to review our cell therapy and cytapheresis protocols and procedures. We retrospectively analyzed 159 adult patients collected between January 2006 and July 2009. Patients were collected on either the COBE Spectra (Caridian BCT, Lakewood, CO) cell separator (n = 85) or Fresenius AS (Fresenius Kabi AG, Bad Homburg, Germany) 104 cell separator (n = 74) and mobilized with granulocyte-colony stimulating factor (G-CSF) alone (n = 47), G-CSF and Plerixafor (n = 36), or G-CSF and chemotherapy (n = 76). Patient characteristics (including age, weight, number of collections, volume processed, disease type, and mobilization strategy) did not differ significantly between the COBE and Fresenius cohorts, and adverse effects from infusion were similar except for 3 of 159 patients who experienced seizures upon infusion of PBSC; all 3 were collected on the COBE and had PBSC product white blood cell (WBC) counts of 590 × 10(3)/µL or above. We prospectively correlated WBC counts midcollection, with final WBC counts to identify products with high WBC concentration during cytapheresis. Fifty-one patients had 66 cytapheresis procedures using the COBE, with WBC counts midway and at the end of collection of 287 × 10(3) ± 150/µL and 273 × 10(3) ± 144/µL, respectively. Mid-WBC therefore correlated with WBC at the end of the collection. Finally, we prospectively collected mid-WBC from 65 patients who underwent 80 PBSC collections between June 2009 and January 2010 to identify products with midcollection WBC concentration >450 × 10(3)/µL. In those cases, additional autologous plasma was collected at the time of collection to dilute the final product before cryopreservation. Patients who received diluted products experienced no delays in engraftment and no additional seizure episodes occurred.

Clinical utility of computed tomography screening of chest, abdomen, and sinuses before hematopoietic stem cell transplantation: the St. Jude experience.

All allogeneic (allo) and autologous (auto) hematopoietic stem cell transplantation (HSCT) recipients at St. Jude Children's Research Hospital undergo pre-HSCT computed tomography (CT) of the sinuses, chest, and abdomen because they are at significant risk for opportunistic infections. We studied whether this extensive routine imaging is warranted to detect infection despite the risk of additional radiation exposure. We reviewed the medical records of all children receiving allo- and auto-HSCT at St. Jude in 2004 and 2005. Of the 184 eligible patients who received 187 transplants, 131 received allografts and 56 autografts. Solid tumors and lymphomas were removed from the final analysis of the chest and abdomen CT as this imaging is typically warranted as part of disease restaging; thus, 111 allogeneic participants were included in this analysis. Both auto- and allo-recipients were evaluated by sinus CT and included in this final analysis. Most allo- and auto-HSCT recipients (> or =80%) did not have sinus, pulmonary, cardiac, or gastrointestinal symptoms; >85% of the evaluable allo-recipients had no prior fungal infection. Eighty-eight allo- and 31 auto-HSCT recipients had abnormal sinus CT findings, all unrelated to the underlying disease. Sixty-two (55.9%) of the allo-recipients had normal chest CT and 85 (76.6%) had normal abdominal CT. Of the 18 allo-recipients who began new therapy based on these findings, only 2 (11.1%) were related to chest CT findings and the other 16 were related to sinus findings. Our findings suggest that pre-HSCT routine CT imaging of the abdomen may not be warranted in a subset of allogeneic recipients who are asymptomatic and without previous infectious findings. Thus, these patients may be spared unnecessary radiation exposure. Recipients undergoing auto-HSCT or allo-HSCT for lymphomas or solid tumors will routinely undergo chest and abdominal CT imaging as part of their disease evaluation. The decision to perform chest CT should be made judiciously based on a careful history and physical examination. Sinus imaging, which was frequently abnormal, may be justified in all patients to plan post-HSCT care.

Total and active rabbit antithymocyte globulin (rATG;Thymoglobulin) pharmacokinetics in pediatric patients undergoing unrelated donor bone marrow transplantation.

Rabbit antithymocyte globulin (rATG; Thymoglobulin) is currently used to prevent or treat graft-versus-host disease (GVHD) during hematopoietic stem cell transplantation (HSCT). The dose and schedule of rATG as part of the preparative regimen for unrelated donor (URD) bone marrow transplantation (BMT) have not been optimized in pediatric patients. We conducted a prospective study of 13 pediatric patients with hematologic malignancies undergoing URD BMT at St. Jude Children's Research Hospital from October 2003 to March 2005, to determine the pharmacokinetics and toxicities of active and total rATG. The conditioning regimen comprised total body irradiation (TBI), thiotepa, and cyclophosphamide (Cy); cyclosporine (CsA) and methotrexate (MTX) were administered as GVHD prophylaxis. Patients received a total dose of 10 mg/kg rATG, and serial blood samples were assayed for total rATG by enzyme linked immunosorbent assay (ELISA) and active rATG by florescein activated cell sorting (FACS). We found that our weight-based dosing regimen for rATG was effective and well tolerated by patients. The half-lives of total and active rATG were comparable to those from previous studies, and despite high doses our patients had low maximum concentrations of active and total rATG. There were no occurrences of grade iii-iv GVHD even in patients having low peak rATG levels, and the overall incidence of grade II GVHD was only 15%. None of the patients had serious infections following transplantation. These data support the use of a 10 mg/kg dose of rATG in children with hematologic malignancies because it can be administered without increasing the risk of graft rejection, or serious infection in pediatric patients with a low rate of GVHD. These conclusions may not apply to patients with nonmalignant disorders.

A prospective cohort study of late sequelae of pediatric allogeneic hematopoietic stem cell transplantation.

As survivors of pediatric allogeneic hematopoietic stem cell transplantations (HSCTs) increase in number, it is increasingly important to evaluate their well-being. We conducted this prospective cohort study to evaluate the cumulative incidence and risk factors for late sequelae of HSCT. Comprehensive surveillance tests were performed annually on every participant, regardless of signs and symptoms, to obtain accurate information on the time-of-onset of each late event to allow hazard function analyses. All participants included in this report had been followed for at least 3 years after HSCT. With a median follow-up of 9 years and a current age of 18.5 years, only 20 of the 155 participants (13%) had no late sequelae; 18 survivors (12%) had 1 chronic health condition, 71 (46%) had 2-4 conditions, and 46 (30%) had 5-9 conditions. Risk factors for increasing number of chronic conditions included young age at the time of HSCT, female sex, high radiation dose, and history of chronic graft-versus-host disease. The cumulative incidence at 10 years for common late events was as follows (ordered by the median time-of-onset): osteonecrosis 13.8%, chronic renal insufficiency 26.8%, hypothyroidism 45.1%, growth hormone deficiency 31.2%, female hypogonadism 57.4%, osteopenia 47.7%, cataracts 43.4%, pulmonary dysfunction 63.2%, and male hypogonadism 20.3%. Coexistence of multiple late sequelae was common in HSCT survivors. Our findings provide a basis for more effective patient counseling, optimal surveillance, and early intervention.

Prophylaxis of Pneumocystis carinii pneumonia with atovaquone in children with leukemia.

BACKGROUND: Despite extensive studies of atovaquone in human immunodeficiency virus (HIV)-infected patients, there is little information about its efficacy as a prophylactic agent for Pneumocystis carinii pneumonia (PCP) in pediatric patients with cancer. Therefore, a retrospective analysis was conducted to determine the incidence of PCP in pediatric patients who received prophylactic atovaquone during treatment for acute leukemia. METHODS: We reviewed the medical records of all patients treated at our institution for acute lymphoblastic leukemia or acute myeloid leukemia between 1994 and 2004. Only patients who were intolerant of trimethoprim-sulfamethoxazole (TMP-SMZ) and received atovaquone prophylaxis were included in the analysis. RESULTS: Eighty-six patients were unable to tolerate TMP-SMZ and received daily atovaquone for PCP prophylaxis. PCP was not diagnosed in any patient who received atovaquone prophylaxis: the upper limit of the 95% confidence interval (CI) was 1.74 per 100 person-years. CONCLUSIONS: Atovaquone is an efficacious alternative for PCP prophylaxis in pediatric patients who have leukemia and are intolerant of TMP-SMZ.

Clofarabine, a novel nucleoside analog, is active in pediatric patients with advanced leukemia.

Despite progress in leukemia therapy, most children who experience relapse have a dismal prognosis. New, effective approaches are needed. We conducted a phase 1 study of a novel nucleoside analog, clofarabine, in pediatric patients with refractory and relapsed leukemia. Clofarabine was infused intravenously over 1 hour each day for 5 days. Six dose levels, between 11.25 and 70 mg/m(2) per day for 5 days, were studied in 25 patients. A modified 3 + 3 phase 1 design was followed with 30% dose escalation until the dose-limiting toxicity (DLT) was defined. The maximum tolerated dose (MTD) was 52 mg/m(2) per day for 5 days. At the end of infusion at MTD, clofarabine triphosphate levels in leukemia blasts varied between 6 microM and 19 microM, which resulted in complete and sustained inhibition of DNA synthesis. The DLT was reversible hepatotoxicity and skin rash at 70 mg/m(2) per day for 5 days. Twenty-five patients were treated. Five patients achieved complete remission (CR), and 3 achieved partial remission (PR), for an overall response rate of 32%. Clofarabine is well tolerated and shows significant antileukemic activity in heavily pretreated children. Multicenter phase 2 trials in pediatric acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) are ongoing.