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Myeloablative conditioning regimens decrease the risk of relapse in pediatric patients undergoing allogeneic hematopoietic stem cell transplant (HCT) for hematologic malignancies, but cause significant toxicities PROCEDURE: This prospective study evaluated the use of a reduced-toxicity, myeloablative regimen with dose-adjusted busulfan, fludarabine, antithymocyte globulin and 400 cGy of total body irradiation in 40 patients 21 years of age undergoing HCT for high-risk leukemias. Busulfan pharmacokinetics were measured to target 4000 μmol*min/day in the first 30 patients; this was increased to 5000 μmol*min/day in the subsequent 10 in efforts to further decrease relapse risk RESULTS: Overall survival at two- and five-years post-HCT was 67% and 51%, respectively. Relapse occurred in 11 patients (28%) at a median of seven months and was the leading cause of death. Transplant-related mortality was 8% and 13% at 100 days and one-year post-HCT, respectively. Trends toward improved survival were seen in patients transplanted for myeloid disease using bone marrow as stem cell source who achieved a busulfan AUC 4000 μmol*min/day with two-year relapse-free survival approaching 80% CONCLUSIONS: This conditioning regimen is safe and effective in patients with high-risk leukemias, particularly myeloid disease. Larger studies are needed to compare its safety and efficacy to other myeloablative regimens in this population.

The Primary Immune Deficiency Treatment Consortium (PIDTC) performed a retrospective analysis of 662 patients with severe combined immunodeficiency (SCID) who received a hematopoietic cell transplantation (HCT) as first-line treatment between 1982 and 2012 in 33 North American institutions. Overall survival was higher after HCT from matched-sibling donors (MSDs). Among recipients of non-MSD HCT, multivariate analysis showed that the SCID genotype strongly influenced survival and immune reconstitution. Overall survival was similar for patients with RAG, IL2RG, or JAK3 defects and was significantly better compared with patients with ADA or DCLRE1C mutations. Patients with RAG or DCLRE1C mutations had poorer immune reconstitution than other genotypes. Although survival did not correlate with the type of conditioning regimen, recipients of reduced-intensity or myeloablative conditioning had a lower incidence of treatment failure and better T- and B-cell reconstitution, but a higher risk for graft-versus-host disease, compared with those receiving no conditioning or immunosuppression only. Infection-free status and younger age at HCT were associated with improved survival. Typical SCID, leaky SCID, and Omenn syndrome had similar outcomes. Landmark analysis identified CD4(+) and CD4(+)CD45RA(+) cell counts at 6 and 12 months post-HCT as biomarkers predictive of overall survival and long-term T-cell reconstitution. Our data emphasize the need for patient-tailored treatment strategies depending upon the underlying SCID genotype. The prognostic significance of CD4(+) cell counts as early as 6 months after HCT emphasizes the importance of close follow-up of immune reconstitution to identify patients who may need additional intervention to prevent poor long-term outcome.

We enrolled 150 patients in a prospective multi-center study of children with acute myeloid leukemia undergoing hematopoietic stem cell transplant (HSCT) comparing detection of measurable residual (MRD) disease by a “Difference from Normal” flow cytometry (ΔN) approach with assessment of Wilms tumor 1 (WT-1) gene expression without access to the diagnostic specimen. Prospective analysis of the specimens using this approach showed that 23% of patients being screened for HSCT had detectable residual disease by ΔN (0.04–53%). Of those patients who proceeded to transplant as being in morphologic remission, 10 had detectable disease (0.04–14%) by ΔN. The disease free survival of this group was 10% (0–35%), compared to 55% (46–64

Survival for high-risk neuroblastoma patients is still suboptimal. Although stem cell transplantation (SCT) is used, there is no consensus as to which conditioning regimen has the greatest efficacy and fewest toxicities. We assessed the incidence of and risk for hepatic veno-occlusive disease (VOD) for neuroblastoma patients who underwent autologous SCT with busulfan and melphalan (BuMel) at eight centers following Children's Oncology Group (COG)-based induction chemotherapy. Data regarding the patients, SCT characteristics, busulfan steady-state concentrations, incidence of VOD, and survival were evaluated. VOD was defined using the modified Seattle criteria. Possible factors associated with VOD (age, busulfan-pharmacokinetic parameters, history of hepatic dysfunction, and day of neutrophil engraftment) were evaluated. Seventy five patients were included and 23 children (31%) developed VOD at a median of 19 days after SCT (range 14-27 days). VOD was the cause of death in 4 patients (5%). In a multivariable analysis, young age (OR 1.7 (95% CI: 1.16-2.56; p = 0.012)) and early day of neutrophil engraftment (OR 1.4 (95% CI: 1.08-2.14; p = 0.041) were associated with the development of VOD. Initial or cumulative busulfan steady-state concentration were not associated with VOD. We found that despite the use of intravenous busulfan with adjusted serum levels, the incidence of VOD remains high in pediatric neuroblastoma patients.

Background: Acute graft versus host disease (aGVHD) affects approximately 30–60% of patients after allogeneic hematopoietic stem cell transplantation (HCT) and our ability to predict who develops this complication and their response to treatment is limited. Fecal calprotectin has recently gained popularity as an effective marker of GI inflammation in patients with Inflammatory Bowel Disease (IBD). Methods: Fecal calprotectin and albumin were evaluated as prognostic and predictive markers of aGVHD in 60 adult and pediatric HCT patients. Stool samples were sent for calprotectin quantification prior to starting conditioning, at day 14 post-HCT, at day 28 post-HCT, and at onset of aGVHD ± 2 days. Results: Fecal calprotectin did not differentiate patients with GI-GVHD and non-GI GVHD and did not vary based on severity. However, in patients with steroid-refractory GI aGVHD, significantly higher fecal calprotectin levels were noted. At onset of lower-GI symptoms, steroid refractory patients (n = 3) had a mean fecal calprotectin level of 449 ug/g (range 116–1111 ug/g) and a mean albumin of 1.93 g/dL (range 1.6–2.3 g/dL) compared with a mean fecal calprotectin of 24 ug/g (range 16–31 ug/g) and a mean albumin of 3.3 g/dL (range 2.3–3.9 g/dL) in steroid responsive patients (n = 9) (fecal calprotectin p = 0.032, albumin p = 0.027). Conclusion: Patients with steroid-refractory GI aGVHD had higher fecal calprotectin levels and lower albumin levels than patients with steroid-responsive disease. We recommend further studies to evaluate non-invasive tests with fecal calprotectin in combination with albumin in predicting steroid refractory disease at onset of symptoms to potentially identify patients that may benefit from upfront escalation in GVHD treatment. Keywords: GVHD, Calprotectin, Albumin

Wilms tumor (WT) treatment regimens are curative for more than 80% of patients, but those with relapsed or refractory disease continue to have poor outcomes. High-dose chemotherapy followed by autologous stem cell rescue is often utilized although outcomes remain variable. We report on HD-ASCR outcomes in 24 patients with relapsed or refractory Wilms tumor. Three-year disease free and overall survival are 46% and 60%, respectively, which is similar to those reported for conventional salvage therapies. These outcomes suggest that conventional salvage therapies should be employed for relapsed and refractory WT rather than HD-ASCR.

Very young children undergoing hematopoietic cell transplantation (HCT) are a unique and vulnerable population. We analyzed outcomes of 717 patients from 117 centers who survived relapse free for year after allogeneic myeloablative HCT for hematologic malignancy at = 1 organ toxicity/late effect >1 year after HCT. The most frequent late effects included growth hormone deficiency/growth disturbance (10-year cumulative incidence, 23%; 95% CI, 19% to 28%), cataracts (18%; 95% CI, 15% to 22%), hypothyroidism (13%; 95% CI, 10% to 16%), gonadal dysfunction/infertility requiring hormone replacement (3%; 95% CI, 2% to 5%), and stroke/seizure (3%; 95% CI, 2% to 5%). Subsequent malignancy was reported in 3.6%. In multivariable analysis, total body irradiation (TBI) was predictive of increased risk of cataracts (HR, 17.2; 95% CI, 7.4 to 39.8; P

Current practice for selecting donor units for umbilical cord blood transplant (UCBT) involves matching at HLA-A and HLA-B by low-resolution typing and the HLA-DRB1 allele by high-resolution (HR) typing. We retrospectively studied the impact of HR allele matching at HLA-A, HLA-B, HLA-C, and HLA-DRB1 on transplant-related outcomes in 60 single-unit UCBTs in pediatric patients with malignant and nonmalignant conditions. Five-year overall survival of our cohort was 71% (95% confidence interval, 58-81); 27% experienced primary graft failure. Applying HR typing, donor-recipient mismatch variability increased ranging from 1/8 to 8/8, however, no impact on primary graft failure, graft-versus-host disease or posttransplant infection was observed. UCBTs with ≥6/8 HR matches did have a better overall survival (P=0.04) and decreased transplant-related mortality (P=0.02) compared with

Introduction Myeloablative conditioning (MAC) regimens decrease the risk of relapse in pediatric patients undergoing hematopoietic stem cell transplant (HCT) but cause significant toxicities: transplant-related mortality (TRM) and late effects. Therefore, a MAC regimen that decreases toxicity has the potential to improve overall survival (OS). Busulfan (Bu), fludarabine (Flu), anti-thymocyte globulin (ATG) and 400 cGy of total body irradiation (TBI), a reduced toxicity, MAC regimen was used in pediatric patients. Objectives To evaluate the safety and toxicity of this regimen. Secondary objectives included determining OS at 2 and 5 years, and incidence of relapse and GVHD. Methods We prospectively evaluated 40 patients ≤21 years of age undergoing HCT for high-risk leukemias who received dose-adjusted Bu, Flu, ATG and TBI. Bu pharmacokinetics were measured after a test dose and regimen dose 1 to target AUC of 4000-5000 uMol*min/day. Results Patients were treated between October 2008 and June 2018 (Table 1). OS was 67% and 51% at 2 and 5 years post-HCT, respectively. OS at 2 and 5 years was 70% and 55% for patients with myeloid disease versus 56% and 37% for patients with lymphoid disease, respectively (p=0.18) (Figure 1). Relapse occurred in 11 (28%) at a median of 7 months. TRM was 8% and 13% at 100 days and 1 year post-HCT, respectively. All patients engrafted. >Grade II acute GVHD was seen in 9 (23%); chronic GVHD was seen in 16 (40%). There was no significant impact of age, disease type, donor source or type on HCT outcomes. Long-term toxicities noted were ovarian insufficiency in 8, and short stature, hypothyroidism and learning disabilities in 2 each. Evaluation of Bu AUCs and multivariate analyses are still ongoing. Conclusions Reduced toxicity, MAC regimen was well tolerated with a low incidence of TRM. This regimen shows a trend toward better efficacy in patients with myeloid disease, however larger studies are needed.

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

Myeloablative conditioning and allogeneic hematopoietic stem cell transplant (alloHSCT) in children with acute myeloid leukemia (AML) in first complete remission (CR1) may be associated with significant acute toxicity and late effects. Reduced-intensity conditioning (RIC) and alloHSCT in children is safe, feasible, and may be associated with less adverse effects. Gemtuzumab ozogamicin (GO) induces a response in 30% of patients with CD33+ relapsed/refractory AML. The dose of GO is significantly lower when combined with chemotherapy. We examined the feasibility and toxicity of RIC alloHSCT followed by GO targeted immunotherapy in children with CD33+ AML in CR1/CR2. Conditioning consisted of fludarabine 30 mg/m2 × 6 days, busulfan 3.2 to 4 mg/kg × 2 days ± rabbit antithymocyte globulin 2 mg/kg × 4 days followed by alloHSCT from matched related/unrelated donors. GO was administered ≥60 days after alloHSCT in 2 doses (8 weeks apart), following a dose-escalation design (4.5, 6, 7.5, and 9 mg/m2). Fourteen patients with average risk AML received RIC alloHSCT and post-GO consolidation: median age 13.5 years at transplant (range, 1 to 21), male-to-female 8:6, and disease status at alloHSCT 11 CR1 and 3 CR2. Eleven patients received alloHSCT from 5-6/6 HLA-matched family donors: 8 received peripheral blood stem cells, 2 received bone marrow, and 1 received related cord blood transplantation. Three patients received an unrelated allograft (two 4-5/6 and one 9/10) from unrelated cord blood unit and bone marrow, respectively. Neutrophil and platelet engraftment was observed in all assessable patients (100%), achieved at median 15.5 days (range, 7 to 31) and 21 days (range, 10 to 52), respectively. Three patients received GO at dose level 1 (4.5 mg/m2 per dose), 5 at dose level 2 (6 mg/m2 per dose), 3 at dose level 3 (7.5 mg/m2 per dose), and 3 at dose level 4 (9 mg/m2 per dose). Three of 14 patients received only 1 dose of GO after alloHSCT. One patient experienced grade III transaminitis, which resolved; no grade IV transaminitis, no grade III/IV hyperbilirubinemia, or sinusoidal obstructive syndrome were observed. The second dose of GO was given at median of 143 days (range, 120 to 209) after alloHSCT. Probability of grades II to IV acute and chronic graft-versus-host disease were 21% and 33.5%, respectively. Probability of overall survival after RIC alloHSCT and GO consolidation at 1 and 5 years was 78% and 61%, respectively. Probability of 5-year event-free survival after RIC alloHSCT and GO consolidation in patients in CR1 was 78%. No dose-limiting toxicities probably or directly related to GO were observed in this cohort. This preliminary data demonstrate that RIC followed by alloHSCT and consolidation with GO appears to be safe in children and adolescents with CD33+ AML in CR1/CR2. A phase II trial is currently underway investigating this approach with a GO dose of 9 mg/m2 per dose.

Chronic myeloid leukemia (CML) is a rare malignancy in the pediatric population, accounting for less than 2% of pediatric leukemia.[1] Before the introduction of tyrosine kinase inhibitors (TKI), a...

International audience; BACKGROUND Donor availability and transplantation-related risks limit the broad use of allogeneic hematopoietic-cell transplantation in patients with transfusion-dependent beta-thalassemia. After previously establishing that lentiviral transfer of a marked beta-globin (beta(A-T87Q)) gene could substitute for long-term red-cell transfusions in a patient with beta-thalassemia, we wanted to evaluate the safety and efficacy of such gene therapy in patients with transfusion-dependent beta-thalassemia. METHODS In two phase 1-2 studies, we obtained mobilized autologous CD34+ cells from 22 patients (12 to 35 years of age) with transfusion-dependent beta-thalassemia and transduced the cells ex vivo with LentiGlobin BB305 vector, which encodes adult hemoglobin (HbA) with a T87Q amino acid substitution (HbA(T87Q)). The cells were then reinfused after the patients had undergone myeloablative busulfan conditioning. We subsequently monitored adverse events, vector integration, and levels of replication-competent lentivirus. Efficacy assessments included levels of total hemoglobin and HbA(T87Q), transfusion requirements, and average vector copy number. RESULTS At a median of 26 months (range, 15 to 42) after infusion of the gene-modified cells, all but 1 of the 13 patients who had a non-beta(0)/beta(0) genotype had stopped receiving red-cell transfusions; the levels of HbA(T87Q) ranged from 3.4 to 10.0 g per deciliter, and the levels of total hemoglobin ranged from 8.2 to 13.7 g per deciliter. Correction of biologic markers of dyserythropoiesis was achieved in evaluated patients with hemoglobin levels near normal ranges. In 9 patients with a beta(0)/beta(0) genotype or two copies of the IVS1-110 mutation, the median annualized transfusion volume was decreased by 73%, and red-cell transfusions were discontinued in 3 patients. Treatment-related adverse events were typical of those associated with autologous stem-cell transplantation. No clonal dominance related to vector integration was observed. CONCLUSIONS Gene therapy with autologous CD34+ cells transduced with the BB305 vector reduced or eliminated the need for long-term red-cell transfusions in 22 patients with severe beta-thalassemia without serious adverse events related to the drug product. (Funded by Bluebird Bio and others; HGB-204 and HGB-205 ClinicalTrials. gov numbers, NCT01745120 and NCT02151526.)

Multimodal treatment in high-risk neuroblastoma has modestly improved survival; limited data exist on the late effects from these regimens. We report the sequelae of treatment incorporating 3 consecutive cycles of high-dose therapy and autologous stem cell transplants (ASCTs) without the use of total body irradiation (TBI). We reviewed the medical records of 61 patients treated on or following the Chicago Pilot 2 protocol between 1991 and 2008. Of the 25 patients who are alive (41%), 19 had near complete data to report. Specific treatment modalities and therapy-related side effects were collected. Fourteen of these 19 patients (74%) received 3 cycles of high-dose therapy with ASCT; follow-up occurred over a median of 13.9 years (range, 5.8 to 18.8 y). The majority of late effects were endocrine-related, including growth failure, hypothyroidism, and hypogonadism. Patients also developed secondary neoplasms and skeletal deformities. The most frequent sequela was hearing loss, seen in 17/19 patients. We found a high prevalence of various late effects in survivors of high-risk neuroblastoma using a non-TBI-based regimen including 3 cycles of high-dose therapy with ASCTs. As current treatment regimens recommend tandem ASCT without TBI, it is imperative that we understand and monitor for the sequelae from these modalities.

The Primary Immune Deficiency Treatment Consortium (PIDTC) is enrolling children with severe combined immunodeficiency (SCID) to a prospective natural history study. We analyzed patients treated with allogeneic hematopoietic cell transplantation (HCT) from 2010 to 2014, including 68 patients with typical SCID and 32 with leaky SCID, Omenn syndrome, or reticular dysgenesis. Most (59%) patients were diagnosed by newborn screening or family history. The 2-year overall survival was 90%, but was 95% for those who were infection-free at HCT vs 81% for those with active infection (P = .009). Other factors, including the diagnosis of typical vs leaky SCID/Omenn syndrome, diagnosis via family history or newborn screening, use of preparative chemotherapy, or the type of donor used, did not impact survival. Although 1-year post-HCT median CD4 counts and freedom from IV immunoglobulin were improved after the use of preparative chemotherapy, other immunologic reconstitution parameters were not affected, and the potential for late sequelae in extremely young infants requires additional evaluation. After a T-cell-replete graft, landmark analysis at day +100 post-HCT revealed that CD3 < 300 cells/μL, CD8 < 50 cells/μL, CD45RA < 10%, or a restricted Vβ T-cell receptor repertoire (

Background Outcomes for high-risk neuroblastoma remain poor. Modern treatment protocols utilizing intense induction followed by myeloablative consolidation chemotherapy with autologous stem cell rescue (ASCR) have improved survival rates, but the long-term sequelae, including development of secondary malignant neoplasms (SMN), are just now surfacing. Methods We retrospectively reviewed data from 87 patients with high-risk neuroblastoma who were treated with intensive induction chemotherapy followed by ASCR between January 1991 and July 2011 following one of two institutional protocols: Chicago Pilot 1 (CP1; n = 12) and Chicago Pilot 2 (CP2; n = 75). Results The 15-year overall survival rate for all 87 patients was 33.9% (95% confidence interval [CI], 23.1–45.0%). The 10- and 15-year cumulative incidence of SMN was 16.5% (95%CI, 7.2–38.0%) and 34.2% (95%CI, 18.6–63.1%), respectively, without evidence of a plateau at 15 years. Six of the 10 patients (n = 2 in CP1 and n = 8 in CP2) who developed SMN had hematologic malignancies including acute myeloid leukemia (AML)/myelodysplastic syndrome (MDS). Solid tumors included thyroid papillary carcinoma, chondrosarcoma, hepatocellular carcinoma, and biliary adenocarcinoma. Conclusion A significantly higher incidence of SMN, especially hematological malignancies, was observed in this cohort compared to older neuroblastoma studies, potentially due to exposure to epipodophyllotoxins and a high cumulative dose of alkylating agents these patients received. The risk of developing an SMN continued to increase with survival time and did not reach the plateau at 15 years. Although the number of the patients is relatively small, our study emphasizes the need for life-long follow-up of survivors who were treated using modern therapy. Pediatr Blood Cancer 2014; 61:1350–1356. © 2014 Wiley Periodicals, Inc.

This study was to determine whether GM-CSF induced WT1 gene expression and to establish an association with markers of proliferation CD71+CD34+ using nPCR and flow cytometry respectively, in samples obtained from 5 newly diagnosed JMML patients. Overtime (day 0 to day 14) there was an insignificant difference in WT1 gene expression and CD71+CD34+ in JMML samples when compared to peripheral blood of normal volunteers (n = 3). Our study suggests that there is a correlation between WT1 gene expression and cellular proliferation and that GMCSF in vitro does not create a significant difference in JMML samples.

Background Patients with transfusion-dependent β-thalassemia (TDT) may experience transfusional iron overload and end-organ damage. While potentially curative, allogeneic hematopoietic stem cell (HSC) transplantation is limited by transplant-related risks and donor availability. Transplantation of autologous CD34+ cells encoding a βA-T87Q-globin gene (LentiGlobin gene therapy for β-thalassemia) may overcome some of these limitations. βA-T87Q-globin is incorporated into adult hemoglobin (Hb), forming gene therapy-derived HbAT87Q, which can be distinguished from other Hb species. The phase 1/2 Northstar study (HGB-204; NCT01745120) using the original manufacturing process evaluated the safety and efficacy of LentiGlobin in adolescents and adults with TDT (≥100 mL/kg/yr of red blood cells [RBCs] or ≥8 RBC transfusions/yr) and non-β0/β0 or β0/β0 genotypes. Methods HSCs were mobilized with G-CSF and plerixafor and collected via apheresis. CD34+ cells were transduced with BB305 lentiviral vector. After busulfan myeloablation, patients were infused with transduced cells. Primary efficacy endpoints were sustained production of ≥2 g/dL HbAT87Q between months 18 and 24 and transfusion independence (TI; weighted average Hb ≥9 g/dL without RBC transfusions for ≥12 months). Patients were monitored for 2 years and subsequently enrolled in the 13-year long-term follow-up study, LTF-303 (NCT02633943). Results are shown as median (min ‒ max) unless otherwise indicated. Results Eighteen patients were treated (age: 20 [12 - 35] yrs) and followed for 40.7 (29.3 - 53.8) months as of 13 December 2018. In the 2 years prior to enrollment, patients had an annualized transfusion volume of 169.0 (124.0 - 273.0) mL/kg/yr and pre-transfusion weighted mean nadir Hb of 9.3 (7.0 - 10.1) g/dL. Neutrophil and platelet engraftment occurred at 18.5 (14 - 30) and 39.5 (19 - 191) days, respectively. No patient had graft failure. Grade ≥3 non-hematologic adverse events (AEs) reported in ≥25% of patients after infusion were stomatitis, febrile neutropenia, and pharyngeal inflammation. No replication-competent lentivirus or death has been reported. The vector integration site profile in all 18 patients has remained polyclonal. The number of unique integration sites (UIS) identified was 1646 (190 - 2888), 1677 (151 - 6935), 2484 (984 - 5511), 1773 (1260 - 2693) at Months 12 (n=18), 24 (n=18), 36 (n=11), 48 (n=4), respectively. The highest mean (SD) frequency of any UIS in patients across all visits was 11.5% (5.8%). No oncogenesis has been reported. In Northstar, 16/18 (89%) patients achieved the primary endpoint of ≥2 g/dL HbAT87Q between months 18 and 24. Eight of 10 (80%) patients with non-β0/β0 genotypes achieved and maintained TI; current duration of TI was 38 (21.2 - 45.3) months (Figure 1). The weighted average total Hb during TI was 10.3 (9.1 - 13.2) g/dL. Total Hb and HbAT87Q remained stable over time. Total Hb in patients with non-β0/β0 genotypes who achieved TI was 10.3, 10.4, 10.6, and 11.1 g/dL at Months 12 (n=8), 24 (n=8), 36 (n=7), 48 (n=3), respectively. Transfusion volumes were reduced by 73% and 43% in the 2 patients still receiving transfusions. Three of 8 (38%) patients with β0/β0 genotypes achieved TI with a current duration of 16.4 (16.1 - 20.8) months. Weighted average total Hb during TI was 9.9 (9.5 - 10.1) g/dL and HbAT87Q was 8.0 - 8.9 g/dL at last visit. One additional patient was transfusion-free for 13.7 months; however, total Hb was Patients who achieved TI resumed iron chelation 13 (2 - 15) months after infusion and all remain on iron chelation as of last follow-up. Serum ferritin and liver iron content (LIC) (Figure 2A, 2B) were reduced in patients who achieved TI by 55% (16 - 78%) and 56% (38 - 83%) from screening to Month 48 (n=4), respectively. Of these 4 patients who had a Month 48 visit, LIC values were 0.8 - 7.1 mg/g at Month 48 compared to 4.8 - 11.5 mg/g at screening. In patients who achieved TI, cardiac T2* ranged from 27.0 - 39.0 msec at screening and 31.4 - 57.6 msec at last visit. Summary With up to 4.5 years of follow-up after LentiGlobin gene therapy, generally stable HbAT87Q levels and durable TI were observed in 8/10 and 3/8 patients with TDT and non-β0/β0 and β0/β0 genotypes, respectively. Iron burden has improved over time in patients who achieved TI. The safety profile of LentiGlobin remains consistent with myeloablative conditioning. Disclosures Kwiatkowski: Imara: Consultancy; Agios: Consultancy; bluebird bio, Inc.: Consultancy, Research Funding; Terumo: Research Funding; Apopharma: Research Funding; Novartis: Research Funding; Celgene: Consultancy. Thompson:bluebird bio, Inc.: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Baxalta: Research Funding. Rasko:GSK: Honoraria; bluebird bio: Honoraria; Imago: Consultancy; Novartis: Honoraria; Cynata: Honoraria; Spark: Honoraria; Takeda: Honoraria; NHMRC Mitochondrial Donation Expert Working Committee: Other: Advisory Committee; Gilead: Honoraria; Cure The Future Foundation: Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria; Genea: Equity Ownership; Rarecyte: Consultancy, Equity Ownership; Gene Technology Technical Advisory, Australian Government: Other: Advisory committee; Celgene: Honoraria; Advisory Committee on Biologics, Australian Government: Other: Advisory Committee; Australian Cancer Research Scientific Advisory Board: Membership on an entity's Board of Directors or advisory committees; FSHD Global Research Foundation: Membership on an entity's Board of Directors or advisory committees. Schiller:Amgen: Other, Research Funding; Agios: Research Funding, Speakers Bureau; Astellas: Research Funding; Biomed Valley Discoveries: Research Funding; Bristol Myer Squibb: Research Funding; Celgene: Research Funding, Speakers Bureau; Constellation Pharmaceutical: Research Funding; Daiichi Sankyo: Research Funding; Eli Lilly and Company: Research Funding; FujiFilm: Research Funding; Genzyme: Research Funding; Gilead: Research Funding; Incyte: Research Funding; J&J: Research Funding; Jazz Pharmaceuticals: Honoraria, Research Funding; Karyopharm: Research Funding; Novartis: Research Funding; Onconova: Research Funding; Pfizer Pharmaceuticals: Equity Ownership, Research Funding; Sangamo Therapeutics: Research Funding. Cavazzana:Smartimmune: Other: Founder of Smartimmune. Ho:Celgene: Other: investigator meeting travel costs; Janssen: Other: investigator meeting travel costs; Novartis: Other: investigator meeting travel costs; La Jolla: Other: investigator meeting travel costs. Schmidt:German Cancer Research Center, Heidelberg, Germany: Employment; GeneWerk GmbH, Heidelberg, Gemrany: Equity Ownership. Vichinsky:Agios: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; GBT: Consultancy, Research Funding; bluebird bio: Consultancy, Research Funding; Novartis: Consultancy, Research Funding. Deary:bluebird bio, Inc.: Employment, Equity Ownership. Chen:bluebird bio, Inc.: Consultancy. Petrusich:bluebird bio, Inc.: Employment, Equity Ownership. Walters:Editas Medicine: Consultancy; TruCode: Consultancy; AllCells, Inc: Consultancy.

Although the role of autologous hematopoietic cell transplantation (auto-HCT) is well established in neuroblastoma (NBL), the role of allogeneic HCT (allo-HCT) is controversial. The Center for International Blood and Marrow Transplant Research conducted a retrospective review of 143 allo-HCT for NBL reported in 1990-2007. Patients were categorized into two different groups: those who had not (Group 1) and had (Group 2) undergone a prior auto-HCT (n=46 and 97, respectively). One-year and five-year OS were 59% and 29% for Group 1 and 50% and 7% for Group 2, respectively. Among donor types, disease-free survival (DFS) and OS were significantly lower for unrelated transplants at 1 and 3 years but not at 5 years post HCT. Patients in CR or very good partial response (VGPR) at transplant had lower relapse rates and better DFS and OS, compared with those not in CR or VGPR. Our analysis indicates that allo-HCT can cure some neuroblastoma patients, with lower relapse rates and improved survival in patients without a history of prior auto-HCT as compared with those patients who had previously undergone auto-HCT. Although the data do not address why either strategy was chosen for patients, allo-HCT after a prior auto-HCT appears to offer minimal benefit. Disease recurrence remains the most common cause of treatment failure.

Increasing treatment intensity has improved outcomes for children with neuroblastoma. We performed a pilot study in the Children’s Oncology Group (COG) to assess feasibility and toxicity of a tandem myeloablative regimen without total body irradiation (TBI) supported by autologous CD34 selected peripheral blood stem cells. Forty-one patients with high-risk neuroblastoma were enrolled; eight patients did not receive any myeloablative consolidation procedure, and seven received only one. Two patients out of 41 (4.9%) experienced transplant-related mortality. CD34 selection was discontinued after subjects were enrolled due to serious viral illness. From the time of study enrollment, the overall 3-year event-free survival (EFS) and overall survival (OS) were 44.8±9.6% and 59.2±9.2% (N=41). These results demonstrate that tandem transplantation in the cooperative group setting is feasible and support a randomized comparison of single versus tandem myeloablative consolidation with PBSC support for high-risk neuroblastoma.

Patients with acute myeloid leukemia (AML) who relapse after hematopoietic stem cell transplantation (HCT) have dismal outcomes. Our ability to predict those at risk for relapse is limited. We examined chimerism trends post-HCT in 63 children who underwent HCT for AML or myelodysplastic syndrome (MDS). Mixed T-cell chimerism at engraftment and absence of chronic graft versus host disease (cGVHD) were associated with relapse (P = 0.04 and P = 0.02, respectively). Mixed T-cell chimerism at engraftment was predictive in patients without cGVHD (P = 0.03). Patients with engraftment mixed T-cell chimerism may warrant closer disease monitoring and consideration for early intervention.

IV pentamidine for Pneumocystis jiroveci pneumonia prophylaxis in pediatric allogeneic stem cell transplant patients

Neuroblastoma (NB) is an enigmatic tumor that often presents with metastatic disease at diagnosis and it is this aggressive propensity which places it among the deadliest pediatric tumors despite intensive multimodal therapy including hematopoietic stem cell transplantation (HSCT). We have previously demonstrated that Wilms tumor 1 gene (WT1) is a surrogate marker of proliferation in leukemia. To determine the potential association between WT1 and a known marker of NB, tyrosine hydroxylase (TH) in this high risk group of patients.A total of 141 random samples from 34 patients were obtained, at diagnosis (n=27), during therapy (n=95), in clinical remission (n=13), and at the time of relapse (n=6). Quantitative RT-PCR was used for the evaluation of the level of gene expression using specific primers.Although similar gene expressions were demonstrated in both controls when evaluating both genes, significant difference was found at each clinical time point. Furthermore, when comparing patient samples from diagnosis to clinical remission and diagnosis to clinical relapse, individual gene expression varied. WT1 demonstrated significance (P=0.0002) and insignificance (P=0.06) whereas TH remained non-significant (P=0.2, P=0.09) respectively.WT1 gene is indicative of cellular proliferation in NB and for this reason it can be adjuvant to TH for the detection minimal residual disease (MRD).

Treatment of high risk neuroblastoma (NBL) remains a signif-icant challenge in pediatric oncology. Improvements in event-freesurvival (EFS) in this disease have been demonstrated in bothEuropean [1] and North American trials [2][3] in which patientsreceive, after initial chemotherapy and surgery, high dose chemo-therapy (HDC) followed by autologous bone marrow or peripheralblood stem cell rescue (SCR).One such regimen, using tandem myeloablative proceduresin rapid succession supported by peripheral blood stem cells(PBSC) after a uniform induction, used carboplatin, etoposide,and cyclophosphamide in myeloablative doses followed 6 weekslater by melphalan and total body irradiation (TBI) in thesecond SCR procedure [4]. The Pediatric Oncology Group9640 study was designed to establish the feasibility of perform-ing tandem HDC/SCR using PBSC in a cooperative groupsetting and to obtain crude estimates of response and PFS ina tandem HDC/SCR regimen that did not include TBI.We report here the results of this single arm trial of inductionchemotherapy, local control measures (surgery and local radia-tion), and tandem HDC/SCR. The protocol also tested the abilityof multiple centers to obtain adequate numbers of PBSC fortandem HDC/SCR in small children and involved three innova-tive aspects of study design: (i) Collection of PBSC early intherapy, presumably before any compromise of hematopoieticstem and progenitor cells had occurred from the induction che-motherapy cycles; (ii) use of non-cross-reactive conditioningregimens for each cycle of HDC/SCR; and (iii) rapid progres-sion from the first to the second cycle of HDC/SCR. We alsoreport the short-term toxicity outcomes and progression-freeoutcomes in this pilot group. Feasibility data from this pilotstudy helped form the basis for subsequent cooperative groupstudies of tandem HDC/SCR.

Childhood obesity has more than tripled in the past 30 years. The prevalence of overweight and obese children has also increased in the pediatric cancer setting, causing substantial concern over proper chemotherapeutic dosing in this population. The purpose of this study was to determine if children with an increased body mass index (BMI) have an alteration in busulfan pharmacokinetics during hematopoietic stem cell transplant (HSCT) conditioning. We retrospectively reviewed data on busulfan pharmacokinetics (PK) on HSCT subjects (subjects were part of a prospective study previously reported by our group at Children's Memorial Hospital) to determine appropriateness of dosing. Subjects were divided into appropriate BMI categories (25th percentile, 25th-85th percentile, ≥ 85th percentile) and busulfan PK dosing was analyzed (test dose, regimen dose, area under the curve [AUC], and clearance). The dosing based on PK test dose data of children with BMI ≥ 85% was compared against the package insert dosing recommendations of using adjusted ideal body weight (AIBW) in obese patients to determine which dosing schema was most accurate. Children with high BMIs had higher AUCs when dosing on actual weight then their normal or low BMI counterparts. This indicates that children with a high BMI require less drug (2.9 mg/kg using actual body weight) to achieve the same AUC as children with normal BMI (4.0 mg/kg) or low BMI (3.6 mg/kg). Using the recommended AIBW dosing schema, 53% of the patients with high BMIs would have had regimen dose AUCs ≥ 20% over/under the target; whereas with the PK test dose method, only 16% of the patients with high BMIs had regimen dose AUCs ≥ 20% over/under the target. PK testing continues to be the gold standard for busulfan dosing in children. Particular vigilance should be paid to PK monitoring in high BMI categories because of the potential risk of imprecise dosing when using the AIBW schema.

We report 23 consecutive pediatric patients with MDS who received allogeneic HSCT on IRB approved protocols between 1992 and 2009 at Children's Memorial Hospital (Chicago, IL). Nine patients had de novo MDS, whereas 14 patients had treatment-related MDS. All patients had a documented cytogenetic abnormality, and monosomy 7/7q- was seen in 12 patients (52%). Fourteen of 23 patients received a myeloablative conditioning regimen; RIC regimens were used for the remaining nine. Five patients relapsed post-transplant, including four patients who received RIC transplant and four patients with treatment-related MDS. For the entire group, estimated five-yr RFS and OS were 47% and 50%, respectively. Treatment-related MDS was associated with decreased RFS in comparison with de novo MDS (33% vs. 70%, p = 0.05). Five-year OS rates reached 80% for those with de novo MDS. RIC regimens were associated with decreased three-yr RFS in comparison with myeloablative regimens (22% vs. 68%, p = 0.02). There was no correlation of survival with blast count at diagnosis, IPSS score, cytogenetic abnormality, donor type, or HLA match. Larger series are needed to confirm prognostic factors so that higher-risk patients can be targeted with novel approaches.

Background Advances in red blood cell (RBC) transfusion and chelation have improved the prognosis of patients with transfusion-dependent β-thalassemia (TDT); however, many patients experience organ damage due to iron overload and other complications. While potentially curative, allogeneic hematopoietic stem cell transplantation confers significant risks of morbidity and mortality and is limited by donor availability. Gene therapy (GT) has the potential to be an effective treatment option for patients with TDT without some of these limitations. LentiGlobin GT contains autologous CD34+ cells transduced ex vivo with the BB305 lentiviral vector (LVV) encoding a β-globin gene with a T87Q substitution. Initial data from the international, multi-center, phase 1/2 Northstar (HGB-204; NCT01745120) study evaluating the safety and efficacy of LentiGlobin in patients with TDT using the original manufacturing process has been published. Herein we present updated results with longer follow-up. Methods Northstar enrolled patients with TDT (history of ≥ 100 mL/kg/yr of RBCs or ≥ 8 RBC transfusions/yr) regardless of genotype. Autologous CD34+ cells were collected by apheresis after G-CSF and plerixafor mobilization and transduced with the BB305 LVV in a centralized facility. Patients received myeloablative conditioning with single-agent busulfan before the transduced cells were infused. Patients were monitored for engraftment, vector copy number (VCN), GT-derived hemoglobin (HbAT87Q), RBC transfusions, transfusion independence (TI; defined as weighted average hemoglobin [Hb] ≥ 9g/dL without RBC transfusions for ≥ 12 months), adverse events (AEs), vector integration, and replication competent lentivirus (RCL). Patients were followed in Northstar for 2 years and then were offered participation in the long-term follow-up study, LTF-303 (NCT02633943). Results Eighteen patients with TDT, 12 - 35 years old, treated with LentiGlobin GT have completed 2-year follow-up in the Northstar study and subsequently enrolled in LTF-303. As of March 7, 2018, the median follow-up duration was 32.1 (min - max: 23.1 - 41.9) months. The median DP VCN was 0.7 (min - max: 0.3 - 1.5) copies/diploid genome (c/dg), the median cell dose was 8.1 x 106 (min - max: 5.2 - 18.1 x 106) CD34+ cells/kg, and the median proportion of transduced CD34+ cells was 32% (min - max: 17 - 58%). All patients engrafted and the median duration of hospitalization from conditioning to discharge was 40 days (min - max: 27 - 69 days). The toxicity profile was typical of myeloablative conditioning. No grade ≥ 3 events were related to LentiGlobin and there was no graft failure, death, or vector-mediated RCL, and no evidence of clonal dominance. Serious AEs reported in ≥ 2 patients were thrombosis and veno-occlusive liver disease; each occurred in 2 patients. Eight of 10 patients with non-β0/β0 genotypes were able to discontinue transfusions at 0.3 - 5.8 months post-DP infusion and have sustained TI for a median duration of 33 months (min - max: 16 - 38 months). At last study visit, peripheral blood VCN for these patients was 0.1 - 1.0 c/dg, HbAT87Q was 3.8 - 10.1 g/dL and total Hb was 9.1 - 13.5 g/dL. Sustained HbAT87Q production was observed in all patients through last follow-up (Figure 1A). The 2 remaining patients with non-β0/β0 genotypes had a reduction in transfusion volume of 82% and 27%. Their peripheral VCN and HbAT87Q levels at last study visit were 0.1 and 0.1 c/dg and 2.9 and 1.1 g/dL, respectively. Of the 8 patients with a β0/β0 genotype, 3 no longer require chronic RBC transfusions for an ongoing duration of 16.4 - 22.1 months. Peripheral VCN, HbAT87Q and total Hb at last visit were 0.7, 0.4, 0.6 c/dg; 8.9, 9.7, 8.1 g/dL (Figure 1B); and 9.3, 10.3, 9.8 g/dL, respectively. The other 5 patients with a β0/β0 genotype experienced median transfusion volume reduction of 53% (min - max: 8 - 74%). Longer follow-up and other analyses including iron measures will be presented. Summary LentiGlobin GT in patients with TDT enrolled in the Northstar study continues to demonstrate a sustained clinical benefit with up to 3.5 years of follow-up. The safety profile is consistent with myeloablative conditioning and 8/10 patients with non-β0/β0 genotypes and 3/8 patients with a β0/β0 genotype remain transfusion free. LentiGlobin GT using refined manufacturing to improve DP characteristics and patient outcomes is being evaluated in 2 ongoing phase 3 studies, Northstar-2 and Northstar-3. Disclosures Rasko: Rarecyte: Consultancy, Equity Ownership; IMAGO Biosciences: Consultancy; Takeda: Speakers Bureau; Abbvie: Speakers Bureau; Gilead: Honoraria; Novartis: Consultancy, Speakers Bureau; Cynata: Consultancy, Honoraria; bluebird bio: Honoraria, Other: Clinical trials ; Spark: Consultancy; Genea: Equity Ownership; Current Cure The Future Foundation: Membership on an entity's Board of Directors or advisory committees; FSHD Global Research Foundation: Membership on an entity's Board of Directors or advisory committees; Gene Technology Technical Advisory, OGTR, Australian Government: Other: Chair; Advisory Committee on Biologics, Therapeutics Goods Administration, Australian Government: Other: Past Chair; International Society for Cellular Therapy: Membership on an entity's Board of Directors or advisory committees; GSK: Honoraria; Pfizer: Honoraria; Celgene: Honoraria. Thompson:Baxalta/Shire: Research Funding; La Jolla Pharmaceutical: Research Funding; Amgen: Research Funding; Biomarin: Research Funding; Celgene: Research Funding; bluebird bio: Consultancy, Research Funding; Novartis: Research Funding. Kwiatkowski:Apopharma: Research Funding; Agios Pharmaceuticals: Consultancy, Research Funding; Novartis: Research Funding; Terumo: Research Funding; bluebird bio: Consultancy, Honoraria, Research Funding. Schiller:bluebird bio: Research Funding; Astellas Pharma: Membership on an entity's Board of Directors or advisory committees, Research Funding. Ho:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Other: Travel to meeting; Celgene: Other: Travel to meeting . Schmidt:GeneWerk GmbH: Employment; German Cancer Research Center: Employment; bluebird bio: Consultancy. Leboulch:bluebird bio: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Vichinsky:bluebird bio: Membership on an entity's Board of Directors or advisory committees; Global Blood Therapeutics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Protagonist: Research Funding. Deary:bluebird bio: Employment, Equity Ownership. Chen:bluebird bio: Consultancy. Asmal:bluebird bio: Employment, Equity Ownership. Walters:Sangamo Therapeutics: Consultancy; ViaCord Processing Lab: Other: Medical Director; AllCells Inc.: Other: Medical Director; bluebird bio: Research Funding.

A nonmyeloablative conditioning regimen consisting of fludarabine (FLU) and 2 Gy TBI has been used extensively and with substantial engraftment success without promoting excessive nonrelapse mortality in medically infirm patients requiring hematopoietic cell transplantation. In this paper, we studied this same low-toxicity regimen as a means of promoting engraftment of unrelated donor hematopoietic cell transplantation in patients with Fanconi anemia (FA). All patients tolerated the regimen well with no mucositis or other severe toxicities. Of six patients transplanted, five achieved stable mixed or full donor chimerism. Acute and chronic GVHD occurred in four and three patients, respectively. Three patients are alive and well at a median of 45.9 (range, 20.9-68.1) months after transplant. In summary, this FLU-based regimen facilitates stable engraftment of unrelated PBSCs, but is associated with significant chronic GVHD.

The role of reduced-intensity conditioning (RIC) regimens in pediatric cancer treatment is unclear. To define the efficacy of a busulfan/fludarabine/antithymocyte globulin RIC regimen in pediatric patients ineligible for myeloablative transplantation, we completed a trial at 23 institutions in the Pediatric Blood and Marrow Transplant Consortium. Forty-seven patients with hematologic malignancies were enrolled. Sustained engraftment occurred in 98%, 89%, and 90%, and full donor chimerism was achieved in 88%, 76%, and 78% of evaluable related bone marrow/peripheral blood stem cells (BM/PBSCs), unrelated BM/PBSCs, and unrelated cord blood recipients. With a median follow-up of 24 months (range, 11-53 months), 2-year event-free survival, overall survival (OS), transplantation-related mortality, and relapse were 40%, 45%, 11%, and 43%, respectively. Univariate analysis revealed an inferior outcome when patients had undergone previous total body irradiation (TBI)–containing myeloablative transplantation (2-year OS, 23% vs 63% vs 52%, previous TBI transplantation vs no TBI transplantation vs no transplantation, P = .02) and when patients not previously treated with TBI had detectable disease at the time of the RIC procedure (2-year OS, 0% vs 63%, detectable vs nondetectable disease, P = .01). Favorable outcomes can be achieved with RIC approaches in pediatric patients in remission who are ineligible for myeloablative transplantation. This study was registered at www.clinicaltrials.gov as #NCT00795132.

We studied the pharmacokinetic (PK) profile of single daily dose i.v. BU in children who underwent reduced-intensity conditioning (RIC) transplantation. A cohort of 19 patientsor =4 years of age (group 1) and 33 patients4 years (group 2) was studied. Patients received a BU test dose for PK studies, followed by two treatment doses adjusted to target an area under the curve (AUC) of 4000 microM min per day. Patients in group 1 attained a lower AUC as compared to group 2 (3568 vs 4035 microM min). In group 1, 67% patients and in group 2, 84% patients achieved AUC within the targeted range. Stable donor chimerism was achieved in 56% patients in group 1 and 79% in group 2. Eight patients required a second transplantation because of graft failure. Because of the concern that a low AUC adversely affected outcomes, a second cohort of 23 patients followed a modified protocol with a targeted AUC of 5000 microM min. A higher AUC was attained (4825 microM min). Stable donor chimerism was achieved in 91% of patients. Our results show that RIC regimens using two single daily doses of i.v. BU are effective in children, but a targeted AUC of 5000 microM min is recommended.

ADV has emerged as an important pathogen in children undergoing allogeneic HPCT. A prospective study of the epidemiology of ADV infection and preemptive therapy of high risk ADV infections in children undergoing HPCT was undertaken. Cultures of throat, urine, and stool for viral pathogens and plasma for ADV PCR were obtained prior to transplantation, weekly for the first 100 days, and then monthly for one yr. Children developing high-risk ADV infections were treated preemptively with cidofovir 1 mg/kg/day given three times weekly for three wk. A case-controlled study was performed to identify risk factors for high-risk ADV infections. Seven (18%) of the 38 subjects developed high-risk ADV infections usually within 100 days of HPCT and were preemptively treated with i.v. cidofovir at a dose of 1 mg/kg/dose three times weekly for nine doses. High-risk ADV infections resolved in all seven patients without renal toxicity. CMV viremia occurred in two of seven patients during or shortly after therapy with cidofovir. A case-control study did not identify any risk factors that achieved statistical significance. Treatment with a modified dosing regimen of cidofovir was well-tolerated and high-risk ADV infections resolved in all patients.

Background Thrombotic complications occur in adult patients undergoing stem cell transplantation (SCT), especially following high dose chemo-radiotherapy. There is little published information in children on the impact of SCT on coagulation, as well as potential correlations between altered coagulation and SCT-associated thrombosis and organ failure. Procedure Forty three pediatric subjects who underwent allogeneic SCT were prospectively evaluated for congenital thrombophilia, anticoagulant levels, coagulation activation, and fibrinolysis at pre-established set points encompassing the period from the 2 to 4 weeks prior to conditioning to 28 days post-transplantation. Results A significant decrease of protein C and antithrombin levels was found in 39% and 31% of subjects respectively, between SCT days +6 and +7. A peak in plasminogen activator inhibitor-1 levels in 31% of subjects was noted between days +9 and +10. No subject experienced a thrombotic event or other SCT-related organ failure. Antithrombin deficiency correlated with underlying malignancy, donor HLA-mismatch, and TBI, whereas decreased PC activity demonstrated a trend of association with lack of T-cell depletion and TBI. Prophylactic heparin did not influence the pattern of acquired hemostatic abnormalities observed in this cohort. Conclusions Children undergoing allogeneic SCT develop a state of acquired thrombophilia in the early post-transplantation period. Although no SCT-related thromboembolic events were observed, our results provide new information about the hemostatic changes in children undergoing allogeneic SCT and their potential clinical triggers. The significance of these findings requires further prospective evaluation in a larger cohort of patients.

Busulfan (Bu) is widely used in conditioning regimens for infants undergoing allogeneic hematopoietic progenitor cell transplantation (HPCT), but the best approach to administer Bu in this population is still unknown. Here, we report a single-center experience of the use of a test dose to guide dose adjustment of intravenous (i.v.) Bu therapy in infants. Between 2004 and 2013, 33 infants younger than 1 year with nonmalignant conditions received allogeneic peripheral blood or cord blood HPCT after a reduced-intensity conditioning (RIC) regimen consisting of fludarabine, antithymocyte globulin, and 2 single daily doses of i.v. Bu. Pharmacokinetic results of a test dose of i.v. Bu (.8 mg/kg) were used to determine the dose of 2 single daily i.v. Bu regimen doses, adjusted to target an area under the curve (AUC) of 4000 μMol*minute per day in a first cohort (n = 12) and 5000 μMol*minute in a second cohort (n = 21). The mean Bu clearance in our infant patients was found to be 3.67 ± 1.03 mL/minute/kg, and the test dose clearance was highly predictive of the regimen dose clearance. The mean AUC achieved after the first single daily regimen dose was 3951 ± 1239 in the AUC 4000 cohort and 4884 ± 766 for the AUC 5000 cohort. No patient in either cohort developed hepatic sinusoidal obstructive syndrome or seizures attributable to Bu. Primary graft failure occurred in 4 patients and secondary graft failure occurred in 3, predominantly in the AUC 4000 cohort (6 of 7). Among the engrafted patients (n = 28), 16 achieved full donor chimerism and 9 patients attained stable mixed chimerism. Overall survival of patients at 6 years after transplantation was 59.5% for the AUC 4000 cohort and 85.4% for the AUC 5000 cohort, with primary graft failure in the first cohort being a major contributor to morbidity. Logistic regression analysis showed that the risk of graft failure increased significantly if cord blood hematopoietic progenitor cells were used or if total Bu exposure was below 4000 μMol*minute per day for 2 days. The difference in clinical outcomes between the 2 cohorts supports the conclusion that targeting a higher Bu AUC of 5000 μMol*minute per day for 2 days improves donor engraftment in infants with nonmalignant conditions undergoing RIC HPCT without increasing toxicity. Measuring i.v. Bu pharmokinetics using a test dose allows timely adjustment of single daily regimen doses and optimization of total Bu exposure, resulting in an effective and safe regimen for these infants.

s / Biol Blood Marrow Transplant 21 (2015) S79eS107 S102 success using HLA-matched related donors; however, use of alternative donors has been associated with increased graft failure, graft versus host disease (GVHD), and transplantrelated mortality (TRM). HSCT using alternative donors with post-transplantation cyclophosphamide (PT/Cy) has been performed for hematologic malignancies with engraftment, GVHD, and TRM comparable to that seen with HLA-matched related donors. There are limited reports of HSCT in nonmalignant disorders using alternative donors and PT/Cy. Design: We transplanted 9 patients with non-malignant conditions (CGD1⁄43, DKC1⁄42, DBA1⁄41, HyperIgM1⁄41, XIAP1⁄41, IPEX1⁄41) using an alemtuzamab/fludarabine based reduced intensity conditioning (RIC). All patients received GVHD prophylaxis with PT/Cy, with the addition of mycophenolate mofetil and tacrolimus for HSCT with haploidentical donors and for alkylator-sensitive diagnoses (DKC). Six patients had 10/10 HLA-matched unrelated donors, and 3 had HLA-haploidentical related donors. Results: All 9 patients successfully engrafted by day 30. Ultimately, all patients have had sustained donor engraftment sufficient to eliminate manifestations of their underlying diseases. 6 of 9 patients are full donor chimeras off immunosuppression,1 patient is a stablemixed donor chimera (76% CD3+ T cells) off immunosuppression, 1 patient is a stable mixed donor chimera on a calcineurin inhibitor (CNI), and 1 patient had secondary graft failure but was ultimately retransplanted with myeloablative conditioning using the same donor, resulting in full donor chimerism and elimination of disease. One patient developed Grade 1 and one patient Grade 2 acute GVHD, both treated successfully with steroids and a CNI. Mild skin chronic GVHD developed in 1 patient, treated successfully with phototherapy. No serious infections occurred and there was no TRM. 1 patient developed veno-occlusive disease, treated successfully with defibrotide. Disease-free survival is 89% with a median follow-up of 14 months (6-30 months). The patient with secondary graft failure is now disease-free after myeloablative transplant, for an overall disease-free survival of 100% at a median of 14 months follow-up (6-60 months). Overall survival is 100%. Conclusion: We have observed successful engraftment sufficient to eliminate manifestations of disease, limited GVHD, and no TRM in 9 patients with nonmalignant disorders using alternative donors, RIC, and PT/Cy. RIC HSCT with PT/Cy shows promise for curing nonmalignant pediatric disorders, and potentially eliminates the need for CNI use after MUD BMT. Development of prospective clinical trials to confirm these observations is warranted.

An important measure to ensure successful follow-up in patients with allogeneic stem cell transplant is to evaluate for engraftment. Recent studies have shown that detecting minimal residual disease is important in order to predict early clinical relapse. We followed 88 leukemic patients with pre- and posttransplant Wilms tumor gene (WT1) levels to predict relapse and variable number of tandem repeats (VNTR) for engraftment. We have found that high pretransplant WT1 levels correlated significantly with relapse in all patient groups, but more significantly in the acute nonlymphoblastic leukemia (ANLL) patients. Posttransplant WT1 level correlated with VNTR status such that low WT1 is associated invariably with VNTR of 100% donor origin, while high WT1 is associated with VNTR of 20%. The association is significant in all patients, specifically in ANLL patients. In this preliminary study, we demonstrate that patients harboring detectable levels of WT1 prior to stem cell transplant have a higher chance of relapse, and posttransplant WT1 and VNTR status appeared to be dependant parameters predicting relapse when present in the posttransplant period. By combining 2 highly sensitive molecular techniques, we have found that this combined technique provided us with a promising alternative for overcoming the limitations imposed by each separate procedure. More studies are necessary before we can come to any significant conclusions.

We studied 30 pediatric patients with malignant (n = 16) or nonmalignant (n = 14) conditions. The preparative regimen consisted of fludarabine, intravenous (IV) busulfan (Bu) for 2 daily doses, and antithymocyte globulin before stem cell transplantation. A test dose of IV Bu (0.8 mg/kg), anticipated to target an area under the concentration-time curve (AUC) of 800 to 1200 micromol.min, was followed later by 2 daily doses adjusted according to the pharmacokinetics (PK) to target an AUC of 3200 to 4800 micromol.min. The median test dose AUC was 953 micromol.min (range, 439-1315 micromol.min). The median AUC of single daily doses was 3798 micromol.min (range, 1511-7254 micromol.min). PK-based dose modification was required in 20 patients: 12 were adjusted to a higher dose, and in 8 the dose was decreased. Nausea and vomiting were noted in 15 patients. No patient developed hepatic veno-occlusive disease or seizures. Full donor chimerism was attained in 20 patients (mean of 24.5 days), 3 achieved partial chimerism, 5 did not engraft, and in 2 it is too early to assess chimerism. Acute graft-versus-host disease developed in 11 patients, grades I to II developed in 10 patients, and grade III developed in 1. Four patients died of infection and 5 of progressive disease. Thus, PK of a test dose of IV Bu provided information to adjust subsequent daily doses of IV Bu: this resulted in a regimen that was feasible, safe, and convenient for administration to children.

Background Our aim was to investigate the impact of the extent of surgical resection on local recurrence and survival in high-risk patients treated with the Chicago Pilot II protocol. Methods Retrospective chart review was performed on 30 patients enrolled in the Chicago Pilot II protocol between 1995 and 2003. Variables studied were location of tumor, extent of resection, timing and location of recurrence, MYCN amplification, surgical complications, event-free survival, and overall survival (OS). Operative reports and postoperative meta -iodobenzylguanidine scans were used to assess extent of resection. Complete resection (CR) was defined as no gross residual tumor including primary and nodal disease. Results Three-year event-free survival and OS of this cohort of 30 patients was 58% and 82%, respectively. Only 1 patient developed a local recurrence, whereas metastatic recurrent disease was observed in 13 (43%) of the 30; and this subset had a significantly worse OS (23% vs 94%, P = .001). The most common relapse location was in bone. Patients with incomplete resection (IR) (11/30) and CR (19/30) had recurrence rates of 64% (7/11) and 32% (6/19, P = .12), respectively. Event-free survival was significantly better for patients with CR (68%) vs IR (27%; P = .05; odds ratio, 2.9). Overall survival rates for patients with CR vs IR were 68% vs 55%, respectively ( P = .25). Conclusions Recurrence rate was the significant determinant of survival. Patients with CR had lower recurrence rates; however, they did not have improved local control. Final outcome of patients with unfavorable neuroblastoma will be determined by metastatic recurrence, not by extent of resection.

We describe the experience with reduced intensity transplants (RIT) in pediatric patients and review the basis for this approach using adult examples and series of patients. We report the experience with RIT in two pediatric studies.

Infants with acute lymphoblastic leukemia (ALL) have a poor prognosis when treated with standard chemotherapy. A subset of these infants, particularly those with mixed-lineage leukemia (MLL) rearrangements, has a high likelihood of relapse. Hematopoietic stem cell transplantation (HSCT) performed early in first remission may improve outcome. We present the results of 16 patients with infant ALL who were treated with HSCT in first remission. Six patients were ≤6 months of age at diagnosis, 11 had an initial white blood cell count of >50000/μL, and all patients with determinable cytogenetics had a high-risk karyotype [t(4:11) abnormality or other MLL rearrangement]. All patients received 150 cGy of total body irradiation for 8 doses (1200 cGy). Fifteen of 16 patients received etoposide at 1000 mg/m2 as a continuous infusion over 24 hours and cyclophosphamide at 60 mg/kg/d for 3 days. Eight patients received HSCT from an HLA-identical sibling, and 8, from unrelated cord blood. Twelve (75%) patients remain long-term survivors (median follow-up, 4.7 years). Two patients, 1 of whom had minimal residual disease at HSCT, died after relapse following HSCT. Two patients died of transplant-related causes. The HSCT was well tolerated; 15 patients achieved neutrophil engraftment at a median of 16 days. Acute and chronic graft-versus-host disease were minimal in these patients. These results support the use of HSCT in the treatment of infant ALL, especially when used as consolidation in first remission. The risk of relapse seems to be decreased with this approach. Further work is being performed to determine the long-term effects from this therapy.

We compared the results of Tc-99 evaluation of glomerular filtration rate (GFR) vs. the calculation of the creatinine clearance (CCrC) as a predictor for the development of renal insufficiency in pediatric patients following hematopoietic stem cell transplantation (HSCT). We reviewed 95 consecutive patients receiving autologous (n = 37) or allogeneic (n = 58) HSCT at Children's Memorial Hospital between January, 1995 and February, 1998. Diagnoses included leukemia (n = 43), solid tumor (n = 27), bone marrow failure syndrome (n = 12), non-malignant disease (n = 8), CNS tumors (n = 5) and immunodeficiency (n = 3). Tc-99 GFR was compared with a calculated creatinine clearance derived from the Schwartz formula (CCrC) prior to HSCT. These measures of renal function were compared with the patient's subsequent clinical course to determine if patients who developed renal insufficiency of sufficient magnitude as to require continuous veno-venous hemofiltration (CVVH) or dialysis, could have been identified. Overall comparison of the two methods of evaluation of renal function showed low correlation with values obtained by CCrC, which were consistently higher in most patients (r-value 0.01 in the regression analysis and a p = 0.08 95% CI −24.15 to 1.48). When stratified for age, correlation between the two methods was excellent only in children younger than 5 yr of age p = 0.02 95%, CI 0.032–0.49). Eleven patients required therapy with CVVH or dialysis but neither CCrC nor Tc-99 GFR prior to transplant predicted this event. Patients who received TBI were statistically more prone to develop renal insufficiency than those without TBI (p

Wilms' tumor 1 (WT1) gene expression is seen in a significant number of cases of human neoplasia; however, the mechanism of action remains to be clarified. We hypothesized that WT1 gene is a surrogate marker of proliferation in normal hematopoietic cells and leukemias. While we and others have recognized its value as a tool for the detection of minimal residual disease (MRD), the objective of this study was to confirm our hypothesis regarding normal.Samples from healthy donors (n=16) and UC blood (n=9) were cultured in Methocult for 21 days. Colonies were analyzed on days 7, 14 and 21 by RT-PCR for WT1 gene expression. Our positive controls were samples from patients with leukemia (n=91). Negative controls were from normal volunteers without stimulation (n=26).Results showed a statistically significant difference (P0.0001) between cultured groups, with the highest level of WT1 gene expression in the positive controls and on day 14, when cells are at their maximal proliferation.In conclusion, WT1 gene expression in the proliferating colonies was highest on day 14, although less than in leukemia samples, confirming our hypothesis that WT1 gene is a surrogate marker of proliferation, not only in leukemogenesis but also, to a lesser degree, in normal cell proliferation.

Bone marrow (BM) mesenchymal stem cells (MSCs) are cells capable of expanding and differentiating in vitro into nonhematopoietic cells. Neurotrophic cytokines, such as human epidermal growth factor (hEGF) and bovine fibroblast growth factor (bFGF) can induce differentiation into neural cells (NCs). When BM MSCs were cultured with hEGF and bFGF, RNA expression of neuronal specific markers Nestin, MAP-2, and tyrosine hydroxylase (TH) were observed. We tested a new cytokine combination to generate mature NCs. The plastic-adherent cells were collected and then split when they were 90% confluent from an enriched mononuclear cell layer. At passage 3, MSCs were cultured in neural differentiation media (dbcAMP, IBMX, FGF-8, BDNF, hEGF, and bFGF in NEUROBASAL media plus B27). Cells were counted on day 6. Immunofluorescent staining and reverse transcriptase (RT)-PCR were performed to evaluate the expression of neural markers. On day 6, 66% of cells developed dendrites and presented typical neural cell morphology. Some cells were positive for early neural markers Nestin and beta-tubulin III. Cells expressing mature neuronal markers (NF, NeuN, Tau, Nurr1, GABA, oligodendryte GalC, and glial GFAP) were also seen. By adding hEGF, bFGF, dbcAMP, IBMX, BDNF, and bFGF-8 into NEUROBASAL media plus B27, BM MSCs were directed toward becoming early and mature NCs.

Purpose To investigate whether response to induction therapy, evaluated by metaiodobenzylguanadine (MIBG) and bone scintigraphy, correlates with event-free survival (EFS) in children with high-risk neuroblastoma (NB). Patients and Methods Twenty-nine high-risk NB patients were treated prospectively with an intensive induction regimen and consolidated with three cycles of high-dose therapy with peripheral blood stem-cell rescue. The scintigraphic response was evaluated by MIBG and bone scans using a semi-quantitative scoring system. The prognostic significance of the imaging scores at diagnosis and following induction therapy was evaluated. Results A trend associating worse 4-year EFS rates for patients with versus without osteomedullary uptake on MIBG scintigraphs at diagnosis was seen (35% ± 11% v 80% ± 18%, respectively; P = .13). Similarly, patients with positive bone scans at diagnosis had worse EFS than those with negative scans, although the difference did not receive statistical significance (34% ± 10% v 83% ± 15%, respectively; P = .06). However, significantly worse EFS was observed in patients with a postinduction MIBG score of ≥ 3 compared to those with scores of less than 3 (0% v 58% ± 11%; P = .002). There was no correlation between bone scan scores and outcome following induction therapy. Conclusion MIBG scores ≥ 3 following induction therapy identifies a subset of NB patients who are likely to relapse following three cycles of high-dose therapy with peripheral blood stem-cell rescue, local radiotherapy, and 13-cis-retinoic acid. Alternative therapeutic strategies should be considered for patients with a poor response to induction therapy.

Purpose To investigate whether high-dose therapy with hematopoietic stem-cell rescue (HSCR) will improve survival for patients with relapsed Wilms’ tumor. Patients and Methods Thirteen children with relapsed Wilms’ tumor were treated with one or two cycles of high-dose chemotherapy (HDT) followed by autologous HSCR. Twelve of 13 patients received reinduction chemotherapy before HDT and HSCR. The median age at diagnosis was 4.8 years, and the median time to relapse was 12 months. The histology was favorable in 12 of 13 patients. The ablative regimens included: (1) thiotepa (TT)/cyclophosphamide (CTX)/carboplatin (CP; n = 2); (2) TT/CTX (n = 5); (3) TT/etoposide (ETP; n = 1); and (4) CP/ETP/CTX (n = 1). Four patients received two cycles of HDT and HSCR. Cycle 1 consisted of CP/ETP/CTX, and melphalan/CTX were used in cycle 2. Results Seven of 13 patients are alive without evidence of disease, with a median follow-up of 30 months. The 4-year estimated event-free survival (EFS) rate is 60% (95% CI, 0.40 to 6.88), and the overall survival (OS) at 4 years is 73% (95% CI, 0.40 to 6.86). There was no transplant-related mortality. All patients engrafted to an absolute neutrophil count 500/μL at a median of 13 days (range, 8 to 62 days) and had an unsustained platelet count > 20.0μ at a median of 16 days (range, 10 to 202 days). Conclusion Our results suggest that HDT with HSCR is an effective treatment for patients with Wilms’ tumor who experience relapse.