CD34+ Hematopoietic Progenitor Cell Selection of Bone Marrow Grafts for Autologous Transplantation in Pediatric Patients

AbstractCD34+-selection of hematopoietic grafts for patients undergoing autologous hematopoietic stem cell transplantation (HSCT) is frequently used to obtain a tumor-free graft. The majority of published experience is with peripheral blood stem cell (PBSC) products; only scant information has been published on bone marrow (BM) grafts. We reviewed our experience using CD34+ selection of BM grafts in children undergoing autologous BM transplantation. After obtaining institutional approval, we performed a retrospective review of the medical records of patients who underwent autologous stem cell collection at St. Jude. From January 1, 1999, to December 31, 2003, 373 patients underwent autologous HSCT; 131 received marrow grafts, 237 received PBSC grafts, and 5 received a combination. Seventeen patients underwent BM harvests for CD34+ selection of their stem cell grafts. Sixteen patients received 19 CD34 purified grafts processed on the Isolex 300i Magnetic Cell Selection System® device. Four patients were not included in the engraftment analysis as 1 did not receive the collected product, 1 received a tandem product, and 2 received products that were composed of 2 or 3 combined purified products. Following selection, marrow grafts contained a median of 1.4 × 106 CD34+ cells/kg (range: 0.09-8.3 × 106/kg) and a median of 0.014 ×108 total nucleated cell cells/kg (range: 0.001-0.09 × 108/kg). The median CD34% recovery was 30.9% (range: 9.3%-57.1%), with the median CD34 purity being 95.5% (range: 62.2%-98.8%). All patients engrafted. The median time to absolute neutrophil count ≥500/mm3 was 19 days (range: 12-35 days), and to platelet recovery was 28 days (range 18-37 days). No patient died from transplant-related complications. Our study demonstrates that CD34+-selection of marrow grafts is feasible, and these grafts are able to successfully reconstitute hematopoiesis in patients undergoing autologous BMT

Staphylococcus aureus bloodstream infection due to contaminated hematopoietic stem-cell graft

To the Editor—The Foundation for the Accreditation of Cellular Therapy and the American Association of Blood Banks publish guidelines to ensure the quality and safety of hematopoietic stem-cell (HSC) products. These HSC products are generally cultured after procurement by the collection facility and following processing at the transplant center. Reported contamination rates of HSC grafts range from 1% to 45%. The clinical significance of infusion of contaminated HSC products is unclear. When fresh products are used, contamination is often not identified prior to HSC infusion. Bacterial contamination is not an absolute contraindication to HSC infusion, as options are limited following a myeloablative preparative regimen. In a review of 12 studies, 91% of contaminated grafts contained bacterial species of low pathogenicity (eg, Staphylococcus epidermidis and Propionibacterium acnes). Of 26 patients who received grafts contaminated with highly pathogenic bacteria (eg, S. aureus), none developed symptoms or had a positive culture matching an organism found in the HSC graft. In prior reports of infections putatively caused by graft contamination, confirmation that the graft was the source of infection was based solely on the finding of identical species. Contrary to these prior reports, we present a case of catheter-related bloodstream infection with methicillin-susceptible S. aureus due to a contaminated HSC graft in which pulsed-field gel electrophoresis (PFGE) confirmed that the graft and patient isolates were identical

Total and Active Rabbit Antithymocyte Globulin (rATG;Thymoglobulin®) Pharmacokinetics in Pediatric Patients Undergoing Unrelated Donor Bone Marrow Transplantation

AbstractRabbit 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

Using Fludarabine to Reduce Exposure to Alkylating Agents in Children with Sickle Cell Disease Receiving Busulfan, Cyclophosphamide, and Antithymocyte Globulin Transplant Conditioning: Results of a Dose De-Escalation Trial

AbstractHigh-dose busulfan, cyclophosphamide, and antithymocyte globulin (BU-CY-ATG) is the most commonly used conditioning regimen in HLA-matched related hematopoietic cell transplantation for children with sickle cell disease. Disease-free survival with this regimen is now approximately 95%; however, it produces significant morbidity. We hypothesized we could create a less toxic regimen by adding fludarabine (FLU) to BU-CY-ATG and reduce the dosages of busulfan and cyclophosphamide. We conducted a multicenter dose de-escalation trial with the objective of decreasing the doses of busulfan and cyclophosphamide by 50% and 55%, respectively. Using day +28 donor-predominant chimerism as a surrogate endpoint for sustained engraftment, we completed the first 2 of 4 planned levels, enrolling 6 patients at each and reducing the total dose of cyclophosphamide from 200 mg/kg to 90 mg/kg. On the third level, which involved a reduction of i.v. busulfan from 12.8 mg/kg to 9.6 mg/kg, the first 2 patients had host-predominant T cell chimerism, which triggered trial-stopping rules. All 14 patients survive disease-free. No patients suffered severe regimen-related toxicity. Our results suggest BU-FLU-CY-ATG using lower dose CY could be a less toxic yet effective regimen. Further evaluation of this regimen in a full-scale clinical trial is warranted

Phase I Study of the Tolerability and Pharmacokinetics of Palifermin in Children Undergoing Allogeneic Hematopoietic Stem Cell Transplantation

The maximum tolerated dose of palifermin, a keratinocyte growth factor, in children is not known, and its pharmacokinetics in this population has not been well studied. This is a phase I study of palifermin was designed to evaluate its tolerability at doses of 40, 60, and 90 μg/kg/day in children age 2–18 years of age, receiving a myeloablative preparative regimen for allogeneic hematopoietic stem cell transplantation (HSCT). In each cohort, palifermin was given for 3 consecutive days before the preparative regimen and for 3 days after the stem cell infusion. Twelve patients were enrolled. Palifermin 90 μg/kg/day was tolerated in 6 patients without dose-limiting toxicity. All patients had at least 1 adverse event, mostly National Cancer Institute grade 1 or 2 severity. Skin rash, grade 2 or lower, was the most common adverse event, seen in 67% of patients. Only 3 patients (25%) had mucositis. The area under the concentration–time curve increased proportionally to the dose, and approximately 97% of palifermin exposure occurred in the first 24 hours after administration. Palifermin clearance increased linearly with body weight, supporting dosing by body weight. The mean clearance was 1893 mL/hour/kg, and it did not change significantly between administration of the first and last doses (P =.80). The mean elimination half-life was 4.6 hours. Our data show that palifermin was tolerated at a dose of 90 μg/kg/day, and exhibits linear pharmacokinetics in children undergoing allogeneic HSCT

Related and unrelated donor transplantation for β-thalassemia major: results of an international survey.

We studied 1110 patients with β-thalassemia major aged ≤25 years who received transplants with grafts from HLA-matched related (n = 677; 61%), HLA-mismatched related (n = 78; 7%), HLA-matched unrelated (n = 252; 23%), and HLA-mismatched unrelated (n = 103; 9%) donors between 2000 and 2016. Ninety percent of transplants were performed in the last decade. Eight-five percent of patients received ≥20 transfusions and 88% were inadequately chelated. All patients received myeloablative-conditioning regimen. Overall and event-free survival were highest for patients aged ≤6 years and after HLA-matched related and HLA-matched unrelated donor transplantation. The 5-year probabilities of overall survival for patients aged ≤6 years, 7 to 15 years, and 16 to 25 years, adjusted for donor type and conditioning regimen were 90%, 84%, and 63%, respectively (P < .001). The corresponding probabilities for event-free survival were 86%, 80%, and 63% (P < .001). Overall and event-free survival did not differ between HLA-matched related and HLA-matched unrelated donor transplantation (89% vs 87% and 86% vs 82%, respectively). Corresponding probabilities after mismatched related and mismatched unrelated donor transplantation were 73% vs 83% and 70% vs 78%. In conclusion, if transplantation is considered as a treatment option it should be offered early (age ≤6 years). An HLA-matched unrelated donor is a suitable alternative if an HLA-matched relative is not available

Using Fludarabine to Reduce Exposure to Alkylating Agents in Children with Sickle Cell Disease Receiving Busulfan, Cyclophosphamide, and Antithymocyte Globulin Transplant Conditioning: Results of a Dose De-Escalation Trial

AbstractHigh-dose busulfan, cyclophosphamide, and antithymocyte globulin (BU-CY-ATG) is the most commonly used conditioning regimen in HLA-matched related hematopoietic cell transplantation for children with sickle cell disease. Disease-free survival with this regimen is now approximately 95%; however, it produces significant morbidity. We hypothesized we could create a less toxic regimen by adding fludarabine (FLU) to BU-CY-ATG and reduce the dosages of busulfan and cyclophosphamide. We conducted a multicenter dose de-escalation trial with the objective of decreasing the doses of busulfan and cyclophosphamide by 50% and 55%, respectively. Using day +28 donor-predominant chimerism as a surrogate endpoint for sustained engraftment, we completed the first 2 of 4 planned levels, enrolling 6 patients at each and reducing the total dose of cyclophosphamide from 200 mg/kg to 90 mg/kg. On the third level, which involved a reduction of i.v. busulfan from 12.8 mg/kg to 9.6 mg/kg, the first 2 patients had host-predominant T cell chimerism, which triggered trial-stopping rules. All 14 patients survive disease-free. No patients suffered severe regimen-related toxicity. Our results suggest BU-FLU-CY-ATG using lower dose CY could be a less toxic yet effective regimen. Further evaluation of this regimen in a full-scale clinical trial is warranted

Late Effects in Hematopoietic Cell Transplant Recipients with Acquired Severe Aplastic Anemia: A Report from the Late Effects Working Committee of the Center for International Blood and Marrow Transplant Research

With improvements in hematopoietic cell transplant (HCT) outcomes for severe aplastic anemia (SAA), there is a growing population of SAA survivors after HCT. However, there is a paucity of information regarding late effects that occur after HCT in SAA survivors. This study describes the malignant and nonmalignant late effects in survivors with SAA after HCT. A descriptive analysis was conducted of 1718 patients post-HCT for acquired SAA between 1995 and 2006 reported to the Center for International Blood and Marrow Transplant Research (CIBMTR). the prevalence and cumulative incidence estimates of late effects are reported for 1-year HCT survivors with SAA. of the HCT recipients, 1176 (68.5%) and 542 (31.5%) patients underwent a matched sibling donor (MSD) or unrelated donor (URD) HCT, respectively. the median age at the time of HCT was 20 years. the median interval from diagnosis to transplantation was 3 months for MSD HCT and 14 months for URD HCT. the median follow-up was 70 months and 67 months for MSD and URD HCT survivors, respectively. Overall survival at I year, 2 years, and 5 years for the entire cohort was 76% (95% confidence interval [CI]: 74-78), 73% (95% CI: 71-75), and 70% (95% CI: 68-72). Among 1-year survivors of MSD HCT, 6% had 1 late effect and 1% had multiple late effects. for 1-year survivors of URD HCT, 13% had 1 late effect and 2% had multiple late effects. Among survivors of MSD HCT, the cumulative incidence estimates of developing late effects were all <3% and did not increase over time. in contrast, for recipients of URD HCT, the cumulative incidence of developing several late effects exceeded 3% by 5 years: gonadal dysfunction 10.5% (95% CI: 7.3-14.3), growth disturbance 7.2% (95% CI: 4.4-10.7), avascular necrosis 6.3% (95% CI: 3.6-9.7), hypothyroidism 5.5% (95% CI: 2.8-9.0), and cataracts 5.1% (95% CI: 2.9-8.0). Our results indicated that all patients undergoing HCT for SAA remain at risk for late effects, must be counseled about, and should be monitored for late effects for the remainder of their lives.Public Health Service Grant from the National Cancer InstituteNational Heart, Lung, and Blood InstituteNational Institute of Allergy and Infectious DiseasesNational Cancer InstituteHealth Resources and Services Administration/Department of Health and Human ServicesOffice of Naval ResearchAllosAmgenAngioblastChildrens Hosp Orange Cty, Dept Hematol, Orange, CA 92668 USACIBMTR Med Coll Wisconsin, Dept Biostat, Milwaukee, WI USAMed Coll Wisconsin, CIBMTR Stat Ctr, Milwaukee, WI 53226 USAKing Faisal Specialist Hosp & Res Ctr, Dept Oncol, Riyadh 11211, Saudi ArabiaNew York Med Coll, Dept Pediat Hematol Oncol & Stem Cell Transplanta, Valhalla, NY 10595 USAStemcyte, Covina, CA USADana Farber Canc Inst, Dept Pediat Oncol, Boston, MA 02115 USAUniv Florida, Dept Hematol Oncol, Gainesville, FL USAPrincess Margaret Hosp, Dept Med, Toronto, ON M4X 1K9, CanadaUniv S Florida, All Childrens Hosp, Dept Pediat Hematol & Oncol, St Petersburg, FL 33701 USAUniv Basel Hosp, Dept Hematol, CH-4031 Basel, SwitzerlandOregon Hlth & Sci Univ, Dept Hematol & Oncol, Portland, OR 97201 USAChildrens Natl Med Ctr, Dept Blood & Marrow Transplantat, Washington, DC 20010 USABaylor Coll Med, Ctr Cell Therapy, Dept Hematol & Oncol, Houston, TX 77030 USAUniv N Carolina Hosp, Dept Pediat, Chapel Hill, NC USAUniv Hosp Case, Med Ctr, Dept Med, Cleveland, OH USAUniv Arkansas Med Sci, Dept Hematol & Oncol, Little Rock, AR 72205 USACincinnati Childrens Hosp Med Ctr, Dept Bone Marrow Transplantat & Immune Deficiency, Cincinnati, OH USATufts Med Ctr, Dept Med & Pediat, Boston, MA USAUniv S Florida, Coll Med, H Lee Moffitt Canc Ctr & Res Inst, Dept Hematol & Oncol, Tampa, FL 33612 USAFlorida Ctr Cellular Therapy, Dept Med, Orlando, FL USAUniv Fed Parana, Dept Bone Marrow Transplantat, BR-80060000 Curitiba, Parana, BrazilVanderbilt Univ, Med Ctr, Dept Med, Nashville, TN USAInst Oncol Pediat, Dept Pediat, São Paulo, BrazilFred Hutchinson Canc Res Ctr, Dept Clin Res & Transplantat, Seattle, WA 98104 USAMt Sinai Med Ctr, Dept Bone Marrow & Stem Cell Transplantat, New York, NY 10029 USAUniv N Carolina Hosp, Dept Hematol & Oncol, Chapel Hill, NC USAUniv Manitoba, CancerCare Manitoba, Dept Manitoba Blood & Marrow Transplant Program, Winnipeg, MB, CanadaKarolinska Univ Hosp, Ctr Allogene Stem Cell Transplantat, Dept Pediat, Stockholm, SwedenLouisiana State Univ, Hlth Sci Ctr, Childrens Hosp, Dept Pediat, New Orleans, LA USADept Natl Marrow Donor Program, Minneapolis, MN USAPublic Health Service Grant from the National Cancer Institute: U24-CA76518National Heart, Lung, and Blood Institute: 5U01HL069294Office of Naval Research: N00014-06-1-0704Office of Naval Research: N00014-08-1-0058HHSH234200637015CWeb of Scienc