Using peripheral blood progenitor cells (PBPC) for transplantation in pediatric patients: a state-of-the-art review

Primed for change: The effect of a blood prime on peripheral blood stem cell collection and accuracy of a prediction tool in pediatric patients

Pediatric apheresis collection of peripheral blood stem cells for autologous transplantation often requires use of a blood prime. We evaluated the relationship between pre-apheresis blood CD34+ counts and final CD34+ yield with use of a blood prime. Forty patients underwent apheresis stem cell collection in a 5 year period in our hospital, of which 27 required blood priming of the apheresis machine. Despite the blood prime group having significantly higher pre-apheresis CD34+ cell counts, this group processed a relatively higher volume of blood due to a higher dilutional effect and collected significantly less than predicted CD34+ cell yield. Use of weight-specific collection efficiencies and dilution-adjusted pre-apheresis CD34+ counts will help in accurately estimating the whole blood volume to process for PBSC collection and therefore increase efficiency and decrease the overall cost of collection.

Impact of CD34+ pre-counting and plerixafor on autologous peripheral blood stem cell collection in Japanese university hospitals in eight years

OBJECTIVE

Over the past decade, there have been two major advancements in autologous peripheral blood stem cell (PBSC) collection, namely enumeration of CD 34+ cells for apheresis prediction and use of plerixafor to assist mobilization of PBSC. This study aimed to investigate changes in the efficacy of PBSC collection from two Japanese university hospitals over an eight-year period.

STUDY DESIGN AND METHODS

A series of 399 PBSC collection procedures from 239 patients with solid malignant tumors (ST, n = 42), malignant lymphoma (ML, n = 91), multiple myeloma (MM, n = 99), and others (amyloidosis and leukemia, n = 7) from two university hospitals from 2011 to 2018 were retrospectively analyzed. We also analyzed the effects of CD34+ pre-counting and plerixafor administration in improving CD34+ cell yield.

RESULTS

Using CD34+ pre-count as a reference, the frequency of apheresis was reduced and the yield of CD34+ cells increased in patients with ST. When administrating plerixafor, especially with a CD34+ pre-count <20/μL, the yield of CD34+ cells was significantly increased in patients with ML (p = 0.02) and MM (p = 0.03).

CONCLUSIONS

We verified that CD34+ cell counting and plerixafor administration contributed to effective PBSC collections in our hospitals for the eight-year study period. In patients with ST, CD34+ pre-count threshold for starting apheresis was ≥10/μL. CD34+ pre-count (<20/μL) was useful to select appropriate patients for plerixafor administration among the patients with ML and MM.

Circulating Blasts Following Chemotherapy in Pediatric Patients: Implications for Complete Remission Definition in Acute Leukemia

We assessed the incidence of circulating blasts occurring post-chemotherapy in 1000 consecutive pediatric blood samples. Blasts with myeloid morphology (<1-3%) were present in post-chemotherapy samples in 19 of 294 (6.4%) patients with acute leukemia in remission and in 11 of 361 (3.4%) patients with solid tumors, non-Hodgkin or Hodgkin lymphoma, and were associated with ANC>1.5x10(9)/l in 13 of 30 (43%) samples, and platelets >100x10(9)/l in 25 of 30 (83%) samples. Our findings suggest that the absence of circulating blasts may not be a prerequisite for remission in acute myeloid leukemia (AML).

Collection of peripheral blood CD34+ progenitor cells from healthy dogs and dogs diagnosed with lymphoproliferative diseases using a Baxter-Fenwal CS-3000 Plus blood cell separator

BACKGROUND

Canine peripheral blood mononuclear cell (PBMC) apheresis using a Baxter-Fenwal CS-3000 Plus automated blood cell separator has not been reported.

OBJECTIVE

To determine the feasibility and safety of using a CS-3000 Plus blood cell separator with a small volume separation container holder (SVSCH) and small volume collection chamber (SVCC) to harvest canine PBMCs from dogs weighing <50 kg.

ANIMALS

Eight healthy mongrel dogs and 11 client-owned dogs in clinical remission for lymphoproliferative diseases (LPD).

METHODS

In this prospective study, aphereses were performed using a Baxter-Fenwal CS-3000 Plus blood cell separator, with or without recombinant human granulocyte colony-stimulating factor (rhG-CSF) treatment.

RESULTS

Aphereses from 6 healthy dogs given rhG-CSF yielded an average of 1.1 × 10(7) ± 8.2 × 10(6) CD34+ cells/kg. Aphereses from LPD dogs given rhG-CSF yielded an average of 5.4 × 10(6) ± 3.25 × 10(6) CD34+ cells/kg (P = .17). Higher hematocrit in both groups of dogs receiving rhG-CSF correlated with an increased number of CD34+ cells/kg harvested (healthy, P = .04; LPD, P = .05). Apheresis was well tolerated by all dogs.

CONCLUSIONS AND CLINICAL IMPORTANCE

Canine PBMC apheresis using the Baxter-Fenwal CS-3000 Plus cell separator with an SVSCH and SVCC is a feasible and safe option for harvesting an adequate number of CD34+ peripheral blood progenitor cells from dogs weighing ≥17 kg for hematopoietic cell transplantation.

Peripheral blood stem cell collection in children: Management, techniques and safety

Peripheral blood stem cell (PBSC) collection as a source of haematopoietic stem cells is steadily increasing. The collection procedure in children is more difficult than in adults because of the low blood volume and the poor venous access. Special apheresis equipment has been developed for paediatric PBSC collections to reduce the extracorporeal volume thereby avoiding circulatory side effects. Priming of the disposable with red blood cells and/or human albumin is recommended for children weighing less than 30kg. Poor venous access usually requires a special paediatric catheter to allow for a blood flow that results in the formation of a cell layer for the collection of PBSC. An optimal time point with a maximum peak of CD34+ cells should be chosen for the harvesting of PBSC to reduce the duration of the apheresis and possible side effects.

Peripheral blood versus bone marrow as a source of hematopoietic stem cells for allogeneic transplantation in children with class I and II beta thalassemia major

Peripheral blood stem cell transplantation (PBSCT) has been extended to treating hematologic disorders, but the benefits over bone marrow transplantation (BMT) still remain unclear, especially in nonmalignant hematologic disorders. In this study, we compared class I-II thalassemic children who underwent HLA-matched PBSCT and BMT for treatment. Conditioning regimens consisted of busulfan and cyclophosphamide, followed by cyclosporine +/- methotrexate for graft-versus-host disease (GVHD) prophylaxis. Using multivariate analysis, the outcomes of 87 PBSCT patients and 96 BMT patients were reported (median follow-up: 29 and 60 months, respectively). The median time to neutrophil and platelet recovery in PBSCT patients (11 and 18 days, respectively) was significantly lower than BMT patients (19 and 26 days, respectively) (P < .001). Grade II-IV acute GVHD was more frequent in PBSCT versus BMT group (72% versus 55%; P = .003) (relative risk = 1.75, 95% confidence interval [CI]: 1.20-2.57). The incidence of chronic GVHD was more frequent in the PBSCT versus BMT group (48% versus 19%; P < .001) (relative risk = 2.62, 95% CI: 1.43-4.82). There was no difference in the 2-year overall survival after PBSCT and BMT (83% and 89%, respectively). The 2-year disease-free survival was 76% in both groups. These results show some advantages of PBSCT, but to improve the risk of GVHD in PBSCT, a better conditioning and prophylaxis regimen is needed.

Use of totally implantable catheters for peripheral blood stem cell apheresis

Collection of PBSC by leukapheresis requires one venous access (VA) for inflow and one for outflow. The use of implantable venous access devices (IVAD) has never been reported in this setting. We retrospectively analyzed the use of IVAD for performing apheresis. The study was conducted between January 2000 and June 2005 on 64 patients (41 children) requiring intensification for treatment of a solid tumor. Mean body weight was 26 kg (range 8-91 kg) for a median age of 8.5 years (range 0.7-66 years). A total of 121 aphereses were performed (mean 1.89 apheresis/patient). The second VA was in a cubital vein in 84 procedures and was a temporary central VA in 31. Mean duration of apheresis was 3 h (range 30-274 min). Mean flow rate was 41.3 ml/min (range 12-85 ml/min). Mean collection rate was 59.2% for CD34+ cells and 70% for mononuclear cells. The total number of CD34+ cells collected was 2.5 x 10(6)/kg per apheresis, and 5.9 x 10(6)/kg per patient. Several complications occurred: one catheter-related sepsis (0.86%), four catheter occlusions (3.47%) and eight hemodynamic instabilities related to extracorporeal volume. Weight <10 kg is a risk factor for complication (P=0.0006). IVAD are effective and safe for PBSC collection. Placement of a second central VA (requiring general anesthesia for children) could be avoided.

Peripheral blood stem cell collection in pediatric patients: feasibility of leukapheresis under anesthesia in uncompliant small children with solid tumors

Leukapheresis demands patient's compliance and adequate vascular accesses, which can require invasive methods in very small children whose treatment protocol includes hemopoietic stem cell collection for myeloablative chemotherapy and stem cell rescue. Since 1998, at the Istituto Nazionale Tumori of Milan, in selected uncompliant small children, the placement of peripheral vascular accesses and leukapheresis have been performed at the same time under general anesthesia. Peripheral venous cannulas were positioned for blood collection, while blood was returned through either peripheral cannulas or mono-lumen central catheters previously installed for chemotherapy. A continuous-flow cell separator was used for leukapheresis. Between 1998 and 2003, 47 children with solid tumors underwent anesthesia for a total of 54 leukaphereses. The patients' age ranged from 12.7 to 93 months (median 30.3) and their weight ranged from 7 to 20 kg (median 14.1). Neither metabolic nor anesthesiological complications were recorded. In 89% of cases, the CD 34(+) cell target was achieved at a single harvest; the median number of CD 34(+) cells was 10.8 x 10(6)/kg/leukapheresis (range 1-117) and the median collection efficiency was 63.4% (range 25-100.6). Leukapheresis under anesthesia is feasible and safe in very low-weight children whose compliance is lacking due to age and disease.

Risks and methods for peripheral blood progenitor cell collection in small children

Peripheral blood progenitor cells (PBPC) are increasingly used as a source of stem cells for either autologous or allogeneic hematopoietic transplantation in children. Although technically similar to adult procedures, apheresis in small children worries some operators and physicians that have little experience in managing pediatric patients or donors. However several published series have showed that these procedures, when performed by experienced teams are safe and can obtain enough amount of PBPC for either autologous or allogeneic hematopoietic transplantation. Some technical aspects must be considered in pediatric apheresis due to the size of the patient/donor. Factors that must be evaluated are extracorporeal circuit volume, blood flow rates, type of anticoagulant and vascular access. Other important issue to be considered is the emotional stress for them and their relatives. Leukaphereses in children may be performed with any of the reported continuous blood cell separator without sedation. Adverse events are mainly related either to vascular access or to metabolic or hemodynamic changes. Anyway, taking all these complications together, they are not higher than those adverse events or toxicities reported after general anesthesia and bone marrow harvesting.

How and when should we monitor chimerism after allogeneic stem cell transplantation?

SUMMARY

Chimerism analysis has become an important tool for the peri-transplant surveillance of engraftment. It offers the possibility to realize impending graft rejection and can serve as an indicator for the recurrence of the underlying malignant or nonmalignant disease. Most recently, these investigations have become the basis for treatment intervention, for example, to avoid graft rejection, to maintain engraftment and to treat imminent relapse by pre-emptive immunotherapy. This invited review focuses on the clinical implications of characterization of hematopoietic chimerism in stem cell transplantation.

Allogeneic peripheral blood stem cell transplantation in children with homozygous beta-thalassemia and severe beta-thalassemia/hemoglobin E disease

To determine the outcome of children with homozygous beta-thalassemia (beta/beta) and severe beta-thalassemia/hemoglobin E disease (beta/E) who underwent allogeneic peripheral blood stem cell transplantation (PBSCT). The authors conducted a cohort study of allogeneic PBSCT in beta/beta and beta/E patients who had 6/6 or 5/6 HLA-matched sibling donors. All patients received a conditioning regimen including busulfan and cyclophosphamide, except one who received busul-fan and cyclophosphamide plus antithymocyte globulin. Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporine A and methotrexate for eight patients and cyclosporine and mycophenolate mofetil for one patient. Donors received G-CSF for 4 days before leukapheresis collections. There were five beta/beta and four beta/E patients in this study. The median age was 9 years (range 1.5-10 years). The median CD34+ cell count was 7.4 x 10(6) cells/kg recipient body weight. All patients achieved neutrophil and platelet engraftment with a median time of 15 days and 21 days respectively. Acute GVHD grade 2 to 4 appeared in four patients (grade 2, n = 3; grade 4, n = 1). Three patients developed chronic GVHD (limited, n = 2; extensive, n = 1). All patients were alive with a median follow-up time of 23 months (range 7-52 months). Neither graft failure nor graft rejection was observed. Allogeneic PBSCT is feasible for children with beta/beta and beta/E, although the incidence of GVHD was apparently high compared with bone marrow transplant study in Thais.

[Cell therapy for cancer treatment in children]

The cure rate for cancer in children is currently almost 75%. This rate has remained fairly constant over the past few years, which suggests that the limits of today's curative treatment potential have been reached. The development of cell therapy techniques opens up new therapeutic possibilities in paediatric oncology. Here, we deal both with a number of cell therapy techniques, which have already proved their efficacy in children, and other more innovative approaches, which require validation. Examples of the use of autologous and allogeneic cells are described. Clinical studies and their results, while often preliminary, are reported. The importance of well run clinical research, a clear and progressive legal framework and the necessary substantial economic support for the development of cell therapy are underlined.

Analysis of factors affecting PBPC collection in low-weight children with malignant disorders

BACKGROUND

PBPC collection in children weighing </=25 kg is hampered by technical and clinical problems related to vascular access, low total blood volume, anticoagulation, side effects, and psychological impact. The aim of this study was to analyze several clinical and technical factors, other than pre-apheresis CD34(+) count, that may affect PBPC collection in these low-weight children.

METHODS

Data from 88 leukaphereses performed in 45 children were analyzed, including pre-apheresis CD34(+) cell count, COBE Spectra software (version 4.7 versus 6.0), apheresis volume [standard versus large-volume leukapheresis (LVL)] and patient's diagnosis, age, weight and sex.

RESULTS

The median number of PBPC collected was 6.68 mononuclear cells (MNC)x10(8)/kg (range 2.36-19.05) and 1.69 CD34(+) cellsx10(6)/kg (range 0.08-13.79). Multivariate analysis showed that factors independently associated with the CD34(+) cell yield per apheresis were pre-apheresis CD34(+) cell count (P<0.001), diagnosis (P=0.008) and apheresis volume (P=0.009). Recruitment of CD34(+) cells was also independently affected by the apheresis volume, being higher in the LVL group (P=0.008).

DISCUSSION

We have demonstrated that, apart from the well-known influence of the pre-apheresis CD34(+) cell count, two other factors have a major impact on the CD34(+) cell yield: patient's diagnosis and apheresis volume. In addition, taking into account that side effects were mild and tolerable, we have confirmed that LVL is a safe and effective procedure in children </=25 kg, and that AutoPBSC software could be reliably used in these patients, provided that an experienced team performs the procedure.

Peripheral blood stem cell collection in children with acute leukemia: effectiveness of the 'DIAVE' mobilizing regimen

Few experiences of peripheral blood (PB) hematopoietic stem cell mobilization for autologous transplantation have been reported to date in children with acute leukemia (AL). The five-drug-chemotherapy 'DIAVE' (dexamethazone, idarubicine, cytosine-arabinoside, vincristine, etoposide), followed by G-CSF, previously reported as consolidation, was adopted as a mobilization regimen in 29 children (median age: 8 years, range: 3-21; median weight: 34 kg, range: 15-73) with ALL in second remission (CR2: 21), in CR3 (2) or ANLL in CR1 (6). A median peak of 94 x 10(6) CD34(+)cells/l (range: 10-604) was reached at a median time of 12 days (range: 10-18) after the beginning of the mobilizing regimen, which was well tolerated. A median of 10.9 x 10(6) CD34(+)cells/kg (range: 2.4-56.6) were collected in 25 patients (86%), approaching 40 x 10(6)/l CD34(+) cells in the PB (ALL in CR2: 20/21, in CR3: 0/2; ANLL: 5/6) by means of one (20) or two (5) leukaphereses; a median of 2.5 blood volumes was processed. Patients with ANLL mobilized more cells than patients with ALL; moreover, the shorter the interval between remission and mobilizing therapy, the higher was the yield. The products collected underwent purification, aiming at achieving complete removal of possibly contaminating leukemic cells, in 21 cases; also, unmanipulated aliquots were stored as rescues for all but one patient. All the 23 patients undergoing transplantation engrafted (ANC >0.5 x 10(9)/l) at a median of 12 days. In conclusion, the DIAVE regimen compares favorably with conventional mobilizing regimens, usually containing cyclophosphamide, in terms of low toxicity, collection time predictability, and efficacy, as shown by the high proportion of patients mobilizing, the large amounts of stem cell collected by means of one or two leukaphereses only, and the prompt engraftment after infusion.

Peripheral blood progenitor cell collection in low-weight children

Peripheral blood progenitor cells (PBPC) are substituting bone marrow as a source of stem cells for either autologous or allogeneic hematopoietic transplantation. Several papers have been published on the experience of various groups in their mobilization and transplantation in children. Some technical problems have derived from the size of the patient or donor in the pediatric setting. Thereby, there is some concern regarding leukapheresis in very small children (weighing less than 15-20 kg). This paper summarizes our own data and that of other groups for the mobilization and collection of PBPC in the smallest children. Data from the literature show that mobilization with cytokines alone or in combination with chemotherapy is well tolerated by these patients. Pediatric donors may be used for allogeneic transplantation with no higher incidence of complications. PBPC collection even in the smallest children is a safe and efficient procedure when performed by experienced apheresis teams.

Clinical applications of hematopoietic growth factors in pediatric oncology

Myeloid growth factors are widely used in both pediatric and adult oncology. Although the literature supporting the use of growth factors in pediatric oncology is less extensive than the adult literature, some uses are clearly established. Both granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor shorten the duration of febrile neutropenia after myelosuppressive chemotherapy, effectively mobilize hematopoietic stem cells for transplantation, and enhance neutrophil engraftment after hematopoietic stem cell transplantation. Although some open-label, uncontrolled trials and retrospective analyses support growth factor use to ameliorate the number of infections, duration of hospitalizations, and duration of intravenous antibiotic use after myelosuppressive chemotherapy or to enhance dose intensity, randomized controlled trials supporting these practices are lacking.

Peripheral blood stem cell transplantation in children with beta-thalassemia

Fifteen patients with beta-thalassemia received an allogeneic peripheral blood stem cell transplant. Median age was 3.5 years (1-15 years). Six were class I, four class II and five class III according to the Pesaro criteria. All of the donors were HLA-phenotypically identical (13 siblings and two parents). Nine patients were given BU + CY and six BU + CY plus ATG as conditioning. All patients received MTX (+1, +3, +6) and CsA (9-12 months) post transplant for GVHD prophylaxis. The median neutrophil and platelet engraftment times were day 12 and day 16, respectively. cGVHD was observed in three patients. Two patients died. Thirteen patients are well, and transfusion-independent 2-30 months after PSCT. No recurrences of thalassemia have been seen. Overall and event-free survival were 86.6%. In conclusion, we suggest that PSCT can be considered a safe and effective treatment for children with beta- thalassemia.