A prospective study on the efficacy of mobilization of autologous peripheral stem cells in pediatric oncohematology patients

Autologous peripheral blood stem cell harvest timing by absolute neutrophil count in children and young adult patients: Single-institute experience

BACKGROUND

Myeloablative, high-dose chemotherapy followed by autologous peripheral blood stem cell transplantation (PBSCT) improves outcome in some high-risk malignant solid tumors and lymphomas in children and young adults.

METHODS

We performed 16 peripheral blood stem cell (PBSC) harvests in 12 children and 2 young adult patients with a high-risk malignant solid tumor or refractory/relapsed Hodgkin's lymphoma from August 2015 to December 2020. In our chemotherapy mobilization protocol, we used an absolute neutrophil count (ANC) of >1 × 109/L following the nadir after chemotherapy as the criterion for undertaking the apheresis.

RESULTS

The median CD34+ cell count per kg body weight of the 33 apheresis products was 4.92 × 106 cells/kg (range, 0.34-22.53 × 106 cells/kg). Thirteen of the 14 patients (93%) had successful PBSC collections that met their goals for PBSCT. Three patients did not receive PBSCT due to disease progression prior to transplantation. Prompt engraftment occurred in all the remaining 11 patients with 17 PBSCTs.

CONCLUSION

Our data suggest that ANC can be helpful as a surrogate parameter in clinical decision-making when the peripheral blood CD34+ count is unavailable.

PEGylated Granulocyte Colony-Stimulating Factor and Plerixafor Enhance Autologous Stem and Progenitor Cell Mobilization and Transplantation in Pediatric Patients

Autologous hematopoietic stem cell transplantation is used to restore bone marrow function after high-dose chemotherapy. For apheresis, granulocyte colony-stimulating factor (G-CSF) is standard of care, but obtaining sufficient stem cells can be challenging. Other mobilization agents include plerixafor and PEGylated G-CSF (PEG-G-CSF). While efficacy of these is established in adults, limited data for their use in pediatric patients are available. Here, we compare Good versus Poor Mobilizers and study success of different mobilization regimens in regard to CD34+cell-collection, -quality, -phenotype and hematologic reconstitution in pediatric patients. In this multi-center retrospective study, we analyzed data of 278 patients with solid tumors and lymphoma, mobilized with either G-CSF (n = 224), PEG-G-CSF (n = 34), or G-CSF/PEG-G-CSF with additional plerixafor (n = 20). In Poor Mobilizers (13.7% of all patients), addition of plerixafor to G-CSF augmented CD34+cell collection, without adverse effects on hematologic reconstitution and CD34+cell quality. PEG-G-CSF-aided mobilization was successful as first-line treatment in two-thirds of patients and did not impair hematological reconstitution, compared to G-CSF-only. Within the Poor Mobilizer group, G-CSF+plerixafor increased primitive (CD45RA-CD38-CD90+CD49f+) and CXCR4-expressing CD34+cells in apheresis products compared to G-CSF-only, without exceeding levels of Good Mobilizers. No plerixafor-related increase in tumor cells was observed in apheresis products. In conclusion, our comprehensive study supports the use of plerixafor and furthermore demonstrates the potential of patient-friendly PEG-G-CSF for mobilization of pediatric patients.

Autologous peripheral blood stem cell mobilization and apheresis in pediatric patients with cancer: A single-center report of 64 procedures

BACKGROUND

The published experience concerning autologous peripheral blood stem cell collection in children is very limited.

METHODS

The data of pediatric patients who underwent autologous stem cell mobilization and apheresis between January 2011 and April 2020 were analyzed retrospectively.

RESULTS

We studied retrospectively 64 mobilization and apheresis procedures in 48 pediatric patients (34 males, 14 females), mean age of 7.31 ± 5.38 (range, 1.5-19.7) years, the underlying disease was mostly neuroblastoma (NBL). The body weight of 21 patients (43.75%) was 15 kg or less. The targeted autologous peripheral stem cell apheresis (APSCA) was successfully achieved in 98% of patients. Neuroblastoma patients were younger than the rest of the patients and underwent apheresis after receiving fewer chemotherapy cycles than others and all of them mobilized within the first session successfully. Plerixafor was added to mobilization in nine heavily pretreated patients (18.7%), median two doses (range, 1-4 doses). 11 patients (22.9%) underwent radiotherapy (RT) before mobilization with doses of median 24 Gy (range, 10.8-54.0 Gy). Patients with RT were older at the time of apheresis and had received more chemotherapy courses than patients without RT. As a result, patients with a history of RT had significantly lower peripheral CD34+ cells and CD34+ yields than those without RT. In 17 patients (35.4%), 22 different complications were noted. The most common complications were catheter-related infections (n:10, 20.8%), followed by catheter-related thrombosis in eight patients (16.7%).

CONCLUSIONS

Patients who had far less therapy before apheresis were more likely to mobilize successfully. Our study provides a detailed practice approach including complications during APSCA aiming to increase the success rates of apheresis in transplantation centers.

Initial prescriptions and medication switches of biological products: an analysis of prescription pathways and determinants in the Swiss healthcare setting

OBJECTIVES

Biological products have contributed to extraordinary advances in disease treatments over the last decade. However, the cost-saving potential of imitator products, so-called biosimilars, is still under-researched in Switzerland. This study aims to assess biosimilars' prescriptions at treatment initiation and their determinants, as well as biological therapy switches.

DESIGN

The study included all patients who had at least one biosimilar available on the market at the time when they were prescribed a biological product. We analysed longitudinal data for biosimilar prescriptions in Switzerland using descriptive statistics and logistic regression to quantify the associations with individual, pharmaceutical and provider-related variables.

SETTING

The analysis is based on de-identified claims data of patients with mandatory health insurance at Helsana, one of the Swiss health insurance companies with a substantial enrollee base in mandatory health insurance.

PARTICIPANTS

Overall, 18 953 patients receiving at least one biological product between 2016 and 2021 were identified.

OUTCOME MEASURES

We differentiated between initial prescriptions and follow-up prescriptions. Our regression focused on initial prescriptions due to evidence indicating that patients tend to follow the medication prescribed at therapy initiation.

RESULTS

Although biosimilars' market share was low (28.6%), the number of prescriptions has increased (from 1016 in 2016 to 6976 in 2021). Few patients with medication switches (n=1492, 8.5%) were detected. Increased relative price difference (difference in the price of available biosimilars relative to price of corresponding reference product) was associated with decreased probability of biosimilar prescriptions, whereas male sex, an increase of available imitator drugs on the market, larger packaging sizes, and prescriptions from specialists or physicians in outpatient settings were associated with increased biosimilar use.

CONCLUSION

The low number of biosimilar prescriptions, despite the proliferating biosimilar market, indicates a high potential for biosimilar diffusion. The findings indicate that patients typically adhere to the therapy options initially chosen and are less inclined to make changes following the initiation of treatment. Our research highlights the need for awareness initiatives to improve understanding among patients and physicians, enabling informed, shared decision-making about biosimilar prescriptions.

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.

Effect of Autograft CD34+ Dose on Outcome in Pediatric Patients Undergoing Autologous Hematopoietic Stem Cell Transplant for Central Nervous System Tumors

Consolidation with autologous hematopoietic stem cell transplantation (HSCT) has improved survival for patients with central nervous system tumors (CNSTs). The impact of the autologous graft CD34+ dose on patient outcomes is unknown. We wanted to analyze the relationship between CD34+ dose, total nucleated cell (TNC) dose, and clinical outcomes, including overall survival (OS), progression-free survival (PFS), relapse, non-relapse mortality (NRM), endothelial-injury complications (EIC), and time to neutrophil engraftment in children undergoing autologous HSCT for CNSTs. A retrospective analysis of the CIBMTR database was performed. Children aged <10 years who underwent autologous HSCT between 2008 to 2018 for an indication of CNST were included. An optimal cut point was identified for patient age, CD34+ cell dose, and TNC, using the maximum likelihood method and PFS as an endpoint. Univariable analysis for PFS, OS, and relapse was described using the Kaplan-Meier estimator. Cox models were fitted for PFS and OS outcomes. Cause-specific hazards models were fitted for relapse and NRM. One hundred fifteen patients met the inclusion criteria. A statistically significant association was identified between autograft CD34+ content and clinical outcomes. Children receiving >3.6×106/kg CD34+ cells experienced superior PFS (p = .04) and OS (p = .04) compared to children receiving ≤3.6 × 106/kg. Relapse rates were lower in patients receiving >3.6 × 106/kg CD34+ cells (p = .05). Higher CD34+ doses were not associated with increased NRM (p = .59). Stratification of CD34+ dose by quartile did not reveal any statistically significant differences between quartiles for 3-year PFS (p = .66), OS (p = .29), risk of relapse (p = .57), or EIC (p = .87). There were no significant differences in patient outcomes based on TNC, and those receiving a TNC >4.4 × 108/kg did not experience superior PFS (p = .26), superior OS (p = .14), reduced risk of relapse (p = .37), or reduced NRM (p = .25). Children with medulloblastoma had superior PFS (p < .001), OS (p = .01), and relapse rates (p = .001) compared to those with other CNS tumor types. Median time to neutrophil engraftment was 10 days versus 12 days in the highest and lowest infused CD34+ quartiles, respectively. For children undergoing autologous HSCT for CNSTs, increasing CD34+ cell dose was associated with significantly improved OS and PFS, and lower relapse rates, without increased NRM or EICs.

Prediction of success of CD34+ collection for autotransplantation in children

INTRODUCTION

Intensive chemotherapy with autologous stem cell transplantation is a therapeutic tool used in paediatric oncology. In adult patients, a peripheral blood CD34+ cell count superior to 20/μL enables an adequate collection of peripheral blood stem cells. There are no recommendations for children. This study aimed to determine whether the count of circulating CD34+ cells on the day before cytapheresis predicts successful collection in paediatric patients.

METHODS

We retrospectively studied all paediatric patients who underwent apheresis for stem cell autotransplantation in the CHU of Rennes between 2010 and 2019. Successful apheresis was defined as a collection superior to 3×10⁶ CD34+/kg. "Success" and "failure" groups were compared.

RESULTS

In total, 122 apheresis procedures were performed in 105 patients. It was a successful procedure in 81% of patients and a failure in 19% of patients. A minimal cut-off of circulating CD34+ count superior to 13/μL on D-1 allowed us to predict a collection of at least 3×10⁶ CD34+/kg (PPV 94,8%, NPV 51,4%). For children aged<6 years, the association with leucocyte increase during the 5 days before the procedure improved the prediction of success.

DISCUSSION

The peripheral blood CD34+ cell count is a predictive factor for successful collection in paediatric patients. The minimal cut-off that allows an adequate collection of peripheral blood stem cells is inferior to the minimal cut-off in adult patients. Nevertheless, this minimal number of circulating CD34+ cells is insufficient to predict the success or failure of apheresis in patients younger than 6 years of age.

Peripheral blood stem cell mobilization with pegylated granulocyte colony stimulating factor in children

BACKGROUND AND AIM

We report here our experience of using pegylated granulocyte colony stimulating factor (peg-GCSF) for peripheral blood stem cell (PBSC) mobilization in children.

METHODS AND RESULTS

A total of nine children suffering from high-risk/relapsed solid tumors were mobilized with chemotherapy and peg-GCSF (100 microgram/kg single dose). Mean age was 7.7 years (range 2-15 years).The mean time from peg-GCSF administration to PBSC harvest was 9.7 days. Adequate stem cells (median dose 26.9 million/kg) could be harvested in all children by a single apheresis procedure. No major adverse events observed.

CONCLUSION

It is feasible and safe to mobilize PBSC with peg-GCSF in children with cancer.

Optimized peripheral blood progenitor cell mobilization for autologous hematopoietic cell transplantation in children with high-risk and refractory malignancies

BACKGROUND

Autologous hematopoietic stem cell transplantation (aHSCT) using hematopoietic progenitor cells (HPCs) has become an important therapeutic modality for patients with high-risk malignancies. Current literature on standardized method for HPC apheresis in children is sparse and failure rate reported as high as 30%.

PATIENTS/METHODS

A retrospective study of 125 pediatric patients with high-risk malignancies undergoing aHSCT in Western Australia between 1997 and 2016 was conducted.

RESULTS

Mobilization was achieved by means of chemotherapy and granulocyte colony-stimulating factor (G-CSF). Patients underwent apheresis the day after CD34⁺ counts reached ≥20/µL and an additional dose of G-CSF. Peripheral arterial and intravenous lines were inserted in pediatric intensive care unit under local anesthetic and/or sedation, omitting the need for general anesthesia as well as facilitating an uninterrupted apheresis flow. Larger apheresis total blood volumes were processed in patients weighing ≤20 kg. The minimal dose of ≥2 × 10⁶ CD34⁺ cells/kg was successfully collected in 98.4% of all patients. The optimal dose of 3-5 × 10⁶ CD34⁺ cells/kg was collected in 96% of patients scheduled for a single aHSCT, 87.5% for tandem, and 100% for triple aHSCT. All HPC collections were completed in one apheresis session. Mobilization after ≤3 chemotherapy cycles and cycles including cyclophosphamide resulted in a significantly higher yield of CD34⁺ cells.

CONCLUSION

Our approach to HPC mobilization by means of chemotherapy and single myeloid growth factor combined with optimal collection timing facilitated by continuous apheresis flow resulted in highly effective HPC harvest in children and adolescents with high-risk cancers.

Significant correlation between peripheral blood CD34+ cell count in children prior to aphaeresis and CD34+ cell yield following aphaeresis: A single-center experience

Numerous adults' studies demonstrated that preaphaeresis CD34+ cells significantly correlate with the number of CD34+ cells collected by the aphaeresis procedure. Equivalent studies in children are scarce. We studied retrospectively 92 aphaeresis procedures performed following chemotherapy (44) or in steady state (48) in 60 pediatric patients (40 males, 20 females), median age of 7.5 years. Aphaeresis procedures were performed using a SPECTRA Optica (TERUMOBCT) continuous flow cell separator. CD34+ cell concentrations were assessed using flow cytometry. A highly significant correlation between peripheral CD34 cell count on the day of aphaeresis and CD34 cell yield per kg (R²  = .824, P < .0001) was demonstrated. A higher preaphaeresis CD34 cell count was demonstrated in patients with higher preaphaeresis white blood cell count, in patients with brain tumors, and in patients who received chemotherapy as part of their mobilization protocol. A threshold number of 20 peripheral CD34+ cell/μL was found to predict harvesting of 3 × 10⁶ stem cells/kg, and 30 peripheral CD34+ cell/μL for harvesting of 5 × 10⁶ stem cells/kg. This significant correlation between peripheral CD34 cell count and CD34 cell yield, and the threshold number of peripheral CD34 found to predict adequate harvesting can be useful in planning the optimal time for aphaeresis in children.

Hematopoietic stem and progenitor cell harvesting: technical advances and clinical utility

Hematopoietic stem and progenitor cell (HSPC) transplantations require prior harvesting of allogeneic or autologous HSPCs. HSPCs are usually present in bone marrow (BM) during the entire life, in cord blood (CB) at birth, or in peripheral blood (PB) under particular circumstances. HSPCs were first harvested in BM and later in CB and PB, as studies showed interesting features of such grafts. All harvesting methods were in use throughout the years, except BM harvesting for HSPC autologous transplantation, which was replaced by PB harvesting. BM, CB, and PB harvesting methods have been developed, and materials and devices technically improved to increase the number of HSPCs harvested. In parallel, knowing the features of the donors or patients associated with successful numbers of HSPCs allows the adaptation of appropriate harvesting methods. Moreover, it is important to ensure the safety of donors or patients while harvesting. This review describes the methods used for harvesting based on recent studies or developments around these methods, and more particularly, the means developed to increase the numbers of HSPCs harvested in each method. It also explains briefly the influence of technical improvements in HSPC harvesting on potential changes in HSPC graft composition.